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autodoc.pl: varargs fcns require full 'Perl_foo'
[perl5.git] / pp_pack.c
index 9a7cc53..8ac5316 100644 (file)
--- a/pp_pack.c
+++ b/pp_pack.c
@@ -1,7 +1,7 @@
 /*    pp_pack.c
  *
- *    Copyright (C) 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999,
- *    2000, 2001, 2002, 2003, 2004, 2005, by Larry Wall and others
+ *    Copyright (C) 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000,
+ *    2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008 by Larry Wall and others
  *
  *    You may distribute under the terms of either the GNU General Public
  *    License or the Artistic License, as specified in the README file.
@@ -14,6 +14,8 @@
  * wooden spoon, a short two-pronged fork and some skewers were stowed; and
  * hidden at the bottom of the pack in a flat wooden box a dwindling treasure,
  * some salt.
+ *
+ *     [p.653 of _The Lord of the Rings_, IV/iv: "Of Herbs and Stewed Rabbit"]
  */
 
 /* This file contains pp ("push/pop") functions that
  * other pp*.c files for the rest of the pp_ functions.
  */
 
-
 #include "EXTERN.h"
 #define PERL_IN_PP_PACK_C
 #include "perl.h"
 
-#if PERL_VERSION >= 9
-# define PERL_PACK_CAN_BYTEORDER
-# define PERL_PACK_CAN_SHRIEKSIGN
+/* Types used by pack/unpack */ 
+typedef enum {
+  e_no_len,     /* no length  */
+  e_number,     /* number, [] */
+  e_star        /* asterisk   */
+} howlen_t;
+
+typedef struct tempsym {
+  const char*    patptr;   /* current template char */
+  const char*    patend;   /* one after last char   */
+  const char*    grpbeg;   /* 1st char of ()-group  */
+  const char*    grpend;   /* end of ()-group       */
+  I32      code;     /* template code (!<>)   */
+  U32      flags;    /* /=4, comma=2, pack=1  */
+                     /*   and group modifiers */
+  SSize_t  length;   /* length/repeat count   */
+  howlen_t howlen;   /* how length is given   */ 
+  int      level;    /* () nesting level      */
+  STRLEN   strbeg;   /* offset of group start */
+  struct tempsym *previous; /* previous group */
+} tempsym_t;
+
+#define TEMPSYM_INIT(symptr, p, e, f) \
+    STMT_START {       \
+       (symptr)->patptr   = (p);       \
+       (symptr)->patend   = (e);       \
+       (symptr)->grpbeg   = NULL;      \
+       (symptr)->grpend   = NULL;      \
+       (symptr)->grpend   = NULL;      \
+       (symptr)->code     = 0;         \
+       (symptr)->length   = 0;         \
+       (symptr)->howlen   = e_no_len;  \
+       (symptr)->level    = 0;         \
+       (symptr)->flags    = (f);       \
+       (symptr)->strbeg   = 0;         \
+       (symptr)->previous = NULL;      \
+   } STMT_END
+
+typedef union {
+    NV nv;
+    U8 bytes[sizeof(NV)];
+} NV_bytes;
+
+#if defined(HAS_LONG_DOUBLE) && defined(USE_LONG_DOUBLE)
+typedef union {
+    long double ld;
+    U8 bytes[sizeof(long double)];
+} ld_bytes;
 #endif
 
 #ifndef CHAR_BIT
 /* CROSSCOMPILE and MULTIARCH are going to affect pp_pack() and pp_unpack().
    --jhi Feb 1999 */
 
-#if U16SIZE > SIZE16 || U32SIZE > SIZE32
-#  if BYTEORDER == 0x1234 || BYTEORDER == 0x12345678    /* little-endian */
-#    define OFF16(p)   ((char*)(p))
-#    define OFF32(p)   ((char*)(p))
-#  else
-#    if BYTEORDER == 0x4321 || BYTEORDER == 0x87654321  /* big-endian */
-#      define OFF16(p) ((char*)(p) + (sizeof(U16) - SIZE16))
-#      define OFF32(p) ((char*)(p) + (sizeof(U32) - SIZE32))
-#    else
-       ++++ bad cray byte order
-#    endif
-#  endif
-#else
+#if U16SIZE <= SIZE16 && U32SIZE <= SIZE32
 #  define OFF16(p)     ((char *) (p))
 #  define OFF32(p)     ((char *) (p))
+#elif BYTEORDER == 0x1234 || BYTEORDER == 0x12345678    /* little-endian */
+#  define OFF16(p)     ((char*)(p))
+#  define OFF32(p)     ((char*)(p))
+#elif BYTEORDER == 0x4321 || BYTEORDER == 0x87654321  /* big-endian */
+#  define OFF16(p)     ((char*)(p) + (sizeof(U16) - SIZE16))
+#  define OFF32(p)     ((char*)(p) + (sizeof(U32) - SIZE32))
+#else
+#  error "bad cray byte order"
 #endif
 
-/* Only to be used inside a loop (see the break) */
-#define SHIFT16(utf8, s, strend, p, datumtype) STMT_START {            \
-    if (utf8) {                                                                \
-       if (!uni_to_bytes(aTHX_ &(s), strend, OFF16(p), SIZE16, datumtype)) break;      \
-    } else {                                                           \
-       Copy(s, OFF16(p), SIZE16, char);                                \
-       (s) += SIZE16;                                                  \
-    }                                                                  \
-} STMT_END
-
-/* Only to be used inside a loop (see the break) */
-#define SHIFT32(utf8, s, strend, p, datumtype) STMT_START {            \
-    if (utf8) {                                                                \
-       if (!uni_to_bytes(aTHX_ &(s), strend, OFF32(p), SIZE32, datumtype)) break;      \
-    } else {                                                           \
-       Copy(s, OFF32(p), SIZE32, char);                                \
-       (s) += SIZE32;                                                  \
-    }                                                                  \
-} STMT_END
+#define PUSH16(utf8, cur, p, needs_swap)                        \
+       PUSH_BYTES(utf8, cur, OFF16(p), SIZE16, needs_swap)
+#define PUSH32(utf8, cur, p, needs_swap)                        \
+       PUSH_BYTES(utf8, cur, OFF32(p), SIZE32, needs_swap)
 
-#define PUSH16(utf8, cur, p) PUSH_BYTES(utf8, cur, OFF16(p), SIZE16)
-#define PUSH32(utf8, cur, p) PUSH_BYTES(utf8, cur, OFF32(p), SIZE32)
+#if BYTEORDER == 0x4321 || BYTEORDER == 0x87654321  /* big-endian */
+#  define NEEDS_SWAP(d)     (TYPE_ENDIANNESS(d) == TYPE_IS_LITTLE_ENDIAN)
+#elif BYTEORDER == 0x1234 || BYTEORDER == 0x12345678  /* little-endian */
+#  define NEEDS_SWAP(d)     (TYPE_ENDIANNESS(d) == TYPE_IS_BIG_ENDIAN)
+#else
+#  error "Unsupported byteorder"
+        /* Need to add code here to re-instate mixed endian support.
+           NEEDS_SWAP would need to hold a flag indicating which action to
+           take, and S_reverse_copy and the code in S_utf8_to_bytes would need
+           logic adding to deal with any mixed-endian transformations needed.
+        */
+#endif
 
 /* Only to be used inside a loop (see the break) */
-#define SHIFT_VAR(utf8, s, strend, var, datumtype)     \
+#define SHIFT_BYTES(utf8, s, strend, buf, len, datumtype, needs_swap)  \
 STMT_START {                                           \
-    if (utf8) {                                                \
-        if (!uni_to_bytes(aTHX_ &s, strend,            \
-            (char *) &var, sizeof(var), datumtype)) break;\
+    if (UNLIKELY(utf8)) {                               \
+        if (!S_utf8_to_bytes(aTHX_ &s, strend,         \
+         (char *) (buf), len, datumtype)) break;       \
     } else {                                           \
-        Copy(s, (char *) &var, sizeof(var), char);     \
-        s += sizeof(var);                              \
+        if (UNLIKELY(needs_swap))                       \
+            S_reverse_copy(s, (char *) (buf), len);     \
+        else                                            \
+            Copy(s, (char *) (buf), len, char);                \
+        s += len;                                      \
     }                                                  \
 } STMT_END
 
-#define PUSH_VAR(utf8, aptr, var)      \
-       PUSH_BYTES(utf8, aptr, &(var), sizeof(var))
+#define SHIFT16(utf8, s, strend, p, datumtype, needs_swap)              \
+       SHIFT_BYTES(utf8, s, strend, OFF16(p), SIZE16, datumtype, needs_swap)
+
+#define SHIFT32(utf8, s, strend, p, datumtype, needs_swap)              \
+       SHIFT_BYTES(utf8, s, strend, OFF32(p), SIZE32, datumtype, needs_swap)
+
+#define SHIFT_VAR(utf8, s, strend, var, datumtype, needs_swap)          \
+       SHIFT_BYTES(utf8, s, strend, &(var), sizeof(var), datumtype, needs_swap)
+
+#define PUSH_VAR(utf8, aptr, var, needs_swap)           \
+       PUSH_BYTES(utf8, aptr, &(var), sizeof(var), needs_swap)
 
 /* Avoid stack overflow due to pathological templates. 100 should be plenty. */
 #define MAX_SUB_TEMPLATE_LEVEL 100
@@ -139,10 +188,11 @@ S_mul128(pTHX_ SV *sv, U8 m)
   STRLEN          len;
   char           *s = SvPV(sv, len);
   char           *t;
-  U32             i = 0;
 
-  if (!strnEQ(s, "0000", 4)) {  /* need to grow sv */
-    SV             *tmpNew = newSVpvn("0000000000", 10);
+  PERL_ARGS_ASSERT_MUL128;
+
+  if (! memBEGINs(s, len, "0000")) {  /* need to grow sv */
+    SV * const tmpNew = newSVpvs("0000000000");
 
     sv_catsv(tmpNew, sv);
     SvREFCNT_dec(sv);          /* free old sv */
@@ -153,7 +203,7 @@ S_mul128(pTHX_ SV *sv, U8 m)
   while (!*t)                   /* trailing '\0'? */
     t--;
   while (t > s) {
-    i = ((*t - '0') << 7) + m;
+    const U32 i = ((*t - '0') << 7) + m;
     *(t--) = '0' + (char)(i % 10);
     m = (char)(i / 10);
   }
@@ -162,16 +212,9 @@ S_mul128(pTHX_ SV *sv, U8 m)
 
 /* Explosives and implosives. */
 
-#if 'I' == 73 && 'J' == 74
-/* On an ASCII/ISO kind of system */
-#define ISUUCHAR(ch)    ((ch) >= ' ' && (ch) < 'a')
-#else
-/*
-  Some other sort of character set - use memchr() so we don't match
-  the null byte.
- */
-#define ISUUCHAR(ch)    (memchr(PL_uuemap, (ch), sizeof(PL_uuemap)-1) || (ch) == ' ')
-#endif
+#define ISUUCHAR(ch)    inRANGE(NATIVE_TO_LATIN1(ch),               \
+                                NATIVE_TO_LATIN1(' '),              \
+                                NATIVE_TO_LATIN1('a') - 1)
 
 /* type modifiers */
 #define TYPE_IS_SHRIEKING      0x100
@@ -182,410 +225,44 @@ S_mul128(pTHX_ SV *sv, U8 m)
 #define TYPE_MODIFIERS(t)      ((t) & ~0xFF)
 #define TYPE_NO_MODIFIERS(t)   ((t) & 0xFF)
 
-#ifdef PERL_PACK_CAN_SHRIEKSIGN
-# define SHRIEKING_ALLOWED_TYPES "sSiIlLxXnNvV@."
-#else
-# define SHRIEKING_ALLOWED_TYPES "sSiIlLxX"
-#endif
-
-#ifndef PERL_PACK_CAN_BYTEORDER
-/* Put "can't" first because it is shorter  */
-# define TYPE_ENDIANNESS(t)    0
-# define TYPE_NO_ENDIANNESS(t) (t)
-
-# define ENDIANNESS_ALLOWED_TYPES   ""
-
-# define DO_BO_UNPACK(var, type)
-# define DO_BO_PACK(var, type)
-# define DO_BO_UNPACK_PTR(var, type, pre_cast, post_cast)
-# define DO_BO_PACK_PTR(var, type, pre_cast, post_cast)
-# define DO_BO_UNPACK_N(var, type)
-# define DO_BO_PACK_N(var, type)
-# define DO_BO_UNPACK_P(var)
-# define DO_BO_PACK_P(var)
-
-#else /* PERL_PACK_CAN_BYTEORDER */
-
 # define TYPE_ENDIANNESS(t)    ((t) & TYPE_ENDIANNESS_MASK)
 # define TYPE_NO_ENDIANNESS(t) ((t) & ~TYPE_ENDIANNESS_MASK)
 
 # define ENDIANNESS_ALLOWED_TYPES   "sSiIlLqQjJfFdDpP("
 
-# define DO_BO_UNPACK(var, type)                                              \
-        STMT_START {                                                          \
-          switch (TYPE_ENDIANNESS(datumtype)) {                               \
-            case TYPE_IS_BIG_ENDIAN:    var = my_betoh ## type (var); break;  \
-            case TYPE_IS_LITTLE_ENDIAN: var = my_letoh ## type (var); break;  \
-            default: break;                                                   \
-          }                                                                   \
-        } STMT_END
-
-# define DO_BO_PACK(var, type)                                                \
-        STMT_START {                                                          \
-          switch (TYPE_ENDIANNESS(datumtype)) {                               \
-            case TYPE_IS_BIG_ENDIAN:    var = my_htobe ## type (var); break;  \
-            case TYPE_IS_LITTLE_ENDIAN: var = my_htole ## type (var); break;  \
-            default: break;                                                   \
-          }                                                                   \
-        } STMT_END
-
-# define DO_BO_UNPACK_PTR(var, type, pre_cast, post_cast)                     \
-        STMT_START {                                                          \
-          switch (TYPE_ENDIANNESS(datumtype)) {                               \
-            case TYPE_IS_BIG_ENDIAN:                                          \
-              var = (post_cast*) my_betoh ## type ((pre_cast) var);           \
-              break;                                                          \
-            case TYPE_IS_LITTLE_ENDIAN:                                       \
-              var = (post_cast *) my_letoh ## type ((pre_cast) var);          \
-              break;                                                          \
-            default:                                                          \
-              break;                                                          \
-          }                                                                   \
-        } STMT_END
-
-# define DO_BO_PACK_PTR(var, type, pre_cast, post_cast)                       \
-        STMT_START {                                                          \
-          switch (TYPE_ENDIANNESS(datumtype)) {                               \
-            case TYPE_IS_BIG_ENDIAN:                                          \
-              var = (post_cast *) my_htobe ## type ((pre_cast) var);          \
-              break;                                                          \
-            case TYPE_IS_LITTLE_ENDIAN:                                       \
-              var = (post_cast *) my_htole ## type ((pre_cast) var);          \
-              break;                                                          \
-            default:                                                          \
-              break;                                                          \
-          }                                                                   \
-        } STMT_END
-
-# define BO_CANT_DOIT(action, type)                                           \
-        STMT_START {                                                          \
-          switch (TYPE_ENDIANNESS(datumtype)) {                               \
-             case TYPE_IS_BIG_ENDIAN:                                         \
-               Perl_croak(aTHX_ "Can't %s big-endian %ss on this "            \
-                                "platform", #action, #type);                  \
-               break;                                                         \
-             case TYPE_IS_LITTLE_ENDIAN:                                      \
-               Perl_croak(aTHX_ "Can't %s little-endian %ss on this "         \
-                                "platform", #action, #type);                  \
-               break;                                                         \
-             default:                                                         \
-               break;                                                         \
-           }                                                                  \
-         } STMT_END
-
-# if PTRSIZE == INTSIZE
-#  define DO_BO_UNPACK_P(var)  DO_BO_UNPACK_PTR(var, i, int, void)
-#  define DO_BO_PACK_P(var)    DO_BO_PACK_PTR(var, i, int, void)
-#  define DO_BO_UNPACK_PC(var) DO_BO_UNPACK_PTR(var, i, int, char)
-#  define DO_BO_PACK_PC(var)   DO_BO_PACK_PTR(var, i, int, char)
-# elif PTRSIZE == LONGSIZE
-#  define DO_BO_UNPACK_P(var)  DO_BO_UNPACK_PTR(var, l, long, void)
-#  define DO_BO_PACK_P(var)    DO_BO_PACK_PTR(var, l, long, void)
-#  define DO_BO_UNPACK_PC(var) DO_BO_UNPACK_PTR(var, l, long, char)
-#  define DO_BO_PACK_PC(var)   DO_BO_PACK_PTR(var, l, long, char)
-# else
-#  define DO_BO_UNPACK_P(var)  BO_CANT_DOIT(unpack, pointer)
-#  define DO_BO_PACK_P(var)    BO_CANT_DOIT(pack, pointer)
-# endif
-
-# if defined(my_htolen) && defined(my_letohn) && \
-    defined(my_htoben) && defined(my_betohn)
-#  define DO_BO_UNPACK_N(var, type)                                           \
-         STMT_START {                                                         \
-           switch (TYPE_ENDIANNESS(datumtype)) {                              \
-             case TYPE_IS_BIG_ENDIAN:    my_betohn(&var, sizeof(type)); break;\
-             case TYPE_IS_LITTLE_ENDIAN: my_letohn(&var, sizeof(type)); break;\
-             default: break;                                                  \
-           }                                                                  \
-         } STMT_END
-
-#  define DO_BO_PACK_N(var, type)                                             \
-         STMT_START {                                                         \
-           switch (TYPE_ENDIANNESS(datumtype)) {                              \
-             case TYPE_IS_BIG_ENDIAN:    my_htoben(&var, sizeof(type)); break;\
-             case TYPE_IS_LITTLE_ENDIAN: my_htolen(&var, sizeof(type)); break;\
-             default: break;                                                  \
-           }                                                                  \
-         } STMT_END
-# else
-#  define DO_BO_UNPACK_N(var, type)    BO_CANT_DOIT(unpack, type)
-#  define DO_BO_PACK_N(var, type)      BO_CANT_DOIT(pack, type)
-# endif
-
-#endif /* PERL_PACK_CAN_BYTEORDER */
-
 #define PACK_SIZE_CANNOT_CSUM          0x80
 #define PACK_SIZE_UNPREDICTABLE                0x40    /* Not a fixed size element */
 #define PACK_SIZE_MASK                 0x3F
 
-/* These tables are regenerated by genpacksizetables.pl (and then hand pasted
-   in).  You're unlikely ever to need to regenerate them.  */
-
-#if TYPE_IS_SHRIEKING != 0x100
-   ++++shriek offset should be 256
-#endif
+#include "packsizetables.inc"
 
-typedef U8 packprops_t;
-#if 'J'-'I' == 1
-/* ASCII */
-const packprops_t packprops[512] = {
-    /* normal */
-    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-    0, 0, 0,
-    /* C */ sizeof(unsigned char) | PACK_SIZE_UNPREDICTABLE,
-#if defined(HAS_LONG_DOUBLE) && defined(USE_LONG_DOUBLE)
-    /* D */ LONG_DOUBLESIZE,
-#else
-    0,
-#endif
-    0,
-    /* F */ NVSIZE,
-    0, 0,
-    /* I */ sizeof(unsigned int),
-    /* J */ UVSIZE,
-    0,
-    /* L */ SIZE32,
-    0,
-    /* N */ SIZE32,
-    0, 0,
-#if defined(HAS_QUAD)
-    /* Q */ sizeof(Uquad_t),
-#else
-    0,
-#endif
-    0,
-    /* S */ SIZE16,
-    0,
-    /* U */ sizeof(char) | PACK_SIZE_UNPREDICTABLE,
-    /* V */ SIZE32,
-    /* W */ sizeof(unsigned char) | PACK_SIZE_UNPREDICTABLE,
-    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-    /* c */ sizeof(char),
-    /* d */ sizeof(double),
-    0,
-    /* f */ sizeof(float),
-    0, 0,
-    /* i */ sizeof(int),
-    /* j */ IVSIZE,
-    0,
-    /* l */ SIZE32,
-    0,
-    /* n */ SIZE16,
-    0,
-    /* p */ sizeof(char *) | PACK_SIZE_CANNOT_CSUM,
-#if defined(HAS_QUAD)
-    /* q */ sizeof(Quad_t),
-#else
-    0,
-#endif
-    0,
-    /* s */ SIZE16,
-    0, 0,
-    /* v */ SIZE16,
-    /* w */ sizeof(char) | PACK_SIZE_UNPREDICTABLE | PACK_SIZE_CANNOT_CSUM,
-    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-    0, 0, 0, 0, 0, 0, 0, 0,
-    /* shrieking */
-    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-    0, 0, 0, 0, 0, 0, 0, 0, 0,
-    /* I */ sizeof(unsigned int),
-    0, 0,
-    /* L */ sizeof(unsigned long),
-    0,
-#if defined(PERL_PACK_CAN_SHRIEKSIGN)
-    /* N */ SIZE32,
-#else
-    0,
-#endif
-    0, 0, 0, 0,
-    /* S */ sizeof(unsigned short),
-    0, 0,
-#if defined(PERL_PACK_CAN_SHRIEKSIGN)
-    /* V */ SIZE32,
-#else
-    0,
-#endif
-    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-    0, 0,
-    /* i */ sizeof(int),
-    0, 0,
-    /* l */ sizeof(long),
-    0,
-#if defined(PERL_PACK_CAN_SHRIEKSIGN)
-    /* n */ SIZE16,
-#else
-    0,
-#endif
-    0, 0, 0, 0,
-    /* s */ sizeof(short),
-    0, 0,
-#if defined(PERL_PACK_CAN_SHRIEKSIGN)
-    /* v */ SIZE16,
-#else
-    0,
-#endif
-    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-    0, 0, 0, 0, 0, 0, 0, 0, 0
-};
-#else
-/* EBCDIC (or bust) */
-const packprops_t packprops[512] = {
-    /* normal */
-    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-    0, 0, 0,
-    /* c */ sizeof(char),
-    /* d */ sizeof(double),
-    0,
-    /* f */ sizeof(float),
-    0, 0,
-    /* i */ sizeof(int),
-    0, 0, 0, 0, 0, 0, 0,
-    /* j */ IVSIZE,
-    0,
-    /* l */ SIZE32,
-    0,
-    /* n */ SIZE16,
-    0,
-    /* p */ sizeof(char *) | PACK_SIZE_CANNOT_CSUM,
-#if defined(HAS_QUAD)
-    /* q */ sizeof(Quad_t),
-#else
-    0,
-#endif
-    0, 0, 0, 0, 0, 0, 0, 0, 0,
-    /* s */ SIZE16,
-    0, 0,
-    /* v */ SIZE16,
-    /* w */ sizeof(char) | PACK_SIZE_UNPREDICTABLE | PACK_SIZE_CANNOT_CSUM,
-    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-    /* C */ sizeof(unsigned char) | PACK_SIZE_UNPREDICTABLE,
-#if defined(HAS_LONG_DOUBLE) && defined(USE_LONG_DOUBLE)
-    /* D */ LONG_DOUBLESIZE,
-#else
-    0,
-#endif
-    0,
-    /* F */ NVSIZE,
-    0, 0,
-    /* I */ sizeof(unsigned int),
-    0, 0, 0, 0, 0, 0, 0,
-    /* J */ UVSIZE,
-    0,
-    /* L */ SIZE32,
-    0,
-    /* N */ SIZE32,
-    0, 0,
-#if defined(HAS_QUAD)
-    /* Q */ sizeof(Uquad_t),
-#else
-    0,
-#endif
-    0, 0, 0, 0, 0, 0, 0, 0, 0,
-    /* S */ SIZE16,
-    0,
-    /* U */ sizeof(char) | PACK_SIZE_UNPREDICTABLE,
-    /* V */ SIZE32,
-    /* W */ sizeof(unsigned char) | PACK_SIZE_UNPREDICTABLE,
-    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-    0, 0, 0, 0, 0, 0, 0, 0, 0,
-    /* shrieking */
-    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-    0, 0, 0, 0, 0, 0, 0, 0, 0,
-    /* i */ sizeof(int),
-    0, 0, 0, 0, 0, 0, 0, 0, 0,
-    /* l */ sizeof(long),
-    0,
-#if defined(PERL_PACK_CAN_SHRIEKSIGN)
-    /* n */ SIZE16,
-#else
-    0,
-#endif
-    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-    /* s */ sizeof(short),
-    0, 0,
-#if defined(PERL_PACK_CAN_SHRIEKSIGN)
-    /* v */ SIZE16,
-#else
-    0,
-#endif
-    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-    0, 0, 0,
-    /* I */ sizeof(unsigned int),
-    0, 0, 0, 0, 0, 0, 0, 0, 0,
-    /* L */ sizeof(unsigned long),
-    0,
-#if defined(PERL_PACK_CAN_SHRIEKSIGN)
-    /* N */ SIZE32,
-#else
-    0,
-#endif
-    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-    /* S */ sizeof(unsigned short),
-    0, 0,
-#if defined(PERL_PACK_CAN_SHRIEKSIGN)
-    /* V */ SIZE32,
-#else
-    0,
-#endif
-    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-    0, 0, 0, 0, 0, 0, 0, 0, 0, 0
-};
-#endif
+static void
+S_reverse_copy(const char *src, char *dest, STRLEN len)
+{
+    dest += len;
+    while (len--)
+        *--dest = *src++;
+}
 
 STATIC U8
-uni_to_byte(pTHX_ char **s, const char *end, I32 datumtype)
+utf8_to_byte(pTHX_ const char **s, const char *end, I32 datumtype)
 {
-    UV val;
     STRLEN retlen;
+    UV val;
+
+    if (*s >= end) {
+       goto croak;
+    }
     val = utf8n_to_uvchr((U8 *) *s, end-*s, &retlen,
                         ckWARN(WARN_UTF8) ? 0 : UTF8_ALLOW_ANY);
-    /* We try to process malformed UTF-8 as much as possible (preferrably with
-       warnings), but these two mean we make no progress in the string and
-       might enter an infinite loop */
-    if (retlen == (STRLEN) -1 || retlen == 0)
+    if (retlen == (STRLEN) -1)
+      croak:
        Perl_croak(aTHX_ "Malformed UTF-8 string in '%c' format in unpack",
                   (int) TYPE_NO_MODIFIERS(datumtype));
     if (val >= 0x100) {
-       if (ckWARN(WARN_UNPACK))
-       Perl_warner(aTHX_ packWARN(WARN_UNPACK),
-                   "Character in '%c' format wrapped in unpack",
-                   (int) TYPE_NO_MODIFIERS(datumtype));
+       Perl_ck_warner(aTHX_ packWARN(WARN_UNPACK),
+                      "Character in '%c' format wrapped in unpack",
+                      (int) TYPE_NO_MODIFIERS(datumtype));
        val &= 0xff;
     }
     *s += retlen;
@@ -593,133 +270,140 @@ uni_to_byte(pTHX_ char **s, const char *end, I32 datumtype)
 }
 
 #define SHIFT_BYTE(utf8, s, strend, datumtype) ((utf8) ? \
-       uni_to_byte(aTHX_ &(s), (strend), (datumtype)) : \
+       utf8_to_byte(aTHX_ &(s), (strend), (datumtype)) : \
        *(U8 *)(s)++)
 
 STATIC bool
-uni_to_bytes(pTHX_ char **s, char *end, char *buf, int buf_len, I32 datumtype)
+S_utf8_to_bytes(pTHX_ const char **s, const char *end, const char *buf, SSize_t buf_len, I32 datumtype)
 {
     UV val;
     STRLEN retlen;
-    char *from = *s;
+    const char *from = *s;
     int bad = 0;
-    U32 flags = ckWARN(WARN_UTF8) ?
+    const U32 flags = ckWARN(WARN_UTF8) ?
        UTF8_CHECK_ONLY : (UTF8_CHECK_ONLY | UTF8_ALLOW_ANY);
+    const bool needs_swap = NEEDS_SWAP(datumtype);
+
+    if (UNLIKELY(needs_swap))
+        buf += buf_len;
+
     for (;buf_len > 0; buf_len--) {
        if (from >= end) return FALSE;
        val = utf8n_to_uvchr((U8 *) from, end-from, &retlen, flags);
-       if (retlen == (STRLEN) -1 || retlen == 0) {
-           from += UTF8SKIP(from);
+       if (retlen == (STRLEN) -1) {
+           from += UTF8_SAFE_SKIP(from, end);
            bad |= 1;
        } else from += retlen;
        if (val >= 0x100) {
            bad |= 2;
            val &= 0xff;
        }
-       *(U8 *)buf++ = (U8)val;
+        if (UNLIKELY(needs_swap))
+            *(U8 *)--buf = (U8)val;
+        else
+            *(U8 *)buf++ = (U8)val;
     }
     /* We have enough characters for the buffer. Did we have problems ? */
     if (bad) {
        if (bad & 1) {
            /* Rewalk the string fragment while warning */
-           char *ptr;
-           flags = ckWARN(WARN_UTF8) ? 0 : UTF8_ALLOW_ANY;
+           const char *ptr;
+           const U32 flags = ckWARN(WARN_UTF8) ? 0 : UTF8_ALLOW_ANY;
            for (ptr = *s; ptr < from; ptr += UTF8SKIP(ptr)) {
                if (ptr >= end) break;
-               utf8n_to_uvuni((U8 *) ptr, end-ptr, &retlen, flags);
+               utf8n_to_uvchr((U8 *) ptr, end-ptr, &retlen, flags);
            }
            if (from > end) from = end;
        }
-       if ((bad & 2) && ckWARN(WARN_UNPACK))
-           Perl_warner(aTHX_ packWARN(datumtype & TYPE_IS_PACK ?
+       if ((bad & 2))
+           Perl_ck_warner(aTHX_ packWARN(datumtype & TYPE_IS_PACK ?
                                       WARN_PACK : WARN_UNPACK),
-                       "Character(s) in '%c' format wrapped in %s",
-                       (int) TYPE_NO_MODIFIERS(datumtype),
-                       datumtype & TYPE_IS_PACK ? "pack" : "unpack");
+                          "Character(s) in '%c' format wrapped in %s",
+                          (int) TYPE_NO_MODIFIERS(datumtype),
+                          datumtype & TYPE_IS_PACK ? "pack" : "unpack");
     }
     *s = from;
     return TRUE;
 }
 
-STATIC bool
-next_uni_uu(pTHX_ char **s, const char *end, I32 *out)
-{
-    UV val;
-    STRLEN retlen;
-    val = utf8n_to_uvchr((U8 *) *s, end-*s, &retlen, UTF8_CHECK_ONLY);
-    if (val >= 0x100 || !ISUUCHAR(val) ||
-       retlen == (STRLEN) -1 || retlen == 0) {
-       *out = 0;
-       return FALSE;
-    }
-    *out = PL_uudmap[val] & 077;
-    *s += retlen;
-    return TRUE;
-}
+STATIC char *
+S_my_bytes_to_utf8(const U8 *start, STRLEN len, char *dest, const bool needs_swap) {
+    PERL_ARGS_ASSERT_MY_BYTES_TO_UTF8;
 
-STATIC void
-bytes_to_uni(pTHX_ U8 *start, STRLEN len, char **dest) {
-    U8 buffer[UTF8_MAXLEN];
-    U8 *end = start + len;
-    char *d = *dest;
-    while (start < end) {
-       int length =
-           uvuni_to_utf8_flags(buffer, NATIVE_TO_UNI(*start), 0) - buffer;
-       switch(length) {
-         case 1:
-           *d++ = buffer[0];
-           break;
-         case 2:
-           *d++ = buffer[0];
-           *d++ = buffer[1];
-           break;
-         default:
-           Perl_croak(aTHX_ "Perl bug: value %d UTF-8 expands to %d bytes",
-                      *start, length);
-       }
-       start++;
+    if (UNLIKELY(needs_swap)) {
+        const U8 *p = start + len;
+        while (p-- > start) {
+            append_utf8_from_native_byte(*p, (U8 **) & dest);
+        }
+    } else {
+        const U8 * const end = start + len;
+        while (start < end) {
+            append_utf8_from_native_byte(*start, (U8 **) & dest);
+            start++;
+        }
     }
-    *dest = d;
+    return dest;
 }
 
-#define PUSH_BYTES(utf8, cur, buf, len)                                \
+#define PUSH_BYTES(utf8, cur, buf, len, needs_swap)             \
 STMT_START {                                                   \
-    if (utf8) bytes_to_uni(aTHX_ (U8 *) buf, len, &(cur));     \
+    if (UNLIKELY(utf8))                                                \
+       (cur) = my_bytes_to_utf8((U8 *) buf, len, (cur), needs_swap);       \
     else {                                                     \
-       Copy(buf, cur, len, char);                              \
+        if (UNLIKELY(needs_swap))                               \
+            S_reverse_copy((char *)(buf), cur, len);            \
+        else                                                    \
+            Copy(buf, cur, len, char);                         \
        (cur) += (len);                                         \
     }                                                          \
 } STMT_END
 
+#define SAFE_UTF8_EXPAND(var)  \
+STMT_START {                           \
+    if ((var) > SSize_t_MAX / UTF8_EXPAND) \
+        Perl_croak(aTHX_ "%s", "Out of memory during pack()"); \
+    (var) = (var) * UTF8_EXPAND; \
+} STMT_END
+
+#define GROWING2(utf8, cat, start, cur, item_size, item_count) \
+STMT_START {                                                   \
+    if (SSize_t_MAX / (item_size) < (item_count))              \
+        Perl_croak(aTHX_ "%s", "Out of memory during pack()"); \
+    GROWING((utf8), (cat), (start), (cur), (item_size) * (item_count)); \
+} STMT_END
+
 #define GROWING(utf8, cat, start, cur, in_len) \
 STMT_START {                                   \
     STRLEN glen = (in_len);                    \
-    if (utf8) glen *= UTF8_EXPAND;             \
-    if ((cur) + glen >= (start) + SvLEN(cat)) {        \
-       (start) = sv_exp_grow(aTHX_ cat, glen); \
+    STRLEN catcur = (STRLEN)((cur) - (start)); \
+    if (utf8) SAFE_UTF8_EXPAND(glen);          \
+    if (SSize_t_MAX - glen < catcur)           \
+        Perl_croak(aTHX_ "%s", "Out of memory during pack()"); \
+    if (catcur + glen >= SvLEN(cat)) { \
+       (start) = sv_exp_grow(cat, glen);       \
        (cur) = (start) + SvCUR(cat);           \
     }                                          \
 } STMT_END
 
 #define PUSH_GROWING_BYTES(utf8, cat, start, cur, buf, in_len) \
 STMT_START {                                   \
-    STRLEN glen = (in_len);                    \
+    const STRLEN glen = (in_len);              \
     STRLEN gl = glen;                          \
-    if (utf8) gl *= UTF8_EXPAND;               \
+    if (utf8) SAFE_UTF8_EXPAND(gl);            \
     if ((cur) + gl >= (start) + SvLEN(cat)) {  \
         *cur = '\0';                           \
         SvCUR_set((cat), (cur) - (start));     \
-       (start) = sv_exp_grow(aTHX_ cat, gl);   \
+       (start) = sv_exp_grow(cat, gl);         \
        (cur) = (start) + SvCUR(cat);           \
     }                                          \
-    PUSH_BYTES(utf8, cur, buf, glen);          \
+    PUSH_BYTES(utf8, cur, buf, glen, 0);        \
 } STMT_END
 
 #define PUSH_BYTE(utf8, s, byte)               \
 STMT_START {                                   \
     if (utf8) {                                        \
-       U8 au8 = (byte);                        \
-       bytes_to_uni(aTHX_ &au8, 1, &(s));      \
+       const U8 au8 = (byte);                  \
+       (s) = my_bytes_to_utf8(&au8, 1, (s), 0);\
     } else *(U8 *)(s)++ = (byte);              \
 } STMT_END
 
@@ -729,28 +413,34 @@ STMT_START {                                                      \
     STRLEN retlen;                                             \
     if (str >= end) break;                                     \
     val = utf8n_to_uvchr((U8 *) str, end-str, &retlen, utf8_flags);    \
-    if (retlen == (STRLEN) -1 || retlen == 0) {                        \
+    if (retlen == (STRLEN) -1) {                               \
        *cur = '\0';                                            \
        Perl_croak(aTHX_ "Malformed UTF-8 string in pack");     \
     }                                                          \
     str += retlen;                                             \
 } STMT_END
 
+static const char *_action( const tempsym_t* symptr )
+{
+    return (const char *)(( symptr->flags & FLAG_PACK ) ? "pack" : "unpack");
+}
+
 /* Returns the sizeof() struct described by pat */
-STATIC I32
+STATIC SSize_t
 S_measure_struct(pTHX_ tempsym_t* symptr)
 {
-    I32 total = 0;
+    SSize_t total = 0;
+
+    PERL_ARGS_ASSERT_MEASURE_STRUCT;
 
     while (next_symbol(symptr)) {
-       I32 len;
-       int star, size;
+       SSize_t len, size;
 
         switch (symptr->howlen) {
          case e_star:
            Perl_croak(aTHX_ "Within []-length '*' not allowed in %s",
-                       symptr->flags & FLAG_PACK ? "pack" : "unpack" );
-            break;
+                        _action( symptr ) );
+
          default:
            /* e_no_len and e_number */
            len = symptr->length;
@@ -759,16 +449,15 @@ S_measure_struct(pTHX_ tempsym_t* symptr)
 
        size = packprops[TYPE_NO_ENDIANNESS(symptr->code)] & PACK_SIZE_MASK;
        if (!size) {
+            SSize_t star;
            /* endianness doesn't influence the size of a type */
            switch(TYPE_NO_ENDIANNESS(symptr->code)) {
            default:
                Perl_croak(aTHX_ "Invalid type '%c' in %s",
                           (int)TYPE_NO_MODIFIERS(symptr->code),
-                          symptr->flags & FLAG_PACK ? "pack" : "unpack" );
-#ifdef PERL_PACK_CAN_SHRIEKSIGN
+                           _action( symptr ) );
            case '.' | TYPE_IS_SHRIEKING:
            case '@' | TYPE_IS_SHRIEKING:
-#endif
            case '@':
            case '.':
            case '/':
@@ -777,7 +466,7 @@ S_measure_struct(pTHX_ tempsym_t* symptr)
            case 'u':
                Perl_croak(aTHX_ "Within []-length '%c' not allowed in %s",
                           (int) TYPE_NO_MODIFIERS(symptr->code),
-                          symptr->flags & FLAG_PACK ? "pack" : "unpack" );
+                           _action( symptr ) );
            case '%':
                size = 0;
                break;
@@ -800,12 +489,11 @@ S_measure_struct(pTHX_ tempsym_t* symptr)
                if (!len)               /* Avoid division by 0 */
                    len = 1;
                len = total % len;      /* Assumed: the start is aligned. */
-               /* FALL THROUGH */
+               /* FALLTHROUGH */
            case 'X':
                size = -1;
                if (total < len)
-                   Perl_croak(aTHX_ "'X' outside of string in %s",
-                              symptr->flags & FLAG_PACK ? "pack" : "unpack" );
+                    Perl_croak(aTHX_ "'X' outside of string in %s", _action( symptr ) );
                break;
            case 'x' | TYPE_IS_SHRIEKING:
                if (!len)               /* Avoid division by 0 */
@@ -815,7 +503,7 @@ S_measure_struct(pTHX_ tempsym_t* symptr)
                    len = len - star;
                else
                    len = 0;
-               /* FALL THROUGH */
+               /* FALLTHROUGH */
            case 'x':
            case 'A':
            case 'Z':
@@ -848,11 +536,13 @@ S_measure_struct(pTHX_ tempsym_t* symptr)
 /* locate matching closing parenthesis or bracket
  * returns char pointer to char after match, or NULL
  */
-STATIC char *
-S_group_end(pTHX_ register char *patptr, register char *patend, char ender)
+STATIC const char *
+S_group_end(pTHX_ const char *patptr, const char *patend, char ender)
 {
+    PERL_ARGS_ASSERT_GROUP_END;
+
     while (patptr < patend) {
-       char c = *patptr++;
+       const char c = *patptr++;
 
        if (isSPACE(c))
            continue;
@@ -869,7 +559,7 @@ S_group_end(pTHX_ register char *patptr, register char *patend, char ender)
     }
     Perl_croak(aTHX_ "No group ending character '%c' found in template",
                ender);
-    return 0;
+    NOT_REACHED; /* NOTREACHED */
 }
 
 
@@ -877,14 +567,18 @@ S_group_end(pTHX_ register char *patptr, register char *patend, char ender)
  * Expects a pointer to the first digit and address of length variable
  * Advances char pointer to 1st non-digit char and returns number
  */
-STATIC char *
-S_get_num(pTHX_ register char *patptr, I32 *lenptr )
+STATIC const char *
+S_get_num(pTHX_ const char *patptr, SSize_t *lenptr )
 {
-  I32 len = *patptr++ - '0';
+  SSize_t len = *patptr++ - '0';
+
+  PERL_ARGS_ASSERT_GET_NUM;
+
   while (isDIGIT(*patptr)) {
-    if (len >= 0x7FFFFFFF/10)
+    SSize_t nlen = (len * 10) + (*patptr++ - '0');
+    if (nlen < 0 || nlen/10 != len)
       Perl_croak(aTHX_ "pack/unpack repeat count overflow");
-    len = (len * 10) + (*patptr++ - '0');
+    len = nlen;
   }
   *lenptr = len;
   return patptr;
@@ -896,9 +590,10 @@ S_get_num(pTHX_ register char *patptr, I32 *lenptr )
 STATIC bool
 S_next_symbol(pTHX_ tempsym_t* symptr )
 {
-  char* patptr = symptr->patptr;
-  char* patend = symptr->patend;
-  const char *allowed = "";
+  const char* patptr = symptr->patptr;
+  const char* const patend = symptr->patend;
+
+  PERL_ARGS_ASSERT_NEXT_SYMBOL;
 
   symptr->flags &= ~FLAG_SLASH;
 
@@ -920,8 +615,7 @@ S_next_symbol(pTHX_ tempsym_t* symptr )
        if (((symptr->flags & FLAG_COMMA) == 0) && ckWARN(WARN_UNPACK)){
           symptr->flags |= FLAG_COMMA;
          Perl_warner(aTHX_ packWARN(WARN_UNPACK),
-                     "Invalid type ',' in %s",
-                      symptr->flags & FLAG_PACK ? "pack" : "unpack" );
+                     "Invalid type ',' in %s", _action( symptr ) );
         }
        continue;
       }
@@ -930,12 +624,12 @@ S_next_symbol(pTHX_ tempsym_t* symptr )
       if (code == '(') {
         if( isDIGIT(*patptr) || *patptr == '*' || *patptr == '[' )
           Perl_croak(aTHX_ "()-group starts with a count in %s",
-                     symptr->flags & FLAG_PACK ? "pack" : "unpack" );
+                        _action( symptr ) );
         symptr->grpbeg = patptr;
         patptr = 1 + ( symptr->grpend = group_end(patptr, patend, ')') );
         if( symptr->level >= MAX_SUB_TEMPLATE_LEVEL )
          Perl_croak(aTHX_ "Too deeply nested ()-groups in %s",
-                     symptr->flags & FLAG_PACK ? "pack" : "unpack" );
+                        _action( symptr ) );
       }
 
       /* look for group modifiers to inherit */
@@ -946,13 +640,13 @@ S_next_symbol(pTHX_ tempsym_t* symptr )
 
       /* look for modifiers */
       while (patptr < patend) {
-        I32 modifier = 0;
+        const char *allowed;
+        I32 modifier;
         switch (*patptr) {
           case '!':
             modifier = TYPE_IS_SHRIEKING;
-            allowed = SHRIEKING_ALLOWED_TYPES;
+            allowed = "sSiIlLxXnNvV@.";
             break;
-#ifdef PERL_PACK_CAN_BYTEORDER
           case '>':
             modifier = TYPE_IS_BIG_ENDIAN;
             allowed = ENDIANNESS_ALLOWED_TYPES;
@@ -961,8 +655,9 @@ S_next_symbol(pTHX_ tempsym_t* symptr )
             modifier = TYPE_IS_LITTLE_ENDIAN;
             allowed = ENDIANNESS_ALLOWED_TYPES;
             break;
-#endif /* PERL_PACK_CAN_BYTEORDER */
           default:
+            allowed = "";
+            modifier = 0;
             break;
         }
 
@@ -971,23 +666,21 @@ S_next_symbol(pTHX_ tempsym_t* symptr )
 
         if (!strchr(allowed, TYPE_NO_MODIFIERS(code)))
           Perl_croak(aTHX_ "'%c' allowed only after types %s in %s", *patptr,
-                     allowed, symptr->flags & FLAG_PACK ? "pack" : "unpack" );
+                        allowed, _action( symptr ) );
 
         if (TYPE_ENDIANNESS(code | modifier) == TYPE_ENDIANNESS_MASK)
           Perl_croak(aTHX_ "Can't use both '<' and '>' after type '%c' in %s",
-                     (int) TYPE_NO_MODIFIERS(code),
-                     symptr->flags & FLAG_PACK ? "pack" : "unpack" );
+                     (int) TYPE_NO_MODIFIERS(code), _action( symptr ) );
         else if (TYPE_ENDIANNESS(code | modifier | inherited_modifiers) ==
                  TYPE_ENDIANNESS_MASK)
           Perl_croak(aTHX_ "Can't use '%c' in a group with different byte-order in %s",
-                     *patptr, symptr->flags & FLAG_PACK ? "pack" : "unpack" );
-
-        if (ckWARN(WARN_UNPACK)) {
-          if (code & modifier)
-           Perl_warner(aTHX_ packWARN(WARN_UNPACK),
-                        "Duplicate modifier '%c' after '%c' in %s",
-                        *patptr, (int) TYPE_NO_MODIFIERS(code),
-                        symptr->flags & FLAG_PACK ? "pack" : "unpack" );
+                     *patptr, _action( symptr ) );
+
+        if ((code & modifier)) {
+           Perl_ck_warner(aTHX_ packWARN(WARN_UNPACK),
+                          "Duplicate modifier '%c' after '%c' in %s",
+                          *patptr, (int) TYPE_NO_MODIFIERS(code),
+                          _action( symptr ) );
         }
 
         code |= modifier;
@@ -1008,7 +701,7 @@ S_next_symbol(pTHX_ tempsym_t* symptr )
           symptr->howlen = e_star;
 
         } else if (*patptr == '[') {
-          char* lenptr = ++patptr;
+          const char* lenptr = ++patptr;
           symptr->howlen = e_number;
           patptr = group_end( patptr, patend, ']' ) + 1;
           /* what kind of [] is it? */
@@ -1016,7 +709,7 @@ S_next_symbol(pTHX_ tempsym_t* symptr )
             lenptr = get_num( lenptr, &symptr->length );
             if( *lenptr != ']' )
               Perl_croak(aTHX_ "Malformed integer in [] in %s",
-                         symptr->flags & FLAG_PACK ? "pack" : "unpack");
+                            _action( symptr ) );
           } else {
             tempsym_t savsym = *symptr;
             symptr->patend = patptr-1;
@@ -1046,7 +739,7 @@ S_next_symbol(pTHX_ tempsym_t* symptr )
               if (patptr < patend &&
                   (isDIGIT(*patptr) || *patptr == '*' || *patptr == '['))
                 Perl_croak(aTHX_ "'/' does not take a repeat count in %s",
-                           symptr->flags & FLAG_PACK ? "pack" : "unpack" );
+                            _action( symptr ) );
             }
             break;
          }
@@ -1079,10 +772,13 @@ STATIC bool
 need_utf8(const char *pat, const char *patend)
 {
     bool first = TRUE;
+
+    PERL_ARGS_ASSERT_NEED_UTF8;
+
     while (pat < patend) {
        if (pat[0] == '#') {
            pat++;
-           pat = (char *) memchr(pat, '\n', patend-pat);
+           pat = (const char *) memchr(pat, '\n', patend-pat);
            if (!pat) return FALSE;
        } else if (pat[0] == 'U') {
            if (first || pat[1] == '0') return TRUE;
@@ -1094,10 +790,12 @@ need_utf8(const char *pat, const char *patend)
 
 STATIC char
 first_symbol(const char *pat, const char *patend) {
+    PERL_ARGS_ASSERT_FIRST_SYMBOL;
+
     while (pat < patend) {
        if (pat[0] != '#') return pat[0];
        pat++;
-       pat = (char *) memchr(pat, '\n', patend-pat);
+       pat = (const char *) memchr(pat, '\n', patend-pat);
        if (!pat) return 0;
        pat++;
     }
@@ -1105,52 +803,35 @@ first_symbol(const char *pat, const char *patend) {
 }
 
 /*
-=for apidoc unpack_str
-
-The engine implementing unpack() Perl function. Note: parameters strbeg, new_s
-and ocnt are not used. This call should not be used, use unpackstring instead.
 
-=cut */
-
-I32
-Perl_unpack_str(pTHX_ char *pat, char *patend, char *s, char *strbeg, char *strend, char **new_s, I32 ocnt, U32 flags)
-{
-    tempsym_t sym = { 0 };
-
-    if (flags & FLAG_DO_UTF8) flags |= FLAG_WAS_UTF8;
-    else if (need_utf8(pat, patend)) {
-       /* We probably should try to avoid this in case a scalar context call
-          wouldn't get to the "U0" */
-       STRLEN len = strend - s;
-       s = (char *) bytes_to_utf8((U8 *) s, &len);
-       SAVEFREEPV(s);
-       strend = s + len;
-       flags |= FLAG_DO_UTF8;
-    }
+=head1 Pack and Unpack
 
-    if (first_symbol(pat, patend) != 'U' && (flags & FLAG_DO_UTF8))
-       flags |= FLAG_PARSE_UTF8;
+=for apidoc unpackstring
 
-    sym.patptr = pat;
-    sym.patend = patend;
-    sym.flags  = flags;
+The engine implementing the C<unpack()> Perl function.
 
-    return unpack_rec(&sym, s, s, strend, NULL );
-}
+Using the template C<pat..patend>, this function unpacks the string
+C<s..strend> into a number of mortal SVs, which it pushes onto the perl
+argument (C<@_>) stack (so you will need to issue a C<PUTBACK> before and
+C<SPAGAIN> after the call to this function).  It returns the number of
+pushed elements.
 
-/*
-=for apidoc unpackstring
+The C<strend> and C<patend> pointers should point to the byte following the
+last character of each string.
 
-The engine implementing unpack() Perl function. C<unpackstring> puts the
-extracted list items on the stack and returns the number of elements.
-Issue C<PUTBACK> before and C<SPAGAIN> after the call to this function.
+Although this function returns its values on the perl argument stack, it
+doesn't take any parameters from that stack (and thus in particular
+there's no need to do a C<PUSHMARK> before calling it, unlike L</call_pv> for
+example).
 
 =cut */
 
-I32
-Perl_unpackstring(pTHX_ char *pat, char *patend, char *s, char *strend, U32 flags)
+SSize_t
+Perl_unpackstring(pTHX_ const char *pat, const char *patend, const char *s, const char *strend, U32 flags)
 {
-    tempsym_t sym = { 0 };
+    tempsym_t sym;
+
+    PERL_ARGS_ASSERT_UNPACKSTRING;
 
     if (flags & FLAG_DO_UTF8) flags |= FLAG_WAS_UTF8;
     else if (need_utf8(pat, patend)) {
@@ -1166,36 +847,36 @@ Perl_unpackstring(pTHX_ char *pat, char *patend, char *s, char *strend, U32 flag
     if (first_symbol(pat, patend) != 'U' && (flags & FLAG_DO_UTF8))
        flags |= FLAG_PARSE_UTF8;
 
-    sym.patptr = pat;
-    sym.patend = patend;
-    sym.flags  = flags;
+    TEMPSYM_INIT(&sym, pat, patend, flags);
 
     return unpack_rec(&sym, s, s, strend, NULL );
 }
 
-STATIC
-I32
-S_unpack_rec(pTHX_ tempsym_t* symptr, char *s, char *strbeg, char *strend, char **new_s )
+STATIC SSize_t
+S_unpack_rec(pTHX_ tempsym_t* symptr, const char *s, const char *strbeg, const char *strend, const char **new_s )
 {
-    dVAR; dSP;
-    SV *sv;
-    I32 start_sp_offset = SP - PL_stack_base;
+    dSP;
+    SV *sv = NULL;
+    const SSize_t start_sp_offset = SP - PL_stack_base;
     howlen_t howlen;
-
-    I32 checksum = 0;
+    SSize_t checksum = 0;
     UV cuv = 0;
     NV cdouble = 0.0;
-    const int bits_in_uv = CHAR_BIT * sizeof(cuv);
+    const SSize_t bits_in_uv = CHAR_BIT * sizeof(cuv);
     bool beyond = FALSE;
     bool explicit_length;
-    bool unpack_only_one = (symptr->flags & FLAG_UNPACK_ONLY_ONE) != 0;
+    const bool unpack_only_one = (symptr->flags & FLAG_UNPACK_ONLY_ONE) != 0;
     bool utf8 = (symptr->flags & FLAG_PARSE_UTF8) ? 1 : 0;
+
+    PERL_ARGS_ASSERT_UNPACK_REC;
+
     symptr->strbeg = s - strbeg;
 
     while (next_symbol(symptr)) {
        packprops_t props;
-       I32 len, ai32;
+       SSize_t len;
         I32 datumtype = symptr->code;
+        bool needs_swap;
        /* do first one only unless in list context
           / is implemented by unpacking the count, then popping it from the
           stack, so must check that we're not in the middle of a /  */
@@ -1221,8 +902,8 @@ S_unpack_rec(pTHX_ tempsym_t* symptr, char *s, char *strbeg, char *strend, char
        props = packprops[TYPE_NO_ENDIANNESS(datumtype)];
        if (props) {
            /* props nonzero means we can process this letter. */
-           long size = props & PACK_SIZE_MASK;
-           long howmany = (strend - s) / size;
+            const SSize_t size = props & PACK_SIZE_MASK;
+            const SSize_t howmany = (strend - s) / size;
            if (len > howmany)
                len = howmany;
 
@@ -1233,6 +914,8 @@ S_unpack_rec(pTHX_ tempsym_t* symptr, char *s, char *strbeg, char *strend, char
            }
        }
 
+        needs_swap = NEEDS_SWAP(datumtype);
+
        switch(TYPE_NO_ENDIANNESS(datumtype)) {
        default:
            Perl_croak(aTHX_ "Invalid type '%c' in unpack", (int)TYPE_NO_MODIFIERS(datumtype) );
@@ -1244,16 +927,17 @@ S_unpack_rec(pTHX_ tempsym_t* symptr, char *s, char *strbeg, char *strend, char
            cuv = 0;
            cdouble = 0;
            continue;
-           break;
+
        case '(':
        {
             tempsym_t savsym = *symptr;
-           U32 group_modifiers = TYPE_MODIFIERS(datumtype & ~symptr->flags);
+            const U32 group_modifiers = TYPE_MODIFIERS(datumtype & ~symptr->flags);
            symptr->flags |= group_modifiers;
             symptr->patend = savsym.grpend;
            symptr->previous = &savsym;
             symptr->level++;
            PUTBACK;
+           if (len && unpack_only_one) len = 1;
            while (len--) {
                symptr->patptr = savsym.grpbeg;
                if (utf8) symptr->flags |=  FLAG_PARSE_UTF8;
@@ -1267,17 +951,11 @@ S_unpack_rec(pTHX_ tempsym_t* symptr, char *s, char *strbeg, char *strend, char
             *symptr = savsym;
            break;
        }
-#ifdef PERL_PACK_CAN_SHRIEKSIGN
        case '.' | TYPE_IS_SHRIEKING:
-#endif
        case '.': {
-           char *from;
+           const char *from;
            SV *sv;
-#ifdef PERL_PACK_CAN_SHRIEKSIGN
-           bool u8 = utf8 && !(datumtype & TYPE_IS_SHRIEKING);
-#else /* PERL_PACK_CAN_SHRIEKSIGN */
-           bool u8 = utf8;
-#endif
+           const bool u8 = utf8 && !(datumtype & TYPE_IS_SHRIEKING);
            if (howlen == e_star) from = strbeg;
            else if (len <= 0) from = s;
            else {
@@ -1289,19 +967,13 @@ S_unpack_rec(pTHX_ tempsym_t* symptr, char *s, char *strbeg, char *strend, char
            sv = from <= s ?
                newSVuv(  u8 ? (UV) utf8_length((const U8*)from, (const U8*)s) : (UV) (s-from)) :
                newSViv(-(u8 ? (IV) utf8_length((const U8*)s, (const U8*)from) : (IV) (from-s)));
-           XPUSHs(sv_2mortal(sv));
+           mXPUSHs(sv);
            break;
        }
-#ifdef PERL_PACK_CAN_SHRIEKSIGN
        case '@' | TYPE_IS_SHRIEKING:
-#endif
        case '@':
            s = strbeg + symptr->strbeg;
-#ifdef PERL_PACK_CAN_SHRIEKSIGN
            if (utf8  && !(datumtype & TYPE_IS_SHRIEKING))
-#else /* PERL_PACK_CAN_SHRIEKSIGN */
-           if (utf8)
-#endif
            {
                while (len > 0) {
                    if (s >= strend)
@@ -1321,8 +993,8 @@ S_unpack_rec(pTHX_ tempsym_t* symptr, char *s, char *strbeg, char *strend, char
            if (!len)                   /* Avoid division by 0 */
                len = 1;
            if (utf8) {
-               char *hop, *last;
-               I32 l = len;
+               const char *hop, *last;
+               SSize_t l = len;
                hop = last = strbeg;
                while (hop < s) {
                    hop += UTF8SKIP(hop);
@@ -1337,7 +1009,7 @@ S_unpack_rec(pTHX_ tempsym_t* symptr, char *s, char *strbeg, char *strend, char
                break;
            }
            len = (s - strbeg) % len;
-           /* FALL THROUGH */
+           /* FALLTHROUGH */
        case 'X':
            if (utf8) {
                while (len > 0) {
@@ -1355,14 +1027,16 @@ S_unpack_rec(pTHX_ tempsym_t* symptr, char *s, char *strbeg, char *strend, char
                s -= len;
            }
            break;
-       case 'x' | TYPE_IS_SHRIEKING:
+       case 'x' | TYPE_IS_SHRIEKING: {
+            SSize_t ai32;
            if (!len)                   /* Avoid division by 0 */
                len = 1;
            if (utf8) ai32 = utf8_length((U8 *) strbeg, (U8 *) s) % len;
            else      ai32 = (s - strbeg)                         % len;
            if (ai32 == 0) break;
            len -= ai32;
-           /* FALL THROUGH */
+            }
+           /* FALLTHROUGH */
        case 'x':
            if (utf8) {
                while (len>0) {
@@ -1379,7 +1053,7 @@ S_unpack_rec(pTHX_ tempsym_t* symptr, char *s, char *strbeg, char *strend, char
            break;
        case '/':
            Perl_croak(aTHX_ "'/' must follow a numeric type in unpack");
-            break;
+
        case 'A':
        case 'Z':
        case 'a':
@@ -1389,8 +1063,8 @@ S_unpack_rec(pTHX_ tempsym_t* symptr, char *s, char *strbeg, char *strend, char
                goto W_checksum;
            }
            if (utf8) {
-               I32 l;
-               char *hop;
+               SSize_t l;
+               const char *hop;
                for (l=len, hop=s; l>0; l--, hop += UTF8SKIP(hop)) {
                    if (hop >= strend) {
                        if (hop > strend)
@@ -1406,7 +1080,7 @@ S_unpack_rec(pTHX_ tempsym_t* symptr, char *s, char *strbeg, char *strend, char
 
            if (datumtype == 'Z') {
                /* 'Z' strips stuff after first null */
-               char *ptr, *end;
+               const char *ptr, *end;
                end = s + len;
                for (ptr = s; ptr < end; ptr++) if (*ptr == 0) break;
                sv = newSVpvn(s, ptr-s);
@@ -1414,11 +1088,16 @@ S_unpack_rec(pTHX_ tempsym_t* symptr, char *s, char *strbeg, char *strend, char
                    len = ptr-s + (ptr != strend ? 1 : 0);
            } else if (datumtype == 'A') {
                /* 'A' strips both nulls and spaces */
-               char *ptr;
+               const char *ptr;
                if (utf8 && (symptr->flags & FLAG_WAS_UTF8)) {
-                   for (ptr = s+len-1; ptr >= s; ptr--)
-                       if (*ptr != 0 && !UTF8_IS_CONTINUATION(*ptr) &&
-                           !is_utf8_space((U8 *) ptr)) break;
+                    for (ptr = s+len-1; ptr >= s; ptr--) {
+                        if (   *ptr != 0
+                            && !UTF8_IS_CONTINUATION(*ptr)
+                            && !isSPACE_utf8_safe(ptr, strend))
+                        {
+                            break;
+                        }
+                    }
                    if (ptr >= s) ptr += UTF8SKIP(ptr);
                    else ptr++;
                    if (ptr > s+len)
@@ -1437,7 +1116,7 @@ S_unpack_rec(pTHX_ tempsym_t* symptr, char *s, char *strbeg, char *strend, char
                if (!(symptr->flags & FLAG_WAS_UTF8))
                    sv_utf8_downgrade(sv, 0);
            }
-           XPUSHs(sv_2mortal(sv));
+           mXPUSHs(sv);
            s += len;
            break;
        case 'B':
@@ -1446,23 +1125,9 @@ S_unpack_rec(pTHX_ tempsym_t* symptr, char *s, char *strbeg, char *strend, char
            if (howlen == e_star || len > (strend - s) * 8)
                len = (strend - s) * 8;
            if (checksum) {
-               if (!PL_bitcount) {
-                   int bits;
-                   Newz(601, PL_bitcount, 256, char);
-                   for (bits = 1; bits < 256; bits++) {
-                       if (bits & 1)   PL_bitcount[bits]++;
-                       if (bits & 2)   PL_bitcount[bits]++;
-                       if (bits & 4)   PL_bitcount[bits]++;
-                       if (bits & 8)   PL_bitcount[bits]++;
-                       if (bits & 16)  PL_bitcount[bits]++;
-                       if (bits & 32)  PL_bitcount[bits]++;
-                       if (bits & 64)  PL_bitcount[bits]++;
-                       if (bits & 128) PL_bitcount[bits]++;
-                   }
-               }
                if (utf8)
                    while (len >= 8 && s < strend) {
-                       cuv += PL_bitcount[uni_to_byte(aTHX_ &s, strend, datumtype)];
+                       cuv += PL_bitcount[utf8_to_byte(aTHX_ &s, strend, datumtype)];
                        len -= 8;
                    }
                else
@@ -1487,109 +1152,124 @@ S_unpack_rec(pTHX_ tempsym_t* symptr, char *s, char *strbeg, char *strend, char
                break;
            }
 
-           sv = sv_2mortal(NEWSV(35, len ? len : 1));
+           sv = sv_2mortal(newSV(len ? len : 1));
            SvPOK_on(sv);
            str = SvPVX(sv);
            if (datumtype == 'b') {
                U8 bits = 0;
-               ai32 = len;
+               const SSize_t ai32 = len;
                for (len = 0; len < ai32; len++) {
                    if (len & 7) bits >>= 1;
                    else if (utf8) {
                        if (s >= strend) break;
-                       bits = uni_to_byte(aTHX_ &s, strend, datumtype);
+                       bits = utf8_to_byte(aTHX_ &s, strend, datumtype);
                    } else bits = *(U8 *) s++;
                    *str++ = bits & 1 ? '1' : '0';
                }
            } else {
                U8 bits = 0;
-               ai32 = len;
+               const SSize_t ai32 = len;
                for (len = 0; len < ai32; len++) {
                    if (len & 7) bits <<= 1;
                    else if (utf8) {
                        if (s >= strend) break;
-                       bits = uni_to_byte(aTHX_ &s, strend, datumtype);
+                       bits = utf8_to_byte(aTHX_ &s, strend, datumtype);
                    } else bits = *(U8 *) s++;
                    *str++ = bits & 0x80 ? '1' : '0';
                }
            }
            *str = '\0';
-           SvCUR_set(sv, str - SvPVX(sv));
+           SvCUR_set(sv, str - SvPVX_const(sv));
            XPUSHs(sv);
            break;
        }
        case 'H':
        case 'h': {
-           char *str;
+           char *str = NULL;
            /* Preliminary length estimate, acceptable for utf8 too */
            if (howlen == e_star || len > (strend - s) * 2)
                len = (strend - s) * 2;
-           sv = sv_2mortal(NEWSV(35, len ? len : 1));
-           SvPOK_on(sv);
-           str = SvPVX(sv);
+           if (!checksum) {
+               sv = sv_2mortal(newSV(len ? len : 1));
+               SvPOK_on(sv);
+               str = SvPVX(sv);
+           }
            if (datumtype == 'h') {
                U8 bits = 0;
-               ai32 = len;
+               SSize_t ai32 = len;
                for (len = 0; len < ai32; len++) {
                    if (len & 1) bits >>= 4;
                    else if (utf8) {
                        if (s >= strend) break;
-                       bits = uni_to_byte(aTHX_ &s, strend, datumtype);
+                       bits = utf8_to_byte(aTHX_ &s, strend, datumtype);
                    } else bits = * (U8 *) s++;
-                   *str++ = PL_hexdigit[bits & 15];
+                   if (!checksum)
+                       *str++ = PL_hexdigit[bits & 15];
                }
            } else {
                U8 bits = 0;
-               ai32 = len;
+               const SSize_t ai32 = len;
                for (len = 0; len < ai32; len++) {
                    if (len & 1) bits <<= 4;
                    else if (utf8) {
                        if (s >= strend) break;
-                       bits = uni_to_byte(aTHX_ &s, strend, datumtype);
+                       bits = utf8_to_byte(aTHX_ &s, strend, datumtype);
                    } else bits = *(U8 *) s++;
-                   *str++ = PL_hexdigit[(bits >> 4) & 15];
+                   if (!checksum)
+                       *str++ = PL_hexdigit[(bits >> 4) & 15];
                }
            }
-           *str = '\0';
-           SvCUR_set(sv, str - SvPVX(sv));
-           XPUSHs(sv);
+           if (!checksum) {
+               *str = '\0';
+               SvCUR_set(sv, str - SvPVX_const(sv));
+               XPUSHs(sv);
+           }
            break;
        }
+       case 'C':
+            if (len == 0) {
+                if (explicit_length)
+                   /* Switch to "character" mode */
+                   utf8 = (symptr->flags & FLAG_DO_UTF8) ? 1 : 0;
+               break;
+           }
+           /* FALLTHROUGH */
        case 'c':
-           while (len-- > 0) {
-               int aint = SHIFT_BYTE(utf8, s, strend, datumtype);
-               if (aint >= 128)        /* fake up signed chars */
+           while (len-- > 0 && s < strend) {
+               int aint;
+               if (utf8)
+                 {
+                   STRLEN retlen;
+                   aint = utf8n_to_uvchr((U8 *) s, strend-s, &retlen,
+                                ckWARN(WARN_UTF8) ? 0 : UTF8_ALLOW_ANY);
+                   if (retlen == (STRLEN) -1)
+                       Perl_croak(aTHX_ "Malformed UTF-8 string in unpack");
+                   s += retlen;
+                 }
+               else
+                 aint = *(U8 *)(s)++;
+               if (aint >= 128 && datumtype != 'C')    /* fake up signed chars */
                    aint -= 256;
                if (!checksum)
-                   PUSHs(sv_2mortal(newSViv((IV)aint)));
+                   mPUSHi(aint);
                else if (checksum > bits_in_uv)
                    cdouble += (NV)aint;
                else
                    cuv += aint;
            }
            break;
-       case 'C':
        case 'W':
          W_checksum:
-            if (len == 0) {
-                if (explicit_length && datumtype == 'C')
-                   /* Switch to "character" mode */
-                   utf8 = (symptr->flags & FLAG_DO_UTF8) ? 1 : 0;
-               break;
-           }
-           if (datumtype == 'C' ?
-                (symptr->flags & FLAG_DO_UTF8) &&
-               !(symptr->flags & FLAG_WAS_UTF8) : utf8) {
+           if (utf8) {
                while (len-- > 0 && s < strend) {
-                   UV val;
                    STRLEN retlen;
-                   val = utf8n_to_uvchr((U8 *) s, strend-s, &retlen,
+                   const UV val = utf8n_to_uvchr((U8 *) s, strend-s, &retlen,
                                         ckWARN(WARN_UTF8) ? 0 : UTF8_ALLOW_ANY);
-                   if (retlen == (STRLEN) -1 || retlen == 0)
+                   if (retlen == (STRLEN) -1)
                        Perl_croak(aTHX_ "Malformed UTF-8 string in unpack");
                    s += retlen;
                    if (!checksum)
-                       PUSHs(sv_2mortal(newSVuv((UV) val)));
+                       mPUSHu(val);
                    else if (checksum > bits_in_uv)
                        cdouble += (NV) val;
                    else
@@ -1597,8 +1277,8 @@ S_unpack_rec(pTHX_ tempsym_t* symptr, char *s, char *strbeg, char *strend, char
                }
            } else if (!checksum)
                while (len-- > 0) {
-                   U8 ch = *(U8 *) s++;
-                   PUSHs(sv_2mortal(newSVuv((UV) ch)));
+                   const U8 ch = *(U8 *) s++;
+                   mPUSHu(ch);
            }
            else if (checksum > bits_in_uv)
                while (len-- > 0) cdouble += (NV) *(U8 *) s++;
@@ -1607,7 +1287,7 @@ S_unpack_rec(pTHX_ tempsym_t* symptr, char *s, char *strbeg, char *strend, char
            break;
        case 'U':
            if (len == 0) {
-                if (explicit_length) {
+                if (explicit_length && howlen != e_star) {
                    /* Switch to "bytes in UTF-8" mode */
                    if (symptr->flags & FLAG_DO_UTF8) utf8 = 0;
                    else
@@ -1626,28 +1306,33 @@ S_unpack_rec(pTHX_ tempsym_t* symptr, char *s, char *strbeg, char *strend, char
                STRLEN retlen;
                UV auv;
                if (utf8) {
-                   U8 result[UTF8_MAXLEN];
-                   char *ptr;
+                   U8 result[UTF8_MAXLEN+1];
+                   const char *ptr = s;
                    STRLEN len;
-                   ptr = s;
                    /* Bug: warns about bad utf8 even if we are short on bytes
                       and will break out of the loop */
-                   if (!uni_to_bytes(aTHX_ &ptr, strend, (char *) result, 1,
+                   if (!S_utf8_to_bytes(aTHX_ &ptr, strend, (char *) result, 1,
                                      'U'))
                        break;
                    len = UTF8SKIP(result);
-                   if (!uni_to_bytes(aTHX_ &ptr, strend,
+                   if (!S_utf8_to_bytes(aTHX_ &ptr, strend,
                                      (char *) &result[1], len-1, 'U')) break;
-                   auv = utf8n_to_uvuni(result, len, &retlen, ckWARN(WARN_UTF8) ? 0 : UTF8_ALLOW_ANYUV);
+                   auv = NATIVE_TO_UNI(utf8n_to_uvchr(result,
+                                                       len,
+                                                       &retlen,
+                                                       UTF8_ALLOW_DEFAULT));
                    s = ptr;
                } else {
-                   auv = utf8n_to_uvuni((U8*)s, strend - s, &retlen, ckWARN(WARN_UTF8) ? 0 : UTF8_ALLOW_ANYUV);
-                   if (retlen == (STRLEN) -1 || retlen == 0)
+                   auv = NATIVE_TO_UNI(utf8n_to_uvchr((U8*)s,
+                                                       strend - s,
+                                                       &retlen,
+                                                       UTF8_ALLOW_DEFAULT));
+                   if (retlen == (STRLEN) -1)
                        Perl_croak(aTHX_ "Malformed UTF-8 string in unpack");
                    s += retlen;
                }
                if (!checksum)
-                   PUSHs(sv_2mortal(newSVuv((UV) auv)));
+                   mPUSHu(auv);
                else if (checksum > bits_in_uv)
                    cdouble += (NV) auv;
                else
@@ -1658,10 +1343,9 @@ S_unpack_rec(pTHX_ tempsym_t* symptr, char *s, char *strbeg, char *strend, char
 #if SHORTSIZE != SIZE16
            while (len-- > 0) {
                short ashort;
-               SHIFT_VAR(utf8, s, strend, ashort, datumtype);
-               DO_BO_UNPACK(ashort, s);
+                SHIFT_VAR(utf8, s, strend, ashort, datumtype, needs_swap);
                if (!checksum)
-                   PUSHs(sv_2mortal(newSViv((IV)ashort)));
+                   mPUSHi(ashort);
                else if (checksum > bits_in_uv)
                    cdouble += (NV)ashort;
                else
@@ -1669,7 +1353,7 @@ S_unpack_rec(pTHX_ tempsym_t* symptr, char *s, char *strbeg, char *strend, char
            }
            break;
 #else
-           /* Fallthrough! */
+           /* FALLTHROUGH */
 #endif
        case 's':
            while (len-- > 0) {
@@ -1678,14 +1362,13 @@ S_unpack_rec(pTHX_ tempsym_t* symptr, char *s, char *strbeg, char *strend, char
 #if U16SIZE > SIZE16
                ai16 = 0;
 #endif
-               SHIFT16(utf8, s, strend, &ai16, datumtype);
-               DO_BO_UNPACK(ai16, 16);
+                SHIFT16(utf8, s, strend, &ai16, datumtype, needs_swap);
 #if U16SIZE > SIZE16
                if (ai16 > 32767)
                    ai16 -= 65536;
 #endif
                if (!checksum)
-                   PUSHs(sv_2mortal(newSViv((IV)ai16)));
+                   mPUSHi(ai16);
                else if (checksum > bits_in_uv)
                    cdouble += (NV)ai16;
                else
@@ -1696,10 +1379,9 @@ S_unpack_rec(pTHX_ tempsym_t* symptr, char *s, char *strbeg, char *strend, char
 #if SHORTSIZE != SIZE16
            while (len-- > 0) {
                unsigned short aushort;
-               SHIFT_VAR(utf8, s, strend, aushort, datumtype);
-               DO_BO_UNPACK(aushort, s);
+               SHIFT_VAR(utf8, s, strend, aushort, datumtype, needs_swap);
                if (!checksum)
-                   PUSHs(sv_2mortal(newSVuv((UV) aushort)));
+                   mPUSHu(aushort);
                else if (checksum > bits_in_uv)
                    cdouble += (NV)aushort;
                else
@@ -1707,7 +1389,7 @@ S_unpack_rec(pTHX_ tempsym_t* symptr, char *s, char *strbeg, char *strend, char
            }
            break;
 #else
-            /* Fallhrough! */
+            /* FALLTHROUGH */
 #endif
        case 'v':
        case 'n':
@@ -1717,25 +1399,19 @@ S_unpack_rec(pTHX_ tempsym_t* symptr, char *s, char *strbeg, char *strend, char
 #if U16SIZE > SIZE16
                au16 = 0;
 #endif
-               SHIFT16(utf8, s, strend, &au16, datumtype);
-               DO_BO_UNPACK(au16, 16);
-#ifdef HAS_NTOHS
+                SHIFT16(utf8, s, strend, &au16, datumtype, needs_swap);
                if (datumtype == 'n')
                    au16 = PerlSock_ntohs(au16);
-#endif
-#ifdef HAS_VTOHS
                if (datumtype == 'v')
                    au16 = vtohs(au16);
-#endif
                if (!checksum)
-                   PUSHs(sv_2mortal(newSVuv((UV)au16)));
+                   mPUSHu(au16);
                else if (checksum > bits_in_uv)
                    cdouble += (NV) au16;
                else
                    cuv += au16;
            }
            break;
-#ifdef PERL_PACK_CAN_SHRIEKSIGN
        case 'v' | TYPE_IS_SHRIEKING:
        case 'n' | TYPE_IS_SHRIEKING:
            while (len-- > 0) {
@@ -1743,32 +1419,28 @@ S_unpack_rec(pTHX_ tempsym_t* symptr, char *s, char *strbeg, char *strend, char
 # if U16SIZE > SIZE16
                ai16 = 0;
 # endif
-               SHIFT16(utf8, s, strend, &ai16, datumtype);
-# ifdef HAS_NTOHS
+                SHIFT16(utf8, s, strend, &ai16, datumtype, needs_swap);
+                /* There should never be any byte-swapping here.  */
+                assert(!TYPE_ENDIANNESS(datumtype));
                if (datumtype == ('n' | TYPE_IS_SHRIEKING))
                    ai16 = (I16) PerlSock_ntohs((U16) ai16);
-# endif /* HAS_NTOHS */
-# ifdef HAS_VTOHS
                if (datumtype == ('v' | TYPE_IS_SHRIEKING))
                    ai16 = (I16) vtohs((U16) ai16);
-# endif /* HAS_VTOHS */
                if (!checksum)
-                   PUSHs(sv_2mortal(newSViv((IV)ai16)));
+                   mPUSHi(ai16);
                else if (checksum > bits_in_uv)
                    cdouble += (NV) ai16;
                else
                    cuv += ai16;
            }
            break;
-#endif /* PERL_PACK_CAN_SHRIEKSIGN */
        case 'i':
        case 'i' | TYPE_IS_SHRIEKING:
            while (len-- > 0) {
                int aint;
-               SHIFT_VAR(utf8, s, strend, aint, datumtype);
-               DO_BO_UNPACK(aint, i);
+                SHIFT_VAR(utf8, s, strend, aint, datumtype, needs_swap);
                if (!checksum)
-                   PUSHs(sv_2mortal(newSViv((IV)aint)));
+                   mPUSHi(aint);
                else if (checksum > bits_in_uv)
                    cdouble += (NV)aint;
                else
@@ -1779,10 +1451,9 @@ S_unpack_rec(pTHX_ tempsym_t* symptr, char *s, char *strbeg, char *strend, char
        case 'I' | TYPE_IS_SHRIEKING:
            while (len-- > 0) {
                unsigned int auint;
-               SHIFT_VAR(utf8, s, strend, auint, datumtype);
-               DO_BO_UNPACK(auint, i);
+                SHIFT_VAR(utf8, s, strend, auint, datumtype, needs_swap);
                if (!checksum)
-                   PUSHs(sv_2mortal(newSVuv((UV)auint)));
+                   mPUSHu(auint);
                else if (checksum > bits_in_uv)
                    cdouble += (NV)auint;
                else
@@ -1792,18 +1463,9 @@ S_unpack_rec(pTHX_ tempsym_t* symptr, char *s, char *strbeg, char *strend, char
        case 'j':
            while (len-- > 0) {
                IV aiv;
-               SHIFT_VAR(utf8, s, strend, aiv, datumtype);
-#if IVSIZE == INTSIZE
-               DO_BO_UNPACK(aiv, i);
-#elif IVSIZE == LONGSIZE
-               DO_BO_UNPACK(aiv, l);
-#elif defined(HAS_QUAD) && IVSIZE == U64SIZE
-               DO_BO_UNPACK(aiv, 64);
-#else
-               Perl_croak(aTHX_ "'j' not supported on this platform");
-#endif
+                SHIFT_VAR(utf8, s, strend, aiv, datumtype, needs_swap);
                if (!checksum)
-                   PUSHs(sv_2mortal(newSViv(aiv)));
+                   mPUSHi(aiv);
                else if (checksum > bits_in_uv)
                    cdouble += (NV)aiv;
                else
@@ -1813,18 +1475,9 @@ S_unpack_rec(pTHX_ tempsym_t* symptr, char *s, char *strbeg, char *strend, char
        case 'J':
            while (len-- > 0) {
                UV auv;
-               SHIFT_VAR(utf8, s, strend, auv, datumtype);
-#if IVSIZE == INTSIZE
-               DO_BO_UNPACK(auv, i);
-#elif IVSIZE == LONGSIZE
-               DO_BO_UNPACK(auv, l);
-#elif defined(HAS_QUAD) && IVSIZE == U64SIZE
-               DO_BO_UNPACK(auv, 64);
-#else
-               Perl_croak(aTHX_ "'J' not supported on this platform");
-#endif
+                SHIFT_VAR(utf8, s, strend, auv, datumtype, needs_swap);
                if (!checksum)
-                   PUSHs(sv_2mortal(newSVuv(auv)));
+                   mPUSHu(auv);
                else if (checksum > bits_in_uv)
                    cdouble += (NV)auv;
                else
@@ -1835,10 +1488,9 @@ S_unpack_rec(pTHX_ tempsym_t* symptr, char *s, char *strbeg, char *strend, char
 #if LONGSIZE != SIZE32
            while (len-- > 0) {
                long along;
-               SHIFT_VAR(utf8, s, strend, along, datumtype);
-               DO_BO_UNPACK(along, l);
+                SHIFT_VAR(utf8, s, strend, along, datumtype, needs_swap);
                if (!checksum)
-                   PUSHs(sv_2mortal(newSViv((IV)along)));
+                   mPUSHi(along);
                else if (checksum > bits_in_uv)
                    cdouble += (NV)along;
                else
@@ -1846,7 +1498,7 @@ S_unpack_rec(pTHX_ tempsym_t* symptr, char *s, char *strbeg, char *strend, char
            }
            break;
 #else
-           /* Fallthrough! */
+           /* FALLTHROUGH */
 #endif
        case 'l':
            while (len-- > 0) {
@@ -1854,13 +1506,12 @@ S_unpack_rec(pTHX_ tempsym_t* symptr, char *s, char *strbeg, char *strend, char
 #if U32SIZE > SIZE32
                ai32 = 0;
 #endif
-               SHIFT32(utf8, s, strend, &ai32, datumtype);
-               DO_BO_UNPACK(ai32, 32);
+                SHIFT32(utf8, s, strend, &ai32, datumtype, needs_swap);
 #if U32SIZE > SIZE32
                if (ai32 > 2147483647) ai32 -= 4294967296;
 #endif
                if (!checksum)
-                   PUSHs(sv_2mortal(newSViv((IV)ai32)));
+                   mPUSHi(ai32);
                else if (checksum > bits_in_uv)
                    cdouble += (NV)ai32;
                else
@@ -1871,10 +1522,9 @@ S_unpack_rec(pTHX_ tempsym_t* symptr, char *s, char *strbeg, char *strend, char
 #if LONGSIZE != SIZE32
            while (len-- > 0) {
                unsigned long aulong;
-               SHIFT_VAR(utf8, s, strend, aulong, datumtype);
-               DO_BO_UNPACK(aulong, l);
+                SHIFT_VAR(utf8, s, strend, aulong, datumtype, needs_swap);
                if (!checksum)
-                   PUSHs(sv_2mortal(newSVuv((UV)aulong)));
+                   mPUSHu(aulong);
                else if (checksum > bits_in_uv)
                    cdouble += (NV)aulong;
                else
@@ -1882,7 +1532,7 @@ S_unpack_rec(pTHX_ tempsym_t* symptr, char *s, char *strbeg, char *strend, char
            }
            break;
 #else
-            /* Fall through! */
+            /* FALLTHROUGH */
 #endif
        case 'V':
        case 'N':
@@ -1892,81 +1542,72 @@ S_unpack_rec(pTHX_ tempsym_t* symptr, char *s, char *strbeg, char *strend, char
 #if U32SIZE > SIZE32
                au32 = 0;
 #endif
-               SHIFT32(utf8, s, strend, &au32, datumtype);
-               DO_BO_UNPACK(au32, 32);
-#ifdef HAS_NTOHL
+                SHIFT32(utf8, s, strend, &au32, datumtype, needs_swap);
                if (datumtype == 'N')
                    au32 = PerlSock_ntohl(au32);
-#endif
-#ifdef HAS_VTOHL
                if (datumtype == 'V')
                    au32 = vtohl(au32);
-#endif
                if (!checksum)
-                   PUSHs(sv_2mortal(newSVuv((UV)au32)));
+                   mPUSHu(au32);
                else if (checksum > bits_in_uv)
                    cdouble += (NV)au32;
                else
                    cuv += au32;
            }
            break;
-#ifdef PERL_PACK_CAN_SHRIEKSIGN
        case 'V' | TYPE_IS_SHRIEKING:
        case 'N' | TYPE_IS_SHRIEKING:
            while (len-- > 0) {
                I32 ai32;
-# if U32SIZE > SIZE32
+#if U32SIZE > SIZE32
                ai32 = 0;
-# endif
-               SHIFT32(utf8, s, strend, &ai32, datumtype);
-# ifdef HAS_NTOHL
+#endif
+                SHIFT32(utf8, s, strend, &ai32, datumtype, needs_swap);
+                /* There should never be any byte swapping here.  */
+                assert(!TYPE_ENDIANNESS(datumtype));
                if (datumtype == ('N' | TYPE_IS_SHRIEKING))
                    ai32 = (I32)PerlSock_ntohl((U32)ai32);
-# endif
-# ifdef HAS_VTOHL
                if (datumtype == ('V' | TYPE_IS_SHRIEKING))
                    ai32 = (I32)vtohl((U32)ai32);
-# endif
                if (!checksum)
-                   PUSHs(sv_2mortal(newSViv((IV)ai32)));
+                   mPUSHi(ai32);
                else if (checksum > bits_in_uv)
                    cdouble += (NV)ai32;
                else
                    cuv += ai32;
            }
            break;
-#endif /* PERL_PACK_CAN_SHRIEKSIGN */
        case 'p':
            while (len-- > 0) {
-               char *aptr;
-               SHIFT_VAR(utf8, s, strend, aptr, datumtype);
-               DO_BO_UNPACK_PC(aptr);
+               const char *aptr;
+                SHIFT_VAR(utf8, s, strend, aptr, datumtype, needs_swap);
                /* newSVpv generates undef if aptr is NULL */
-               PUSHs(sv_2mortal(newSVpv(aptr, 0)));
+               mPUSHs(newSVpv(aptr, 0));
            }
            break;
        case 'w':
            {
                UV auv = 0;
-               U32 bytes = 0;
+               size_t bytes = 0;
 
                while (len > 0 && s < strend) {
                    U8 ch;
                    ch = SHIFT_BYTE(utf8, s, strend, datumtype);
                    auv = (auv << 7) | (ch & 0x7f);
-                   /* UTF8_IS_XXXXX not right here - using constant 0x80 */
+                    /* UTF8_IS_XXXXX not right here because this is a BER, not
+                     * UTF-8 format - using constant 0x80 */
                    if (ch < 0x80) {
                        bytes = 0;
-                       PUSHs(sv_2mortal(newSVuv(auv)));
+                       mPUSHu(auv);
                        len--;
                        auv = 0;
                        continue;
                    }
                    if (++bytes >= sizeof(UV)) {        /* promote to string */
-                       char *t;
-                       STRLEN n_a;
+                       const char *t;
 
-                       sv = Perl_newSVpvf(aTHX_ "%.*"UVf, (int)TYPE_DIGITS(UV), auv);
+                       sv = Perl_newSVpvf(aTHX_ "%.*" UVuf,
+                                                 (int)TYPE_DIGITS(UV), auv);
                        while (s < strend) {
                            ch = SHIFT_BYTE(utf8, s, strend, datumtype);
                            sv = mul128(sv, (U8)(ch & 0x7f));
@@ -1975,11 +1616,11 @@ S_unpack_rec(pTHX_ tempsym_t* symptr, char *s, char *strbeg, char *strend, char
                                break;
                            }
                        }
-                       t = SvPV(sv, n_a);
+                       t = SvPV_nolen_const(sv);
                        while (*t == '0')
                            t++;
                        sv_chop(sv, t);
-                       PUSHs(sv_2mortal(sv));
+                       mPUSHs(sv);
                        len--;
                        auv = 0;
                    }
@@ -1992,23 +1633,20 @@ S_unpack_rec(pTHX_ tempsym_t* symptr, char *s, char *strbeg, char *strend, char
            if (symptr->howlen == e_star)
                Perl_croak(aTHX_ "'P' must have an explicit size in unpack");
            EXTEND(SP, 1);
-           if (sizeof(char*) <= strend - s) {
+           if (s + sizeof(char*) <= strend) {
                char *aptr;
-               SHIFT_VAR(utf8, s, strend, aptr, datumtype);
-               DO_BO_UNPACK_PC(aptr);
+                SHIFT_VAR(utf8, s, strend, aptr, datumtype, needs_swap);
                /* newSVpvn generates undef if aptr is NULL */
-               PUSHs(sv_2mortal(newSVpvn(aptr, len)));
+               PUSHs(newSVpvn_flags(aptr, len, SVs_TEMP));
            }
            break;
-#ifdef HAS_QUAD
+#if defined(HAS_QUAD) && IVSIZE >= 8
        case 'q':
            while (len-- > 0) {
                Quad_t aquad;
-               SHIFT_VAR(utf8, s, strend, aquad, datumtype);
-               DO_BO_UNPACK(aquad, 64);
+                SHIFT_VAR(utf8, s, strend, aquad, datumtype, needs_swap);
                if (!checksum)
-                    PUSHs(sv_2mortal(aquad >= IV_MIN && aquad <= IV_MAX ?
-                                    newSViv((IV)aquad) : newSVnv((NV)aquad)));
+                    mPUSHs(newSViv((IV)aquad));
                else if (checksum > bits_in_uv)
                    cdouble += (NV)aquad;
                else
@@ -2018,26 +1656,23 @@ S_unpack_rec(pTHX_ tempsym_t* symptr, char *s, char *strbeg, char *strend, char
        case 'Q':
            while (len-- > 0) {
                Uquad_t auquad;
-               SHIFT_VAR(utf8, s, strend, auquad, datumtype);
-               DO_BO_UNPACK(auquad, 64);
+                SHIFT_VAR(utf8, s, strend, auquad, datumtype, needs_swap);
                if (!checksum)
-                   PUSHs(sv_2mortal(auquad <= UV_MAX ?
-                                    newSVuv((UV)auquad):newSVnv((NV)auquad)));
+                   mPUSHs(newSVuv((UV)auquad));
                else if (checksum > bits_in_uv)
                    cdouble += (NV)auquad;
                else
                    cuv += auquad;
            }
            break;
-#endif /* HAS_QUAD */
+#endif
        /* float and double added gnb@melba.bby.oz.au 22/11/89 */
        case 'f':
            while (len-- > 0) {
                float afloat;
-               SHIFT_VAR(utf8, s, strend, afloat, datumtype);
-               DO_BO_UNPACK_N(afloat, float);
+                SHIFT_VAR(utf8, s, strend, afloat, datumtype, needs_swap);
                if (!checksum)
-                   PUSHs(sv_2mortal(newSVnv((NV)afloat)));
+                   mPUSHn(afloat);
                else
                    cdouble += afloat;
            }
@@ -2045,131 +1680,109 @@ S_unpack_rec(pTHX_ tempsym_t* symptr, char *s, char *strbeg, char *strend, char
        case 'd':
            while (len-- > 0) {
                double adouble;
-               SHIFT_VAR(utf8, s, strend, adouble, datumtype);
-               DO_BO_UNPACK_N(adouble, double);
+                SHIFT_VAR(utf8, s, strend, adouble, datumtype, needs_swap);
                if (!checksum)
-                   PUSHs(sv_2mortal(newSVnv((NV)adouble)));
+                   mPUSHn(adouble);
                else
                    cdouble += adouble;
            }
            break;
        case 'F':
            while (len-- > 0) {
-               NV anv;
-               SHIFT_VAR(utf8, s, strend, anv, datumtype);
-               DO_BO_UNPACK_N(anv, NV);
+               NV_bytes anv;
+                SHIFT_BYTES(utf8, s, strend, anv.bytes, sizeof(anv.bytes),
+                            datumtype, needs_swap);
                if (!checksum)
-                   PUSHs(sv_2mortal(newSVnv(anv)));
+                   mPUSHn(anv.nv);
                else
-                   cdouble += anv;
+                   cdouble += anv.nv;
            }
            break;
 #if defined(HAS_LONG_DOUBLE) && defined(USE_LONG_DOUBLE)
        case 'D':
            while (len-- > 0) {
-               long double aldouble;
-               SHIFT_VAR(utf8, s, strend, aldouble, datumtype);
-               DO_BO_UNPACK_N(aldouble, long double);
+               ld_bytes aldouble;
+                SHIFT_BYTES(utf8, s, strend, aldouble.bytes,
+                            sizeof(aldouble.bytes), datumtype, needs_swap);
+                /* The most common long double format, the x86 80-bit
+                 * extended precision, has either 2 or 6 unused bytes,
+                 * which may contain garbage, which may contain
+                 * unintentional data.  While we do zero the bytes of
+                 * the long double data in pack(), here in unpack() we
+                 * don't, because it's really hard to envision that
+                 * reading the long double off aldouble would be
+                 * affected by the unused bytes.
+                 *
+                 * Note that trying to unpack 'long doubles' of 'long
+                 * doubles' packed in another system is in the general
+                 * case doomed without having more detail. */
                if (!checksum)
-                   PUSHs(sv_2mortal(newSVnv((NV)aldouble)));
+                   mPUSHn(aldouble.ld);
                else
-                   cdouble += aldouble;
+                   cdouble += aldouble.ld;
            }
            break;
 #endif
        case 'u':
-           /* MKS:
-            * Initialise the decode mapping.  By using a table driven
-             * algorithm, the code will be character-set independent
-             * (and just as fast as doing character arithmetic)
-             */
-            if (PL_uudmap['M'] == 0) {
-                int i;
-
-                for (i = 0; i < sizeof(PL_uuemap); i += 1)
-                    PL_uudmap[(U8)PL_uuemap[i]] = i;
-                /*
-                 * Because ' ' and '`' map to the same value,
-                 * we need to decode them both the same.
-                 */
-                PL_uudmap[' '] = 0;
+           if (!checksum) {
+                const STRLEN l = (STRLEN) (strend - s) * 3 / 4;
+               sv = sv_2mortal(newSV(l));
+               if (l) {
+                    SvPOK_on(sv);
+                    *SvEND(sv) = '\0';
+                }
+           }
+
+            /* Note that all legal uuencoded strings are ASCII printables, so
+             * have the same representation under UTF-8 vs not.  This means we
+             * can ignore UTF8ness on legal input.  For illegal we stop at the
+             * first failure, and don't report where/what that is, so again we
+             * can ignore UTF8ness */
+
+            while (s < strend && *s != ' ' && ISUUCHAR(*s)) {
+                I32 a, b, c, d;
+                char hunk[3];
+
+                len = PL_uudmap[*(U8*)s++] & 077;
+                while (len > 0) {
+                    if (s < strend && ISUUCHAR(*s))
+                        a = PL_uudmap[*(U8*)s++] & 077;
+                    else
+                        a = 0;
+                    if (s < strend && ISUUCHAR(*s))
+                        b = PL_uudmap[*(U8*)s++] & 077;
+                    else
+                        b = 0;
+                    if (s < strend && ISUUCHAR(*s))
+                        c = PL_uudmap[*(U8*)s++] & 077;
+                    else
+                        c = 0;
+                    if (s < strend && ISUUCHAR(*s))
+                        d = PL_uudmap[*(U8*)s++] & 077;
+                    else
+                        d = 0;
+                    hunk[0] = (char)((a << 2) | (b >> 4));
+                    hunk[1] = (char)((b << 4) | (c >> 2));
+                    hunk[2] = (char)((c << 6) | d);
+                    if (!checksum)
+                        sv_catpvn(sv, hunk, (len > 3) ? 3 : len);
+                    len -= 3;
+                }
+                if (*s == '\n')
+                    s++;
+                else   /* possible checksum byte */
+                    if (s + 1 < strend && s[1] == '\n')
+                        s += 2;
             }
-           {
-               STRLEN l = (STRLEN) (strend - s) * 3 / 4;
-               sv = sv_2mortal(NEWSV(42, l));
-               if (l) SvPOK_on(sv);
-           }
-           if (utf8) {
-               while (next_uni_uu(aTHX_ &s, strend, &len)) {
-                   I32 a, b, c, d;
-                   char hunk[4];
-
-                   hunk[3] = '\0';
-                   while (len > 0) {
-                       next_uni_uu(aTHX_ &s, strend, &a);
-                       next_uni_uu(aTHX_ &s, strend, &b);
-                       next_uni_uu(aTHX_ &s, strend, &c);
-                       next_uni_uu(aTHX_ &s, strend, &d);
-                       hunk[0] = (char)((a << 2) | (b >> 4));
-                       hunk[1] = (char)((b << 4) | (c >> 2));
-                       hunk[2] = (char)((c << 6) | d);
-                       sv_catpvn(sv, hunk, (len > 3) ? 3 : len);
-                       len -= 3;
-                   }
-                   if (s < strend) {
-                       if (*s == '\n') s++;
-                       else {
-                           /* possible checksum byte */
-                           char *skip = s+UTF8SKIP(s);
-                           if (skip < strend && *skip == '\n') s = skip+1;
-                       }
-                   }
-               }
-           } else {
-               while (s < strend && *s > ' ' && ISUUCHAR(*s)) {
-                   I32 a, b, c, d;
-                   char hunk[4];
-
-                   hunk[3] = '\0';
-                   len = PL_uudmap[*(U8*)s++] & 077;
-                   while (len > 0) {
-                       if (s < strend && ISUUCHAR(*s))
-                           a = PL_uudmap[*(U8*)s++] & 077;
-                       else
-                           a = 0;
-                       if (s < strend && ISUUCHAR(*s))
-                           b = PL_uudmap[*(U8*)s++] & 077;
-                       else
-                           b = 0;
-                       if (s < strend && ISUUCHAR(*s))
-                           c = PL_uudmap[*(U8*)s++] & 077;
-                       else
-                           c = 0;
-                       if (s < strend && ISUUCHAR(*s))
-                           d = PL_uudmap[*(U8*)s++] & 077;
-                       else
-                           d = 0;
-                       hunk[0] = (char)((a << 2) | (b >> 4));
-                       hunk[1] = (char)((b << 4) | (c >> 2));
-                       hunk[2] = (char)((c << 6) | d);
-                       sv_catpvn(sv, hunk, (len > 3) ? 3 : len);
-                       len -= 3;
-                   }
-                   if (*s == '\n')
-                       s++;
-                   else        /* possible checksum byte */
-                       if (s + 1 < strend && s[1] == '\n')
-                           s += 2;
-               }
-           }
-           XPUSHs(sv);
+           if (!checksum)
+               XPUSHs(sv);
            break;
-       }
+       } /* End of switch */
 
        if (checksum) {
-           if (strchr("fFdD", TYPE_NO_MODIFIERS(datumtype)) ||
+           if (memCHRs("fFdD", TYPE_NO_MODIFIERS(datumtype)) ||
              (checksum > bits_in_uv &&
-              strchr("cCsSiIlLnNUWvVqQjJ", TYPE_NO_MODIFIERS(datumtype))) ) {
+              memCHRs("cCsSiIlLnNUWvVqQjJ", TYPE_NO_MODIFIERS(datumtype))) ) {
                NV trouble, anv;
 
                 anv = (NV) (1 << (checksum & 15));
@@ -2179,7 +1792,18 @@ S_unpack_rec(pTHX_ tempsym_t* symptr, char *s, char *strbeg, char *strend, char
                }
                while (cdouble < 0.0)
                    cdouble += anv;
-               cdouble = Perl_modf(cdouble / anv, &trouble) * anv;
+               cdouble = Perl_modf(cdouble / anv, &trouble);
+#ifdef LONGDOUBLE_DOUBLEDOUBLE
+                /* Workaround for powerpc doubledouble modfl bug:
+                 * close to 1.0L and -1.0L cdouble is 0, and trouble
+                 * is cdouble / anv. */
+                if (trouble != Perl_ceil(trouble)) {
+                  cdouble = trouble;
+                  if (cdouble >  1.0L) cdouble -= 1.0L;
+                  if (cdouble < -1.0L) cdouble += 1.0L;
+                }
+#endif
+                cdouble *= anv;
                sv = newSVnv(cdouble);
            }
            else {
@@ -2189,13 +1813,13 @@ S_unpack_rec(pTHX_ tempsym_t* symptr, char *s, char *strbeg, char *strend, char
                }
                sv = newSVuv(cuv);
            }
-           XPUSHs(sv_2mortal(sv));
+           mXPUSHs(sv);
            checksum = 0;
        }
 
         if (symptr->flags & FLAG_SLASH){
             if (SP - PL_stack_base - start_sp_offset <= 0)
-                Perl_croak(aTHX_ "'/' must follow a numeric type in unpack");
+               break;
             if( next_symbol(symptr) ){
               if( symptr->howlen == e_number )
                Perl_croak(aTHX_ "Count after length/code in unpack" );
@@ -2227,14 +1851,14 @@ PP(pp_unpack)
 {
     dSP;
     dPOPPOPssrl;
-    I32 gimme = GIMME_V;
+    U8 gimme = GIMME_V;
     STRLEN llen;
     STRLEN rlen;
-    char *pat = SvPV(left,  llen);
-    char *s   = SvPV(right, rlen);
-    char *strend = s + rlen;
-    char *patend = pat + llen;
-    I32 cnt;
+    const char *pat = SvPV_const(left,  llen);
+    const char *s   = SvPV_const(right, rlen);
+    const char *strend = s + rlen;
+    const char *patend = pat + llen;
+    SSize_t cnt;
 
     PUTBACK;
     cnt = unpackstring(pat, patend, s, strend,
@@ -2248,7 +1872,7 @@ PP(pp_unpack)
 }
 
 STATIC U8 *
-doencodes(U8 *h, char *s, I32 len)
+doencodes(U8 *h, const U8 *s, SSize_t len)
 {
     *h++ = PL_uuemap[len];
     while (len > 2) {
@@ -2260,7 +1884,7 @@ doencodes(U8 *h, char *s, I32 len)
        len -= 3;
     }
     if (len > 0) {
-       char r = (len > 1 ? s[1] : '\0');
+        const U8 r = (len > 1 ? s[1] : '\0');
        *h++ = PL_uuemap[(077 & (s[0] >> 2))];
        *h++ = PL_uuemap[(077 & (((s[0] << 4) & 060) | ((r >> 4) & 017)))];
        *h++ = PL_uuemap[(077 & ((r << 2) & 074))];
@@ -2271,14 +1895,15 @@ doencodes(U8 *h, char *s, I32 len)
 }
 
 STATIC SV *
-S_is_an_int(pTHX_ char *s, STRLEN l)
+S_is_an_int(pTHX_ const char *s, STRLEN l)
 {
-  STRLEN        n_a;
-  SV             *result = newSVpvn(s, l);
-  char           *result_c = SvPV(result, n_a);        /* convenience */
-  char           *out = result_c;
-  bool            skip = 1;
-  bool            ignore = 0;
+  SV *result = newSVpvn(s, l);
+  char *const result_c = SvPV_nolen(result);   /* convenience */
+  char *out = result_c;
+  bool skip = 1;
+  bool ignore = 0;
+
+  PERL_ARGS_ASSERT_IS_AN_INT;
 
   while (*s) {
     switch (*s) {
@@ -2323,74 +1948,50 @@ S_is_an_int(pTHX_ char *s, STRLEN l)
 STATIC int
 S_div128(pTHX_ SV *pnum, bool *done)
 {
-  STRLEN          len;
-  char           *s = SvPV(pnum, len);
-  int             m = 0;
-  int             r = 0;
-  char           *t = s;
-
-  *done = 1;
-  while (*t) {
-    int             i;
-
-    i = m * 10 + (*t - '0');
-    m = i & 0x7F;
-    r = (i >> 7);              /* r < 10 */
-    if (r) {
-      *done = 0;
+    STRLEN len;
+    char * const s = SvPV(pnum, len);
+    char *t = s;
+    int m = 0;
+
+    PERL_ARGS_ASSERT_DIV128;
+
+    *done = 1;
+    while (*t) {
+       const int i = m * 10 + (*t - '0');
+       const int r = (i >> 7); /* r < 10 */
+       m = i & 0x7F;
+       if (r) {
+           *done = 0;
+       }
+       *(t++) = '0' + r;
     }
-    *(t++) = '0' + r;
-  }
-  *(t++) = '\0';
-  SvCUR_set(pnum, (STRLEN) (t - s));
-  return (m);
-}
-
-
-
-/*
-=for apidoc pack_cat
-
-The engine implementing pack() Perl function. Note: parameters next_in_list and
-flags are not used. This call should not be used; use packlist instead.
-
-=cut */
-
-
-void
-Perl_pack_cat(pTHX_ SV *cat, char *pat, register char *patend, register SV **beglist, SV **endlist, SV ***next_in_list, U32 flags)
-{
-    tempsym_t sym = { 0 };
-    sym.patptr = pat;
-    sym.patend = patend;
-    sym.flags  = FLAG_PACK;
-
-    (void)pack_rec( cat, &sym, beglist, endlist );
+    *(t++) = '\0';
+    SvCUR_set(pnum, (STRLEN) (t - s));
+    return (m);
 }
 
-
 /*
 =for apidoc packlist
 
-The engine implementing pack() Perl function.
-
-=cut */
+The engine implementing C<pack()> Perl function.
 
+=cut
+*/
 
 void
-Perl_packlist(pTHX_ SV *cat, char *pat, register char *patend, register SV **beglist, SV **endlist )
+Perl_packlist(pTHX_ SV *cat, const char *pat, const char *patend, SV **beglist, SV **endlist )
 {
-    STRLEN no_len;
-    tempsym_t sym = { 0 };
+    tempsym_t sym;
+
+    PERL_ARGS_ASSERT_PACKLIST;
 
-    sym.patptr = pat;
-    sym.patend = patend;
-    sym.flags  = FLAG_PACK;
+    TEMPSYM_INIT(&sym, pat, patend, FLAG_PACK);
 
     /* We're going to do changes through SvPVX(cat). Make sure it's valid.
        Also make sure any UTF8 flag is loaded */
-    SvPV_force(cat, no_len);
-    if (DO_UTF8(cat)) sym.flags |= FLAG_PARSE_UTF8 | FLAG_DO_UTF8;
+    SvPV_force_nolen(cat);
+    if (DO_UTF8(cat))
+       sym.flags |= FLAG_PARSE_UTF8 | FLAG_DO_UTF8;
 
     (void)pack_rec( cat, &sym, beglist, endlist );
 }
@@ -2400,14 +2001,15 @@ STATIC void
 marked_upgrade(pTHX_ SV *sv, tempsym_t *sym_ptr) {
     STRLEN len;
     tempsym_t *group;
-    char *from_ptr, *to_start, *to_ptr, **marks, **m, *from_start, *from_end;
+    const char *from_ptr, *from_start, *from_end, **marks, **m;
+    char *to_start, *to_ptr;
 
     if (SvUTF8(sv)) return;
 
-    from_start = SvPVX(sv);
+    from_start = SvPVX_const(sv);
     from_end = from_start + SvCUR(sv);
     for (from_ptr = from_start; from_ptr < from_end; from_ptr++)
-       if (!NATIVE_IS_INVARIANT(*from_ptr)) break;
+       if (!NATIVE_BYTE_IS_INVARIANT(*from_ptr)) break;
     if (from_ptr == from_end) {
        /* Simple case: no character needs to be changed */
        SvUTF8_on(sv);
@@ -2415,11 +2017,11 @@ marked_upgrade(pTHX_ SV *sv, tempsym_t *sym_ptr) {
     }
 
     len = (from_end-from_ptr)*UTF8_EXPAND+(from_ptr-from_start)+1;
-    New('U', to_start, len, char);
+    Newx(to_start, len, char);
     Copy(from_start, to_start, from_ptr-from_start, char);
     to_ptr = to_start + (from_ptr-from_start);
 
-    New('U', marks, sym_ptr->level+2, char *);
+    Newx(marks, sym_ptr->level+2, const char *);
     for (group=sym_ptr; group; group = group->previous)
        marks[group->level] = from_start + group->strbeg;
     marks[sym_ptr->level+1] = from_end+1;
@@ -2436,7 +2038,8 @@ marked_upgrade(pTHX_ SV *sv, tempsym_t *sym_ptr) {
     if (m != marks + sym_ptr->level+1) {
        Safefree(marks);
        Safefree(to_start);
-       Perl_croak(aTHX_ "Assertion: marks beyond string end");
+       Perl_croak(aTHX_ "panic: marks beyond string end, m=%p, marks=%p, "
+                  "level=%d", m, marks, sym_ptr->level);
     }
     for (group=sym_ptr; group; group = group->previous)
        group->strbeg = marks[group->level] - to_start;
@@ -2463,23 +2066,52 @@ marked_upgrade(pTHX_ SV *sv, tempsym_t *sym_ptr) {
    Only grows the string if there is an actual lack of space
 */
 STATIC char *
-sv_exp_grow(pTHX_ SV *sv, STRLEN needed) {
-    STRLEN cur = SvCUR(sv);
-    STRLEN len = SvLEN(sv);
+S_sv_exp_grow(pTHX_ SV *sv, STRLEN needed) {
+    const STRLEN cur = SvCUR(sv);
+    const STRLEN len = SvLEN(sv);
     STRLEN extend;
+
+    PERL_ARGS_ASSERT_SV_EXP_GROW;
+
     if (len - cur > needed) return SvPVX(sv);
     extend = needed > len ? needed : len;
     return SvGROW(sv, len+extend+1);
 }
 
+static SV *
+S_sv_check_infnan(pTHX_ SV *sv, I32 datumtype)
+{
+    SvGETMAGIC(sv);
+    if (UNLIKELY(SvAMAGIC(sv)))
+       sv = sv_2num(sv);
+    if (UNLIKELY(isinfnansv(sv))) {
+       const I32 c = TYPE_NO_MODIFIERS(datumtype);
+       const NV nv = SvNV_nomg(sv);
+       if (c == 'w')
+           Perl_croak(aTHX_ "Cannot compress %" NVgf " in pack", nv);
+       else
+           Perl_croak(aTHX_ "Cannot pack %" NVgf " with '%c'", nv, (int) c);
+    }
+    return sv;
+}
+
+#define SvIV_no_inf(sv,d) \
+       ((sv) = S_sv_check_infnan(aTHX_ sv,d), SvIV_nomg(sv))
+#define SvUV_no_inf(sv,d) \
+       ((sv) = S_sv_check_infnan(aTHX_ sv,d), SvUV_nomg(sv))
+
 STATIC
 SV **
 S_pack_rec(pTHX_ SV *cat, tempsym_t* symptr, SV **beglist, SV **endlist )
 {
     tempsym_t lookahead;
-    I32 items  = endlist - beglist;
+    SSize_t items  = endlist - beglist;
     bool found = next_symbol(symptr);
     bool utf8 = (symptr->flags & FLAG_PARSE_UTF8) ? 1 : 0;
+    bool warn_utf8 = ckWARN(WARN_UTF8);
+    char* from;
+
+    PERL_ARGS_ASSERT_PACK_REC;
 
     if (symptr->level == 0 && found && symptr->code == 'U') {
        marked_upgrade(aTHX_ cat, symptr);
@@ -2491,18 +2123,20 @@ S_pack_rec(pTHX_ SV *cat, tempsym_t* symptr, SV **beglist, SV **endlist )
     while (found) {
        SV *fromstr;
        STRLEN fromlen;
-       I32 len;
-       SV *lengthcode = Nullsv;
+       SSize_t len;
+       SV *lengthcode = NULL;
         I32 datumtype = symptr->code;
         howlen_t howlen = symptr->howlen;
        char *start = SvPVX(cat);
        char *cur   = start + SvCUR(cat);
+        bool needs_swap;
 
-#define NEXTFROM (lengthcode ? lengthcode : items-- > 0 ? *beglist++ : &PL_sv_no)
+#define NEXTFROM (lengthcode ? lengthcode : items > 0 ? (--items, *beglist++) : &PL_sv_no)
+#define PEEKFROM (lengthcode ? lengthcode : items > 0 ? *beglist : &PL_sv_no)
 
         switch (howlen) {
          case e_star:
-           len = strchr("@Xxu", TYPE_NO_MODIFIERS(datumtype)) ?
+           len = memCHRs("@Xxu", TYPE_NO_MODIFIERS(datumtype)) ?
                0 : items;
            break;
          default:
@@ -2517,7 +2151,7 @@ S_pack_rec(pTHX_ SV *cat, tempsym_t* symptr, SV **beglist, SV **endlist )
            if (props && !(props & PACK_SIZE_UNPREDICTABLE)) {
                /* We can process this letter. */
                STRLEN size = props & PACK_SIZE_MASK;
-               GROWING(utf8, cat, start, cur, (STRLEN) len * size);
+               GROWING2(utf8, cat, start, cur, size, (STRLEN)len);
            }
         }
 
@@ -2527,12 +2161,12 @@ S_pack_rec(pTHX_ SV *cat, tempsym_t* symptr, SV **beglist, SV **endlist )
        if (symptr->flags & FLAG_SLASH) {
            IV count;
            if (!found) Perl_croak(aTHX_ "Code missing after '/' in pack");
-           if (strchr("aAZ", lookahead.code)) {
+           if (memCHRs("aAZ", lookahead.code)) {
                if (lookahead.howlen == e_number) count = lookahead.length;
                else {
-                   if (items > 0)
-                       count = DO_UTF8(*beglist) ?
-                           sv_len_utf8(*beglist) : sv_len(*beglist);
+                   if (items > 0) {
+                       count = sv_len_utf8(*beglist);
+                   }
                    else count = 0;
                    if (lookahead.code == 'Z') count++;
                }
@@ -2546,20 +2180,19 @@ S_pack_rec(pTHX_ SV *cat, tempsym_t* symptr, SV **beglist, SV **endlist )
            lengthcode = sv_2mortal(newSViv(count));
        }
 
+        needs_swap = NEEDS_SWAP(datumtype);
+
        /* Code inside the switch must take care to properly update
           cat (CUR length and '\0' termination) if it updated *cur and
           doesn't simply leave using break */
-       switch(TYPE_NO_ENDIANNESS(datumtype)) {
+       switch (TYPE_NO_ENDIANNESS(datumtype)) {
        default:
            Perl_croak(aTHX_ "Invalid type '%c' in pack",
                       (int) TYPE_NO_MODIFIERS(datumtype));
        case '%':
            Perl_croak(aTHX_ "'%%' may not be used in pack");
-       {
-           char *from;
-#ifdef PERL_PACK_CAN_SHRIEKSIGN
+
        case '.' | TYPE_IS_SHRIEKING:
-#endif
        case '.':
            if (howlen == e_star) from = start;
            else if (len == 0) from = cur;
@@ -2570,19 +2203,13 @@ S_pack_rec(pTHX_ SV *cat, tempsym_t* symptr, SV **beglist, SV **endlist )
                from = group ? start + group->strbeg : start;
            }
            fromstr = NEXTFROM;
-           len = SvIV(fromstr);
+           len = SvIV_no_inf(fromstr, datumtype);
            goto resize;
-#ifdef PERL_PACK_CAN_SHRIEKSIGN
        case '@' | TYPE_IS_SHRIEKING:
-#endif
        case '@':
            from = start + symptr->strbeg;
          resize:
-#ifdef PERL_PACK_CAN_SHRIEKSIGN
            if (utf8  && !(datumtype & TYPE_IS_SHRIEKING))
-#else /* PERL_PACK_CAN_SHRIEKSIGN */
-           if (utf8)
-#endif
                if (len >= 0) {
                    while (len && from < cur) {
                        from += UTF8SKIP(from);
@@ -2613,7 +2240,7 @@ S_pack_rec(pTHX_ SV *cat, tempsym_t* symptr, SV **beglist, SV **endlist )
                goto shrink;
            }
            break;
-       }
+
        case '(': {
             tempsym_t savsym = *symptr;
            U32 group_modifiers = TYPE_MODIFIERS(datumtype & ~symptr->flags);
@@ -2635,6 +2262,7 @@ S_pack_rec(pTHX_ SV *cat, tempsym_t* symptr, SV **beglist, SV **endlist )
                if (savsym.howlen == e_star && beglist == endlist)
                    break;              /* No way to continue */
            }
+           items = endlist - beglist;
            lookahead.flags  = symptr->flags & ~group_modifiers;
            goto no_change;
        }
@@ -2643,7 +2271,7 @@ S_pack_rec(pTHX_ SV *cat, tempsym_t* symptr, SV **beglist, SV **endlist )
                len = 1;
            if (utf8) {
                char *hop, *last;
-               I32 l = len;
+               SSize_t l = len;
                hop = last = start;
                while (hop < cur) {
                    hop += UTF8SKIP(hop);
@@ -2658,7 +2286,7 @@ S_pack_rec(pTHX_ SV *cat, tempsym_t* symptr, SV **beglist, SV **endlist )
                break;
            }
            len = (cur-start) % len;
-           /* FALL THROUGH */
+           /* FALLTHROUGH */
        case 'X':
            if (utf8) {
                if (len < 1) goto no_change;
@@ -2684,7 +2312,7 @@ S_pack_rec(pTHX_ SV *cat, tempsym_t* symptr, SV **beglist, SV **endlist )
            if (cur < start+symptr->strbeg) {
                /* Make sure group starts don't point into the void */
                tempsym_t *group;
-               STRLEN length = cur-start;
+               const STRLEN length = cur-start;
                for (group = symptr;
                     group && length < group->strbeg;
                     group = group->previous) group->strbeg = length;
@@ -2692,7 +2320,7 @@ S_pack_rec(pTHX_ SV *cat, tempsym_t* symptr, SV **beglist, SV **endlist )
            }
            break;
        case 'x' | TYPE_IS_SHRIEKING: {
-           I32 ai32;
+           SSize_t ai32;
            if (!len)                   /* Avoid division by 0 */
                len = 1;
            if (utf8) ai32 = utf8_length((U8 *) start, (U8 *) cur) % len;
@@ -2700,18 +2328,18 @@ S_pack_rec(pTHX_ SV *cat, tempsym_t* symptr, SV **beglist, SV **endlist )
            if (ai32 == 0) goto no_change;
            len -= ai32;
        }
-       /* FALL THROUGH */
+       /* FALLTHROUGH */
        case 'x':
            goto grow;
        case 'A':
        case 'Z':
        case 'a': {
-           char *aptr;
+           const char *aptr;
 
            fromstr = NEXTFROM;
-           aptr = SvPV(fromstr, fromlen);
+           aptr = SvPV_const(fromstr, fromlen);
            if (DO_UTF8(fromstr)) {
-               char *end, *s;
+                const char *end, *s;
 
                if (!utf8 && !SvUTF8(cat)) {
                    marked_upgrade(aTHX_ cat, symptr);
@@ -2728,7 +2356,7 @@ S_pack_rec(pTHX_ SV *cat, tempsym_t* symptr, SV **beglist, SV **endlist )
                s = aptr;
                end = aptr + fromlen;
                fromlen = datumtype == 'Z' ? len-1 : len;
-               while ((I32) fromlen > 0 && s < end) {
+               while ((SSize_t) fromlen > 0 && s < end) {
                    s += UTF8SKIP(s);
                    fromlen--;
                }
@@ -2749,9 +2377,11 @@ S_pack_rec(pTHX_ SV *cat, tempsym_t* symptr, SV **beglist, SV **endlist )
                    if (datumtype == 'Z') len++;
                }
                GROWING(0, cat, start, cur, len);
-               if (!uni_to_bytes(aTHX_ &aptr, end, cur, fromlen,
+               if (!S_utf8_to_bytes(aTHX_ &aptr, end, cur, fromlen,
                                  datumtype | TYPE_IS_PACK))
-                   Perl_croak(aTHX_ "Perl bug: predicted utf8 length not available");
+                   Perl_croak(aTHX_ "panic: predicted utf8 length not available, "
+                              "for '%c', aptr=%p end=%p cur=%p, fromlen=%zu",
+                              (int)datumtype, aptr, end, cur, fromlen);
                cur += fromlen;
                len -= fromlen;
            } else if (utf8) {
@@ -2759,7 +2389,7 @@ S_pack_rec(pTHX_ SV *cat, tempsym_t* symptr, SV **beglist, SV **endlist )
                    len = fromlen;
                    if (datumtype == 'Z') len++;
                }
-               if (len <= (I32) fromlen) {
+               if (len <= (SSize_t) fromlen) {
                    fromlen = len;
                    if (datumtype == 'Z' && fromlen > 0) fromlen--;
                }
@@ -2779,7 +2409,7 @@ S_pack_rec(pTHX_ SV *cat, tempsym_t* symptr, SV **beglist, SV **endlist )
                    len = fromlen;
                    if (datumtype == 'Z') len++;
                }
-               if (len <= (I32) fromlen) {
+               if (len <= (SSize_t) fromlen) {
                    fromlen = len;
                    if (datumtype == 'Z' && fromlen > 0) fromlen--;
                }
@@ -2790,22 +2420,23 @@ S_pack_rec(pTHX_ SV *cat, tempsym_t* symptr, SV **beglist, SV **endlist )
            }
            memset(cur, datumtype == 'A' ? ' ' : '\0', len);
            cur += len;
+           SvTAINT(cat);
            break;
        }
        case 'B':
        case 'b': {
-           char *str, *end;
-           I32 l, field_len;
+           const char *str, *end;
+           SSize_t l, field_len;
            U8 bits;
            bool utf8_source;
            U32 utf8_flags;
 
            fromstr = NEXTFROM;
-           str = SvPV(fromstr, fromlen);
+           str = SvPV_const(fromstr, fromlen);
            end = str + fromlen;
            if (DO_UTF8(fromstr)) {
                utf8_source = TRUE;
-               utf8_flags  = ckWARN(WARN_UTF8) ? 0 : UTF8_ALLOW_ANY;
+               utf8_flags  = warn_utf8 ? 0 : UTF8_ALLOW_ANY;
            } else {
                utf8_source = FALSE;
                utf8_flags  = 0; /* Unused, but keep compilers happy */
@@ -2813,13 +2444,13 @@ S_pack_rec(pTHX_ SV *cat, tempsym_t* symptr, SV **beglist, SV **endlist )
            if (howlen == e_star) len = fromlen;
            field_len = (len+7)/8;
            GROWING(utf8, cat, start, cur, field_len);
-           if (len > (I32)fromlen) len = fromlen;
+           if (len > (SSize_t)fromlen) len = fromlen;
            bits = 0;
            l = 0;
            if (datumtype == 'B')
                while (l++ < len) {
                    if (utf8_source) {
-                       UV val;
+                       UV val = 0;
                        NEXT_UNI_VAL(val, cur, str, end, utf8_flags);
                        bits |= val & 1;
                    } else bits |= *str++ & 1;
@@ -2833,7 +2464,7 @@ S_pack_rec(pTHX_ SV *cat, tempsym_t* symptr, SV **beglist, SV **endlist )
                /* datumtype == 'b' */
                while (l++ < len) {
                    if (utf8_source) {
-                       UV val;
+                       UV val = 0;
                        NEXT_UNI_VAL(val, cur, str, end, utf8_flags);
                        if (val & 1) bits |= 0x80;
                    } else if (*str++ & 1)
@@ -2863,18 +2494,18 @@ S_pack_rec(pTHX_ SV *cat, tempsym_t* symptr, SV **beglist, SV **endlist )
        }
        case 'H':
        case 'h': {
-           char *str, *end;
-           I32 l, field_len;
+           const char *str, *end;
+           SSize_t l, field_len;
            U8 bits;
            bool utf8_source;
            U32 utf8_flags;
 
            fromstr = NEXTFROM;
-           str = SvPV(fromstr, fromlen);
+           str = SvPV_const(fromstr, fromlen);
            end = str + fromlen;
            if (DO_UTF8(fromstr)) {
                utf8_source = TRUE;
-               utf8_flags  = ckWARN(WARN_UTF8) ? 0 : UTF8_ALLOW_ANY;
+               utf8_flags  = warn_utf8 ? 0 : UTF8_ALLOW_ANY;
            } else {
                utf8_source = FALSE;
                utf8_flags  = 0; /* Unused, but keep compilers happy */
@@ -2882,13 +2513,13 @@ S_pack_rec(pTHX_ SV *cat, tempsym_t* symptr, SV **beglist, SV **endlist )
            if (howlen == e_star) len = fromlen;
            field_len = (len+1)/2;
            GROWING(utf8, cat, start, cur, field_len);
-           if (!utf8 && len > (I32)fromlen) len = fromlen;
+           if (!utf8_source && len > (SSize_t)fromlen) len = fromlen;
            bits = 0;
            l = 0;
            if (datumtype == 'H')
                while (l++ < len) {
                    if (utf8_source) {
-                       UV val;
+                       UV val = 0;
                        NEXT_UNI_VAL(val, cur, str, end, utf8_flags);
                        if (val < 256 && isALPHA(val))
                            bits |= (val + 9) & 0xf;
@@ -2907,7 +2538,7 @@ S_pack_rec(pTHX_ SV *cat, tempsym_t* symptr, SV **beglist, SV **endlist )
            else
                while (l++ < len) {
                    if (utf8_source) {
-                       UV val;
+                       UV val = 0;
                        NEXT_UNI_VAL(val, cur, str, end, utf8_flags);
                        if (val < 256 && isALPHA(val))
                            bits |= ((val + 9) & 0xf) << 4;
@@ -2940,12 +2571,11 @@ S_pack_rec(pTHX_ SV *cat, tempsym_t* symptr, SV **beglist, SV **endlist )
            while (len-- > 0) {
                IV aiv;
                fromstr = NEXTFROM;
-               aiv = SvIV(fromstr);
-               if ((-128 > aiv || aiv > 127) &&
-                   ckWARN(WARN_PACK))
-                   Perl_warner(aTHX_ packWARN(WARN_PACK),
-                               "Character in 'c' format wrapped in pack");
-               PUSH_BYTE(utf8, cur, aiv & 0xff);
+                aiv = SvIV_no_inf(fromstr, datumtype);
+               if ((-128 > aiv || aiv > 127))
+                   Perl_ck_warner(aTHX_ packWARN(WARN_PACK),
+                                  "Character in 'c' format wrapped in pack");
+               PUSH_BYTE(utf8, cur, (U8)(aiv & 0xff));
            }
            break;
        case 'C':
@@ -2953,42 +2583,37 @@ S_pack_rec(pTHX_ SV *cat, tempsym_t* symptr, SV **beglist, SV **endlist )
                utf8 = (symptr->flags & FLAG_DO_UTF8) ? 1 : 0;
                break;
            }
-           GROWING(0, cat, start, cur, len);
            while (len-- > 0) {
                IV aiv;
                fromstr = NEXTFROM;
-               aiv = SvIV(fromstr);
-               if ((0 > aiv || aiv > 0xff) &&
-                   ckWARN(WARN_PACK))
-                   Perl_warner(aTHX_ packWARN(WARN_PACK),
-                               "Character in 'C' format wrapped in pack");
-               *cur++ = aiv & 0xff;
+                aiv = SvIV_no_inf(fromstr, datumtype);
+               if ((0 > aiv || aiv > 0xff))
+                   Perl_ck_warner(aTHX_ packWARN(WARN_PACK),
+                                  "Character in 'C' format wrapped in pack");
+               PUSH_BYTE(utf8, cur, (U8)(aiv & 0xff));
            }
            break;
        case 'W': {
            char *end;
-           U8 in_bytes = IN_BYTES;
+           U8 in_bytes = (U8)IN_BYTES;
 
            end = start+SvLEN(cat)-1;
            if (utf8) end -= UTF8_MAXLEN-1;
            while (len-- > 0) {
                UV auv;
                fromstr = NEXTFROM;
-               auv = SvUV(fromstr);
+               auv = SvUV_no_inf(fromstr, datumtype);
                if (in_bytes) auv = auv % 0x100;
                if (utf8) {
                  W_utf8:
-                   if (cur > end) {
+                   if (cur >= end) {
                        *cur = '\0';
                        SvCUR_set(cat, cur - start);
 
                        GROWING(0, cat, start, cur, len+UTF8_MAXLEN);
                        end = start+SvLEN(cat)-UTF8_MAXLEN;
                    }
-                   cur = (char *) uvuni_to_utf8_flags((U8 *) cur,
-                                                      NATIVE_TO_UNI(auv),
-                                                      ckWARN(WARN_UTF8) ?
-                                                      0 : UNICODE_ALLOW_ANY);
+                   cur = (char *) uvchr_to_utf8_flags((U8 *) cur, auv, 0);
                } else {
                    if (auv >= 0x100) {
                        if (!SvUTF8(cat)) {
@@ -3003,9 +2628,8 @@ S_pack_rec(pTHX_ SV *cat, tempsym_t* symptr, SV **beglist, SV **endlist )
                            end = start+SvLEN(cat)-UTF8_MAXLEN;
                            goto W_utf8;
                        }
-                       if (ckWARN(WARN_PACK))
-                           Perl_warner(aTHX_ packWARN(WARN_PACK),
-                                       "Character in 'W' format wrapped in pack");
+                       Perl_ck_warner(aTHX_ packWARN(WARN_PACK),
+                                      "Character in 'W' format wrapped in pack");
                        auv &= 0xff;
                    }
                    if (cur >= end) {
@@ -3037,12 +2661,10 @@ S_pack_rec(pTHX_ SV *cat, tempsym_t* symptr, SV **beglist, SV **endlist )
            while (len-- > 0) {
                UV auv;
                fromstr = NEXTFROM;
-               auv = SvUV(fromstr);
+               auv = SvUV_no_inf(fromstr, datumtype);
                if (utf8) {
-                   U8 buffer[UTF8_MAXLEN], *endb;
-                   endb = uvuni_to_utf8_flags(buffer, auv,
-                                              ckWARN(WARN_UTF8) ?
-                                              0 : UNICODE_ALLOW_ANY);
+                   U8 buffer[UTF8_MAXLEN+1], *endb;
+                   endb = uvchr_to_utf8_flags(buffer, UNI_TO_NATIVE(auv), 0);
                    if (cur+(endb-buffer)*UTF8_EXPAND >= end) {
                        *cur = '\0';
                        SvCUR_set(cat, cur - start);
@@ -3050,7 +2672,7 @@ S_pack_rec(pTHX_ SV *cat, tempsym_t* symptr, SV **beglist, SV **endlist )
                                len+(endb-buffer)*UTF8_EXPAND);
                        end = start+SvLEN(cat);
                    }
-                   bytes_to_uni(aTHX_ buffer, endb-buffer, &cur);
+                    cur = my_bytes_to_utf8(buffer, endb-buffer, cur, 0);
                } else {
                    if (cur >= end) {
                        *cur = '\0';
@@ -3058,9 +2680,9 @@ S_pack_rec(pTHX_ SV *cat, tempsym_t* symptr, SV **beglist, SV **endlist )
                        GROWING(0, cat, start, cur, len+UTF8_MAXLEN);
                        end = start+SvLEN(cat)-UTF8_MAXLEN;
                    }
-                   cur = (char *) uvuni_to_utf8_flags((U8 *) cur, auv,
-                                                      ckWARN(WARN_UTF8) ?
-                                                      0 : UNICODE_ALLOW_ANY);
+                   cur = (char *) uvchr_to_utf8_flags((U8 *) cur,
+                                                       UNI_TO_NATIVE(auv),
+                                                      0);
                }
            }
            break;
@@ -3072,20 +2694,7 @@ S_pack_rec(pTHX_ SV *cat, tempsym_t* symptr, SV **beglist, SV **endlist )
                NV anv;
                fromstr = NEXTFROM;
                anv = SvNV(fromstr);
-#ifdef __VOS__
-               /* VOS does not automatically map a floating-point overflow
-                  during conversion from double to float into infinity, so we
-                  do it by hand.  This code should either be generalized for
-                  any OS that needs it, or removed if and when VOS implements
-                  posix-976 (suggestion to support mapping to infinity).
-                  Paul.Green@stratus.com 02-04-02.  */
-               if (anv > FLT_MAX)
-                   afloat = _float_constants[0];   /* single prec. inf. */
-               else if (anv < -FLT_MAX)
-                   afloat = _float_constants[0];   /* single prec. inf. */
-               else afloat = (float) anv;
-#else /* __VOS__ */
-# if defined(VMS) && !defined(__IEEE_FP)
+# if (defined(VMS) && !defined(_IEEE_FP)) || defined(DOUBLE_IS_VAX_FLOAT)
                /* IEEE fp overflow shenanigans are unavailable on VAX and optional
                 * on Alpha; fake it if we don't have them.
                 */
@@ -3095,11 +2704,19 @@ S_pack_rec(pTHX_ SV *cat, tempsym_t* symptr, SV **beglist, SV **endlist )
                    afloat = -FLT_MAX;
                else afloat = (float)anv;
 # else
-               afloat = (float)anv;
+#  if defined(NAN_COMPARE_BROKEN) && defined(Perl_isnan)
+               if(Perl_isnan(anv))
+                   afloat = (float)NV_NAN;
+               else
+#  endif
+#  ifdef NV_INF
+                /* a simple cast to float is undefined if outside
+                 * the range of values that can be represented */
+               afloat = (float)(anv >  FLT_MAX ?  NV_INF :
+                                 anv < -FLT_MAX ? -NV_INF : anv);
+#  endif
 # endif
-#endif /* __VOS__ */
-               DO_BO_PACK_N(afloat, float);
-               PUSH_VAR(utf8, cur, afloat);
+                PUSH_VAR(utf8, cur, afloat, needs_swap);
            }
            break;
        case 'd':
@@ -3108,20 +2725,7 @@ S_pack_rec(pTHX_ SV *cat, tempsym_t* symptr, SV **beglist, SV **endlist )
                NV anv;
                fromstr = NEXTFROM;
                anv = SvNV(fromstr);
-#ifdef __VOS__
-               /* VOS does not automatically map a floating-point overflow
-                  during conversion from long double to double into infinity,
-                  so we do it by hand.  This code should either be generalized
-                  for any OS that needs it, or removed if and when VOS
-                  implements posix-976 (suggestion to support mapping to
-                  infinity).  Paul.Green@stratus.com 02-04-02.  */
-               if (anv > DBL_MAX)
-                   adouble = _double_constants[0];   /* double prec. inf. */
-               else if (anv < -DBL_MAX)
-                   adouble = _double_constants[0];   /* double prec. inf. */
-               else adouble = (double) anv;
-#else /* __VOS__ */
-# if defined(VMS) && !defined(__IEEE_FP)
+# if (defined(VMS) && !defined(_IEEE_FP)) || defined(DOUBLE_IS_VAX_FLOAT)
                /* IEEE fp overflow shenanigans are unavailable on VAX and optional
                 * on Alpha; fake it if we don't have them.
                 */
@@ -3133,62 +2737,72 @@ S_pack_rec(pTHX_ SV *cat, tempsym_t* symptr, SV **beglist, SV **endlist )
 # else
                adouble = (double)anv;
 # endif
-#endif /* __VOS__ */
-               DO_BO_PACK_N(adouble, double);
-               PUSH_VAR(utf8, cur, adouble);
+                PUSH_VAR(utf8, cur, adouble, needs_swap);
            }
            break;
        case 'F': {
-           NV anv;
+           NV_bytes anv;
            Zero(&anv, 1, NV); /* can be long double with unused bits */
            while (len-- > 0) {
                fromstr = NEXTFROM;
-               anv = SvNV(fromstr);
-               DO_BO_PACK_N(anv, NV);
-               PUSH_VAR(utf8, cur, anv);
+#ifdef __GNUC__
+               /* to work round a gcc/x86 bug; don't use SvNV */
+               anv.nv = sv_2nv(fromstr);
+#    if defined(LONGDOUBLE_X86_80_BIT) && defined(USE_LONG_DOUBLE) \
+         && LONG_DOUBLESIZE > 10
+                /* GCC sometimes overwrites the padding in the
+                   assignment above */
+                Zero(anv.bytes+10, sizeof(anv.bytes) - 10, U8);
+#    endif
+#else
+               anv.nv = SvNV(fromstr);
+#endif
+                PUSH_BYTES(utf8, cur, anv.bytes, sizeof(anv.bytes), needs_swap);
            }
            break;
        }
 #if defined(HAS_LONG_DOUBLE) && defined(USE_LONG_DOUBLE)
        case 'D': {
-           long double aldouble;
+           ld_bytes aldouble;
            /* long doubles can have unused bits, which may be nonzero */
            Zero(&aldouble, 1, long double);
            while (len-- > 0) {
                fromstr = NEXTFROM;
-               aldouble = (long double)SvNV(fromstr);
-               DO_BO_PACK_N(aldouble, long double);
-               PUSH_VAR(utf8, cur, aldouble);
+#  ifdef __GNUC__
+               /* to work round a gcc/x86 bug; don't use SvNV */
+               aldouble.ld = (long double)sv_2nv(fromstr);
+#    if defined(LONGDOUBLE_X86_80_BIT) && LONG_DOUBLESIZE > 10
+                /* GCC sometimes overwrites the padding in the
+                   assignment above */
+                Zero(aldouble.bytes+10, sizeof(aldouble.bytes) - 10, U8);
+#    endif
+#  else
+               aldouble.ld = (long double)SvNV(fromstr);
+#  endif
+                PUSH_BYTES(utf8, cur, aldouble.bytes, sizeof(aldouble.bytes),
+                           needs_swap);
            }
            break;
        }
 #endif
-#ifdef PERL_PACK_CAN_SHRIEKSIGN
        case 'n' | TYPE_IS_SHRIEKING:
-#endif
        case 'n':
            while (len-- > 0) {
                I16 ai16;
                fromstr = NEXTFROM;
-               ai16 = (I16)SvIV(fromstr);
-#ifdef HAS_HTONS
+               ai16 = (I16)SvIV_no_inf(fromstr, datumtype);
                ai16 = PerlSock_htons(ai16);
-#endif
-               PUSH16(utf8, cur, &ai16);
+                PUSH16(utf8, cur, &ai16, FALSE);
            }
            break;
-#ifdef PERL_PACK_CAN_SHRIEKSIGN
        case 'v' | TYPE_IS_SHRIEKING:
-#endif
        case 'v':
            while (len-- > 0) {
                I16 ai16;
                fromstr = NEXTFROM;
-               ai16 = (I16)SvIV(fromstr);
-#ifdef HAS_HTOVS
+               ai16 = (I16)SvIV_no_inf(fromstr, datumtype);
                ai16 = htovs(ai16);
-#endif
-               PUSH16(utf8, cur, &ai16);
+                PUSH16(utf8, cur, &ai16, FALSE);
            }
            break;
         case 'S' | TYPE_IS_SHRIEKING:
@@ -3196,21 +2810,19 @@ S_pack_rec(pTHX_ SV *cat, tempsym_t* symptr, SV **beglist, SV **endlist )
            while (len-- > 0) {
                unsigned short aushort;
                fromstr = NEXTFROM;
-               aushort = SvUV(fromstr);
-               DO_BO_PACK(aushort, s);
-               PUSH_VAR(utf8, cur, aushort);
+               aushort = SvUV_no_inf(fromstr, datumtype);
+                PUSH_VAR(utf8, cur, aushort, needs_swap);
            }
             break;
 #else
-            /* Fall through! */
+            /* FALLTHROUGH */
 #endif
        case 'S':
            while (len-- > 0) {
                U16 au16;
                fromstr = NEXTFROM;
-               au16 = (U16)SvUV(fromstr);
-               DO_BO_PACK(au16, 16);
-               PUSH16(utf8, cur, &au16);
+               au16 = (U16)SvUV_no_inf(fromstr, datumtype);
+                PUSH16(utf8, cur, &au16, needs_swap);
            }
            break;
        case 's' | TYPE_IS_SHRIEKING:
@@ -3218,21 +2830,19 @@ S_pack_rec(pTHX_ SV *cat, tempsym_t* symptr, SV **beglist, SV **endlist )
            while (len-- > 0) {
                short ashort;
                fromstr = NEXTFROM;
-               ashort = SvIV(fromstr);
-               DO_BO_PACK(ashort, s);
-               PUSH_VAR(utf8, cur, ashort);
+               ashort = SvIV_no_inf(fromstr, datumtype);
+                PUSH_VAR(utf8, cur, ashort, needs_swap);
            }
             break;
 #else
-            /* Fall through! */
+            /* FALLTHROUGH */
 #endif
        case 's':
            while (len-- > 0) {
                I16 ai16;
                fromstr = NEXTFROM;
-               ai16 = (I16)SvIV(fromstr);
-               DO_BO_PACK(ai16, 16);
-               PUSH16(utf8, cur, &ai16);
+               ai16 = (I16)SvIV_no_inf(fromstr, datumtype);
+                PUSH16(utf8, cur, &ai16, needs_swap);
            }
            break;
        case 'I':
@@ -3240,50 +2850,32 @@ S_pack_rec(pTHX_ SV *cat, tempsym_t* symptr, SV **beglist, SV **endlist )
            while (len-- > 0) {
                unsigned int auint;
                fromstr = NEXTFROM;
-               auint = SvUV(fromstr);
-               DO_BO_PACK(auint, i);
-               PUSH_VAR(utf8, cur, auint);
+               auint = SvUV_no_inf(fromstr, datumtype);
+                PUSH_VAR(utf8, cur, auint, needs_swap);
            }
            break;
        case 'j':
            while (len-- > 0) {
                IV aiv;
                fromstr = NEXTFROM;
-               aiv = SvIV(fromstr);
-#if IVSIZE == INTSIZE
-               DO_BO_PACK(aiv, i);
-#elif IVSIZE == LONGSIZE
-               DO_BO_PACK(aiv, l);
-#elif defined(HAS_QUAD) && IVSIZE == U64SIZE
-               DO_BO_PACK(aiv, 64);
-#else
-               Perl_croak(aTHX_ "'j' not supported on this platform");
-#endif
-               PUSH_VAR(utf8, cur, aiv);
+               aiv = SvIV_no_inf(fromstr, datumtype);
+                PUSH_VAR(utf8, cur, aiv, needs_swap);
            }
            break;
        case 'J':
            while (len-- > 0) {
                UV auv;
                fromstr = NEXTFROM;
-               auv = SvUV(fromstr);
-#if UVSIZE == INTSIZE
-               DO_BO_PACK(auv, i);
-#elif UVSIZE == LONGSIZE
-               DO_BO_PACK(auv, l);
-#elif defined(HAS_QUAD) && UVSIZE == U64SIZE
-               DO_BO_PACK(auv, 64);
-#else
-               Perl_croak(aTHX_ "'J' not supported on this platform");
-#endif
-               PUSH_VAR(utf8, cur, auv);
+               auv = SvUV_no_inf(fromstr, datumtype);
+                PUSH_VAR(utf8, cur, auv, needs_swap);
            }
            break;
        case 'w':
             while (len-- > 0) {
                NV anv;
                fromstr = NEXTFROM;
-               anv = SvNV(fromstr);
+               S_sv_check_infnan(aTHX_ fromstr, datumtype);
+               anv = SvNV_nomg(fromstr);
 
                if (anv < 0) {
                    *cur = '\0';
@@ -3299,7 +2891,7 @@ S_pack_rec(pTHX_ SV *cat, tempsym_t* symptr, SV **beglist, SV **endlist )
                if (SvIOK(fromstr) || anv < UV_MAX_P1) {
                    char   buf[(sizeof(UV)*CHAR_BIT)/7+1];
                    char  *in = buf + sizeof(buf);
-                   UV     auv = SvUV(fromstr);
+                   UV     auv = SvUV_nomg(fromstr);
 
                    do {
                        *--in = (char)((auv & 0x7f) | 0x80);
@@ -3312,7 +2904,7 @@ S_pack_rec(pTHX_ SV *cat, tempsym_t* symptr, SV **beglist, SV **endlist )
                    goto w_string;
                else if (SvNOKp(fromstr)) {
                    /* 10**NV_MAX_10_EXP is the largest power of 10
-                      so 10**(NV_MAX_10_EXP+1) is definately unrepresentable
+                      so 10**(NV_MAX_10_EXP+1) is definitely unrepresentable
                       given 10**(NV_MAX_10_EXP+1) == 128 ** x solve for x:
                       x = (NV_MAX_10_EXP+1) * log (10) / log (128)
                       And with that many bytes only Inf can overflow.
@@ -3330,9 +2922,9 @@ S_pack_rec(pTHX_ SV *cat, tempsym_t* symptr, SV **beglist, SV **endlist )
 #endif
                    char  *in = buf + sizeof(buf);
 
-                    anv = Perl_floor(anv);
+                   anv = Perl_floor(anv);
                    do {
-                       NV next = Perl_floor(anv / 128);
+                       const NV next = Perl_floor(anv / 128);
                        if (in <= buf)  /* this cannot happen ;-) */
                            Perl_croak(aTHX_ "Cannot compress integer in pack");
                        *--in = (unsigned char)(anv - (next * 128)) | 0x80;
@@ -3342,18 +2934,19 @@ S_pack_rec(pTHX_ SV *cat, tempsym_t* symptr, SV **beglist, SV **endlist )
                    PUSH_GROWING_BYTES(utf8, cat, start, cur,
                                       in, (buf + sizeof(buf)) - in);
                } else {
-                   char           *from, *result, *in;
+                   const char     *from;
+                   char           *result, *in;
                    SV             *norm;
                    STRLEN          len;
                    bool            done;
 
                  w_string:
                    /* Copy string and check for compliance */
-                   from = SvPV(fromstr, len);
+                   from = SvPV_nomg_const(fromstr, len);
                    if ((norm = is_an_int(from, len)) == NULL)
                        Perl_croak(aTHX_ "Can only compress unsigned integers in pack");
 
-                   New('w', result, len, char);
+                   Newx(result, len, char);
                    in = result + len;
                    done = FALSE;
                    while (!done) *--in = div128(norm, &done) | 0x80;
@@ -3370,37 +2963,28 @@ S_pack_rec(pTHX_ SV *cat, tempsym_t* symptr, SV **beglist, SV **endlist )
            while (len-- > 0) {
                int aint;
                fromstr = NEXTFROM;
-               aint = SvIV(fromstr);
-               DO_BO_PACK(aint, i);
-               PUSH_VAR(utf8, cur, aint);
+               aint = SvIV_no_inf(fromstr, datumtype);
+                PUSH_VAR(utf8, cur, aint, needs_swap);
            }
            break;
-#ifdef PERL_PACK_CAN_SHRIEKSIGN
        case 'N' | TYPE_IS_SHRIEKING:
-#endif
        case 'N':
            while (len-- > 0) {
                U32 au32;
                fromstr = NEXTFROM;
-               au32 = SvUV(fromstr);
-#ifdef HAS_HTONL
+               au32 = SvUV_no_inf(fromstr, datumtype);
                au32 = PerlSock_htonl(au32);
-#endif
-               PUSH32(utf8, cur, &au32);
+                PUSH32(utf8, cur, &au32, FALSE);
            }
            break;
-#ifdef PERL_PACK_CAN_SHRIEKSIGN
        case 'V' | TYPE_IS_SHRIEKING:
-#endif
        case 'V':
            while (len-- > 0) {
                U32 au32;
                fromstr = NEXTFROM;
-               au32 = SvUV(fromstr);
-#ifdef HAS_HTOVL
+               au32 = SvUV_no_inf(fromstr, datumtype);
                au32 = htovl(au32);
-#endif
-               PUSH32(utf8, cur, &au32);
+                PUSH32(utf8, cur, &au32, FALSE);
            }
            break;
        case 'L' | TYPE_IS_SHRIEKING:
@@ -3408,9 +2992,8 @@ S_pack_rec(pTHX_ SV *cat, tempsym_t* symptr, SV **beglist, SV **endlist )
            while (len-- > 0) {
                unsigned long aulong;
                fromstr = NEXTFROM;
-               aulong = SvUV(fromstr);
-               DO_BO_PACK(aulong, l);
-               PUSH_VAR(utf8, cur, aulong);
+               aulong = SvUV_no_inf(fromstr, datumtype);
+                PUSH_VAR(utf8, cur, aulong, needs_swap);
            }
            break;
 #else
@@ -3420,9 +3003,8 @@ S_pack_rec(pTHX_ SV *cat, tempsym_t* symptr, SV **beglist, SV **endlist )
            while (len-- > 0) {
                U32 au32;
                fromstr = NEXTFROM;
-               au32 = SvUV(fromstr);
-               DO_BO_PACK(au32, 32);
-               PUSH32(utf8, cur, &au32);
+               au32 = SvUV_no_inf(fromstr, datumtype);
+                PUSH32(utf8, cur, &au32, needs_swap);
            }
            break;
        case 'l' | TYPE_IS_SHRIEKING:
@@ -3430,9 +3012,8 @@ S_pack_rec(pTHX_ SV *cat, tempsym_t* symptr, SV **beglist, SV **endlist )
            while (len-- > 0) {
                long along;
                fromstr = NEXTFROM;
-               along = SvIV(fromstr);
-               DO_BO_PACK(along, l);
-               PUSH_VAR(utf8, cur, along);
+               along = SvIV_no_inf(fromstr, datumtype);
+                PUSH_VAR(utf8, cur, along, needs_swap);
            }
            break;
 #else
@@ -3442,106 +3023,103 @@ S_pack_rec(pTHX_ SV *cat, tempsym_t* symptr, SV **beglist, SV **endlist )
             while (len-- > 0) {
                I32 ai32;
                fromstr = NEXTFROM;
-               ai32 = SvIV(fromstr);
-               DO_BO_PACK(ai32, 32);
-               PUSH32(utf8, cur, &ai32);
+               ai32 = SvIV_no_inf(fromstr, datumtype);
+                PUSH32(utf8, cur, &ai32, needs_swap);
            }
            break;
-#ifdef HAS_QUAD
+#if defined(HAS_QUAD) && IVSIZE >= 8
        case 'Q':
            while (len-- > 0) {
                Uquad_t auquad;
                fromstr = NEXTFROM;
-               auquad = (Uquad_t) SvUV(fromstr);
-               DO_BO_PACK(auquad, 64);
-               PUSH_VAR(utf8, cur, auquad);
+               auquad = (Uquad_t) SvUV_no_inf(fromstr, datumtype);
+                PUSH_VAR(utf8, cur, auquad, needs_swap);
            }
            break;
        case 'q':
            while (len-- > 0) {
                Quad_t aquad;
                fromstr = NEXTFROM;
-               aquad = (Quad_t)SvIV(fromstr);
-               DO_BO_PACK(aquad, 64);
-               PUSH_VAR(utf8, cur, aquad);
+               aquad = (Quad_t)SvIV_no_inf(fromstr, datumtype);
+                PUSH_VAR(utf8, cur, aquad, needs_swap);
            }
            break;
-#endif /* HAS_QUAD */
+#endif
        case 'P':
            len = 1;            /* assume SV is correct length */
            GROWING(utf8, cat, start, cur, sizeof(char *));
-           /* Fall through! */
+           /* FALLTHROUGH */
        case 'p':
            while (len-- > 0) {
-               char *aptr;
+               const char *aptr;
 
                fromstr = NEXTFROM;
                SvGETMAGIC(fromstr);
                if (!SvOK(fromstr)) aptr = NULL;
                else {
-                   STRLEN n_a;
                    /* XXX better yet, could spirit away the string to
                     * a safe spot and hang on to it until the result
                     * of pack() (and all copies of the result) are
                     * gone.
                     */
-                   if (ckWARN(WARN_PACK) &&
-                       (SvTEMP(fromstr) || (SvPADTMP(fromstr) &&
-                                            !SvREADONLY(fromstr)))) {
-                       Perl_warner(aTHX_ packWARN(WARN_PACK),
-                                   "Attempt to pack pointer to temporary value");
+                   if (((SvTEMP(fromstr) && SvREFCNT(fromstr) == 1)
+                        || (SvPADTMP(fromstr) &&
+                            !SvREADONLY(fromstr)))) {
+                       Perl_ck_warner(aTHX_ packWARN(WARN_PACK),
+                                      "Attempt to pack pointer to temporary value");
                    }
                    if (SvPOK(fromstr) || SvNIOK(fromstr))
-                       aptr = SvPV_flags(fromstr, n_a, 0);
+                       aptr = SvPV_nomg_const_nolen(fromstr);
                    else
-                       aptr = SvPV_force_flags(fromstr, n_a, 0);
+                       aptr = SvPV_force_flags_nolen(fromstr, 0);
                }
-               DO_BO_PACK_PC(aptr);
-               PUSH_VAR(utf8, cur, aptr);
+                PUSH_VAR(utf8, cur, aptr, needs_swap);
            }
            break;
        case 'u': {
-           char *aptr, *aend;
+           const char *aptr, *aend;
            bool from_utf8;
 
            fromstr = NEXTFROM;
            if (len <= 2) len = 45;
            else len = len / 3 * 3;
            if (len >= 64) {
-               Perl_warner(aTHX_ packWARN(WARN_PACK),
-                           "Field too wide in 'u' format in pack");
+               Perl_ck_warner(aTHX_ packWARN(WARN_PACK),
+                              "Field too wide in 'u' format in pack");
                len = 63;
            }
-           aptr = SvPV(fromstr, fromlen);
+           aptr = SvPV_const(fromstr, fromlen);
            from_utf8 = DO_UTF8(fromstr);
            if (from_utf8) {
                aend = aptr + fromlen;
-               fromlen = sv_len_utf8(fromstr);
+               fromlen = sv_len_utf8_nomg(fromstr);
            } else aend = NULL; /* Unused, but keep compilers happy */
            GROWING(utf8, cat, start, cur, (fromlen+2) / 3 * 4 + (fromlen+len-1)/len * 2);
            while (fromlen > 0) {
                U8 *end;
-               I32 todo;
+               SSize_t todo;
                U8 hunk[1+63/3*4+1];
 
-               if ((I32)fromlen > len)
+               if ((SSize_t)fromlen > len)
                    todo = len;
                else
                    todo = fromlen;
                if (from_utf8) {
                    char buffer[64];
-                   if (!uni_to_bytes(aTHX_ &aptr, aend, buffer, todo,
+                   if (!S_utf8_to_bytes(aTHX_ &aptr, aend, buffer, todo,
                                      'u' | TYPE_IS_PACK)) {
                        *cur = '\0';
                        SvCUR_set(cat, cur - start);
-                       Perl_croak(aTHX_ "Assertion: string is shorter than advertised");
+                       Perl_croak(aTHX_ "panic: string is shorter than advertised, "
+                                  "aptr=%p, aend=%p, buffer=%p, todo=%zd",
+                                  aptr, aend, buffer, todo);
                    }
-                   end = doencodes(hunk, buffer, todo);
+                   end = doencodes(hunk, (const U8 *)buffer, todo);
                } else {
-                   end = doencodes(hunk, aptr, todo);
+                   end = doencodes(hunk, (const U8 *)aptr, todo);
                    aptr += todo;
                }
-               PUSH_BYTES(utf8, cur, hunk, end-hunk);
+               PUSH_BYTES(utf8, cur, hunk, end-hunk, 0);
                fromlen -= todo;
            }
            break;
@@ -3560,17 +3138,33 @@ S_pack_rec(pTHX_ SV *cat, tempsym_t* symptr, SV **beglist, SV **endlist )
 PP(pp_pack)
 {
     dSP; dMARK; dORIGMARK; dTARGET;
-    register SV *cat = TARG;
+    SV *cat = TARG;
     STRLEN fromlen;
-    register char *pat = SvPVx(*++MARK, fromlen);
-    register char *patend = pat + fromlen;
+    SV *pat_sv = *++MARK;
+    const char *pat = SvPV_const(pat_sv, fromlen);
+    const char *patend = pat + fromlen;
 
     MARK++;
-    sv_setpvn(cat, "", 0);
+    SvPVCLEAR(cat);
     SvUTF8_off(cat);
 
     packlist(cat, pat, patend, MARK, SP + 1);
 
+    if (SvUTF8(cat)) {
+        STRLEN result_len;
+        const char * result = SvPV_nomg(cat, result_len);
+        const U8 * error_pos;
+
+        if (! is_utf8_string_loc((U8 *) result, result_len, &error_pos)) {
+            _force_out_malformed_utf8_message(error_pos,
+                                              (U8 *) result + result_len,
+                                              0, /* no flags */
+                                              1 /* Die */
+                                            );
+            NOT_REACHED; /* NOTREACHED */
+        }
+    }
+
     SvSETMAGIC(cat);
     SP = ORIGMARK;
     PUSHs(cat);
@@ -3578,11 +3172,5 @@ PP(pp_pack)
 }
 
 /*
- * Local variables:
- * c-indentation-style: bsd
- * c-basic-offset: 4
- * indent-tabs-mode: t
- * End:
- *
- * vim: shiftwidth=4:
-*/
+ * ex: set ts=8 sts=4 sw=4 et:
+ */