X-Git-Url: https://perl5.git.perl.org/perl5.git/blobdiff_plain/3818b22bb9ef820a2553aa5e3504220f3b156f21..cea6626fc5e04af2c1d079dd4d3784eb2c21174b:/hv.h

diff --git a/hv.h b/hv.h
index 5bc38a0..a1652d8 100644
--- a/hv.h
+++ b/hv.h
@@ -1,27 +1,31 @@
 /*    hv.h
  *
- *    Copyright (c) 1991-2000, Larry Wall
+ *    Copyright (c) 1991-2001, Larry Wall
  *
  *    You may distribute under the terms of either the GNU General Public
  *    License or the Artistic License, as specified in the README file.
  *
  */
 
+/* typedefs to eliminate some typing */
 typedef struct he HE;
 typedef struct hek HEK;
 
+/* entry in hash value chain */
 struct he {
-    HE		*hent_next;
-    HEK		*hent_hek;
-    SV		*hent_val;
+    HE		*hent_next;	/* next entry in chain */
+    HEK		*hent_hek;	/* hash key */
+    SV		*hent_val;	/* scalar value that was hashed */
 };
 
+/* hash key -- defined separately for use as shared pointer */
 struct hek {
-    U32		hek_hash;
-    I32		hek_len;
-    char	hek_key[1];
+    U32		hek_hash;	/* hash of key */
+    I32		hek_len;	/* length of hash key */
+    char	hek_key[1];	/* variable-length hash key */
 };
 
+/* hash structure: */
 /* This structure must match the beginning of struct xpvmg in sv.h. */
 struct xpvhv {
     char *	xhv_array;	/* pointer to malloced string */
@@ -38,14 +42,23 @@ struct xpvhv {
     char	*xhv_name;	/* name, if a symbol table */
 };
 
+/* hash a key */
+/* FYI: This is the "One-at-a-Time" algorithm by Bob Jenkins */
+/* from requirements by Colin Plumb. */
+/* (http://burtleburtle.net/bob/hash/doobs.html) */
 #define PERL_HASH(hash,str,len) \
      STMT_START	{ \
 	register const char *s_PeRlHaSh = str; \
 	register I32 i_PeRlHaSh = len; \
 	register U32 hash_PeRlHaSh = 0; \
-	while (i_PeRlHaSh--) \
-	    hash_PeRlHaSh = hash_PeRlHaSh * 33 + *s_PeRlHaSh++; \
-	(hash) = hash_PeRlHaSh + (hash_PeRlHaSh>>5); \
+	while (i_PeRlHaSh--) { \
+	    hash_PeRlHaSh += *s_PeRlHaSh++; \
+	    hash_PeRlHaSh += (hash_PeRlHaSh << 10); \
+	    hash_PeRlHaSh ^= (hash_PeRlHaSh >> 6); \
+	} \
+	hash_PeRlHaSh += (hash_PeRlHaSh << 3); \
+	hash_PeRlHaSh ^= (hash_PeRlHaSh >> 11); \
+	(hash) = (hash_PeRlHaSh += (hash_PeRlHaSh << 15)); \
     } STMT_END
 
 /*
@@ -146,6 +159,8 @@ C<SV*>.
 #define HeKEY(he)		HEK_KEY(HeKEY_hek(he))
 #define HeKEY_sv(he)		(*(SV**)HeKEY(he))
 #define HeKLEN(he)		HEK_LEN(HeKEY_hek(he))
+#define HeKUTF8(he)  HEK_UTF8(HeKEY_hek(he))
+#define HeKLEN_UTF8(he)  (HeKUTF8(he) ? -HeKLEN(he) : HeKLEN(he))
 #define HeVAL(he)		(he)->hent_val
 #define HeHASH(he)		HEK_HASH(HeKEY_hek(he))
 #define HePV(he,lp)		((HeKLEN(he) == HEf_SVKEY) ?		\
@@ -170,7 +185,9 @@ C<SV*>.
 #define HEK_HASH(hek)		(hek)->hek_hash
 #define HEK_LEN(hek)		(hek)->hek_len
 #define HEK_KEY(hek)		(hek)->hek_key
+#define HEK_UTF8(hek)  (*(HEK_KEY(hek)+HEK_LEN(hek)))
 
+/* calculate HV array allocation */
 #if defined(STRANGE_MALLOC) || defined(MYMALLOC)
 #  define PERL_HV_ARRAY_ALLOC_BYTES(size) ((size) * sizeof(HE*))
 #else