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[perl5.git] / sv.c

/*    sv.c
 *
 *    Copyright (c) 1991-1997, 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.
 *
 */

/*
 * "I wonder what the Entish is for 'yes' and 'no'," he thought.
 */

#include "EXTERN.h"
#include "perl.h"

#ifdef OVR_DBL_DIG
/* Use an overridden DBL_DIG */
# ifdef DBL_DIG
#  undef DBL_DIG
# endif
# define DBL_DIG OVR_DBL_DIG
#else
/* The following is all to get DBL_DIG, in order to pick a nice
   default value for printing floating point numbers in Gconvert.
   (see config.h)
*/
#ifdef I_LIMITS
#include <limits.h>
#endif
#ifdef I_FLOAT
#include <float.h>
#endif
#ifndef HAS_DBL_DIG
#define DBL_DIG	15   /* A guess that works lots of places */
#endif
#endif

#ifdef PERL_OBJECT
#define FCALL this->*f
#define VTBL this->*vtbl

#else /* !PERL_OBJECT */

static IV asIV _((SV* sv));
static UV asUV _((SV* sv));
static SV *more_sv _((void));
static void more_xiv _((void));
static void more_xnv _((void));
static void more_xpv _((void));
static void more_xrv _((void));
static XPVIV *new_xiv _((void));
static XPVNV *new_xnv _((void));
static XPV *new_xpv _((void));
static XRV *new_xrv _((void));
static void del_xiv _((XPVIV* p));
static void del_xnv _((XPVNV* p));
static void del_xpv _((XPV* p));
static void del_xrv _((XRV* p));
static void sv_mortalgrow _((void));
static void sv_unglob _((SV* sv));
static void sv_check_thinkfirst _((SV *sv));

#ifndef PURIFY
static void *my_safemalloc(MEM_SIZE size);
#endif

typedef void (*SVFUNC) _((SV*));
#define VTBL *vtbl
#define FCALL *f

#endif /* PERL_OBJECT */

#define SV_CHECK_THINKFIRST(sv) if (SvTHINKFIRST(sv)) sv_check_thinkfirst(sv)

#ifdef PURIFY

#define new_SV(p)			\
    do {				\
	LOCK_SV_MUTEX;			\
	(p) = (SV*)safemalloc(sizeof(SV)); \
	reg_add(p);			\
	UNLOCK_SV_MUTEX;		\
    } while (0)

#define del_SV(p)			\
    do {				\
	LOCK_SV_MUTEX;			\
	reg_remove(p);			\
        Safefree((char*)(p));		\
	UNLOCK_SV_MUTEX;		\
    } while (0)

static SV **registry;
static I32 registry_size;

#define REGHASH(sv,size)  ((((U32)(sv)) >> 2) % (size))

#define REG_REPLACE(sv,a,b) \
    do {				\
	void* p = sv->sv_any;		\
	I32 h = REGHASH(sv, registry_size);	\
	I32 i = h;			\
	while (registry[i] != (a)) {	\
	    if (++i >= registry_size)	\
		i = 0;			\
	    if (i == h)			\
		die("SV registry bug");	\
	}				\
	registry[i] = (b);		\
    } while (0)

#define REG_ADD(sv)	REG_REPLACE(sv,Nullsv,sv)
#define REG_REMOVE(sv)	REG_REPLACE(sv,sv,Nullsv)

static void
reg_add(sv)
SV* sv;
{
    if (PL_sv_count >= (registry_size >> 1))
    {
	SV **oldreg = registry;
	I32 oldsize = registry_size;

	registry_size = registry_size ? ((registry_size << 2) + 1) : 2037;
	Newz(707, registry, registry_size, SV*);

	if (oldreg) {
	    I32 i;

	    for (i = 0; i < oldsize; ++i) {
		SV* oldsv = oldreg[i];
		if (oldsv)
		    REG_ADD(oldsv);
	    }
	    Safefree(oldreg);
	}
    }

    REG_ADD(sv);
    ++PL_sv_count;
}

static void
reg_remove(sv)
SV* sv;
{
    REG_REMOVE(sv);
    --PL_sv_count;
}

static void
visit(f)
SVFUNC f;
{
    I32 i;

    for (i = 0; i < registry_size; ++i) {
	SV* sv = registry[i];
	if (sv && SvTYPE(sv) != SVTYPEMASK)
	    (*f)(sv);
    }
}

void
sv_add_arena(ptr, size, flags)
char* ptr;
U32 size;
U32 flags;
{
    if (!(flags & SVf_FAKE))
	Safefree(ptr);
}

#else /* ! PURIFY */

/*
 * "A time to plant, and a time to uproot what was planted..."
 */

#define plant_SV(p)			\
    do {				\
	SvANY(p) = (void *)PL_sv_root;	\
	SvFLAGS(p) = SVTYPEMASK;	\
	PL_sv_root = (p);			\
	--PL_sv_count;			\
    } while (0)

/* sv_mutex must be held while calling uproot_SV() */
#define uproot_SV(p)			\
    do {				\
	(p) = PL_sv_root;			\
	PL_sv_root = (SV*)SvANY(p);	\
	++PL_sv_count;			\
    } while (0)

#define new_SV(p)	do {	\
	LOCK_SV_MUTEX;		\
	if (PL_sv_root)		\
	    uproot_SV(p);	\
	else			\
	    (p) = more_sv();	\
	UNLOCK_SV_MUTEX;	\
    } while (0)

#ifdef DEBUGGING

#define del_SV(p)	do {	\
	LOCK_SV_MUTEX;		\
	if (PL_debug & 32768)	\
	    del_sv(p);		\
	else			\
	    plant_SV(p);	\
	UNLOCK_SV_MUTEX;	\
    } while (0)

STATIC void
del_sv(SV *p)
{
    if (PL_debug & 32768) {
	SV* sva;
	SV* sv;
	SV* svend;
	int ok = 0;
	for (sva = PL_sv_arenaroot; sva; sva = (SV *) SvANY(sva)) {
	    sv = sva + 1;
	    svend = &sva[SvREFCNT(sva)];
	    if (p >= sv && p < svend)
		ok = 1;
	}
	if (!ok) {
	    warn("Attempt to free non-arena SV: 0x%lx", (unsigned long)p);
	    return;
	}
    }
    plant_SV(p);
}

#else /* ! DEBUGGING */

#define del_SV(p)   plant_SV(p)

#endif /* DEBUGGING */

void
sv_add_arena(char *ptr, U32 size, U32 flags)
{
    SV* sva = (SV*)ptr;
    register SV* sv;
    register SV* svend;
    Zero(sva, size, char);

    /* The first SV in an arena isn't an SV. */
    SvANY(sva) = (void *) PL_sv_arenaroot;		/* ptr to next arena */
    SvREFCNT(sva) = size / sizeof(SV);		/* number of SV slots */
    SvFLAGS(sva) = flags;			/* FAKE if not to be freed */

    PL_sv_arenaroot = sva;
    PL_sv_root = sva + 1;

    svend = &sva[SvREFCNT(sva) - 1];
    sv = sva + 1;
    while (sv < svend) {
	SvANY(sv) = (void *)(SV*)(sv + 1);
	SvFLAGS(sv) = SVTYPEMASK;
	sv++;
    }
    SvANY(sv) = 0;
    SvFLAGS(sv) = SVTYPEMASK;
}

/* sv_mutex must be held while calling more_sv() */
STATIC SV*
more_sv(void)
{
    register SV* sv;

    if (PL_nice_chunk) {
	sv_add_arena(PL_nice_chunk, PL_nice_chunk_size, 0);
	PL_nice_chunk = Nullch;
    }
    else {
	char *chunk;                /* must use New here to match call to */
	New(704,chunk,1008,char);   /* Safefree() in sv_free_arenas()     */
	sv_add_arena(chunk, 1008, 0);
    }
    uproot_SV(sv);
    return sv;
}

STATIC void
visit(SVFUNC f)
{
    SV* sva;
    SV* sv;
    register SV* svend;

    for (sva = PL_sv_arenaroot; sva; sva = (SV*)SvANY(sva)) {
	svend = &sva[SvREFCNT(sva)];
	for (sv = sva + 1; sv < svend; ++sv) {
	    if (SvTYPE(sv) != SVTYPEMASK)
		(FCALL)(sv);
	}
    }
}

#endif /* PURIFY */

STATIC void
do_report_used(SV *sv)
{
    if (SvTYPE(sv) != SVTYPEMASK) {
	/* XXX Perhaps this ought to go to Perl_debug_log, if DEBUGGING. */
	PerlIO_printf(PerlIO_stderr(), "****\n");
	sv_dump(sv);
    }
}

void
sv_report_used(void)
{
    visit(FUNC_NAME_TO_PTR(do_report_used));
}

STATIC void
do_clean_objs(SV *sv)
{
    SV* rv;

    if (SvROK(sv) && SvOBJECT(rv = SvRV(sv))) {
	DEBUG_D((PerlIO_printf(Perl_debug_log, "Cleaning object ref:\n "), sv_dump(sv));)
	SvROK_off(sv);
	SvRV(sv) = 0;
	SvREFCNT_dec(rv);
    }

    /* XXX Might want to check arrays, etc. */
}

#ifndef DISABLE_DESTRUCTOR_KLUDGE
STATIC void
do_clean_named_objs(SV *sv)
{
    if (SvTYPE(sv) == SVt_PVGV) {
	if ( SvOBJECT(GvSV(sv)) ||
	     GvAV(sv) && SvOBJECT(GvAV(sv)) ||
	     GvHV(sv) && SvOBJECT(GvHV(sv)) ||
	     GvIO(sv) && SvOBJECT(GvIO(sv)) ||
	     GvCV(sv) && SvOBJECT(GvCV(sv)) )
	{
	    DEBUG_D((PerlIO_printf(Perl_debug_log, "Cleaning named glob object:\n "), sv_dump(sv));)
	    SvREFCNT_dec(sv);
	}
    }
}
#endif

void
sv_clean_objs(void)
{
    PL_in_clean_objs = TRUE;
    visit(FUNC_NAME_TO_PTR(do_clean_objs));
#ifndef DISABLE_DESTRUCTOR_KLUDGE
    /* some barnacles may yet remain, clinging to typeglobs */
    visit(FUNC_NAME_TO_PTR(do_clean_named_objs));
#endif
    PL_in_clean_objs = FALSE;
}

STATIC void
do_clean_all(SV *sv)
{
    DEBUG_D((PerlIO_printf(Perl_debug_log, "Cleaning loops: SV at 0x%lx\n", sv) );)
    SvFLAGS(sv) |= SVf_BREAK;
    SvREFCNT_dec(sv);
}

void
sv_clean_all(void)
{
    PL_in_clean_all = TRUE;
    visit(FUNC_NAME_TO_PTR(do_clean_all));
    PL_in_clean_all = FALSE;
}

void
sv_free_arenas(void)
{
    SV* sva;
    SV* svanext;

    /* Free arenas here, but be careful about fake ones.  (We assume
       contiguity of the fake ones with the corresponding real ones.) */

    for (sva = PL_sv_arenaroot; sva; sva = svanext) {
	svanext = (SV*) SvANY(sva);
	while (svanext && SvFAKE(svanext))
	    svanext = (SV*) SvANY(svanext);

	if (!SvFAKE(sva))
	    Safefree((void *)sva);
    }

    if (PL_nice_chunk)
	Safefree(PL_nice_chunk);
    PL_nice_chunk = Nullch;
    PL_nice_chunk_size = 0;
    PL_sv_arenaroot = 0;
    PL_sv_root = 0;
}

STATIC XPVIV*
new_xiv(void)
{
    IV* xiv;
    LOCK_SV_MUTEX;
    if (!PL_xiv_root)
	more_xiv();
    xiv = PL_xiv_root;
    /*
     * See comment in more_xiv() -- RAM.
     */
    PL_xiv_root = *(IV**)xiv;
    UNLOCK_SV_MUTEX;
    return (XPVIV*)((char*)xiv - STRUCT_OFFSET(XPVIV, xiv_iv));
}

STATIC void
del_xiv(XPVIV *p)
{
    IV* xiv = (IV*)((char*)(p) + STRUCT_OFFSET(XPVIV, xiv_iv));
    LOCK_SV_MUTEX;
    *(IV**)xiv = PL_xiv_root;
    PL_xiv_root = xiv;
    UNLOCK_SV_MUTEX;
}

STATIC void
more_xiv(void)
{
    register IV* xiv;
    register IV* xivend;
    XPV* ptr;
    New(705, ptr, 1008/sizeof(XPV), XPV);
    ptr->xpv_pv = (char*)PL_xiv_arenaroot;		/* linked list of xiv arenas */
    PL_xiv_arenaroot = ptr;			/* to keep Purify happy */

    xiv = (IV*) ptr;
    xivend = &xiv[1008 / sizeof(IV) - 1];
    xiv += (sizeof(XPV) - 1) / sizeof(IV) + 1;   /* fudge by size of XPV */
    PL_xiv_root = xiv;
    while (xiv < xivend) {
	*(IV**)xiv = (IV *)(xiv + 1);
	xiv++;
    }
    *(IV**)xiv = 0;
}

STATIC XPVNV*
new_xnv(void)
{
    double* xnv;
    LOCK_SV_MUTEX;
    if (!PL_xnv_root)
	more_xnv();
    xnv = PL_xnv_root;
    PL_xnv_root = *(double**)xnv;
    UNLOCK_SV_MUTEX;
    return (XPVNV*)((char*)xnv - STRUCT_OFFSET(XPVNV, xnv_nv));
}

STATIC void
del_xnv(XPVNV *p)
{
    double* xnv = (double*)((char*)(p) + STRUCT_OFFSET(XPVNV, xnv_nv));
    LOCK_SV_MUTEX;
    *(double**)xnv = PL_xnv_root;
    PL_xnv_root = xnv;
    UNLOCK_SV_MUTEX;
}

STATIC void
more_xnv(void)
{
    register double* xnv;
    register double* xnvend;
    New(711, xnv, 1008/sizeof(double), double);
    xnvend = &xnv[1008 / sizeof(double) - 1];
    xnv += (sizeof(XPVIV) - 1) / sizeof(double) + 1; /* fudge by sizeof XPVIV */
    PL_xnv_root = xnv;
    while (xnv < xnvend) {
	*(double**)xnv = (double*)(xnv + 1);
	xnv++;
    }
    *(double**)xnv = 0;
}

STATIC XRV*
new_xrv(void)
{
    XRV* xrv;
    LOCK_SV_MUTEX;
    if (!PL_xrv_root)
	more_xrv();
    xrv = PL_xrv_root;
    PL_xrv_root = (XRV*)xrv->xrv_rv;
    UNLOCK_SV_MUTEX;
    return xrv;
}

STATIC void
del_xrv(XRV *p)
{
    LOCK_SV_MUTEX;
    p->xrv_rv = (SV*)PL_xrv_root;
    PL_xrv_root = p;
    UNLOCK_SV_MUTEX;
}

STATIC void
more_xrv(void)
{
    register XRV* xrv;
    register XRV* xrvend;
    New(712, PL_xrv_root, 1008/sizeof(XRV), XRV);
    xrv = PL_xrv_root;
    xrvend = &xrv[1008 / sizeof(XRV) - 1];
    while (xrv < xrvend) {
	xrv->xrv_rv = (SV*)(xrv + 1);
	xrv++;
    }
    xrv->xrv_rv = 0;
}

STATIC XPV*
new_xpv(void)
{
    XPV* xpv;
    LOCK_SV_MUTEX;
    if (!PL_xpv_root)
	more_xpv();
    xpv = PL_xpv_root;
    PL_xpv_root = (XPV*)xpv->xpv_pv;
    UNLOCK_SV_MUTEX;
    return xpv;
}

STATIC void
del_xpv(XPV *p)
{
    LOCK_SV_MUTEX;
    p->xpv_pv = (char*)PL_xpv_root;
    PL_xpv_root = p;
    UNLOCK_SV_MUTEX;
}

STATIC void
more_xpv(void)
{
    register XPV* xpv;
    register XPV* xpvend;
    New(713, PL_xpv_root, 1008/sizeof(XPV), XPV);
    xpv = PL_xpv_root;
    xpvend = &xpv[1008 / sizeof(XPV) - 1];
    while (xpv < xpvend) {
	xpv->xpv_pv = (char*)(xpv + 1);
	xpv++;
    }
    xpv->xpv_pv = 0;
}

#ifdef PURIFY
#define new_XIV() (void*)safemalloc(sizeof(XPVIV))
#define del_XIV(p) Safefree((char*)p)
#else
#define new_XIV() (void*)new_xiv()
#define del_XIV(p) del_xiv((XPVIV*) p)
#endif

#ifdef PURIFY
#define new_XNV() (void*)safemalloc(sizeof(XPVNV))
#define del_XNV(p) Safefree((char*)p)
#else
#define new_XNV() (void*)new_xnv()
#define del_XNV(p) del_xnv((XPVNV*) p)
#endif

#ifdef PURIFY
#define new_XRV() (void*)safemalloc(sizeof(XRV))
#define del_XRV(p) Safefree((char*)p)
#else
#define new_XRV() (void*)new_xrv()
#define del_XRV(p) del_xrv((XRV*) p)
#endif

#ifdef PURIFY
#define new_XPV() (void*)safemalloc(sizeof(XPV))
#define del_XPV(p) Safefree((char*)p)
#else
#define new_XPV() (void*)new_xpv()
#define del_XPV(p) del_xpv((XPV *)p)
#endif

#ifdef PURIFY
#  define my_safemalloc(s) safemalloc(s)
#  define my_safefree(s) safefree(s)
#else
STATIC void* 
my_safemalloc(MEM_SIZE size)
{
    char *p;
    New(717, p, size, char);
    return (void*)p;
}
#  define my_safefree(s) Safefree(s)
#endif 

#define new_XPVIV() (void*)my_safemalloc(sizeof(XPVIV))
#define del_XPVIV(p) my_safefree((char*)p)
  
#define new_XPVNV() (void*)my_safemalloc(sizeof(XPVNV))
#define del_XPVNV(p) my_safefree((char*)p)
  
#define new_XPVMG() (void*)my_safemalloc(sizeof(XPVMG))
#define del_XPVMG(p) my_safefree((char*)p)
  
#define new_XPVLV() (void*)my_safemalloc(sizeof(XPVLV))
#define del_XPVLV(p) my_safefree((char*)p)
  
#define new_XPVAV() (void*)my_safemalloc(sizeof(XPVAV))
#define del_XPVAV(p) my_safefree((char*)p)
  
#define new_XPVHV() (void*)my_safemalloc(sizeof(XPVHV))
#define del_XPVHV(p) my_safefree((char*)p)
  
#define new_XPVCV() (void*)my_safemalloc(sizeof(XPVCV))
#define del_XPVCV(p) my_safefree((char*)p)
  
#define new_XPVGV() (void*)my_safemalloc(sizeof(XPVGV))
#define del_XPVGV(p) my_safefree((char*)p)
  
#define new_XPVBM() (void*)my_safemalloc(sizeof(XPVBM))
#define del_XPVBM(p) my_safefree((char*)p)
  
#define new_XPVFM() (void*)my_safemalloc(sizeof(XPVFM))
#define del_XPVFM(p) my_safefree((char*)p)
  
#define new_XPVIO() (void*)my_safemalloc(sizeof(XPVIO))
#define del_XPVIO(p) my_safefree((char*)p)

bool
sv_upgrade(register SV *sv, U32 mt)
{
    char*	pv;
    U32		cur;
    U32		len;
    IV		iv;
    double	nv;
    MAGIC*	magic;
    HV*		stash;

    if (SvTYPE(sv) == mt)
	return TRUE;

    if (mt < SVt_PVIV)
	(void)SvOOK_off(sv);

    switch (SvTYPE(sv)) {
    case SVt_NULL:
	pv	= 0;
	cur	= 0;
	len	= 0;
	iv	= 0;
	nv	= 0.0;
	magic	= 0;
	stash	= 0;
	break;
    case SVt_IV:
	pv	= 0;
	cur	= 0;
	len	= 0;
	iv	= SvIVX(sv);
	nv	= (double)SvIVX(sv);
	del_XIV(SvANY(sv));
	magic	= 0;
	stash	= 0;
	if (mt == SVt_NV)
	    mt = SVt_PVNV;
	else if (mt < SVt_PVIV)
	    mt = SVt_PVIV;
	break;
    case SVt_NV:
	pv	= 0;
	cur	= 0;
	len	= 0;
	nv	= SvNVX(sv);
	iv	= I_V(nv);
	magic	= 0;
	stash	= 0;
	del_XNV(SvANY(sv));
	SvANY(sv) = 0;
	if (mt < SVt_PVNV)
	    mt = SVt_PVNV;
	break;
    case SVt_RV:
	pv	= (char*)SvRV(sv);
	cur	= 0;
	len	= 0;
	iv	= (IV)pv;
	nv	= (double)(unsigned long)pv;
	del_XRV(SvANY(sv));
	magic	= 0;
	stash	= 0;
	break;
    case SVt_PV:
	pv	= SvPVX(sv);
	cur	= SvCUR(sv);
	len	= SvLEN(sv);
	iv	= 0;
	nv	= 0.0;
	magic	= 0;
	stash	= 0;
	del_XPV(SvANY(sv));
	if (mt <= SVt_IV)
	    mt = SVt_PVIV;
	else if (mt == SVt_NV)
	    mt = SVt_PVNV;
	break;
    case SVt_PVIV:
	pv	= SvPVX(sv);
	cur	= SvCUR(sv);
	len	= SvLEN(sv);
	iv	= SvIVX(sv);
	nv	= 0.0;
	magic	= 0;
	stash	= 0;
	del_XPVIV(SvANY(sv));
	break;
    case SVt_PVNV:
	pv	= SvPVX(sv);
	cur	= SvCUR(sv);
	len	= SvLEN(sv);
	iv	= SvIVX(sv);
	nv	= SvNVX(sv);
	magic	= 0;
	stash	= 0;
	del_XPVNV(SvANY(sv));
	break;
    case SVt_PVMG:
	pv	= SvPVX(sv);
	cur	= SvCUR(sv);
	len	= SvLEN(sv);
	iv	= SvIVX(sv);
	nv	= SvNVX(sv);
	magic	= SvMAGIC(sv);
	stash	= SvSTASH(sv);
	del_XPVMG(SvANY(sv));
	break;
    default:
	croak("Can't upgrade that kind of scalar");
    }

    switch (mt) {
    case SVt_NULL:
	croak("Can't upgrade to undef");
    case SVt_IV:
	SvANY(sv) = new_XIV();
	SvIVX(sv)	= iv;
	break;
    case SVt_NV:
	SvANY(sv) = new_XNV();
	SvNVX(sv)	= nv;
	break;
    case SVt_RV:
	SvANY(sv) = new_XRV();
	SvRV(sv) = (SV*)pv;
	break;
    case SVt_PV:
	SvANY(sv) = new_XPV();
	SvPVX(sv)	= pv;
	SvCUR(sv)	= cur;
	SvLEN(sv)	= len;
	break;
    case SVt_PVIV:
	SvANY(sv) = new_XPVIV();
	SvPVX(sv)	= pv;
	SvCUR(sv)	= cur;
	SvLEN(sv)	= len;
	SvIVX(sv)	= iv;
	if (SvNIOK(sv))
	    (void)SvIOK_on(sv);
	SvNOK_off(sv);
	break;
    case SVt_PVNV:
	SvANY(sv) = new_XPVNV();
	SvPVX(sv)	= pv;
	SvCUR(sv)	= cur;
	SvLEN(sv)	= len;
	SvIVX(sv)	= iv;
	SvNVX(sv)	= nv;
	break;
    case SVt_PVMG:
	SvANY(sv) = new_XPVMG();
	SvPVX(sv)	= pv;
	SvCUR(sv)	= cur;
	SvLEN(sv)	= len;
	SvIVX(sv)	= iv;
	SvNVX(sv)	= nv;
	SvMAGIC(sv)	= magic;
	SvSTASH(sv)	= stash;
	break;
    case SVt_PVLV:
	SvANY(sv) = new_XPVLV();
	SvPVX(sv)	= pv;
	SvCUR(sv)	= cur;
	SvLEN(sv)	= len;
	SvIVX(sv)	= iv;
	SvNVX(sv)	= nv;
	SvMAGIC(sv)	= magic;
	SvSTASH(sv)	= stash;
	LvTARGOFF(sv)	= 0;
	LvTARGLEN(sv)	= 0;
	LvTARG(sv)	= 0;
	LvTYPE(sv)	= 0;
	break;
    case SVt_PVAV:
	SvANY(sv) = new_XPVAV();
	if (pv)
	    Safefree(pv);
	SvPVX(sv)	= 0;
	AvMAX(sv)	= -1;
	AvFILLp(sv)	= -1;
	SvIVX(sv)	= 0;
	SvNVX(sv)	= 0.0;
	SvMAGIC(sv)	= magic;
	SvSTASH(sv)	= stash;
	AvALLOC(sv)	= 0;
	AvARYLEN(sv)	= 0;
	AvFLAGS(sv)	= 0;
	break;
    case SVt_PVHV:
	SvANY(sv) = new_XPVHV();
	if (pv)
	    Safefree(pv);
	SvPVX(sv)	= 0;
	HvFILL(sv)	= 0;
	HvMAX(sv)	= 0;
	HvKEYS(sv)	= 0;
	SvNVX(sv)	= 0.0;
	SvMAGIC(sv)	= magic;
	SvSTASH(sv)	= stash;
	HvRITER(sv)	= 0;
	HvEITER(sv)	= 0;
	HvPMROOT(sv)	= 0;
	HvNAME(sv)	= 0;
	break;
    case SVt_PVCV:
	SvANY(sv) = new_XPVCV();
	Zero(SvANY(sv), 1, XPVCV);
	SvPVX(sv)	= pv;
	SvCUR(sv)	= cur;
	SvLEN(sv)	= len;
	SvIVX(sv)	= iv;
	SvNVX(sv)	= nv;
	SvMAGIC(sv)	= magic;
	SvSTASH(sv)	= stash;
	break;
    case SVt_PVGV:
	SvANY(sv) = new_XPVGV();
	SvPVX(sv)	= pv;
	SvCUR(sv)	= cur;
	SvLEN(sv)	= len;
	SvIVX(sv)	= iv;
	SvNVX(sv)	= nv;
	SvMAGIC(sv)	= magic;
	SvSTASH(sv)	= stash;
	GvGP(sv)	= 0;
	GvNAME(sv)	= 0;
	GvNAMELEN(sv)	= 0;
	GvSTASH(sv)	= 0;
	GvFLAGS(sv)	= 0;
	break;
    case SVt_PVBM:
	SvANY(sv) = new_XPVBM();
	SvPVX(sv)	= pv;
	SvCUR(sv)	= cur;
	SvLEN(sv)	= len;
	SvIVX(sv)	= iv;
	SvNVX(sv)	= nv;
	SvMAGIC(sv)	= magic;
	SvSTASH(sv)	= stash;
	BmRARE(sv)	= 0;
	BmUSEFUL(sv)	= 0;
	BmPREVIOUS(sv)	= 0;
	break;
    case SVt_PVFM:
	SvANY(sv) = new_XPVFM();
	Zero(SvANY(sv), 1, XPVFM);
	SvPVX(sv)	= pv;
	SvCUR(sv)	= cur;
	SvLEN(sv)	= len;
	SvIVX(sv)	= iv;
	SvNVX(sv)	= nv;
	SvMAGIC(sv)	= magic;
	SvSTASH(sv)	= stash;
	break;
    case SVt_PVIO:
	SvANY(sv) = new_XPVIO();
	Zero(SvANY(sv), 1, XPVIO);
	SvPVX(sv)	= pv;
	SvCUR(sv)	= cur;
	SvLEN(sv)	= len;
	SvIVX(sv)	= iv;
	SvNVX(sv)	= nv;
	SvMAGIC(sv)	= magic;
	SvSTASH(sv)	= stash;
	IoPAGE_LEN(sv)	= 60;
	break;
    }
    SvFLAGS(sv) &= ~SVTYPEMASK;
    SvFLAGS(sv) |= mt;
    return TRUE;
}

int
sv_backoff(register SV *sv)
{
    assert(SvOOK(sv));
    if (SvIVX(sv)) {
	char *s = SvPVX(sv);
	SvLEN(sv) += SvIVX(sv);
	SvPVX(sv) -= SvIVX(sv);
	SvIV_set(sv, 0);
	Move(s, SvPVX(sv), SvCUR(sv)+1, char);
    }
    SvFLAGS(sv) &= ~SVf_OOK;
    return 0;
}

char *
sv_grow(register SV *sv, register STRLEN newlen)
{
    register char *s;

#ifdef HAS_64K_LIMIT
    if (newlen >= 0x10000) {
	PerlIO_printf(Perl_debug_log, "Allocation too large: %lx\n", newlen);
	my_exit(1);
    }
#endif /* HAS_64K_LIMIT */
    if (SvROK(sv))
	sv_unref(sv);
    if (SvTYPE(sv) < SVt_PV) {
	sv_upgrade(sv, SVt_PV);
	s = SvPVX(sv);
    }
    else if (SvOOK(sv)) {	/* pv is offset? */
	sv_backoff(sv);
	s = SvPVX(sv);
	if (newlen > SvLEN(sv))
	    newlen += 10 * (newlen - SvCUR(sv)); /* avoid copy each time */
#ifdef HAS_64K_LIMIT
	if (newlen >= 0x10000)
	    newlen = 0xFFFF;
#endif
    }
    else
	s = SvPVX(sv);
    if (newlen > SvLEN(sv)) {		/* need more room? */
	if (SvLEN(sv) && s) {
#if defined(MYMALLOC) && !defined(PURIFY) && !defined(LEAKTEST)
	    STRLEN l = malloced_size((void*)SvPVX(sv));
	    if (newlen <= l) {
		SvLEN_set(sv, l);
		return s;
	    } else
#endif
	    Renew(s,newlen,char);
	}
        else
	    New(703,s,newlen,char);
	SvPV_set(sv, s);
        SvLEN_set(sv, newlen);
    }
    return s;
}

void
sv_setiv(register SV *sv, IV i)
{
    SV_CHECK_THINKFIRST(sv);
    switch (SvTYPE(sv)) {
    case SVt_NULL:
	sv_upgrade(sv, SVt_IV);
	break;
    case SVt_NV:
	sv_upgrade(sv, SVt_PVNV);
	break;
    case SVt_RV:
    case SVt_PV:
	sv_upgrade(sv, SVt_PVIV);
	break;

    case SVt_PVGV:
	if (SvFAKE(sv)) {
	    sv_unglob(sv);
	    break;
	}
	/* FALL THROUGH */
    case SVt_PVAV:
    case SVt_PVHV:
    case SVt_PVCV:
    case SVt_PVFM:
    case SVt_PVIO:
	{
	    dTHR;
	    croak("Can't coerce %s to integer in %s", sv_reftype(sv,0),
		  PL_op_desc[PL_op->op_type]);
	}
    }
    (void)SvIOK_only(sv);			/* validate number */
    SvIVX(sv) = i;
    SvTAINT(sv);
}

void
sv_setiv_mg(register SV *sv, IV i)
{
    sv_setiv(sv,i);
    SvSETMAGIC(sv);
}

void
sv_setuv(register SV *sv, UV u)
{
    if (u <= IV_MAX)
	sv_setiv(sv, u);
    else
	sv_setnv(sv, (double)u);
}

void
sv_setuv_mg(register SV *sv, UV u)
{
    sv_setuv(sv,u);
    SvSETMAGIC(sv);
}

void
sv_setnv(register SV *sv, double num)
{
    SV_CHECK_THINKFIRST(sv);
    switch (SvTYPE(sv)) {
    case SVt_NULL:
    case SVt_IV:
	sv_upgrade(sv, SVt_NV);
	break;
    case SVt_RV:
    case SVt_PV:
    case SVt_PVIV:
	sv_upgrade(sv, SVt_PVNV);
	break;

    case SVt_PVGV:
	if (SvFAKE(sv)) {
	    sv_unglob(sv);
	    break;
	}
	/* FALL THROUGH */
    case SVt_PVAV:
    case SVt_PVHV:
    case SVt_PVCV:
    case SVt_PVFM:
    case SVt_PVIO:
	{
	    dTHR;
	    croak("Can't coerce %s to number in %s", sv_reftype(sv,0),
		  PL_op_name[PL_op->op_type]);
	}
    }
    SvNVX(sv) = num;
    (void)SvNOK_only(sv);			/* validate number */
    SvTAINT(sv);
}

void
sv_setnv_mg(register SV *sv, double num)
{
    sv_setnv(sv,num);
    SvSETMAGIC(sv);
}

STATIC void
not_a_number(SV *sv)
{
    dTHR;
    char tmpbuf[64];
    char *d = tmpbuf;
    char *s;
    char *limit = tmpbuf + sizeof(tmpbuf) - 8;
                  /* each *s can expand to 4 chars + "...\0",
                     i.e. need room for 8 chars */

    for (s = SvPVX(sv); *s && d < limit; s++) {
	int ch = *s & 0xFF;
	if (ch & 128 && !isPRINT_LC(ch)) {
	    *d++ = 'M';
	    *d++ = '-';
	    ch &= 127;
	}
	if (ch == '\n') {
	    *d++ = '\\';
	    *d++ = 'n';
	}
	else if (ch == '\r') {
	    *d++ = '\\';
	    *d++ = 'r';
	}
	else if (ch == '\f') {
	    *d++ = '\\';
	    *d++ = 'f';
	}
	else if (ch == '\\') {
	    *d++ = '\\';
	    *d++ = '\\';
	}
	else if (isPRINT_LC(ch))
	    *d++ = ch;
	else {
	    *d++ = '^';
	    *d++ = toCTRL(ch);
	}
    }
    if (*s) {
	*d++ = '.';
	*d++ = '.';
	*d++ = '.';
    }
    *d = '\0';

    if (PL_op)
	warner(WARN_NUMERIC, "Argument \"%s\" isn't numeric in %s", tmpbuf,
		PL_op_name[PL_op->op_type]);
    else
	warner(WARN_NUMERIC, "Argument \"%s\" isn't numeric", tmpbuf);
}

IV
sv_2iv(register SV *sv)
{
    if (!sv)
	return 0;
    if (SvGMAGICAL(sv)) {
	mg_get(sv);
	if (SvIOKp(sv))
	    return SvIVX(sv);
	if (SvNOKp(sv)) {
	    if (SvNVX(sv) < 0.0)
		return I_V(SvNVX(sv));
	    else
		return (IV) U_V(SvNVX(sv));
	}
	if (SvPOKp(sv) && SvLEN(sv))
	    return asIV(sv);
	if (!SvROK(sv)) {
	    if (!(SvFLAGS(sv) & SVs_PADTMP)) {
		dTHR;
		if (ckWARN(WARN_UNINITIALIZED) && !PL_localizing)
		    warner(WARN_UNINITIALIZED, PL_warn_uninit);
	    }
	    return 0;
	}
    }
    if (SvTHINKFIRST(sv)) {
	if (SvROK(sv)) {
	  SV* tmpstr;
	  if (SvAMAGIC(sv) && (tmpstr=AMG_CALLun(sv, numer)))
	      return SvIV(tmpstr);
	  return (IV)SvRV(sv);
	}
	if (SvREADONLY(sv)) {
	    if (SvNOKp(sv)) {
		if (SvNVX(sv) < 0.0)
		    return I_V(SvNVX(sv));
		else
		    return (IV) U_V(SvNVX(sv));
	    }
	    if (SvPOKp(sv) && SvLEN(sv))
		return asIV(sv);
	    {
		dTHR;
		if (ckWARN(WARN_UNINITIALIZED))
		    warner(WARN_UNINITIALIZED, PL_warn_uninit);
	    }
	    return 0;
	}
    }
    switch (SvTYPE(sv)) {
    case SVt_NULL:
	sv_upgrade(sv, SVt_IV);
	break;
    case SVt_PV:
	sv_upgrade(sv, SVt_PVIV);
	break;
    case SVt_NV:
	sv_upgrade(sv, SVt_PVNV);
	break;
    }
    if (SvNOKp(sv)) {
	(void)SvIOK_on(sv);
	if (SvNVX(sv) < 0.0)
	    SvIVX(sv) = I_V(SvNVX(sv));
	else
	    SvUVX(sv) = U_V(SvNVX(sv));
    }
    else if (SvPOKp(sv) && SvLEN(sv)) {
	(void)SvIOK_on(sv);
	SvIVX(sv) = asIV(sv);
    }
    else  {
	dTHR;
	if (ckWARN(WARN_UNINITIALIZED) && !PL_localizing && !(SvFLAGS(sv) & SVs_PADTMP))
	    warner(WARN_UNINITIALIZED, PL_warn_uninit);
	return 0;
    }
    DEBUG_c(PerlIO_printf(Perl_debug_log, "0x%lx 2iv(%ld)\n",
	(unsigned long)sv,(long)SvIVX(sv)));
    return SvIVX(sv);
}

UV
sv_2uv(register SV *sv)
{
    if (!sv)
	return 0;
    if (SvGMAGICAL(sv)) {
	mg_get(sv);
	if (SvIOKp(sv))
	    return SvUVX(sv);
	if (SvNOKp(sv))
	    return U_V(SvNVX(sv));
	if (SvPOKp(sv) && SvLEN(sv))
	    return asUV(sv);
	if (!SvROK(sv)) {
	    if (!(SvFLAGS(sv) & SVs_PADTMP)) {
		dTHR;
		if (ckWARN(WARN_UNINITIALIZED) && !PL_localizing)
		    warner(WARN_UNINITIALIZED, PL_warn_uninit);
	    }
	    return 0;
	}
    }
    if (SvTHINKFIRST(sv)) {
	if (SvROK(sv)) {
	  SV* tmpstr;
	  if (SvAMAGIC(sv) && (tmpstr=AMG_CALLun(sv, numer)))
	      return SvUV(tmpstr);
	  return (UV)SvRV(sv);
	}
	if (SvREADONLY(sv)) {
	    if (SvNOKp(sv)) {
		return U_V(SvNVX(sv));
	    }
	    if (SvPOKp(sv) && SvLEN(sv))
		return asUV(sv);
	    {
		dTHR;
		if (ckWARN(WARN_UNINITIALIZED))
		    warner(WARN_UNINITIALIZED, PL_warn_uninit);
	    }
	    return 0;
	}
    }
    switch (SvTYPE(sv)) {
    case SVt_NULL:
	sv_upgrade(sv, SVt_IV);
	break;
    case SVt_PV:
	sv_upgrade(sv, SVt_PVIV);
	break;
    case SVt_NV:
	sv_upgrade(sv, SVt_PVNV);
	break;
    }
    if (SvNOKp(sv)) {
	(void)SvIOK_on(sv);
	SvUVX(sv) = U_V(SvNVX(sv));
    }
    else if (SvPOKp(sv) && SvLEN(sv)) {
	(void)SvIOK_on(sv);
	SvUVX(sv) = asUV(sv);
    }
    else  {
	if (!(SvFLAGS(sv) & SVs_PADTMP)) {
	    dTHR;
	    if (ckWARN(WARN_UNINITIALIZED) && !PL_localizing)
		warner(WARN_UNINITIALIZED, PL_warn_uninit);
	}
	return 0;
    }
    DEBUG_c(PerlIO_printf(Perl_debug_log, "0x%lx 2uv(%lu)\n",
	(unsigned long)sv,SvUVX(sv)));
    return SvUVX(sv);
}

double
sv_2nv(register SV *sv)
{
    if (!sv)
	return 0.0;
    if (SvGMAGICAL(sv)) {
	mg_get(sv);
	if (SvNOKp(sv))
	    return SvNVX(sv);
	if (SvPOKp(sv) && SvLEN(sv)) {
	    dTHR;
	    if (ckWARN(WARN_NUMERIC) && !SvIOKp(sv) && !looks_like_number(sv))
		not_a_number(sv);
	    SET_NUMERIC_STANDARD();
	    return atof(SvPVX(sv));
	}
	if (SvIOKp(sv))
	    return (double)SvIVX(sv);
        if (!SvROK(sv)) {
	    if (!(SvFLAGS(sv) & SVs_PADTMP)) {
		dTHR;
		if (ckWARN(WARN_UNINITIALIZED) && !PL_localizing)
		    warner(WARN_UNINITIALIZED, PL_warn_uninit);
	    }
            return 0;
        }
    }
    if (SvTHINKFIRST(sv)) {
	if (SvROK(sv)) {
	  SV* tmpstr;
	  if (SvAMAGIC(sv) && (tmpstr=AMG_CALLun(sv,numer)))
	      return SvNV(tmpstr);
	  return (double)(unsigned long)SvRV(sv);
	}
	if (SvREADONLY(sv)) {
	    dTHR;
	    if (SvPOKp(sv) && SvLEN(sv)) {
		if (ckWARN(WARN_NUMERIC) && !SvIOKp(sv) && !looks_like_number(sv))
		    not_a_number(sv);
		SET_NUMERIC_STANDARD();
		return atof(SvPVX(sv));
	    }
	    if (SvIOKp(sv))
		return (double)SvIVX(sv);
	    if (ckWARN(WARN_UNINITIALIZED))
		warner(WARN_UNINITIALIZED, PL_warn_uninit);
	    return 0.0;
	}
    }
    if (SvTYPE(sv) < SVt_NV) {
	if (SvTYPE(sv) == SVt_IV)
	    sv_upgrade(sv, SVt_PVNV);
	else
	    sv_upgrade(sv, SVt_NV);
	DEBUG_c(SET_NUMERIC_STANDARD());
	DEBUG_c(PerlIO_printf(Perl_debug_log,
			      "0x%lx num(%g)\n",(unsigned long)sv,SvNVX(sv)));
    }
    else if (SvTYPE(sv) < SVt_PVNV)
	sv_upgrade(sv, SVt_PVNV);
    if (SvIOKp(sv) &&
	    (!SvPOKp(sv) || !strchr(SvPVX(sv),'.') || !looks_like_number(sv)))
    {
	SvNVX(sv) = (double)SvIVX(sv);
    }
    else if (SvPOKp(sv) && SvLEN(sv)) {
	dTHR;
	if (ckWARN(WARN_NUMERIC) && !SvIOKp(sv) && !looks_like_number(sv))
	    not_a_number(sv);
	SET_NUMERIC_STANDARD();
	SvNVX(sv) = atof(SvPVX(sv));
    }
    else  {
	dTHR;
	if (ckWARN(WARN_UNINITIALIZED) && !PL_localizing && !(SvFLAGS(sv) & SVs_PADTMP))
	    warner(WARN_UNINITIALIZED, PL_warn_uninit);
	return 0.0;
    }
    SvNOK_on(sv);
    DEBUG_c(SET_NUMERIC_STANDARD());
    DEBUG_c(PerlIO_printf(Perl_debug_log,
			  "0x%lx 2nv(%g)\n",(unsigned long)sv,SvNVX(sv)));
    return SvNVX(sv);
}

STATIC IV
asIV(SV *sv)
{
    I32 numtype = looks_like_number(sv);
    double d;

    if (numtype == 1)
	return atol(SvPVX(sv));
    if (!numtype) {
	dTHR;
	if (ckWARN(WARN_NUMERIC))
	    not_a_number(sv);
    }
    SET_NUMERIC_STANDARD();
    d = atof(SvPVX(sv));
    if (d < 0.0)
	return I_V(d);
    else
	return (IV) U_V(d);
}

STATIC UV
asUV(SV *sv)
{
    I32 numtype = looks_like_number(sv);

#ifdef HAS_STRTOUL
    if (numtype == 1)
	return strtoul(SvPVX(sv), Null(char**), 10);
#endif
    if (!numtype) {
	dTHR;
	if (ckWARN(WARN_NUMERIC))
	    not_a_number(sv);
    }
    SET_NUMERIC_STANDARD();
    return U_V(atof(SvPVX(sv)));
}

I32
looks_like_number(SV *sv)
{
    register char *s;
    register char *send;
    register char *sbegin;
    I32 numtype;
    STRLEN len;

    if (SvPOK(sv)) {
	sbegin = SvPVX(sv); 
	len = SvCUR(sv);
    }
    else if (SvPOKp(sv))
	sbegin = SvPV(sv, len);
    else
	return 1;
    send = sbegin + len;

    s = sbegin;
    while (isSPACE(*s))
	s++;
    if (*s == '+' || *s == '-')
	s++;

    /* next must be digit or '.' */
    if (isDIGIT(*s)) {
        do {
	    s++;
        } while (isDIGIT(*s));
        if (*s == '.') {
	    s++;
            while (isDIGIT(*s))  /* optional digits after "." */
                s++;
        }
    }
    else if (*s == '.') {
        s++;
        /* no digits before '.' means we need digits after it */
        if (isDIGIT(*s)) {
	    do {
	        s++;
            } while (isDIGIT(*s));
        }
        else
	    return 0;
    }
    else
        return 0;

    /*
     * we return 1 if the number can be converted to _integer_ with atol()
     * and 2 if you need (int)atof().
     */
    numtype = 1;

    /* we can have an optional exponent part */
    if (*s == 'e' || *s == 'E') {
	numtype = 2;
	s++;
	if (*s == '+' || *s == '-')
	    s++;
        if (isDIGIT(*s)) {
            do {
                s++;
            } while (isDIGIT(*s));
        }
        else
            return 0;
    }
    while (isSPACE(*s))
	s++;
    if (s >= send)
	return numtype;
    if (len == 10 && memEQ(sbegin, "0 but true", 10))
	return 1;
    return 0;
}

char *
sv_2pv(register SV *sv, STRLEN *lp)
{
    register char *s;
    int olderrno;
    SV *tsv;
    char tmpbuf[64];	/* Must fit sprintf/Gconvert of longest IV/NV */

    if (!sv) {
	*lp = 0;
	return "";
    }
    if (SvGMAGICAL(sv)) {
	mg_get(sv);
	if (SvPOKp(sv)) {
	    *lp = SvCUR(sv);
	    return SvPVX(sv);
	}
	if (SvIOKp(sv)) {
	    (void)sprintf(tmpbuf,"%ld",(long)SvIVX(sv));
	    tsv = Nullsv;
	    goto tokensave;
	}
	if (SvNOKp(sv)) {
	    SET_NUMERIC_STANDARD();
	    Gconvert(SvNVX(sv), DBL_DIG, 0, tmpbuf);
	    tsv = Nullsv;
	    goto tokensave;
	}
        if (!SvROK(sv)) {
	    if (!(SvFLAGS(sv) & SVs_PADTMP)) {
		dTHR;
		if (ckWARN(WARN_UNINITIALIZED) && !PL_localizing)
		    warner(WARN_UNINITIALIZED, PL_warn_uninit);
	    }
            *lp = 0;
            return "";
        }
    }
    if (SvTHINKFIRST(sv)) {
	if (SvROK(sv)) {
	    SV* tmpstr;
	    if (SvAMAGIC(sv) && (tmpstr=AMG_CALLun(sv,string)))
		return SvPV(tmpstr,*lp);
	    sv = (SV*)SvRV(sv);
	    if (!sv)
		s = "NULLREF";
	    else {
		MAGIC *mg;
		
		switch (SvTYPE(sv)) {
		case SVt_PVMG:
		    if ( ((SvFLAGS(sv) &
			   (SVs_OBJECT|SVf_OK|SVs_GMG|SVs_SMG|SVs_RMG)) 
			  == (SVs_OBJECT|SVs_RMG))
			 && strEQ(s=HvNAME(SvSTASH(sv)), "Regexp")
			 && (mg = mg_find(sv, 'r'))) {
			dTHR;
			regexp *re = (regexp *)mg->mg_obj;

			if (!mg->mg_ptr) {
			    char *fptr = "msix";
			    char reflags[6];
			    char ch;
			    int left = 0;
			    int right = 4;
 			    U16 reganch = (re->reganch & PMf_COMPILETIME) >> 12;

 			    while(ch = *fptr++) {
 				if(reganch & 1) {
 				    reflags[left++] = ch;
 				}
 				else {
 				    reflags[right--] = ch;
 				}
 				reganch >>= 1;
 			    }
 			    if(left != 4) {
 				reflags[left] = '-';
 				left = 5;
 			    }

			    mg->mg_len = re->prelen + 4 + left;
			    New(616, mg->mg_ptr, mg->mg_len + 1 + left, char);
			    Copy("(?", mg->mg_ptr, 2, char);
			    Copy(reflags, mg->mg_ptr+2, left, char);
			    Copy(":", mg->mg_ptr+left+2, 1, char);
			    Copy(re->precomp, mg->mg_ptr+3+left, re->prelen, char);
			    mg->mg_ptr[mg->mg_len - 1] = ')';
			    mg->mg_ptr[mg->mg_len] = 0;
			}
			PL_reginterp_cnt += re->program[0].next_off;
			*lp = mg->mg_len;
			return mg->mg_ptr;
		    }
					/* Fall through */
		case SVt_NULL:
		case SVt_IV:
		case SVt_NV:
		case SVt_RV:
		case SVt_PV:
		case SVt_PVIV:
		case SVt_PVNV:
		case SVt_PVBM:	s = "SCALAR";			break;
		case SVt_PVLV:	s = "LVALUE";			break;
		case SVt_PVAV:	s = "ARRAY";			break;
		case SVt_PVHV:	s = "HASH";			break;
		case SVt_PVCV:	s = "CODE";			break;
		case SVt_PVGV:	s = "GLOB";			break;
		case SVt_PVFM:	s = "FORMAT";			break;
		case SVt_PVIO:	s = "IO";			break;
		default:	s = "UNKNOWN";			break;
		}
		tsv = NEWSV(0,0);
		if (SvOBJECT(sv))
		    sv_setpvf(tsv, "%s=%s", HvNAME(SvSTASH(sv)), s);
		else
		    sv_setpv(tsv, s);
		sv_catpvf(tsv, "(0x%lx)", (unsigned long)sv);
		goto tokensaveref;
	    }
	    *lp = strlen(s);
	    return s;
	}
	if (SvREADONLY(sv)) {
	    if (SvNOKp(sv)) {
		SET_NUMERIC_STANDARD();
		Gconvert(SvNVX(sv), DBL_DIG, 0, tmpbuf);
		tsv = Nullsv;
		goto tokensave;
	    }
	    if (SvIOKp(sv)) {
		(void)sprintf(tmpbuf,"%ld",(long)SvIVX(sv));
		tsv = Nullsv;
		goto tokensave;
	    }
	    {
		dTHR;
		if (ckWARN(WARN_UNINITIALIZED))
		    warner(WARN_UNINITIALIZED, PL_warn_uninit);
	    }
	    *lp = 0;
	    return "";
	}
    }
    (void)SvUPGRADE(sv, SVt_PV);
    if (SvNOKp(sv)) {
	if (SvTYPE(sv) < SVt_PVNV)
	    sv_upgrade(sv, SVt_PVNV);
	SvGROW(sv, 28);
	s = SvPVX(sv);
	olderrno = errno;	/* some Xenix systems wipe out errno here */
#ifdef apollo
	if (SvNVX(sv) == 0.0)
	    (void)strcpy(s,"0");
	else
#endif /*apollo*/
	{
	    SET_NUMERIC_STANDARD();
	    Gconvert(SvNVX(sv), DBL_DIG, 0, s);
	}
	errno = olderrno;
#ifdef FIXNEGATIVEZERO
        if (*s == '-' && s[1] == '0' && !s[2])
	    strcpy(s,"0");
#endif
	while (*s) s++;
#ifdef hcx
	if (s[-1] == '.')
	    *--s = '\0';
#endif
    }
    else if (SvIOKp(sv)) {
	U32 oldIOK = SvIOK(sv);
	if (SvTYPE(sv) < SVt_PVIV)
	    sv_upgrade(sv, SVt_PVIV);
	olderrno = errno;	/* some Xenix systems wipe out errno here */
	sv_setpviv(sv, SvIVX(sv));
	errno = olderrno;
	s = SvEND(sv);
	if (oldIOK)
	    SvIOK_on(sv);
	else
	    SvIOKp_on(sv);
    }
    else {
	dTHR;
	if (ckWARN(WARN_UNINITIALIZED) && !PL_localizing && !(SvFLAGS(sv) & SVs_PADTMP))
	    warner(WARN_UNINITIALIZED, PL_warn_uninit);
	*lp = 0;
	return "";
    }
    *lp = s - SvPVX(sv);
    SvCUR_set(sv, *lp);
    SvPOK_on(sv);
    DEBUG_c(PerlIO_printf(Perl_debug_log, "0x%lx 2pv(%s)\n",(unsigned long)sv,SvPVX(sv)));
    return SvPVX(sv);

  tokensave:
    if (SvROK(sv)) {	/* XXX Skip this when sv_pvn_force calls */
	/* Sneaky stuff here */

      tokensaveref:
	if (!tsv)
	    tsv = newSVpv(tmpbuf, 0);
	sv_2mortal(tsv);
	*lp = SvCUR(tsv);
	return SvPVX(tsv);
    }
    else {
	STRLEN len;
	char *t;

	if (tsv) {
	    sv_2mortal(tsv);
	    t = SvPVX(tsv);
	    len = SvCUR(tsv);
	}
	else {
	    t = tmpbuf;
	    len = strlen(tmpbuf);
	}
#ifdef FIXNEGATIVEZERO
	if (len == 2 && t[0] == '-' && t[1] == '0') {
	    t = "0";
	    len = 1;
	}
#endif
	(void)SvUPGRADE(sv, SVt_PV);
	*lp = len;
	s = SvGROW(sv, len + 1);
	SvCUR_set(sv, len);
	(void)strcpy(s, t);
	SvPOKp_on(sv);
	return s;
    }
}

/* This function is only called on magical items */
bool
sv_2bool(register SV *sv)
{
    if (SvGMAGICAL(sv))
	mg_get(sv);

    if (!SvOK(sv))
	return 0;
    if (SvROK(sv)) {
	dTHR;
	SV* tmpsv;
	if (SvAMAGIC(sv) && (tmpsv = AMG_CALLun(sv,bool_)))
	    return SvTRUE(tmpsv);
      return SvRV(sv) != 0;
    }
    if (SvPOKp(sv)) {
	register XPV* Xpvtmp;
	if ((Xpvtmp = (XPV*)SvANY(sv)) &&
		(*Xpvtmp->xpv_pv > '0' ||
		Xpvtmp->xpv_cur > 1 ||
		(Xpvtmp->xpv_cur && *Xpvtmp->xpv_pv != '0')))
	    return 1;
	else
	    return 0;
    }
    else {
	if (SvIOKp(sv))
	    return SvIVX(sv) != 0;
	else {
	    if (SvNOKp(sv))
		return SvNVX(sv) != 0.0;
	    else
		return FALSE;
	}
    }
}

/* Note: sv_setsv() should not be called with a source string that needs
 * to be reused, since it may destroy the source string if it is marked
 * as temporary.
 */

void
sv_setsv(SV *dstr, register SV *sstr)
{
    dTHR;
    register U32 sflags;
    register int dtype;
    register int stype;

    if (sstr == dstr)
	return;
    SV_CHECK_THINKFIRST(dstr);
    if (!sstr)
	sstr = &PL_sv_undef;
    stype = SvTYPE(sstr);
    dtype = SvTYPE(dstr);

    if (dtype == SVt_PVGV && (SvFLAGS(dstr) & SVf_FAKE)) {
        sv_unglob(dstr);     /* so fake GLOB won't perpetuate */
	sv_setpvn(dstr, "", 0);
        (void)SvPOK_only(dstr);
        dtype = SvTYPE(dstr);
    }

    SvAMAGIC_off(dstr);

    /* There's a lot of redundancy below but we're going for speed here */

    switch (stype) {
    case SVt_NULL:
      undef_sstr:
	if (dtype != SVt_PVGV) {
	    (void)SvOK_off(dstr);
	    return;
	}
	break;
    case SVt_IV:
	if (SvIOK(sstr)) {
	    switch (dtype) {
	    case SVt_NULL:
		sv_upgrade(dstr, SVt_IV);
		break;
	    case SVt_NV:
		sv_upgrade(dstr, SVt_PVNV);
		break;
	    case SVt_RV:
	    case SVt_PV:
		sv_upgrade(dstr, SVt_PVIV);
		break;
	    }
	    (void)SvIOK_only(dstr);
	    SvIVX(dstr) = SvIVX(sstr);
	    SvTAINT(dstr);
	    return;
	}
	goto undef_sstr;

    case SVt_NV:
	if (SvNOK(sstr)) {
	    switch (dtype) {
	    case SVt_NULL:
	    case SVt_IV:
		sv_upgrade(dstr, SVt_NV);
		break;
	    case SVt_RV:
	    case SVt_PV:
	    case SVt_PVIV:
		sv_upgrade(dstr, SVt_PVNV);
		break;
	    }
	    SvNVX(dstr) = SvNVX(sstr);
	    (void)SvNOK_only(dstr);
	    SvTAINT(dstr);
	    return;
	}
	goto undef_sstr;

    case SVt_RV:
	if (dtype < SVt_RV)
	    sv_upgrade(dstr, SVt_RV);
	else if (dtype == SVt_PVGV &&
		 SvTYPE(SvRV(sstr)) == SVt_PVGV) {
	    sstr = SvRV(sstr);
	    if (sstr == dstr) {
		if (PL_curcop->cop_stash != GvSTASH(dstr))
		    GvIMPORTED_on(dstr);
		GvMULTI_on(dstr);
		return;
	    }
	    goto glob_assign;
	}
	break;
    case SVt_PV:
    case SVt_PVFM:
	if (dtype < SVt_PV)
	    sv_upgrade(dstr, SVt_PV);
	break;
    case SVt_PVIV:
	if (dtype < SVt_PVIV)
	    sv_upgrade(dstr, SVt_PVIV);
	break;
    case SVt_PVNV:
	if (dtype < SVt_PVNV)
	    sv_upgrade(dstr, SVt_PVNV);
	break;
    case SVt_PVAV:
    case SVt_PVHV:
    case SVt_PVCV:
    case SVt_PVIO:
	if (PL_op)
	    croak("Bizarre copy of %s in %s", sv_reftype(sstr, 0),
		PL_op_name[PL_op->op_type]);
	else
	    croak("Bizarre copy of %s", sv_reftype(sstr, 0));
	break;

    case SVt_PVGV:
	if (dtype <= SVt_PVGV) {
  glob_assign:
	    if (dtype != SVt_PVGV) {
		char *name = GvNAME(sstr);
		STRLEN len = GvNAMELEN(sstr);
		sv_upgrade(dstr, SVt_PVGV);
		sv_magic(dstr, dstr, '*', name, len);
		GvSTASH(dstr) = (HV*)SvREFCNT_inc(GvSTASH(sstr));
		GvNAME(dstr) = savepvn(name, len);
		GvNAMELEN(dstr) = len;
		SvFAKE_on(dstr);	/* can coerce to non-glob */
	    }
	    /* ahem, death to those who redefine active sort subs */
	    else if (PL_curstackinfo->si_type == PERLSI_SORT
		     && GvCV(dstr) && PL_sortcop == CvSTART(GvCV(dstr)))
		croak("Can't redefine active sort subroutine %s",
		      GvNAME(dstr));
	    (void)SvOK_off(dstr);
	    GvINTRO_off(dstr);		/* one-shot flag */
	    gp_free((GV*)dstr);
	    GvGP(dstr) = gp_ref(GvGP(sstr));
	    SvTAINT(dstr);
	    if (PL_curcop->cop_stash != GvSTASH(dstr))
		GvIMPORTED_on(dstr);
	    GvMULTI_on(dstr);
	    return;
	}
	/* FALL THROUGH */

    default:
	if (SvGMAGICAL(sstr)) {
	    mg_get(sstr);
	    if (SvTYPE(sstr) != stype) {
		stype = SvTYPE(sstr);
		if (stype == SVt_PVGV && dtype <= SVt_PVGV)
		    goto glob_assign;
	    }
	}
	if (stype == SVt_PVLV)
	    SvUPGRADE(dstr, SVt_PVNV);
	else
	    SvUPGRADE(dstr, stype);
    }

    sflags = SvFLAGS(sstr);

    if (sflags & SVf_ROK) {
	if (dtype >= SVt_PV) {
	    if (dtype == SVt_PVGV) {
		SV *sref = SvREFCNT_inc(SvRV(sstr));
		SV *dref = 0;
		int intro = GvINTRO(dstr);

		if (intro) {
		    GP *gp;
		    GvGP(dstr)->gp_refcnt--;
		    GvINTRO_off(dstr);	/* one-shot flag */
		    Newz(602,gp, 1, GP);
		    GvGP(dstr) = gp_ref(gp);
		    GvSV(dstr) = NEWSV(72,0);
		    GvLINE(dstr) = PL_curcop->cop_line;
		    GvEGV(dstr) = (GV*)dstr;
		}
		GvMULTI_on(dstr);
		switch (SvTYPE(sref)) {
		case SVt_PVAV:
		    if (intro)
			SAVESPTR(GvAV(dstr));
		    else
			dref = (SV*)GvAV(dstr);
		    GvAV(dstr) = (AV*)sref;
		    if (PL_curcop->cop_stash != GvSTASH(dstr))
			GvIMPORTED_AV_on(dstr);
		    break;
		case SVt_PVHV:
		    if (intro)
			SAVESPTR(GvHV(dstr));
		    else
			dref = (SV*)GvHV(dstr);
		    GvHV(dstr) = (HV*)sref;
		    if (PL_curcop->cop_stash != GvSTASH(dstr))
			GvIMPORTED_HV_on(dstr);
		    break;
		case SVt_PVCV:
		    if (intro) {
			if (GvCVGEN(dstr) && GvCV(dstr) != (CV*)sref) {
			    SvREFCNT_dec(GvCV(dstr));
			    GvCV(dstr) = Nullcv;
			    GvCVGEN(dstr) = 0; /* Switch off cacheness. */
			    PL_sub_generation++;
			}
			SAVESPTR(GvCV(dstr));
		    }
		    else
			dref = (SV*)GvCV(dstr);
		    if (GvCV(dstr) != (CV*)sref) {
			CV* cv = GvCV(dstr);
			if (cv) {
			    if (!GvCVGEN((GV*)dstr) &&
				(CvROOT(cv) || CvXSUB(cv)))
			    {
				SV *const_sv = cv_const_sv(cv);
				bool const_changed = TRUE; 
				if(const_sv)
				    const_changed = sv_cmp(const_sv, 
					   op_const_sv(CvSTART((CV*)sref), 
						       Nullcv));
				/* ahem, death to those who redefine
				 * active sort subs */
				if (PL_curstackinfo->si_type == PERLSI_SORT &&
				      PL_sortcop == CvSTART(cv))
				    croak(
				    "Can't redefine active sort subroutine %s",
					  GvENAME((GV*)dstr));
				if (ckWARN(WARN_REDEFINE) || (const_changed && const_sv)) {
				    if (!(CvGV(cv) && GvSTASH(CvGV(cv))
					  && HvNAME(GvSTASH(CvGV(cv)))
					  && strEQ(HvNAME(GvSTASH(CvGV(cv))),
						   "autouse")))
					warner(WARN_REDEFINE, const_sv ? 
					     "Constant subroutine %s redefined"
					     : "Subroutine %s redefined", 
					     GvENAME((GV*)dstr));
				}
			    }
			    cv_ckproto(cv, (GV*)dstr,
				       SvPOK(sref) ? SvPVX(sref) : Nullch);
			}
			GvCV(dstr) = (CV*)sref;
			GvCVGEN(dstr) = 0; /* Switch off cacheness. */
			GvASSUMECV_on(dstr);
			PL_sub_generation++;
		    }
		    if (PL_curcop->cop_stash != GvSTASH(dstr))
			GvIMPORTED_CV_on(dstr);
		    break;
		case SVt_PVIO:
		    if (intro)
			SAVESPTR(GvIOp(dstr));
		    else
			dref = (SV*)GvIOp(dstr);
		    GvIOp(dstr) = (IO*)sref;
		    break;
		default:
		    if (intro)
			SAVESPTR(GvSV(dstr));
		    else
			dref = (SV*)GvSV(dstr);
		    GvSV(dstr) = sref;
		    if (PL_curcop->cop_stash != GvSTASH(dstr))
			GvIMPORTED_SV_on(dstr);
		    break;
		}
		if (dref)
		    SvREFCNT_dec(dref);
		if (intro)
		    SAVEFREESV(sref);
		SvTAINT(dstr);
		return;
	    }
	    if (SvPVX(dstr)) {
		(void)SvOOK_off(dstr);		/* backoff */
		Safefree(SvPVX(dstr));
		SvLEN(dstr)=SvCUR(dstr)=0;
	    }
	}
	(void)SvOK_off(dstr);
	SvRV(dstr) = SvREFCNT_inc(SvRV(sstr));
	SvROK_on(dstr);
	if (sflags & SVp_NOK) {
	    SvNOK_on(dstr);
	    SvNVX(dstr) = SvNVX(sstr);
	}
	if (sflags & SVp_IOK) {
	    (void)SvIOK_on(dstr);
	    SvIVX(dstr) = SvIVX(sstr);
	}
	if (SvAMAGIC(sstr)) {
	    SvAMAGIC_on(dstr);
	}
    }
    else if (sflags & SVp_POK) {

	/*
	 * Check to see if we can just swipe the string.  If so, it's a
	 * possible small lose on short strings, but a big win on long ones.
	 * It might even be a win on short strings if SvPVX(dstr)
	 * has to be allocated and SvPVX(sstr) has to be freed.
	 */

	if (SvTEMP(sstr) &&		/* slated for free anyway? */
	    SvREFCNT(sstr) == 1 && 	/* and no other references to it? */
	    !(sflags & SVf_OOK)) 	/* and not involved in OOK hack? */
	{
	    if (SvPVX(dstr)) {		/* we know that dtype >= SVt_PV */
		if (SvOOK(dstr)) {
		    SvFLAGS(dstr) &= ~SVf_OOK;
		    Safefree(SvPVX(dstr) - SvIVX(dstr));
		}
		else
		    Safefree(SvPVX(dstr));
	    }
	    (void)SvPOK_only(dstr);
	    SvPV_set(dstr, SvPVX(sstr));
	    SvLEN_set(dstr, SvLEN(sstr));
	    SvCUR_set(dstr, SvCUR(sstr));
	    SvTEMP_off(dstr);
	    (void)SvOK_off(sstr);
	    SvPV_set(sstr, Nullch);
	    SvLEN_set(sstr, 0);
	    SvCUR_set(sstr, 0);
	    SvTEMP_off(sstr);
	}
	else {					/* have to copy actual string */
	    STRLEN len = SvCUR(sstr);

	    SvGROW(dstr, len + 1);		/* inlined from sv_setpvn */
	    Move(SvPVX(sstr),SvPVX(dstr),len,char);
	    SvCUR_set(dstr, len);
	    *SvEND(dstr) = '\0';
	    (void)SvPOK_only(dstr);
	}
	/*SUPPRESS 560*/
	if (sflags & SVp_NOK) {
	    SvNOK_on(dstr);
	    SvNVX(dstr) = SvNVX(sstr);
	}
	if (sflags & SVp_IOK) {
	    (void)SvIOK_on(dstr);
	    SvIVX(dstr) = SvIVX(sstr);
	}
    }
    else if (sflags & SVp_NOK) {
	SvNVX(dstr) = SvNVX(sstr);
	(void)SvNOK_only(dstr);
	if (SvIOK(sstr)) {
	    (void)SvIOK_on(dstr);
	    SvIVX(dstr) = SvIVX(sstr);
	}
    }
    else if (sflags & SVp_IOK) {
	(void)SvIOK_only(dstr);
	SvIVX(dstr) = SvIVX(sstr);
    }
    else {
	if (dtype == SVt_PVGV) {
	    if (ckWARN(WARN_UNSAFE))
		warner(WARN_UNSAFE, "Undefined value assigned to typeglob");
	}
	else
	    (void)SvOK_off(dstr);
    }
    SvTAINT(dstr);
}

void
sv_setsv_mg(SV *dstr, register SV *sstr)
{
    sv_setsv(dstr,sstr);
    SvSETMAGIC(dstr);
}

void
sv_setpvn(register SV *sv, register const char *ptr, register STRLEN len)
{
    register char *dptr;
    assert(len >= 0);  /* STRLEN is probably unsigned, so this may
			  elicit a warning, but it won't hurt. */
    SV_CHECK_THINKFIRST(sv);
    if (!ptr) {
	(void)SvOK_off(sv);
	return;
    }
    if (SvTYPE(sv) >= SVt_PV) {
	if (SvFAKE(sv) && SvTYPE(sv) == SVt_PVGV)
	    sv_unglob(sv);
    }
    else
	sv_upgrade(sv, SVt_PV);

    SvGROW(sv, len + 1);
    dptr = SvPVX(sv);
    Move(ptr,dptr,len,char);
    dptr[len] = '\0';
    SvCUR_set(sv, len);
    (void)SvPOK_only(sv);		/* validate pointer */
    SvTAINT(sv);
}

void
sv_setpvn_mg(register SV *sv, register const char *ptr, register STRLEN len)
{
    sv_setpvn(sv,ptr,len);
    SvSETMAGIC(sv);
}

void
sv_setpv(register SV *sv, register const char *ptr)
{
    register STRLEN len;

    SV_CHECK_THINKFIRST(sv);
    if (!ptr) {
	(void)SvOK_off(sv);
	return;
    }
    len = strlen(ptr);
    if (SvTYPE(sv) >= SVt_PV) {
	if (SvFAKE(sv) && SvTYPE(sv) == SVt_PVGV)
	    sv_unglob(sv);
    }
    else 
	sv_upgrade(sv, SVt_PV);

    SvGROW(sv, len + 1);
    Move(ptr,SvPVX(sv),len+1,char);
    SvCUR_set(sv, len);
    (void)SvPOK_only(sv);		/* validate pointer */
    SvTAINT(sv);
}

void
sv_setpv_mg(register SV *sv, register const char *ptr)
{
    sv_setpv(sv,ptr);
    SvSETMAGIC(sv);
}

void
sv_usepvn(register SV *sv, register char *ptr, register STRLEN len)
{
    SV_CHECK_THINKFIRST(sv);
    (void)SvUPGRADE(sv, SVt_PV);
    if (!ptr) {
	(void)SvOK_off(sv);
	return;
    }
    (void)SvOOK_off(sv);
    if (SvPVX(sv))
	Safefree(SvPVX(sv));
    Renew(ptr, len+1, char);
    SvPVX(sv) = ptr;
    SvCUR_set(sv, len);
    SvLEN_set(sv, len+1);
    *SvEND(sv) = '\0';
    (void)SvPOK_only(sv);		/* validate pointer */
    SvTAINT(sv);
}

void
sv_usepvn_mg(register SV *sv, register char *ptr, register STRLEN len)
{
    sv_usepvn(sv,ptr,len);
    SvSETMAGIC(sv);
}

STATIC void
sv_check_thinkfirst(register SV *sv)
{
    if (SvREADONLY(sv)) {
	dTHR;
	if (PL_curcop != &PL_compiling)
	    croak(PL_no_modify);
    }
    if (SvROK(sv))
	sv_unref(sv);
}
    
void
sv_chop(register SV *sv, register char *ptr)	/* like set but assuming ptr is in sv */
                
                   
{
    register STRLEN delta;

    if (!ptr || !SvPOKp(sv))
	return;
    SV_CHECK_THINKFIRST(sv);
    if (SvTYPE(sv) < SVt_PVIV)
	sv_upgrade(sv,SVt_PVIV);

    if (!SvOOK(sv)) {
	SvIVX(sv) = 0;
	SvFLAGS(sv) |= SVf_OOK;
    }
    SvFLAGS(sv) &= ~(SVf_IOK|SVf_NOK|SVp_IOK|SVp_NOK);
    delta = ptr - SvPVX(sv);
    SvLEN(sv) -= delta;
    SvCUR(sv) -= delta;
    SvPVX(sv) += delta;
    SvIVX(sv) += delta;
}

void
sv_catpvn(register SV *sv, register char *ptr, register STRLEN len)
{
    STRLEN tlen;
    char *junk;

    junk = SvPV_force(sv, tlen);
    SvGROW(sv, tlen + len + 1);
    if (ptr == junk)
	ptr = SvPVX(sv);
    Move(ptr,SvPVX(sv)+tlen,len,char);
    SvCUR(sv) += len;
    *SvEND(sv) = '\0';
    (void)SvPOK_only(sv);		/* validate pointer */
    SvTAINT(sv);
}

void
sv_catpvn_mg(register SV *sv, register char *ptr, register STRLEN len)
{
    sv_catpvn(sv,ptr,len);
    SvSETMAGIC(sv);
}

void
sv_catsv(SV *dstr, register SV *sstr)
{
    char *s;
    STRLEN len;
    if (!sstr)
	return;
    if (s = SvPV(sstr, len))
	sv_catpvn(dstr,s,len);
}

void
sv_catsv_mg(SV *dstr, register SV *sstr)
{
    sv_catsv(dstr,sstr);
    SvSETMAGIC(dstr);
}

void
sv_catpv(register SV *sv, register char *ptr)
{
    register STRLEN len;
    STRLEN tlen;
    char *junk;

    if (!ptr)
	return;
    junk = SvPV_force(sv, tlen);
    len = strlen(ptr);
    SvGROW(sv, tlen + len + 1);
    if (ptr == junk)
	ptr = SvPVX(sv);
    Move(ptr,SvPVX(sv)+tlen,len+1,char);
    SvCUR(sv) += len;
    (void)SvPOK_only(sv);		/* validate pointer */
    SvTAINT(sv);
}

void
sv_catpv_mg(register SV *sv, register char *ptr)
{
    sv_catpv(sv,ptr);
    SvSETMAGIC(sv);
}

SV *
newSV(STRLEN len)
{
    register SV *sv;
    
    new_SV(sv);
    SvANY(sv) = 0;
    SvREFCNT(sv) = 1;
    SvFLAGS(sv) = 0;
    if (len) {
	sv_upgrade(sv, SVt_PV);
	SvGROW(sv, len + 1);
    }
    return sv;
}

/* name is assumed to contain an SV* if (name && namelen == HEf_SVKEY) */

void
sv_magic(register SV *sv, SV *obj, int how, char *name, I32 namlen)
{
    MAGIC* mg;
    
    if (SvREADONLY(sv)) {
	dTHR;
	if (PL_curcop != &PL_compiling && !strchr("gBf", how))
	    croak(PL_no_modify);
    }
    if (SvMAGICAL(sv) || (how == 't' && SvTYPE(sv) >= SVt_PVMG)) {
	if (SvMAGIC(sv) && (mg = mg_find(sv, how))) {
	    if (how == 't')
		mg->mg_len |= 1;
	    return;
	}
    }
    else {
        (void)SvUPGRADE(sv, SVt_PVMG);
    }
    Newz(702,mg, 1, MAGIC);
    mg->mg_moremagic = SvMAGIC(sv);

    SvMAGIC(sv) = mg;
    if (!obj || obj == sv || how == '#' || how == 'r')
	mg->mg_obj = obj;
    else {
	dTHR;
	mg->mg_obj = SvREFCNT_inc(obj);
	mg->mg_flags |= MGf_REFCOUNTED;
    }
    mg->mg_type = how;
    mg->mg_len = namlen;
    if (name)
	if (namlen >= 0)
	    mg->mg_ptr = savepvn(name, namlen);
	else if (namlen == HEf_SVKEY)
	    mg->mg_ptr = (char*)SvREFCNT_inc((SV*)name);
    
    switch (how) {
    case 0:
	mg->mg_virtual = &PL_vtbl_sv;
	break;
    case 'A':
        mg->mg_virtual = &PL_vtbl_amagic;
        break;
    case 'a':
        mg->mg_virtual = &PL_vtbl_amagicelem;
        break;
    case 'c':
        mg->mg_virtual = 0;
        break;
    case 'B':
	mg->mg_virtual = &PL_vtbl_bm;
	break;
    case 'D':
	mg->mg_virtual = &PL_vtbl_regdata;
	break;
    case 'd':
	mg->mg_virtual = &PL_vtbl_regdatum;
	break;
    case 'E':
	mg->mg_virtual = &PL_vtbl_env;
	break;
    case 'f':
	mg->mg_virtual = &PL_vtbl_fm;
	break;
    case 'e':
	mg->mg_virtual = &PL_vtbl_envelem;
	break;
    case 'g':
	mg->mg_virtual = &PL_vtbl_mglob;
	break;
    case 'I':
	mg->mg_virtual = &PL_vtbl_isa;
	break;
    case 'i':
	mg->mg_virtual = &PL_vtbl_isaelem;
	break;
    case 'k':
	mg->mg_virtual = &PL_vtbl_nkeys;
	break;
    case 'L':
	SvRMAGICAL_on(sv);
	mg->mg_virtual = 0;
	break;
    case 'l':
	mg->mg_virtual = &PL_vtbl_dbline;
	break;
#ifdef USE_THREADS
    case 'm':
	mg->mg_virtual = &PL_vtbl_mutex;
	break;
#endif /* USE_THREADS */
#ifdef USE_LOCALE_COLLATE
    case 'o':
        mg->mg_virtual = &PL_vtbl_collxfrm;
        break;
#endif /* USE_LOCALE_COLLATE */
    case 'P':
	mg->mg_virtual = &PL_vtbl_pack;
	break;
    case 'p':
    case 'q':
	mg->mg_virtual = &PL_vtbl_packelem;
	break;
    case 'r':
	mg->mg_virtual = &PL_vtbl_regexp;
	break;
    case 'S':
	mg->mg_virtual = &PL_vtbl_sig;
	break;
    case 's':
	mg->mg_virtual = &PL_vtbl_sigelem;
	break;
    case 't':
	mg->mg_virtual = &PL_vtbl_taint;
	mg->mg_len = 1;
	break;
    case 'U':
	mg->mg_virtual = &PL_vtbl_uvar;
	break;
    case 'v':
	mg->mg_virtual = &PL_vtbl_vec;
	break;
    case 'x':
	mg->mg_virtual = &PL_vtbl_substr;
	break;
    case 'y':
	mg->mg_virtual = &PL_vtbl_defelem;
	break;
    case '*':
	mg->mg_virtual = &PL_vtbl_glob;
	break;
    case '#':
	mg->mg_virtual = &PL_vtbl_arylen;
	break;
    case '.':
	mg->mg_virtual = &PL_vtbl_pos;
	break;
    case '~':	/* Reserved for use by extensions not perl internals.	*/
	/* Useful for attaching extension internal data to perl vars.	*/
	/* Note that multiple extensions may clash if magical scalars	*/
	/* etc holding private data from one are passed to another.	*/
	SvRMAGICAL_on(sv);
	break;
    default:
	croak("Don't know how to handle magic of type '%c'", how);
    }
    mg_magical(sv);
    if (SvGMAGICAL(sv))
	SvFLAGS(sv) &= ~(SVf_IOK|SVf_NOK|SVf_POK);
}

int
sv_unmagic(SV *sv, int type)
{
    MAGIC* mg;
    MAGIC** mgp;
    if (SvTYPE(sv) < SVt_PVMG || !SvMAGIC(sv))
	return 0;
    mgp = &SvMAGIC(sv);
    for (mg = *mgp; mg; mg = *mgp) {
	if (mg->mg_type == type) {
	    MGVTBL* vtbl = mg->mg_virtual;
	    *mgp = mg->mg_moremagic;
	    if (vtbl && (vtbl->svt_free != NULL))
		(VTBL->svt_free)(sv, mg);
	    if (mg->mg_ptr && mg->mg_type != 'g')
		if (mg->mg_len >= 0)
		    Safefree(mg->mg_ptr);
		else if (mg->mg_len == HEf_SVKEY)
		    SvREFCNT_dec((SV*)mg->mg_ptr);
	    if (mg->mg_flags & MGf_REFCOUNTED)
		SvREFCNT_dec(mg->mg_obj);
	    Safefree(mg);
	}
	else
	    mgp = &mg->mg_moremagic;
    }
    if (!SvMAGIC(sv)) {
	SvMAGICAL_off(sv);
	SvFLAGS(sv) |= (SvFLAGS(sv) & (SVp_IOK|SVp_NOK|SVp_POK)) >> PRIVSHIFT;
    }

    return 0;
}

void
sv_insert(SV *bigstr, STRLEN offset, STRLEN len, char *little, STRLEN littlelen)
{
    register char *big;
    register char *mid;
    register char *midend;
    register char *bigend;
    register I32 i;
    STRLEN curlen;
    

    if (!bigstr)
	croak("Can't modify non-existent substring");
    SvPV_force(bigstr, curlen);
    if (offset + len > curlen) {
	SvGROW(bigstr, offset+len+1);
	Zero(SvPVX(bigstr)+curlen, offset+len-curlen, char);
	SvCUR_set(bigstr, offset+len);
    }

    i = littlelen - len;
    if (i > 0) {			/* string might grow */
	big = SvGROW(bigstr, SvCUR(bigstr) + i + 1);
	mid = big + offset + len;
	midend = bigend = big + SvCUR(bigstr);
	bigend += i;
	*bigend = '\0';
	while (midend > mid)		/* shove everything down */
	    *--bigend = *--midend;
	Move(little,big+offset,littlelen,char);
	SvCUR(bigstr) += i;
	SvSETMAGIC(bigstr);
	return;
    }
    else if (i == 0) {
	Move(little,SvPVX(bigstr)+offset,len,char);
	SvSETMAGIC(bigstr);
	return;
    }

    big = SvPVX(bigstr);
    mid = big + offset;
    midend = mid + len;
    bigend = big + SvCUR(bigstr);

    if (midend > bigend)
	croak("panic: sv_insert");

    if (mid - big > bigend - midend) {	/* faster to shorten from end */
	if (littlelen) {
	    Move(little, mid, littlelen,char);
	    mid += littlelen;
	}
	i = bigend - midend;
	if (i > 0) {
	    Move(midend, mid, i,char);
	    mid += i;
	}
	*mid = '\0';
	SvCUR_set(bigstr, mid - big);
    }
    /*SUPPRESS 560*/
    else if (i = mid - big) {	/* faster from front */
	midend -= littlelen;
	mid = midend;
	sv_chop(bigstr,midend-i);
	big += i;
	while (i--)
	    *--midend = *--big;
	if (littlelen)
	    Move(little, mid, littlelen,char);
    }
    else if (littlelen) {
	midend -= littlelen;
	sv_chop(bigstr,midend);
	Move(little,midend,littlelen,char);
    }
    else {
	sv_chop(bigstr,midend);
    }
    SvSETMAGIC(bigstr);
}

/* make sv point to what nstr did */

void
sv_replace(register SV *sv, register SV *nsv)
{
    U32 refcnt = SvREFCNT(sv);
    SV_CHECK_THINKFIRST(sv);
    if (SvREFCNT(nsv) != 1)
	warn("Reference miscount in sv_replace()");
    if (SvMAGICAL(sv)) {
	if (SvMAGICAL(nsv))
	    mg_free(nsv);
	else
	    sv_upgrade(nsv, SVt_PVMG);
	SvMAGIC(nsv) = SvMAGIC(sv);
	SvFLAGS(nsv) |= SvMAGICAL(sv);
	SvMAGICAL_off(sv);
	SvMAGIC(sv) = 0;
    }
    SvREFCNT(sv) = 0;
    sv_clear(sv);
    assert(!SvREFCNT(sv));
    StructCopy(nsv,sv,SV);
    SvREFCNT(sv) = refcnt;
    SvFLAGS(nsv) |= SVTYPEMASK;		/* Mark as freed */
    del_SV(nsv);
}

void
sv_clear(register SV *sv)
{
    HV* stash;
    assert(sv);
    assert(SvREFCNT(sv) == 0);

    if (SvOBJECT(sv)) {
	dTHR;
	if (PL_defstash) {		/* Still have a symbol table? */
	    djSP;
	    GV* destructor;
	    SV tmpref;

	    Zero(&tmpref, 1, SV);
	    sv_upgrade(&tmpref, SVt_RV);
	    SvROK_on(&tmpref);
	    SvREADONLY_on(&tmpref);	/* DESTROY() could be naughty */
	    SvREFCNT(&tmpref) = 1;

	    do {
		stash = SvSTASH(sv);
		destructor = gv_fetchmethod(SvSTASH(sv), "DESTROY");
		if (destructor) {
		    ENTER;
		    PUSHSTACKi(PERLSI_DESTROY);
		    SvRV(&tmpref) = SvREFCNT_inc(sv);
		    EXTEND(SP, 2);
		    PUSHMARK(SP);
		    PUSHs(&tmpref);
		    PUTBACK;
		    perl_call_sv((SV*)GvCV(destructor),
				 G_DISCARD|G_EVAL|G_KEEPERR);
		    SvREFCNT(sv)--;
		    POPSTACK;
		    SPAGAIN;
		    LEAVE;
		}
	    } while (SvOBJECT(sv) && SvSTASH(sv) != stash);

	    del_XRV(SvANY(&tmpref));
	}

	if (SvOBJECT(sv)) {
	    SvREFCNT_dec(SvSTASH(sv));	/* possibly of changed persuasion */
	    SvOBJECT_off(sv);	/* Curse the object. */
	    if (SvTYPE(sv) != SVt_PVIO)
		--PL_sv_objcount;	/* XXX Might want something more general */
	}
	if (SvREFCNT(sv)) {
		if (PL_in_clean_objs)
		    croak("DESTROY created new reference to dead object");
		/* DESTROY gave object new lease on life */
		return;
	}
    }
    if (SvTYPE(sv) >= SVt_PVMG && SvMAGIC(sv))
	mg_free(sv);
    stash = NULL;
    switch (SvTYPE(sv)) {
    case SVt_PVIO:
	if (IoIFP(sv) &&
	    IoIFP(sv) != PerlIO_stdin() &&
	    IoIFP(sv) != PerlIO_stdout() &&
	    IoIFP(sv) != PerlIO_stderr())
	  io_close((IO*)sv);
	Safefree(IoTOP_NAME(sv));
	Safefree(IoFMT_NAME(sv));
	Safefree(IoBOTTOM_NAME(sv));
	/* FALL THROUGH */
    case SVt_PVBM:
	goto freescalar;
    case SVt_PVCV:
    case SVt_PVFM:
	cv_undef((CV*)sv);
	goto freescalar;
    case SVt_PVHV:
	hv_undef((HV*)sv);
	break;
    case SVt_PVAV:
	av_undef((AV*)sv);
	break;
    case SVt_PVLV:
	SvREFCNT_dec(LvTARG(sv));
	goto freescalar;
    case SVt_PVGV:
	gp_free((GV*)sv);
	Safefree(GvNAME(sv));
	/* cannot decrease stash refcount yet, as we might recursively delete
	   ourselves when the refcnt drops to zero. Delay SvREFCNT_dec
	   of stash until current sv is completely gone.
	   -- JohnPC, 27 Mar 1998 */
	stash = GvSTASH(sv);
	/* FALL THROUGH */
    case SVt_PVMG:
    case SVt_PVNV:
    case SVt_PVIV:
      freescalar:
	(void)SvOOK_off(sv);
	/* FALL THROUGH */
    case SVt_PV:
    case SVt_RV:
	if (SvROK(sv))
	    SvREFCNT_dec(SvRV(sv));
	else if (SvPVX(sv) && SvLEN(sv))
	    Safefree(SvPVX(sv));
	break;
/*
    case SVt_NV:
    case SVt_IV:
    case SVt_NULL:
	break;
*/
    }

    switch (SvTYPE(sv)) {
    case SVt_NULL:
	break;
    case SVt_IV:
	del_XIV(SvANY(sv));
	break;
    case SVt_NV:
	del_XNV(SvANY(sv));
	break;
    case SVt_RV:
	del_XRV(SvANY(sv));
	break;
    case SVt_PV:
	del_XPV(SvANY(sv));
	break;
    case SVt_PVIV:
	del_XPVIV(SvANY(sv));
	break;
    case SVt_PVNV:
	del_XPVNV(SvANY(sv));
	break;
    case SVt_PVMG:
	del_XPVMG(SvANY(sv));
	break;
    case SVt_PVLV:
	del_XPVLV(SvANY(sv));
	break;
    case SVt_PVAV:
	del_XPVAV(SvANY(sv));
	break;
    case SVt_PVHV:
	del_XPVHV(SvANY(sv));
	break;
    case SVt_PVCV:
	del_XPVCV(SvANY(sv));
	break;
    case SVt_PVGV:
	del_XPVGV(SvANY(sv));
	/* code duplication for increased performance. */
	SvFLAGS(sv) &= SVf_BREAK;
	SvFLAGS(sv) |= SVTYPEMASK;
	/* decrease refcount of the stash that owns this GV, if any */
	if (stash)
	    SvREFCNT_dec(stash);
	return; /* not break, SvFLAGS reset already happened */
    case SVt_PVBM:
	del_XPVBM(SvANY(sv));
	break;
    case SVt_PVFM:
	del_XPVFM(SvANY(sv));
	break;
    case SVt_PVIO:
	del_XPVIO(SvANY(sv));
	break;
    }
    SvFLAGS(sv) &= SVf_BREAK;
    SvFLAGS(sv) |= SVTYPEMASK;
}

SV *
sv_newref(SV *sv)
{
    if (sv)
	ATOMIC_INC(SvREFCNT(sv));
    return sv;
}

void
sv_free(SV *sv)
{
    int refcount_is_zero;

    if (!sv)
	return;
    if (SvREFCNT(sv) == 0) {
	if (SvFLAGS(sv) & SVf_BREAK)
	    return;
	if (PL_in_clean_all) /* All is fair */
	    return;
	if (SvREADONLY(sv) && SvIMMORTAL(sv)) {
	    /* make sure SvREFCNT(sv)==0 happens very seldom */
	    SvREFCNT(sv) = (~(U32)0)/2;
	    return;
	}
	warn("Attempt to free unreferenced scalar");
	return;
    }
    ATOMIC_DEC_AND_TEST(refcount_is_zero, SvREFCNT(sv));
    if (!refcount_is_zero)
	return;
#ifdef DEBUGGING
    if (SvTEMP(sv)) {
	warn("Attempt to free temp prematurely: SV 0x%lx", (unsigned long)sv);
	return;
    }
#endif
    if (SvREADONLY(sv) && SvIMMORTAL(sv)) {
	/* make sure SvREFCNT(sv)==0 happens very seldom */
	SvREFCNT(sv) = (~(U32)0)/2;
	return;
    }
    sv_clear(sv);
    if (! SvREFCNT(sv))
	del_SV(sv);
}

STRLEN
sv_len(register SV *sv)
{
    char *junk;
    STRLEN len;

    if (!sv)
	return 0;

    if (SvGMAGICAL(sv))
	len = mg_length(sv);
    else
	junk = SvPV(sv, len);
    return len;
}

STRLEN
sv_len_utf8(register SV *sv)
{
    U8 *s;
    U8 *send;
    STRLEN len;

    if (!sv)
	return 0;

#ifdef NOTYET
    if (SvGMAGICAL(sv))
	len = mg_length(sv);
    else
#endif
	s = (U8*)SvPV(sv, len);
    send = s + len;
    len = 0;
    while (s < send) {
	s += UTF8SKIP(s);
	len++;
    }
    return len;
}

void
sv_pos_u2b(register SV *sv, I32* offsetp, I32* lenp)
{
    U8 *start;
    U8 *s;
    U8 *send;
    I32 uoffset = *offsetp;
    STRLEN len;

    if (!sv)
	return;

    start = s = (U8*)SvPV(sv, len);
    send = s + len;
    while (s < send && uoffset--)
	s += UTF8SKIP(s);
    if (s >= send)
	s = send;
    *offsetp = s - start;
    if (lenp) {
	I32 ulen = *lenp;
	start = s;
	while (s < send && ulen--)
	    s += UTF8SKIP(s);
	if (s >= send)
	    s = send;
	*lenp = s - start;
    }
    return;
}

void
sv_pos_b2u(register SV *sv, I32* offsetp)
{
    U8 *s;
    U8 *send;
    STRLEN len;

    if (!sv)
	return;

    s = (U8*)SvPV(sv, len);
    if (len < *offsetp)
	croak("panic: bad byte offset");
    send = s + *offsetp;
    len = 0;
    while (s < send) {
	s += UTF8SKIP(s);
	++len;
    }
    if (s != send) {
	warn("Malformed UTF-8 character");
	--len;
    }
    *offsetp = len;
    return;
}

I32
sv_eq(register SV *str1, register SV *str2)
{
    char *pv1;
    STRLEN cur1;
    char *pv2;
    STRLEN cur2;

    if (!str1) {
	pv1 = "";
	cur1 = 0;
    }
    else
	pv1 = SvPV(str1, cur1);

    if (!str2)
	return !cur1;
    else
	pv2 = SvPV(str2, cur2);

    if (cur1 != cur2)
	return 0;

    return memEQ(pv1, pv2, cur1);
}

I32
sv_cmp(register SV *str1, register SV *str2)
{
    STRLEN cur1 = 0;
    char *pv1 = str1 ? SvPV(str1, cur1) : (char *) NULL;
    STRLEN cur2 = 0;
    char *pv2 = str2 ? SvPV(str2, cur2) : (char *) NULL;
    I32 retval;

    if (!cur1)
	return cur2 ? -1 : 0;

    if (!cur2)
	return 1;

    retval = memcmp((void*)pv1, (void*)pv2, cur1 < cur2 ? cur1 : cur2);

    if (retval)
	return retval < 0 ? -1 : 1;

    if (cur1 == cur2)
	return 0;
    else
	return cur1 < cur2 ? -1 : 1;
}

I32
sv_cmp_locale(register SV *sv1, register SV *sv2)
{
#ifdef USE_LOCALE_COLLATE

    char *pv1, *pv2;
    STRLEN len1, len2;
    I32 retval;

    if (PL_collation_standard)
	goto raw_compare;

    len1 = 0;
    pv1 = sv1 ? sv_collxfrm(sv1, &len1) : (char *) NULL;
    len2 = 0;
    pv2 = sv2 ? sv_collxfrm(sv2, &len2) : (char *) NULL;

    if (!pv1 || !len1) {
	if (pv2 && len2)
	    return -1;
	else
	    goto raw_compare;
    }
    else {
	if (!pv2 || !len2)
	    return 1;
    }

    retval = memcmp((void*)pv1, (void*)pv2, len1 < len2 ? len1 : len2);

    if (retval)
	return retval < 0 ? -1 : 1;

    /*
     * When the result of collation is equality, that doesn't mean
     * that there are no differences -- some locales exclude some
     * characters from consideration.  So to avoid false equalities,
     * we use the raw string as a tiebreaker.
     */

  raw_compare:
    /* FALL THROUGH */

#endif /* USE_LOCALE_COLLATE */

    return sv_cmp(sv1, sv2);
}

#ifdef USE_LOCALE_COLLATE
/*
 * Any scalar variable may carry an 'o' magic that contains the
 * scalar data of the variable transformed to such a format that
 * a normal memory comparison can be used to compare the data
 * according to the locale settings.
 */
char *
sv_collxfrm(SV *sv, STRLEN *nxp)
{
    MAGIC *mg;

    mg = SvMAGICAL(sv) ? mg_find(sv, 'o') : (MAGIC *) NULL;
    if (!mg || !mg->mg_ptr || *(U32*)mg->mg_ptr != PL_collation_ix) {
	char *s, *xf;
	STRLEN len, xlen;

	if (mg)
	    Safefree(mg->mg_ptr);
	s = SvPV(sv, len);
	if ((xf = mem_collxfrm(s, len, &xlen))) {
	    if (SvREADONLY(sv)) {
		SAVEFREEPV(xf);
		*nxp = xlen;
		return xf + sizeof(PL_collation_ix);
	    }
	    if (! mg) {
		sv_magic(sv, 0, 'o', 0, 0);
		mg = mg_find(sv, 'o');
		assert(mg);
	    }
	    mg->mg_ptr = xf;
	    mg->mg_len = xlen;
	}
	else {
	    if (mg) {
		mg->mg_ptr = NULL;
		mg->mg_len = -1;
	    }
	}
    }
    if (mg && mg->mg_ptr) {
	*nxp = mg->mg_len;
	return mg->mg_ptr + sizeof(PL_collation_ix);
    }
    else {
	*nxp = 0;
	return NULL;
    }
}

#endif /* USE_LOCALE_COLLATE */

char *
sv_gets(register SV *sv, register PerlIO *fp, I32 append)
{
    dTHR;
    char *rsptr;
    STRLEN rslen;
    register STDCHAR rslast;
    register STDCHAR *bp;
    register I32 cnt;
    I32 i;

    SV_CHECK_THINKFIRST(sv);
    (void)SvUPGRADE(sv, SVt_PV);
    SvSCREAM_off(sv);

    if (RsSNARF(PL_rs)) {
	rsptr = NULL;
	rslen = 0;
    }
    else if (RsRECORD(PL_rs)) {
      I32 recsize, bytesread;
      char *buffer;

      /* Grab the size of the record we're getting */
      recsize = SvIV(SvRV(PL_rs));
      (void)SvPOK_only(sv);    /* Validate pointer */
      buffer = SvGROW(sv, recsize + 1);
      /* Go yank in */
#ifdef VMS
      /* VMS wants read instead of fread, because fread doesn't respect */
      /* RMS record boundaries. This is not necessarily a good thing to be */
      /* doing, but we've got no other real choice */
      bytesread = PerlLIO_read(PerlIO_fileno(fp), buffer, recsize);
#else
      bytesread = PerlIO_read(fp, buffer, recsize);
#endif
      SvCUR_set(sv, bytesread);
      buffer[bytesread] = '\0';
      return(SvCUR(sv) ? SvPVX(sv) : Nullch);
    }
    else if (RsPARA(PL_rs)) {
	rsptr = "\n\n";
	rslen = 2;
    }
    else
	rsptr = SvPV(PL_rs, rslen);
    rslast = rslen ? rsptr[rslen - 1] : '\0';

    if (RsPARA(PL_rs)) {		/* have to do this both before and after */
	do {			/* to make sure file boundaries work right */
	    if (PerlIO_eof(fp))
		return 0;
	    i = PerlIO_getc(fp);
	    if (i != '\n') {
		if (i == -1)
		    return 0;
		PerlIO_ungetc(fp,i);
		break;
	    }
	} while (i != EOF);
    }

    /* See if we know enough about I/O mechanism to cheat it ! */

    /* This used to be #ifdef test - it is made run-time test for ease
       of abstracting out stdio interface. One call should be cheap 
       enough here - and may even be a macro allowing compile
       time optimization.
     */

    if (PerlIO_fast_gets(fp)) {

    /*
     * We're going to steal some values from the stdio struct
     * and put EVERYTHING in the innermost loop into registers.
     */
    register STDCHAR *ptr;
    STRLEN bpx;
    I32 shortbuffered;

#if defined(VMS) && defined(PERLIO_IS_STDIO)
    /* An ungetc()d char is handled separately from the regular
     * buffer, so we getc() it back out and stuff it in the buffer.
     */
    i = PerlIO_getc(fp);
    if (i == EOF) return 0;
    *(--((*fp)->_ptr)) = (unsigned char) i;
    (*fp)->_cnt++;
#endif

    /* Here is some breathtakingly efficient cheating */

    cnt = PerlIO_get_cnt(fp);			/* get count into register */
    (void)SvPOK_only(sv);		/* validate pointer */
    if (SvLEN(sv) - append <= cnt + 1) { /* make sure we have the room */
	if (cnt > 80 && SvLEN(sv) > append) {
	    shortbuffered = cnt - SvLEN(sv) + append + 1;
	    cnt -= shortbuffered;
	}
	else {
	    shortbuffered = 0;
	    /* remember that cnt can be negative */
	    SvGROW(sv, append + (cnt <= 0 ? 2 : (cnt + 1)));
	}
    }
    else
	shortbuffered = 0;
    bp = (STDCHAR*)SvPVX(sv) + append;  /* move these two too to registers */
    ptr = (STDCHAR*)PerlIO_get_ptr(fp);
    DEBUG_P(PerlIO_printf(Perl_debug_log,
	"Screamer: entering, ptr=%ld, cnt=%ld\n",(long)ptr,(long)cnt));
    DEBUG_P(PerlIO_printf(Perl_debug_log,
	"Screamer: entering: FILE * thinks ptr=%ld, cnt=%ld, base=%ld\n",
	       (long)PerlIO_get_ptr(fp), (long)PerlIO_get_cnt(fp), 
	       (long)(PerlIO_has_base(fp) ? PerlIO_get_base(fp) : 0)));
    for (;;) {
      screamer:
	if (cnt > 0) {
	    if (rslen) {
		while (cnt > 0) {		     /* this     |  eat */
		    cnt--;
		    if ((*bp++ = *ptr++) == rslast)  /* really   |  dust */
			goto thats_all_folks;	     /* screams  |  sed :-) */
		}
	    }
	    else {
	        Copy(ptr, bp, cnt, char);	     /* this     |  eat */    
		bp += cnt;			     /* screams  |  dust */   
		ptr += cnt;			     /* louder   |  sed :-) */
		cnt = 0;
	    }
	}
	
	if (shortbuffered) {		/* oh well, must extend */
	    cnt = shortbuffered;
	    shortbuffered = 0;
	    bpx = bp - (STDCHAR*)SvPVX(sv); /* box up before relocation */
	    SvCUR_set(sv, bpx);
	    SvGROW(sv, SvLEN(sv) + append + cnt + 2);
	    bp = (STDCHAR*)SvPVX(sv) + bpx; /* unbox after relocation */
	    continue;
	}

	DEBUG_P(PerlIO_printf(Perl_debug_log,
	    "Screamer: going to getc, ptr=%ld, cnt=%ld\n",(long)ptr,(long)cnt));
	PerlIO_set_ptrcnt(fp, ptr, cnt); /* deregisterize cnt and ptr */
	DEBUG_P(PerlIO_printf(Perl_debug_log,
	    "Screamer: pre: FILE * thinks ptr=%ld, cnt=%ld, base=%ld\n",
	    (long)PerlIO_get_ptr(fp), (long)PerlIO_get_cnt(fp), 
	    (long)(PerlIO_has_base (fp) ? PerlIO_get_base(fp) : 0)));
	/* This used to call 'filbuf' in stdio form, but as that behaves like 
	   getc when cnt <= 0 we use PerlIO_getc here to avoid introducing
	   another abstraction.  */
	i   = PerlIO_getc(fp);		/* get more characters */
	DEBUG_P(PerlIO_printf(Perl_debug_log,
	    "Screamer: post: FILE * thinks ptr=%ld, cnt=%ld, base=%ld\n",
	    (long)PerlIO_get_ptr(fp), (long)PerlIO_get_cnt(fp), 
	    (long)(PerlIO_has_base (fp) ? PerlIO_get_base(fp) : 0)));
	cnt = PerlIO_get_cnt(fp);
	ptr = (STDCHAR*)PerlIO_get_ptr(fp);	/* reregisterize cnt and ptr */
	DEBUG_P(PerlIO_printf(Perl_debug_log,
	    "Screamer: after getc, ptr=%ld, cnt=%ld\n",(long)ptr,(long)cnt));

	if (i == EOF)			/* all done for ever? */
	    goto thats_really_all_folks;

	bpx = bp - (STDCHAR*)SvPVX(sv);	/* box up before relocation */
	SvCUR_set(sv, bpx);
	SvGROW(sv, bpx + cnt + 2);
	bp = (STDCHAR*)SvPVX(sv) + bpx;	/* unbox after relocation */

	*bp++ = i;			/* store character from PerlIO_getc */

	if (rslen && (STDCHAR)i == rslast)  /* all done for now? */
	    goto thats_all_folks;
    }

thats_all_folks:
    if ((rslen > 1 && (bp - (STDCHAR*)SvPVX(sv) < rslen)) ||
	  memNE((char*)bp - rslen, rsptr, rslen))
	goto screamer;				/* go back to the fray */
thats_really_all_folks:
    if (shortbuffered)
	cnt += shortbuffered;
	DEBUG_P(PerlIO_printf(Perl_debug_log,
	    "Screamer: quitting, ptr=%ld, cnt=%ld\n",(long)ptr,(long)cnt));
    PerlIO_set_ptrcnt(fp, ptr, cnt);	/* put these back or we're in trouble */
    DEBUG_P(PerlIO_printf(Perl_debug_log,
	"Screamer: end: FILE * thinks ptr=%ld, cnt=%ld, base=%ld\n",
	(long)PerlIO_get_ptr(fp), (long)PerlIO_get_cnt(fp), 
	(long)(PerlIO_has_base (fp) ? PerlIO_get_base(fp) : 0)));
    *bp = '\0';
    SvCUR_set(sv, bp - (STDCHAR*)SvPVX(sv));	/* set length */
    DEBUG_P(PerlIO_printf(Perl_debug_log,
	"Screamer: done, len=%ld, string=|%.*s|\n",
	(long)SvCUR(sv),(int)SvCUR(sv),SvPVX(sv)));
    }
   else
    {
       /*The big, slow, and stupid way */
	STDCHAR buf[8192];

screamer2:
	if (rslen) {
	    register STDCHAR *bpe = buf + sizeof(buf);
	    bp = buf;
	    while ((i = PerlIO_getc(fp)) != EOF && (*bp++ = i) != rslast && bp < bpe)
		; /* keep reading */
	    cnt = bp - buf;
	}
	else {
	    cnt = PerlIO_read(fp,(char*)buf, sizeof(buf));
	    /* Accomodate broken VAXC compiler, which applies U8 cast to
	     * both args of ?: operator, causing EOF to change into 255
	     */
	    if (cnt) { i = (U8)buf[cnt - 1]; } else { i = EOF; }
	}

	if (append)
	    sv_catpvn(sv, (char *) buf, cnt);
	else
	    sv_setpvn(sv, (char *) buf, cnt);

	if (i != EOF &&			/* joy */
	    (!rslen ||
	     SvCUR(sv) < rslen ||
	     memNE(SvPVX(sv) + SvCUR(sv) - rslen, rsptr, rslen)))
	{
	    append = -1;
	    /*
	     * If we're reading from a TTY and we get a short read,
	     * indicating that the user hit his EOF character, we need
	     * to notice it now, because if we try to read from the TTY
	     * again, the EOF condition will disappear.
	     *
	     * The comparison of cnt to sizeof(buf) is an optimization
	     * that prevents unnecessary calls to feof().
	     *
	     * - jik 9/25/96
	     */
	    if (!(cnt < sizeof(buf) && PerlIO_eof(fp)))
		goto screamer2;
	}
    }

    if (RsPARA(PL_rs)) {		/* have to do this both before and after */  
        while (i != EOF) {	/* to make sure file boundaries work right */
	    i = PerlIO_getc(fp);
	    if (i != '\n') {
		PerlIO_ungetc(fp,i);
		break;
	    }
	}
    }

#ifdef WIN32
    win32_strip_return(sv);
#endif

    return (SvCUR(sv) - append) ? SvPVX(sv) : Nullch;
}


void
sv_inc(register SV *sv)
{
    register char *d;
    int flags;

    if (!sv)
	return;
    if (SvGMAGICAL(sv))
	mg_get(sv);
    if (SvTHINKFIRST(sv)) {
	if (SvREADONLY(sv)) {
	    dTHR;
	    if (PL_curcop != &PL_compiling)
		croak(PL_no_modify);
	}
	if (SvROK(sv)) {
	    IV i;
	    if (SvAMAGIC(sv) && AMG_CALLun(sv,inc))
		return;
	    i = (IV)SvRV(sv);
	    sv_unref(sv);
	    sv_setiv(sv, i);
	}
    }
    flags = SvFLAGS(sv);
    if (flags & SVp_NOK) {
	(void)SvNOK_only(sv);
	SvNVX(sv) += 1.0;
	return;
    }
    if (flags & SVp_IOK) {
	if (SvIVX(sv) == IV_MAX)
	    sv_setnv(sv, (double)IV_MAX + 1.0);
	else {
	    (void)SvIOK_only(sv);
	    ++SvIVX(sv);
	}
	return;
    }
    if (!(flags & SVp_POK) || !*SvPVX(sv)) {
	if ((flags & SVTYPEMASK) < SVt_PVNV)
	    sv_upgrade(sv, SVt_NV);
	SvNVX(sv) = 1.0;
	(void)SvNOK_only(sv);
	return;
    }
    d = SvPVX(sv);
    while (isALPHA(*d)) d++;
    while (isDIGIT(*d)) d++;
    if (*d) {
	SET_NUMERIC_STANDARD();
	sv_setnv(sv,atof(SvPVX(sv)) + 1.0);  /* punt */
	return;
    }
    d--;
    while (d >= SvPVX(sv)) {
	if (isDIGIT(*d)) {
	    if (++*d <= '9')
		return;
	    *(d--) = '0';
	}
	else {
#ifdef EBCDIC
	    /* MKS: The original code here died if letters weren't consecutive.
	     * at least it didn't have to worry about non-C locales.  The
	     * new code assumes that ('z'-'a')==('Z'-'A'), letters are
	     * arranged in order (although not consecutively) and that only 
	     * [A-Za-z] are accepted by isALPHA in the C locale.
	     */
	    if (*d != 'z' && *d != 'Z') {
		do { ++*d; } while (!isALPHA(*d));
		return;
	    }
	    *(d--) -= 'z' - 'a';
#else
	    ++*d;
	    if (isALPHA(*d))
		return;
	    *(d--) -= 'z' - 'a' + 1;
#endif
	}
    }
    /* oh,oh, the number grew */
    SvGROW(sv, SvCUR(sv) + 2);
    SvCUR(sv)++;
    for (d = SvPVX(sv) + SvCUR(sv); d > SvPVX(sv); d--)
	*d = d[-1];
    if (isDIGIT(d[1]))
	*d = '1';
    else
	*d = d[1];
}

void
sv_dec(register SV *sv)
{
    int flags;

    if (!sv)
	return;
    if (SvGMAGICAL(sv))
	mg_get(sv);
    if (SvTHINKFIRST(sv)) {
	if (SvREADONLY(sv)) {
	    dTHR;
	    if (PL_curcop != &PL_compiling)
		croak(PL_no_modify);
	}
	if (SvROK(sv)) {
	    IV i;
	    if (SvAMAGIC(sv) && AMG_CALLun(sv,dec))
		return;
	    i = (IV)SvRV(sv);
	    sv_unref(sv);
	    sv_setiv(sv, i);
	}
    }
    flags = SvFLAGS(sv);
    if (flags & SVp_NOK) {
	SvNVX(sv) -= 1.0;
	(void)SvNOK_only(sv);
	return;
    }
    if (flags & SVp_IOK) {
	if (SvIVX(sv) == IV_MIN)
	    sv_setnv(sv, (double)IV_MIN - 1.0);
	else {
	    (void)SvIOK_only(sv);
	    --SvIVX(sv);
	}
	return;
    }
    if (!(flags & SVp_POK)) {
	if ((flags & SVTYPEMASK) < SVt_PVNV)
	    sv_upgrade(sv, SVt_NV);
	SvNVX(sv) = -1.0;
	(void)SvNOK_only(sv);
	return;
    }
    SET_NUMERIC_STANDARD();
    sv_setnv(sv,atof(SvPVX(sv)) - 1.0);	/* punt */
}

/* Make a string that will exist for the duration of the expression
 * evaluation.  Actually, it may have to last longer than that, but
 * hopefully we won't free it until it has been assigned to a
 * permanent location. */

STATIC void
sv_mortalgrow(void)
{
    dTHR;
    PL_tmps_max += (PL_tmps_max < 512) ? 128 : 512;
    Renew(PL_tmps_stack, PL_tmps_max, SV*);
}

SV *
sv_mortalcopy(SV *oldstr)
{
    dTHR;
    register SV *sv;

    new_SV(sv);
    SvANY(sv) = 0;
    SvREFCNT(sv) = 1;
    SvFLAGS(sv) = 0;
    sv_setsv(sv,oldstr);
    if (++PL_tmps_ix >= PL_tmps_max)
	sv_mortalgrow();
    PL_tmps_stack[PL_tmps_ix] = sv;
    SvTEMP_on(sv);
    return sv;
}

SV *
sv_newmortal(void)
{
    dTHR;
    register SV *sv;

    new_SV(sv);
    SvANY(sv) = 0;
    SvREFCNT(sv) = 1;
    SvFLAGS(sv) = SVs_TEMP;
    if (++PL_tmps_ix >= PL_tmps_max)
	sv_mortalgrow();
    PL_tmps_stack[PL_tmps_ix] = sv;
    return sv;
}

/* same thing without the copying */