clean up some stray "global" symbols

[perl5.git] / sv.c

/*    sv.c
 *
 *    Copyright (c) 1991-1999, 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_unglob (SV* sv);
static void sv_add_backref (SV *tsv, SV *sv);
static void sv_del_backref (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_force_normal(sv)

#ifdef PURIFY

#define new_SV(p) \
    STMT_START {					\
	LOCK_SV_MUTEX;					\
	(p) = (SV*)safemalloc(sizeof(SV));		\
	reg_add(p);					\
	UNLOCK_SV_MUTEX;				\
	SvANY(p) = 0;					\
	SvREFCNT(p) = 1;				\
	SvFLAGS(p) = 0;					\
    } STMT_END

#define del_SV(p) \
    STMT_START {					\
	LOCK_SV_MUTEX;					\
	reg_remove(p);					\
        Safefree((char*)(p));				\
	UNLOCK_SV_MUTEX;				\
    } STMT_END

static SV **registry;
static I32 registry_size;

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

#define REG_REPLACE(sv,a,b) \
    STMT_START {					\
	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);				\
    } STMT_END

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

STATIC void
reg_add(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)
{
    REG_REMOVE(sv);
    --PL_sv_count;
}

STATIC void
visit(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(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) \
    STMT_START {					\
	SvANY(p) = (void *)PL_sv_root;			\
	SvFLAGS(p) = SVTYPEMASK;			\
	PL_sv_root = (p);				\
	--PL_sv_count;					\
    } STMT_END

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

#define new_SV(p) \
    STMT_START {					\
	LOCK_SV_MUTEX;					\
	if (PL_sv_root)					\
	    uproot_SV(p);				\
	else						\
	    (p) = more_sv();				\
	UNLOCK_SV_MUTEX;				\
	SvANY(p) = 0;					\
	SvREFCNT(p) = 1;				\
	SvFLAGS(p) = 0;					\
    } STMT_END

#ifdef DEBUGGING

#define del_SV(p) \
    STMT_START {					\
	LOCK_SV_MUTEX;					\
	if (PL_debug & 32768)				\
	    del_sv(p);					\
	else						\
	    plant_SV(p);				\
	UNLOCK_SV_MUTEX;				\
    } STMT_END

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:
    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)
{
    sv_setiv(sv, 0);
    SvIsUV_on(sv);
    SvUVX(sv) = 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:
    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);
}

/* the number can be converted to _integer_ with atol() */
#define IS_NUMBER_TO_INT_BY_ATOL 0x01
#define IS_NUMBER_TO_INT_BY_ATOF 0x02 /* atol() may be != atof() */
#define IS_NUMBER_NOT_IV	 0x04 /* (IV)atof() may be != atof() */
#define IS_NUMBER_NEG		 0x08 /* not good to cache UV */

/* Actually, ISO C leaves conversion of UV to IV undefined, but
   until proven guilty, assume that things are not that bad... */

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)) {
	    return I_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)) {
		return I_V(SvNVX(sv));
	    }
	    if (SvPOKp(sv) && SvLEN(sv))
		return asIV(sv);
	    {
		dTHR;
		if (ckWARN(WARN_UNINITIALIZED))
		    warner(WARN_UNINITIALIZED, PL_warn_uninit);
	    }
	    return 0;
	}
    }
    if (SvIOKp(sv)) {
	if (SvIsUV(sv)) {
	    return (IV)(SvUVX(sv));
	}
	else {
	    return SvIVX(sv);
	}
    }
    if (SvNOKp(sv)) {
	/* We can cache the IV/UV value even if it not good enough
	 * to reconstruct NV, since the conversion to PV will prefer
	 * NV over IV/UV.				XXXX 64-bit?
	 */

	if (SvTYPE(sv) == SVt_NV)
	    sv_upgrade(sv, SVt_PVNV);

	(void)SvIOK_on(sv);
	if (SvNVX(sv) < (double)IV_MAX + 0.5)
	    SvIVX(sv) = I_V(SvNVX(sv));
	else {
	    SvUVX(sv) = U_V(SvNVX(sv));
	    SvIsUV_on(sv);
	  ret_iv_max:
	    DEBUG_c(PerlIO_printf(Perl_debug_log, 
				  "0x%lx 2iv(%lu => %ld) (as unsigned)\n",
				  (unsigned long)sv,
				  (unsigned long)SvUVX(sv), (long)(IV)SvUVX(sv)));
	    return (IV)SvUVX(sv);
	}
    }
    else if (SvPOKp(sv) && SvLEN(sv)) {
	I32 numtype = looks_like_number(sv);

	/* We want to avoid a possible problem when we cache an IV which
	   may be later translated to an NV, and the resulting NV is not
	   the translation of the initial data.
	  
	   This means that if we cache such an IV, we need to cache the
	   NV as well.  Moreover, we trade speed for space, and do not
	   cache the NV if not needed.
	 */
	if (numtype & IS_NUMBER_NOT_IV) {
	    /* May be not an integer.  Need to cache NV if we cache IV
	     * - otherwise future conversion to NV will be wrong.  */
	    double d;

	    SET_NUMERIC_STANDARD();
	    d = atof(SvPVX(sv));

	    if (SvTYPE(sv) < SVt_PVNV)
		sv_upgrade(sv, SVt_PVNV);
	    SvNVX(sv) = d;
	    (void)SvNOK_on(sv);
	    (void)SvIOK_on(sv);
	    DEBUG_c(PerlIO_printf(Perl_debug_log,
				  "0x%lx 2nv(%g)\n",(unsigned long)sv,
				  SvNVX(sv)));
	    if (SvNVX(sv) < (double)IV_MAX + 0.5)
		SvIVX(sv) = I_V(SvNVX(sv));
	    else {
		SvUVX(sv) = U_V(SvNVX(sv));
		SvIsUV_on(sv);
		goto ret_iv_max;
	    }
	}
	else if (numtype) {
	    /* The NV may be reconstructed from IV - safe to cache IV,
	       which may be calculated by atol(). */
	    if (SvTYPE(sv) == SVt_PV)
		sv_upgrade(sv, SVt_PVIV);
	    (void)SvIOK_on(sv);
	    SvIVX(sv) = atol(SvPVX(sv)); /* XXXX 64-bit? */
	}
	else {				/* Not a number.  Cache 0. */
	    dTHR;

	    if (SvTYPE(sv) < SVt_PVIV)
		sv_upgrade(sv, SVt_PVIV);
	    SvIVX(sv) = 0;
	    (void)SvIOK_on(sv);
	    if (ckWARN(WARN_NUMERIC))
		not_a_number(sv);
	}
    }
    else  {
	dTHR;
	if (ckWARN(WARN_UNINITIALIZED) && !PL_localizing && !(SvFLAGS(sv) & SVs_PADTMP))
	    warner(WARN_UNINITIALIZED, PL_warn_uninit);
	if (SvTYPE(sv) < SVt_IV)
	    /* Typically the caller expects that sv_any is not NULL now.  */
	    sv_upgrade(sv, SVt_IV);
	return 0;
    }
    DEBUG_c(PerlIO_printf(Perl_debug_log, "0x%lx 2iv(%ld)\n",
	(unsigned long)sv,(long)SvIVX(sv)));
    return SvIsUV(sv) ? (IV)SvUVX(sv) : 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;
	}
    }
    if (SvIOKp(sv)) {
	if (SvIsUV(sv)) {
	    return SvUVX(sv);
	}
	else {
	    return (UV)SvIVX(sv);
	}
    }
    if (SvNOKp(sv)) {
	/* We can cache the IV/UV value even if it not good enough
	 * to reconstruct NV, since the conversion to PV will prefer
	 * NV over IV/UV.				XXXX 64-bit?
	 */
	if (SvTYPE(sv) == SVt_NV)
	    sv_upgrade(sv, SVt_PVNV);
	(void)SvIOK_on(sv);
	if (SvNVX(sv) >= -0.5) {
	    SvIsUV_on(sv);
	    SvUVX(sv) = U_V(SvNVX(sv));
	}
	else {
	    SvIVX(sv) = I_V(SvNVX(sv));
	  ret_zero:
	    DEBUG_c(PerlIO_printf(Perl_debug_log, 
				  "0x%lx 2uv(%ld => %lu) (as signed)\n",
				  (unsigned long)sv,(long)SvIVX(sv),
				  (long)(UV)SvIVX(sv)));
	    return (UV)SvIVX(sv);
	}
    }
    else if (SvPOKp(sv) && SvLEN(sv)) {
	I32 numtype = looks_like_number(sv);

	/* We want to avoid a possible problem when we cache a UV which
	   may be later translated to an NV, and the resulting NV is not
	   the translation of the initial data.
	  
	   This means that if we cache such a UV, we need to cache the
	   NV as well.  Moreover, we trade speed for space, and do not
	   cache the NV if not needed.
	 */
	if (numtype & IS_NUMBER_NOT_IV) {
	    /* May be not an integer.  Need to cache NV if we cache IV
	     * - otherwise future conversion to NV will be wrong.  */
	    double d;

	    SET_NUMERIC_STANDARD();
	    d = atof(SvPVX(sv));	/* XXXX 64-bit? */

	    if (SvTYPE(sv) < SVt_PVNV)
		sv_upgrade(sv, SVt_PVNV);
	    SvNVX(sv) = d;
	    (void)SvNOK_on(sv);
	    (void)SvIOK_on(sv);
	    DEBUG_c(PerlIO_printf(Perl_debug_log,
				  "0x%lx 2nv(%g)\n",(unsigned long)sv,
				  SvNVX(sv)));
	    if (SvNVX(sv) < -0.5) {
		SvIVX(sv) = I_V(SvNVX(sv));
		goto ret_zero;
	    } else {
		SvUVX(sv) = U_V(SvNVX(sv));
		SvIsUV_on(sv);
	    }
	}
	else if (numtype & IS_NUMBER_NEG) {
	    /* The NV may be reconstructed from IV - safe to cache IV,
	       which may be calculated by atol(). */
	    if (SvTYPE(sv) == SVt_PV)
		sv_upgrade(sv, SVt_PVIV);
	    (void)SvIOK_on(sv);
	    SvIVX(sv) = (IV)atol(SvPVX(sv)); /* XXXX 64-bit? */
	}
	else if (numtype) {		/* Non-negative */
	    /* The NV may be reconstructed from UV - safe to cache UV,
	       which may be calculated by strtoul()/atol. */
	    if (SvTYPE(sv) == SVt_PV)
		sv_upgrade(sv, SVt_PVIV);
	    (void)SvIOK_on(sv);
	    (void)SvIsUV_on(sv);
#ifdef HAS_STRTOUL
	    SvUVX(sv) = strtoul(SvPVX(sv), Null(char**), 10); /* XXXX 64-bit? */
#else			/* no atou(), but we know the number fits into IV... */
	    		/* The only problem may be if it is negative... */
	    SvUVX(sv) = (UV)atol(SvPVX(sv)); /* XXXX 64-bit? */
#endif
	}
	else {				/* Not a number.  Cache 0. */
	    dTHR;

	    if (SvTYPE(sv) < SVt_PVIV)
		sv_upgrade(sv, SVt_PVIV);
	    SvUVX(sv) = 0;		/* We assume that 0s have the
					   same bitmap in IV and UV. */
	    (void)SvIOK_on(sv);
	    (void)SvIsUV_on(sv);
	    if (ckWARN(WARN_NUMERIC))
		not_a_number(sv);
	}
    }
    else  {
	if (!(SvFLAGS(sv) & SVs_PADTMP)) {
	    dTHR;
	    if (ckWARN(WARN_UNINITIALIZED) && !PL_localizing)
		warner(WARN_UNINITIALIZED, PL_warn_uninit);
	}
	if (SvTYPE(sv) < SVt_IV)
	    /* Typically the caller expects that sv_any is not NULL now.  */
	    sv_upgrade(sv, SVt_IV);
	return 0;
    }

    DEBUG_c(PerlIO_printf(Perl_debug_log, "0x%lx 2uv(%lu)\n",
	(unsigned long)sv,SvUVX(sv)));
    return SvIsUV(sv) ? SvUVX(sv) : (UV)SvIVX(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)) {
	    if (SvIsUV(sv)) 
		return (double)SvUVX(sv);
	    else
		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)) {
		if (SvIsUV(sv)) 
		    return (double)SvUVX(sv);
		else
		    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) = SvIsUV(sv) ? (double)SvUVX(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);
	if (SvTYPE(sv) < SVt_NV)
	    /* Typically the caller expects that sv_any is not NULL now.  */
	    sv_upgrade(sv, SVt_NV);
	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 & IS_NUMBER_TO_INT_BY_ATOL)
	return atol(SvPVX(sv));		/* XXXX 64-bit? */
    if (!numtype) {
	dTHR;
	if (ckWARN(WARN_NUMERIC))
	    not_a_number(sv);
    }
    SET_NUMERIC_STANDARD();
    d = atof(SvPVX(sv));
    return I_V(d);
}

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

#ifdef HAS_STRTOUL
    if (numtype & IS_NUMBER_TO_INT_BY_ATOL)
	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)));
}

/*
 * Returns a combination of (advisory only - can get false negatives)
 * 	IS_NUMBER_TO_INT_BY_ATOL, IS_NUMBER_TO_INT_BY_ATOF, IS_NUMBER_NOT_IV,
 *	IS_NUMBER_NEG
 * 0 if does not look like number.
 *
 * In fact possible values are 0 and
 * IS_NUMBER_TO_INT_BY_ATOL				123
 * IS_NUMBER_TO_INT_BY_ATOL | IS_NUMBER_NOT_IV		123.1
 * IS_NUMBER_TO_INT_BY_ATOF | IS_NUMBER_NOT_IV		123e0
 * with a possible addition of IS_NUMBER_NEG.
 */

I32
looks_like_number(SV *sv)
{
    /* XXXX 64-bit?  It may be not IS_NUMBER_TO_INT_BY_ATOL, but
     * using atof() may lose precision. */
    register char *s;
    register char *send;
    register char *sbegin;
    register char *nbegin;
    I32 numtype = 0;
    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++;
	numtype = IS_NUMBER_NEG;
    }
    else if (*s == '+')
	s++;

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

    /* next must be digit or '.' */
    if (isDIGIT(*s)) {
        do {
	    s++;
        } while (isDIGIT(*s));

	if (s - nbegin >= TYPE_DIGITS(IV))	/* Cannot cache ato[ul]() */
	    numtype |= IS_NUMBER_TO_INT_BY_ATOF | IS_NUMBER_NOT_IV;
	else
	    numtype |= IS_NUMBER_TO_INT_BY_ATOL;

        if (*s == '.') {
	    s++;
	    numtype |= IS_NUMBER_NOT_IV;
            while (isDIGIT(*s))  /* optional digits after "." */
                s++;
        }
    }
    else if (*s == '.') {
        s++;
	numtype |= IS_NUMBER_TO_INT_BY_ATOL | IS_NUMBER_NOT_IV;
        /* no digits before '.' means we need digits after it */
        if (isDIGIT(*s)) {
	    do {
	        s++;
            } while (isDIGIT(*s));
        }
        else
	    return 0;
    }
    else
        return 0;

    /* we can have an optional exponent part */
    if (*s == 'e' || *s == 'E') {
	numtype &= ~IS_NUMBER_NEG;
	numtype |= IS_NUMBER_TO_INT_BY_ATOF | IS_NUMBER_NOT_IV;
	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 IS_NUMBER_TO_INT_BY_ATOL;
    return 0;
}

char *
sv_2pv_nolen(register SV *sv)
{
    STRLEN n_a;
    return sv_2pv(sv, &n_a);
}

/* We assume that buf is at least TYPE_CHARS(UV) long. */
STATIC char *
uiv_2buf(char *buf, IV iv, UV uv, int is_uv, char **peob)
{
    STRLEN len;
    char *ptr = buf + TYPE_CHARS(UV);
    char *ebuf = ptr;
    int sign;
    char *p;

    if (is_uv)
	sign = 0;
    else if (iv >= 0) {
	uv = iv;
	sign = 0;
    } else {
	uv = -iv;
	sign = 1;
    }
    do {
	*--ptr = '0' + (uv % 10);
    } while (uv /= 10);
    if (sign)
	*--ptr = '-';
    *peob = ebuf;
    return ptr;
}

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

    if (!sv) {
	*lp = 0;
	return "";
    }
    if (SvGMAGICAL(sv)) {
	mg_get(sv);
	if (SvPOKp(sv)) {
	    *lp = SvCUR(sv);
	    return SvPVX(sv);
	}
	if (SvIOKp(sv)) {		/* XXXX 64-bit? */
	    if (SvIsUV(sv)) 
		(void)sprintf(tmpbuf,"%lu",(unsigned long)SvUVX(sv));
	    else
		(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);
		/* XXXX 64-bit? */
		sv_catpvf(tsv, "(0x%lx)", (unsigned long)sv);
		goto tokensaveref;
	    }
	    *lp = strlen(s);
	    return s;
	}
	if (SvREADONLY(sv)) {
	    if (SvNOKp(sv)) {		/* See note in sv_2uv() */
		/* XXXX 64-bit?  IV may have better precision... */
		SET_NUMERIC_STANDARD();
		Gconvert(SvNVX(sv), DBL_DIG, 0, tmpbuf);
		tsv = Nullsv;
		goto tokensave;
	    }
	    if (SvIOKp(sv)) {
		char *ebuf;

		if (SvIsUV(sv))
		    tmpbuf = uiv_2buf(tbuf, 0, SvUVX(sv), 1, &ebuf);
		else
		    tmpbuf = uiv_2buf(tbuf, SvIVX(sv), 0, 0, &ebuf);
		*ebuf = 0;
		tsv = Nullsv;
		goto tokensave;
	    }
	    {
		dTHR;
		if (ckWARN(WARN_UNINITIALIZED))
		    warner(WARN_UNINITIALIZED, PL_warn_uninit);
	    }
	    *lp = 0;
	    return "";
	}
    }
    if (SvNOKp(sv)) {			/* See note in sv_2uv() */
	/* XXXX 64-bit?  IV may have better precision... */
	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 isIOK = SvIOK(sv);
	char buf[TYPE_CHARS(UV)];
	char *ebuf, *ptr;

	if (SvTYPE(sv) < SVt_PVIV)
	    sv_upgrade(sv, SVt_PVIV);
	if (SvIsUV(sv)) {
	    ptr = uiv_2buf(buf, 0, SvUVX(sv), 1, &ebuf);
	    sv_setpvn(sv, ptr, ebuf - ptr);
	    SvIsUV_on(sv);
	}
	else {
	    ptr = uiv_2buf(buf, SvIVX(sv), 0, 0, &ebuf);
	    sv_setpvn(sv, ptr, ebuf - ptr);
	}
	s = SvEND(sv);
	if (isIOK)
	    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;
	if (SvTYPE(sv) < SVt_PV)
	    /* Typically the caller expects that sv_any is not NULL now.  */
	    sv_upgrade(sv, SVt_PV);
	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);

    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);
	    if (SvIsUV(sstr))
		SvIsUV_on(dstr);
	    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)
	    (void)SvUPGRADE(dstr, SVt_PVNV);
	else
	    (void)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 */
		if (SvLEN(dstr))
		    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 (SvIsUV(sstr))
		SvIsUV_on(dstr);
	}
	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 if (SvLEN(dstr))
		    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);
	    if (SvIsUV(sstr))
		SvIsUV_on(dstr);
	}
    }
    else if (sflags & SVp_NOK) {
	SvNVX(dstr) = SvNVX(sstr);
	(void)SvNOK_only(dstr);
	if (SvIOK(sstr)) {
	    (void)SvIOK_on(dstr);
	    SvIVX(dstr) = SvIVX(sstr);
	    /* XXXX Do we want to set IsUV for IV(ROK)?  Be extra safe... */
	    if (SvIsUV(sstr))
		SvIsUV_on(dstr);
	}
    }
    else if (sflags & SVp_IOK) {
	(void)SvIOK_only(dstr);
	SvIVX(dstr) = SvIVX(sstr);
	if (SvIsUV(sstr))
	    SvIsUV_on(dstr);
    }
    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;
    }
    (void)SvUPGRADE(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);
    (void)SvUPGRADE(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) && SvLEN(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);
}

void
sv_force_normal(register SV *sv)
{
    if (SvREADONLY(sv)) {
	dTHR;
	if (PL_curcop != &PL_compiling)
	    croak(PL_no_modify);
    }
    if (SvROK(sv))
	sv_unref(sv);
    else if (SvFAKE(sv) && SvTYPE(sv) == SVt_PVGV)
	sv_unglob(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)) {
	if (!SvLEN(sv)) { /* make copy of shared string */
	    char *pvx = SvPVX(sv);
	    STRLEN len = SvCUR(sv);
	    SvGROW(sv, len + 1);
	    Move(pvx,SvPVX(sv),len,char);
	    *SvEND(sv) = '\0';
	}
	SvIVX(sv) = 0;
	SvFLAGS(sv) |= SVf_OOK;
    }
    SvFLAGS(sv) &= ~(SVf_IOK|SVf_NOK|SVp_IOK|SVp_NOK|SVf_IVisUV);
    delta = ptr - SvPVX(sv);
    SvLEN(sv) -= delta;
    SvCUR(sv) -= delta;
    SvPVX(sv) += delta;
    SvIVX(sv) += delta;
}

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

SV *
newSV(STRLEN len)
{
    register SV *sv;
    
    new_SV(sv);
    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, const 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 '<':
	mg->mg_virtual = &PL_vtbl_backref;
	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;
}

SV *
sv_rvweaken(SV *sv)
{
    SV *tsv;
    if (!SvOK(sv))  /* let undefs pass */
	return sv;
    if (!SvROK(sv))
	croak("Can't weaken a nonreference");
    else if (SvWEAKREF(sv)) {
	dTHR;
	if (ckWARN(WARN_MISC))
	    warner(WARN_MISC, "Reference is already weak");
	return sv;
    }
    tsv = SvRV(sv);
    sv_add_backref(tsv, sv);
    SvWEAKREF_on(sv);
    SvREFCNT_dec(tsv);              
    return sv;
}

STATIC void
sv_add_backref(SV *tsv, SV *sv)
{
    AV *av;
    MAGIC *mg;
    if (SvMAGICAL(tsv) && (mg = mg_find(tsv, '<')))
	av = (AV*)mg->mg_obj;
    else {
	av = newAV();
	sv_magic(tsv, (SV*)av, '<', NULL, 0);
	SvREFCNT_dec(av);           /* for sv_magic */
    }
    av_push(av,sv);
}

STATIC void 
sv_del_backref(SV *sv)
{
    AV *av;
    SV **svp;
    I32 i;
    SV *tsv = SvRV(sv);
    MAGIC *mg;
    if (!SvMAGICAL(tsv) || !(mg = mg_find(tsv, '<')))
	croak("panic: del_backref");
    av = (AV *)mg->mg_obj;
    svp = AvARRAY(av);
    i = AvFILLp(av);
    while (i >= 0) {
	if (svp[i] == sv) {
	    svp[i] = &PL_sv_undef; /* XXX */
	}
	i--;
    }
}

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 (SvREFCNT(sv)) {
		if (PL_in_clean_objs)
		    croak("DESTROY created new reference to dead object '%s'",
			  HvNAME(stash));
		/* DESTROY gave object new lease on life */
		return;
	    }
	}

	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 (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);
	}
	if (IoDIRP(sv)) {
	    PerlDir_close(IoDIRP(sv));
	    IoDIRP(sv) = 0;
	}
	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)) {
	    if (SvWEAKREF(sv))
	        sv_del_backref(sv);
	    else
	        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];