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[perl5.git] / sv.c

/*    sv.c
 *
 *    Copyright (c) 1991-2001, Larry Wall
 *
 *    You may distribute under the terms of either the GNU General Public
 *    License or the Artistic License, as specified in the README file.
 *
 */

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

#include "EXTERN.h"
#define PERL_IN_SV_C
#include "perl.h"

#define FCALL *f
#define SV_CHECK_THINKFIRST(sv) if (SvTHINKFIRST(sv)) sv_force_normal(sv)

static void do_report_used(pTHXo_ SV *sv);
static void do_clean_objs(pTHXo_ SV *sv);
#ifndef DISABLE_DESTRUCTOR_KLUDGE
static void do_clean_named_objs(pTHXo_ SV *sv);
#endif
static void do_clean_all(pTHXo_ SV *sv);

/*
 * "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 (DEBUG_D_TEST)				\
	    del_sv(p);					\
	else						\
	    plant_SV(p);				\
	UNLOCK_SV_MUTEX;				\
    } STMT_END

STATIC void
S_del_sv(pTHX_ SV *p)
{
    if (DEBUG_D_TEST) {
	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) {
	    if (ckWARN_d(WARN_INTERNAL))	
	        Perl_warner(aTHX_ WARN_INTERNAL,
			    "Attempt to free non-arena SV: 0x%"UVxf,
			    PTR2UV(p));
	    return;
	}
    }
    plant_SV(p);
}

#else /* ! DEBUGGING */

#define del_SV(p)   plant_SV(p)

#endif /* DEBUGGING */

void
Perl_sv_add_arena(pTHX_ char *ptr, U32 size, U32 flags)
{
    SV* sva = (SV*)ptr;
    register SV* sv;
    register SV* svend;
    Zero(ptr, 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*
S_more_sv(pTHX)
{
    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
S_visit(pTHX_ SVFUNC_t 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)(aTHXo_ sv);
	}
    }
}

void
Perl_sv_report_used(pTHX)
{
    visit(do_report_used);
}

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

void
Perl_sv_clean_all(pTHX)
{
    PL_in_clean_all = TRUE;
    visit(do_clean_all);
    PL_in_clean_all = FALSE;
}

void
Perl_sv_free_arenas(pTHX)
{
    SV* sva;
    SV* svanext;
    XPV *arena, *arenanext;

    /* 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);
    }

    for (arena = PL_xiv_arenaroot; arena; arena = arenanext) {
	arenanext = (XPV*)arena->xpv_pv;
	Safefree(arena);
    }
    PL_xiv_arenaroot = 0;

    for (arena = PL_xnv_arenaroot; arena; arena = arenanext) {
	arenanext = (XPV*)arena->xpv_pv;
	Safefree(arena);
    }
    PL_xnv_arenaroot = 0;

    for (arena = PL_xrv_arenaroot; arena; arena = arenanext) {
	arenanext = (XPV*)arena->xpv_pv;
	Safefree(arena);
    }
    PL_xrv_arenaroot = 0;

    for (arena = PL_xpv_arenaroot; arena; arena = arenanext) {
	arenanext = (XPV*)arena->xpv_pv;
	Safefree(arena);
    }
    PL_xpv_arenaroot = 0;

    for (arena = (XPV*)PL_xpviv_arenaroot; arena; arena = arenanext) {
	arenanext = (XPV*)arena->xpv_pv;
	Safefree(arena);
    }
    PL_xpviv_arenaroot = 0;

    for (arena = (XPV*)PL_xpvnv_arenaroot; arena; arena = arenanext) {
	arenanext = (XPV*)arena->xpv_pv;
	Safefree(arena);
    }
    PL_xpvnv_arenaroot = 0;

    for (arena = (XPV*)PL_xpvcv_arenaroot; arena; arena = arenanext) {
	arenanext = (XPV*)arena->xpv_pv;
	Safefree(arena);
    }
    PL_xpvcv_arenaroot = 0;

    for (arena = (XPV*)PL_xpvav_arenaroot; arena; arena = arenanext) {
	arenanext = (XPV*)arena->xpv_pv;
	Safefree(arena);
    }
    PL_xpvav_arenaroot = 0;

    for (arena = (XPV*)PL_xpvhv_arenaroot; arena; arena = arenanext) {
	arenanext = (XPV*)arena->xpv_pv;
	Safefree(arena);
    }
    PL_xpvhv_arenaroot = 0;

    for (arena = (XPV*)PL_xpvmg_arenaroot; arena; arena = arenanext) {
	arenanext = (XPV*)arena->xpv_pv;
	Safefree(arena);
    }
    PL_xpvmg_arenaroot = 0;

    for (arena = (XPV*)PL_xpvlv_arenaroot; arena; arena = arenanext) {
	arenanext = (XPV*)arena->xpv_pv;
	Safefree(arena);
    }
    PL_xpvlv_arenaroot = 0;

    for (arena = (XPV*)PL_xpvbm_arenaroot; arena; arena = arenanext) {
	arenanext = (XPV*)arena->xpv_pv;
	Safefree(arena);
    }
    PL_xpvbm_arenaroot = 0;

    for (arena = (XPV*)PL_he_arenaroot; arena; arena = arenanext) {
	arenanext = (XPV*)arena->xpv_pv;
	Safefree(arena);
    }
    PL_he_arenaroot = 0;

    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;
}

void
Perl_report_uninit(pTHX)
{
    if (PL_op)
	Perl_warner(aTHX_ WARN_UNINITIALIZED, PL_warn_uninit,
		    " in ", PL_op_desc[PL_op->op_type]);
    else
	Perl_warner(aTHX_ WARN_UNINITIALIZED, PL_warn_uninit, "", "");
}

STATIC XPVIV*
S_new_xiv(pTHX)
{
    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
S_del_xiv(pTHX_ 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
S_more_xiv(pTHX)
{
    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*
S_new_xnv(pTHX)
{
    NV* xnv;
    LOCK_SV_MUTEX;
    if (!PL_xnv_root)
	more_xnv();
    xnv = PL_xnv_root;
    PL_xnv_root = *(NV**)xnv;
    UNLOCK_SV_MUTEX;
    return (XPVNV*)((char*)xnv - STRUCT_OFFSET(XPVNV, xnv_nv));
}

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

STATIC void
S_more_xnv(pTHX)
{
    register NV* xnv;
    register NV* xnvend;
    XPV *ptr;
    New(711, ptr, 1008/sizeof(XPV), XPV);
    ptr->xpv_pv = (char*)PL_xnv_arenaroot;
    PL_xnv_arenaroot = ptr;

    xnv = (NV*) ptr;
    xnvend = &xnv[1008 / sizeof(NV) - 1];
    xnv += (sizeof(XPVIV) - 1) / sizeof(NV) + 1; /* fudge by sizeof XPVIV */
    PL_xnv_root = xnv;
    while (xnv < xnvend) {
	*(NV**)xnv = (NV*)(xnv + 1);
	xnv++;
    }
    *(NV**)xnv = 0;
}

STATIC XRV*
S_new_xrv(pTHX)
{
    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
S_del_xrv(pTHX_ XRV *p)
{
    LOCK_SV_MUTEX;
    p->xrv_rv = (SV*)PL_xrv_root;
    PL_xrv_root = p;
    UNLOCK_SV_MUTEX;
}

STATIC void
S_more_xrv(pTHX)
{
    register XRV* xrv;
    register XRV* xrvend;
    XPV *ptr;
    New(712, ptr, 1008/sizeof(XPV), XPV);
    ptr->xpv_pv = (char*)PL_xrv_arenaroot;
    PL_xrv_arenaroot = ptr;

    xrv = (XRV*) ptr;
    xrvend = &xrv[1008 / sizeof(XRV) - 1];
    xrv += (sizeof(XPV) - 1) / sizeof(XRV) + 1;
    PL_xrv_root = xrv;
    while (xrv < xrvend) {
	xrv->xrv_rv = (SV*)(xrv + 1);
	xrv++;
    }
    xrv->xrv_rv = 0;
}

STATIC XPV*
S_new_xpv(pTHX)
{
    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
S_del_xpv(pTHX_ XPV *p)
{
    LOCK_SV_MUTEX;
    p->xpv_pv = (char*)PL_xpv_root;
    PL_xpv_root = p;
    UNLOCK_SV_MUTEX;
}

STATIC void
S_more_xpv(pTHX)
{
    register XPV* xpv;
    register XPV* xpvend;
    New(713, xpv, 1008/sizeof(XPV), XPV);
    xpv->xpv_pv = (char*)PL_xpv_arenaroot;
    PL_xpv_arenaroot = xpv;

    xpvend = &xpv[1008 / sizeof(XPV) - 1];
    PL_xpv_root = ++xpv;
    while (xpv < xpvend) {
	xpv->xpv_pv = (char*)(xpv + 1);
	xpv++;
    }
    xpv->xpv_pv = 0;
}

STATIC XPVIV*
S_new_xpviv(pTHX)
{
    XPVIV* xpviv;
    LOCK_SV_MUTEX;
    if (!PL_xpviv_root)
	more_xpviv();
    xpviv = PL_xpviv_root;
    PL_xpviv_root = (XPVIV*)xpviv->xpv_pv;
    UNLOCK_SV_MUTEX;
    return xpviv;
}

STATIC void
S_del_xpviv(pTHX_ XPVIV *p)
{
    LOCK_SV_MUTEX;
    p->xpv_pv = (char*)PL_xpviv_root;
    PL_xpviv_root = p;
    UNLOCK_SV_MUTEX;
}

STATIC void
S_more_xpviv(pTHX)
{
    register XPVIV* xpviv;
    register XPVIV* xpvivend;
    New(714, xpviv, 1008/sizeof(XPVIV), XPVIV);
    xpviv->xpv_pv = (char*)PL_xpviv_arenaroot;
    PL_xpviv_arenaroot = xpviv;

    xpvivend = &xpviv[1008 / sizeof(XPVIV) - 1];
    PL_xpviv_root = ++xpviv;
    while (xpviv < xpvivend) {
	xpviv->xpv_pv = (char*)(xpviv + 1);
	xpviv++;
    }
    xpviv->xpv_pv = 0;
}

STATIC XPVNV*
S_new_xpvnv(pTHX)
{
    XPVNV* xpvnv;
    LOCK_SV_MUTEX;
    if (!PL_xpvnv_root)
	more_xpvnv();
    xpvnv = PL_xpvnv_root;
    PL_xpvnv_root = (XPVNV*)xpvnv->xpv_pv;
    UNLOCK_SV_MUTEX;
    return xpvnv;
}

STATIC void
S_del_xpvnv(pTHX_ XPVNV *p)
{
    LOCK_SV_MUTEX;
    p->xpv_pv = (char*)PL_xpvnv_root;
    PL_xpvnv_root = p;
    UNLOCK_SV_MUTEX;
}

STATIC void
S_more_xpvnv(pTHX)
{
    register XPVNV* xpvnv;
    register XPVNV* xpvnvend;
    New(715, xpvnv, 1008/sizeof(XPVNV), XPVNV);
    xpvnv->xpv_pv = (char*)PL_xpvnv_arenaroot;
    PL_xpvnv_arenaroot = xpvnv;

    xpvnvend = &xpvnv[1008 / sizeof(XPVNV) - 1];
    PL_xpvnv_root = ++xpvnv;
    while (xpvnv < xpvnvend) {
	xpvnv->xpv_pv = (char*)(xpvnv + 1);
	xpvnv++;
    }
    xpvnv->xpv_pv = 0;
}

STATIC XPVCV*
S_new_xpvcv(pTHX)
{
    XPVCV* xpvcv;
    LOCK_SV_MUTEX;
    if (!PL_xpvcv_root)
	more_xpvcv();
    xpvcv = PL_xpvcv_root;
    PL_xpvcv_root = (XPVCV*)xpvcv->xpv_pv;
    UNLOCK_SV_MUTEX;
    return xpvcv;
}

STATIC void
S_del_xpvcv(pTHX_ XPVCV *p)
{
    LOCK_SV_MUTEX;
    p->xpv_pv = (char*)PL_xpvcv_root;
    PL_xpvcv_root = p;
    UNLOCK_SV_MUTEX;
}

STATIC void
S_more_xpvcv(pTHX)
{
    register XPVCV* xpvcv;
    register XPVCV* xpvcvend;
    New(716, xpvcv, 1008/sizeof(XPVCV), XPVCV);
    xpvcv->xpv_pv = (char*)PL_xpvcv_arenaroot;
    PL_xpvcv_arenaroot = xpvcv;

    xpvcvend = &xpvcv[1008 / sizeof(XPVCV) - 1];
    PL_xpvcv_root = ++xpvcv;
    while (xpvcv < xpvcvend) {
	xpvcv->xpv_pv = (char*)(xpvcv + 1);
	xpvcv++;
    }
    xpvcv->xpv_pv = 0;
}

STATIC XPVAV*
S_new_xpvav(pTHX)
{
    XPVAV* xpvav;
    LOCK_SV_MUTEX;
    if (!PL_xpvav_root)
	more_xpvav();
    xpvav = PL_xpvav_root;
    PL_xpvav_root = (XPVAV*)xpvav->xav_array;
    UNLOCK_SV_MUTEX;
    return xpvav;
}

STATIC void
S_del_xpvav(pTHX_ XPVAV *p)
{
    LOCK_SV_MUTEX;
    p->xav_array = (char*)PL_xpvav_root;
    PL_xpvav_root = p;
    UNLOCK_SV_MUTEX;
}

STATIC void
S_more_xpvav(pTHX)
{
    register XPVAV* xpvav;
    register XPVAV* xpvavend;
    New(717, xpvav, 1008/sizeof(XPVAV), XPVAV);
    xpvav->xav_array = (char*)PL_xpvav_arenaroot;
    PL_xpvav_arenaroot = xpvav;

    xpvavend = &xpvav[1008 / sizeof(XPVAV) - 1];
    PL_xpvav_root = ++xpvav;
    while (xpvav < xpvavend) {
	xpvav->xav_array = (char*)(xpvav + 1);
	xpvav++;
    }
    xpvav->xav_array = 0;
}

STATIC XPVHV*
S_new_xpvhv(pTHX)
{
    XPVHV* xpvhv;
    LOCK_SV_MUTEX;
    if (!PL_xpvhv_root)
	more_xpvhv();
    xpvhv = PL_xpvhv_root;
    PL_xpvhv_root = (XPVHV*)xpvhv->xhv_array;
    UNLOCK_SV_MUTEX;
    return xpvhv;
}

STATIC void
S_del_xpvhv(pTHX_ XPVHV *p)
{
    LOCK_SV_MUTEX;
    p->xhv_array = (char*)PL_xpvhv_root;
    PL_xpvhv_root = p;
    UNLOCK_SV_MUTEX;
}

STATIC void
S_more_xpvhv(pTHX)
{
    register XPVHV* xpvhv;
    register XPVHV* xpvhvend;
    New(718, xpvhv, 1008/sizeof(XPVHV), XPVHV);
    xpvhv->xhv_array = (char*)PL_xpvhv_arenaroot;
    PL_xpvhv_arenaroot = xpvhv;

    xpvhvend = &xpvhv[1008 / sizeof(XPVHV) - 1];
    PL_xpvhv_root = ++xpvhv;
    while (xpvhv < xpvhvend) {
	xpvhv->xhv_array = (char*)(xpvhv + 1);
	xpvhv++;
    }
    xpvhv->xhv_array = 0;
}

STATIC XPVMG*
S_new_xpvmg(pTHX)
{
    XPVMG* xpvmg;
    LOCK_SV_MUTEX;
    if (!PL_xpvmg_root)
	more_xpvmg();
    xpvmg = PL_xpvmg_root;
    PL_xpvmg_root = (XPVMG*)xpvmg->xpv_pv;
    UNLOCK_SV_MUTEX;
    return xpvmg;
}

STATIC void
S_del_xpvmg(pTHX_ XPVMG *p)
{
    LOCK_SV_MUTEX;
    p->xpv_pv = (char*)PL_xpvmg_root;
    PL_xpvmg_root = p;
    UNLOCK_SV_MUTEX;
}

STATIC void
S_more_xpvmg(pTHX)
{
    register XPVMG* xpvmg;
    register XPVMG* xpvmgend;
    New(719, xpvmg, 1008/sizeof(XPVMG), XPVMG);
    xpvmg->xpv_pv = (char*)PL_xpvmg_arenaroot;
    PL_xpvmg_arenaroot = xpvmg;

    xpvmgend = &xpvmg[1008 / sizeof(XPVMG) - 1];
    PL_xpvmg_root = ++xpvmg;
    while (xpvmg < xpvmgend) {
	xpvmg->xpv_pv = (char*)(xpvmg + 1);
	xpvmg++;
    }
    xpvmg->xpv_pv = 0;
}

STATIC XPVLV*
S_new_xpvlv(pTHX)
{
    XPVLV* xpvlv;
    LOCK_SV_MUTEX;
    if (!PL_xpvlv_root)
	more_xpvlv();
    xpvlv = PL_xpvlv_root;
    PL_xpvlv_root = (XPVLV*)xpvlv->xpv_pv;
    UNLOCK_SV_MUTEX;
    return xpvlv;
}

STATIC void
S_del_xpvlv(pTHX_ XPVLV *p)
{
    LOCK_SV_MUTEX;
    p->xpv_pv = (char*)PL_xpvlv_root;
    PL_xpvlv_root = p;
    UNLOCK_SV_MUTEX;
}

STATIC void
S_more_xpvlv(pTHX)
{
    register XPVLV* xpvlv;
    register XPVLV* xpvlvend;
    New(720, xpvlv, 1008/sizeof(XPVLV), XPVLV);
    xpvlv->xpv_pv = (char*)PL_xpvlv_arenaroot;
    PL_xpvlv_arenaroot = xpvlv;

    xpvlvend = &xpvlv[1008 / sizeof(XPVLV) - 1];
    PL_xpvlv_root = ++xpvlv;
    while (xpvlv < xpvlvend) {
	xpvlv->xpv_pv = (char*)(xpvlv + 1);
	xpvlv++;
    }
    xpvlv->xpv_pv = 0;
}

STATIC XPVBM*
S_new_xpvbm(pTHX)
{
    XPVBM* xpvbm;
    LOCK_SV_MUTEX;
    if (!PL_xpvbm_root)
	more_xpvbm();
    xpvbm = PL_xpvbm_root;
    PL_xpvbm_root = (XPVBM*)xpvbm->xpv_pv;
    UNLOCK_SV_MUTEX;
    return xpvbm;
}

STATIC void
S_del_xpvbm(pTHX_ XPVBM *p)
{
    LOCK_SV_MUTEX;
    p->xpv_pv = (char*)PL_xpvbm_root;
    PL_xpvbm_root = p;
    UNLOCK_SV_MUTEX;
}

STATIC void
S_more_xpvbm(pTHX)
{
    register XPVBM* xpvbm;
    register XPVBM* xpvbmend;
    New(721, xpvbm, 1008/sizeof(XPVBM), XPVBM);
    xpvbm->xpv_pv = (char*)PL_xpvbm_arenaroot;
    PL_xpvbm_arenaroot = xpvbm;

    xpvbmend = &xpvbm[1008 / sizeof(XPVBM) - 1];
    PL_xpvbm_root = ++xpvbm;
    while (xpvbm < xpvbmend) {
	xpvbm->xpv_pv = (char*)(xpvbm + 1);
	xpvbm++;
    }
    xpvbm->xpv_pv = 0;
}

#ifdef LEAKTEST
#  define my_safemalloc(s)	(void*)safexmalloc(717,s)
#  define my_safefree(p)	safexfree((char*)p)
#else
#  define my_safemalloc(s)	(void*)safemalloc(s)
#  define my_safefree(p)	safefree((char*)p)
#endif

#ifdef PURIFY

#define new_XIV()	my_safemalloc(sizeof(XPVIV))
#define del_XIV(p)	my_safefree(p)

#define new_XNV()	my_safemalloc(sizeof(XPVNV))
#define del_XNV(p)	my_safefree(p)

#define new_XRV()	my_safemalloc(sizeof(XRV))
#define del_XRV(p)	my_safefree(p)

#define new_XPV()	my_safemalloc(sizeof(XPV))
#define del_XPV(p)	my_safefree(p)

#define new_XPVIV()	my_safemalloc(sizeof(XPVIV))
#define del_XPVIV(p)	my_safefree(p)

#define new_XPVNV()	my_safemalloc(sizeof(XPVNV))
#define del_XPVNV(p)	my_safefree(p)

#define new_XPVCV()	my_safemalloc(sizeof(XPVCV))
#define del_XPVCV(p)	my_safefree(p)

#define new_XPVAV()	my_safemalloc(sizeof(XPVAV))
#define del_XPVAV(p)	my_safefree(p)

#define new_XPVHV()	my_safemalloc(sizeof(XPVHV))
#define del_XPVHV(p)	my_safefree(p)

#define new_XPVMG()	my_safemalloc(sizeof(XPVMG))
#define del_XPVMG(p)	my_safefree(p)

#define new_XPVLV()	my_safemalloc(sizeof(XPVLV))
#define del_XPVLV(p)	my_safefree(p)

#define new_XPVBM()	my_safemalloc(sizeof(XPVBM))
#define del_XPVBM(p)	my_safefree(p)

#else /* !PURIFY */

#define new_XIV()	(void*)new_xiv()
#define del_XIV(p)	del_xiv((XPVIV*) p)

#define new_XNV()	(void*)new_xnv()
#define del_XNV(p)	del_xnv((XPVNV*) p)

#define new_XRV()	(void*)new_xrv()
#define del_XRV(p)	del_xrv((XRV*) p)

#define new_XPV()	(void*)new_xpv()
#define del_XPV(p)	del_xpv((XPV *)p)

#define new_XPVIV()	(void*)new_xpviv()
#define del_XPVIV(p)	del_xpviv((XPVIV *)p)

#define new_XPVNV()	(void*)new_xpvnv()
#define del_XPVNV(p)	del_xpvnv((XPVNV *)p)

#define new_XPVCV()	(void*)new_xpvcv()
#define del_XPVCV(p)	del_xpvcv((XPVCV *)p)

#define new_XPVAV()	(void*)new_xpvav()
#define del_XPVAV(p)	del_xpvav((XPVAV *)p)

#define new_XPVHV()	(void*)new_xpvhv()
#define del_XPVHV(p)	del_xpvhv((XPVHV *)p)

#define new_XPVMG()	(void*)new_xpvmg()
#define del_XPVMG(p)	del_xpvmg((XPVMG *)p)

#define new_XPVLV()	(void*)new_xpvlv()
#define del_XPVLV(p)	del_xpvlv((XPVLV *)p)

#define new_XPVBM()	(void*)new_xpvbm()
#define del_XPVBM(p)	del_xpvbm((XPVBM *)p)

#endif /* PURIFY */

#define new_XPVGV()	my_safemalloc(sizeof(XPVGV))
#define del_XPVGV(p)	my_safefree(p)

#define new_XPVFM()	my_safemalloc(sizeof(XPVFM))
#define del_XPVFM(p)	my_safefree(p)

#define new_XPVIO()	my_safemalloc(sizeof(XPVIO))
#define del_XPVIO(p)	my_safefree(p)

/*
=for apidoc sv_upgrade

Upgrade an SV to a more complex form.  Use C<SvUPGRADE>.  See
C<svtype>.

=cut
*/

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

    if (mt != SVt_PV && SvREADONLY(sv) && SvFAKE(sv)) {
	sv_force_normal(sv);
    }

    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	= (NV)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	= PTR2IV(pv);
	nv	= PTR2NV(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:
	Perl_croak(aTHX_ "Can't upgrade that kind of scalar");
    }

    switch (mt) {
    case SVt_NULL:
	Perl_croak(aTHX_ "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
Perl_sv_backoff(pTHX_ 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;
}

/*
=for apidoc sv_grow

Expands the character buffer in the SV.  This will use C<sv_unref> and will
upgrade the SV to C<SVt_PV>.  Returns a pointer to the character buffer.
Use C<SvGROW>.

=cut
*/

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

#ifdef HAS_64K_LIMIT
    if (newlen >= 0x10000) {
	PerlIO_printf(Perl_debug_log,
		      "Allocation too large: %"UVxf"\n", (UV)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(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;
}

/*
=for apidoc sv_setiv

Copies an integer into the given SV.  Does not handle 'set' magic.  See
C<sv_setiv_mg>.

=cut
*/

void
Perl_sv_setiv(pTHX_ 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:
	Perl_croak(aTHX_ "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);
}

/*
=for apidoc sv_setiv_mg

Like C<sv_setiv>, but also handles 'set' magic.

=cut
*/

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

/*
=for apidoc sv_setuv

Copies an unsigned integer into the given SV.  Does not handle 'set' magic.
See C<sv_setuv_mg>.

=cut
*/

void
Perl_sv_setuv(pTHX_ register SV *sv, UV u)
{
    /* With these two if statements:
       u=1.49  s=0.52  cu=72.49  cs=10.64  scripts=270  tests=20865

       without
       u=1.35  s=0.47  cu=73.45  cs=11.43  scripts=270  tests=20865

       If you wish to remove them, please benchmark to see what the effect is
    */
    if (u <= (UV)IV_MAX) {
       sv_setiv(sv, (IV)u);
       return;
    }
    sv_setiv(sv, 0);
    SvIsUV_on(sv);
    SvUVX(sv) = u;
}

/*
=for apidoc sv_setuv_mg

Like C<sv_setuv>, but also handles 'set' magic.

=cut
*/

void
Perl_sv_setuv_mg(pTHX_ register SV *sv, UV u)
{
    /* With these two if statements:
       u=1.49  s=0.52  cu=72.49  cs=10.64  scripts=270  tests=20865

       without
       u=1.35  s=0.47  cu=73.45  cs=11.43  scripts=270  tests=20865

       If you wish to remove them, please benchmark to see what the effect is
    */
    if (u <= (UV)IV_MAX) {
       sv_setiv(sv, (IV)u);
    } else {
       sv_setiv(sv, 0);
       SvIsUV_on(sv);
       sv_setuv(sv,u);
    }
    SvSETMAGIC(sv);
}

/*
=for apidoc sv_setnv

Copies a double into the given SV.  Does not handle 'set' magic.  See
C<sv_setnv_mg>.

=cut
*/

void
Perl_sv_setnv(pTHX_ register SV *sv, NV 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:
	Perl_croak(aTHX_ "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);
}

/*
=for apidoc sv_setnv_mg

Like C<sv_setnv>, but also handles 'set' magic.

=cut
*/

void
Perl_sv_setnv_mg(pTHX_ register SV *sv, NV num)
{
    sv_setnv(sv,num);
    SvSETMAGIC(sv);
}

STATIC void
S_not_a_number(pTHX_ SV *sv)
{
    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)
	Perl_warner(aTHX_ WARN_NUMERIC,
		    "Argument \"%s\" isn't numeric in %s", tmpbuf,
		PL_op_desc[PL_op->op_type]);
    else
	Perl_warner(aTHX_ WARN_NUMERIC,
		    "Argument \"%s\" isn't numeric", tmpbuf);
}

/* the number can be converted to integer with atol() or atoll() although */
#define IS_NUMBER_TO_INT_BY_ATOL     0x01 /* integer (may have decimals) */
#define IS_NUMBER_TO_INT_BY_STRTOL   0x02 /* it may exceed IV_MAX */
#define IS_NUMBER_TO_INT_BY_ATOF     0x04 /* seen something like 123e4 */
#define IS_NUMBER_LONGER_THAN_IV_MAX 0x08 /* more digits than IV_MAX */
#define IS_NUMBER_AS_LONG_AS_IV_MAX  0x10 /* may(be not) larger than IV_MAX */
#define IS_NUMBER_NOT_INT	     0x20 /* seen a decimal point or e */
#define IS_NUMBER_NEG		     0x40 /* seen a leading - */
#define IS_NUMBER_INFINITY	     0x80 /* /^\s*-?Infinity\s*$/i */

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

/* As 64 bit platforms often have an NV that doesn't preserve all bits of
   an IV (an assumption perl has been based on to date) it becomes necessary
   to remove the assumption that the NV always carries enough precision to
   recreate the IV whenever needed, and that the NV is the canonical form.
   Instead, IV/UV and NV need to be given equal rights. So as to not lose
   precision as an side effect of conversion (which would lead to insanity
   and the dragon(s) in t/op/numconvert.t getting very angry) the intent is
   1) to distinguish between IV/UV/NV slots that have cached a valid
      conversion where precision was lost and IV/UV/NV slots that have a
      valid conversion which has lost no precision
   2) to ensure that if a numeric conversion to one form is request that
      would lose precision, the precise conversion (or differently
      imprecise conversion) is also performed and cached, to prevent
      requests for different numeric formats on the same SV causing
      lossy conversion chains. (lossless conversion chains are perfectly
      acceptable (still))


   flags are used:
   SvIOKp is true if the IV slot contains a valid value
   SvIOK  is true only if the IV value is accurate (UV if SvIOK_UV true)
   SvNOKp is true if the NV slot contains a valid value
   SvNOK  is true only if the NV value is accurate

   so
   while converting from PV to NV check to see if converting that NV to an
   IV(or UV) would lose accuracy over a direct conversion from PV to
   IV(or UV). If it would, cache both conversions, return NV, but mark
   SV as IOK NOKp (ie not NOK).

   while converting from PV to IV check to see if converting that IV to an
   NV would lose accuracy over a direct conversion from PV to NV. If it
   would, cache both conversions, flag similarly.

   Before, the SV value "3.2" could become NV=3.2 IV=3 NOK, IOK quite
   correctly because if IV & NV were set NV *always* overruled.
   Now, "3.2" will become NV=3.2 IV=3 NOK, IOKp, because the flags meaning
   changes - now IV and NV together means that the two are interchangeable
   SvIVX == (IV) SvNVX && SvNVX == (NV) SvIVX;

   The benefit of this is operations such as pp_add know that if SvIOK is
   true for both left and right operands, then integer addition can be
   used instead of floating point. (for cases where the result won't
   overflow) Before, floating point was always used, which could lead to
   loss of precision compared with integer addition.

   * making IV and NV equal status should make maths accurate on 64 bit
     platforms
   * may speed up maths somewhat if pp_add and friends start to use
     integers when possible instead of fp. (hopefully the overhead in
     looking for SvIOK and checking for overflow will not outweigh the
     fp to integer speedup)
   * will slow down integer operations (callers of SvIV) on "inaccurate"
     values, as the change from SvIOK to SvIOKp will cause a call into
     sv_2iv each time rather than a macro access direct to the IV slot
   * should speed up number->string conversion on integers as IV is
     favoured when IV and NV equally accurate

   ####################################################################
   You had better be using SvIOK_notUV if you want an IV for arithmetic
   SvIOK is true if (IV or UV), so you might be getting (IV)SvUV
   SvUOK is true iff UV.
   ####################################################################

   Your mileage will vary depending your CPUs relative fp to integer
   performance ratio.
*/

#ifndef NV_PRESERVES_UV
#define IS_NUMBER_UNDERFLOW_IV 1
#define IS_NUMBER_UNDERFLOW_UV 2
#define IS_NUMBER_IV_AND_UV 2
#define IS_NUMBER_OVERFLOW_IV 4
#define IS_NUMBER_OVERFLOW_UV 5
/* Hopefully your optimiser will consider inlining these two functions.  */
STATIC int
S_sv_2inuv_non_preserve (pTHX_ register SV *sv, I32 numtype) {
    NV nv = SvNVX(sv);		/* Code simpler and had compiler problems if */
    UV nv_as_uv = U_V(nv);	/*  these are not in simple variables.   */
    DEBUG_c(PerlIO_printf(Perl_debug_log,"sv_2inuv_non '%s', IV=0x%"UVxf" NV=%g inttype=%"UVXf"\n", SvPVX(sv), SvIVX(sv), nv, (UV)numtype));
    if (nv_as_uv <= (UV)IV_MAX) {
	(void)SvIOKp_on(sv);
	(void)SvNOKp_on(sv);
	/* Within suitable range to fit in an IV,  atol won't overflow */
	/* XXX quite sure? Is that your final answer? not really, I'm
	   trusting that nv_as_uv to round down if NV is (IV_MAX + 1) */
	SvIVX(sv) = (IV)Atol(SvPVX(sv));
	if (numtype & IS_NUMBER_NOT_INT) {
	    /* I believe that even if the original PV had decimals, they
	       are lost beyond the limit of the FP precision.
	       However, neither is canonical, so both only get p flags.
	       NWC, 2000/11/25 */
	    /* Both already have p flags, so do nothing */
	} else if (SvIVX(sv) == I_V(nv)) {
	    SvNOK_on(sv);
	    SvIOK_on(sv);
	} else {
	    SvIOK_on(sv);
	    /* It had no "." so it must be integer.  assert (get in here from
	       sv_2iv and sv_2uv only for ndef HAS_STRTOL and
	       IS_NUMBER_AS_LONG_AS_IV_MAX) or my logic is faulty and all
	       conversion routines need audit.  */
	}
	return nv < 0 ? IS_NUMBER_UNDERFLOW_UV : IS_NUMBER_IV_AND_UV;
    }
    /* between IV_MAX and NV(UV_MAX). Could be slightly> UV_MAX */
    (void)SvIOKp_on(sv);
    (void)SvNOKp_on(sv);
#ifdef HAS_STRTOUL
    {
	int save_errno = errno;
	errno = 0;
	SvUVX(sv) = Strtoul(SvPVX(sv), Null(char**), 10);
	if (errno == 0) {
	    if (numtype & IS_NUMBER_NOT_INT) {
		/* UV and NV both imprecise.  */
		SvIsUV_on(sv);
	    } else if (SvUVX(sv) == nv_as_uv && SvUVX(sv) != UV_MAX) {
		SvNOK_on(sv);
		SvIOK_on(sv);
		SvIsUV_on(sv);
	    } else {
		SvIOK_on(sv);
		SvIsUV_on(sv);
	    }
	    errno = save_errno;
	    return IS_NUMBER_OVERFLOW_IV;
	}
	errno = save_errno;
	SvNOK_on(sv);
	/* Must have just overflowed UV, but not enough that an NV could spot
	   this.. */
	return IS_NUMBER_OVERFLOW_UV;
    }
#else
    /* We've just lost integer precision, nothing we could do. */
    SvUVX(sv) = nv_as_uv;
    DEBUG_c(PerlIO_printf(Perl_debug_log,"sv_2niuv_non UV? '%s', UV=0x%"UVxf" NV=%g U_V(NV)=0x%"UVxf" inttype=%"UVXf"\n", SvPVX(sv), SvIVX(sv), nv, nv_as_uv, (UV)numtype));
    /* UV and NV slots equally valid only if we have casting symmetry. */
    if (numtype & IS_NUMBER_NOT_INT) {
	SvIsUV_on(sv);
    } else if (SvUVX(sv) == nv_as_uv && SvUVX(sv) != UV_MAX) {
	/* UV_MAX can cast up to NV (UV_MAX+1), that NV casts down to UV_MAX
	   UV_MAX ought to be 0xFF...FFF which won't preserve (We only
	   get to this point if NVs don't preserve UVs) */
	SvNOK_on(sv);
	SvIOK_on(sv);
	SvIsUV_on(sv);
    } else {
	/* As above, I believe UV at least as good as NV */
	SvIsUV_on(sv);
    }
#endif /* HAS_STRTOUL */
    return IS_NUMBER_OVERFLOW_IV;
}

/* For sv_2nv these three cases are "SvNOK and don't bother casting"  */
STATIC int
S_sv_2iuv_non_preserve (pTHX_ register SV *sv, I32 numtype)
{
    DEBUG_c(PerlIO_printf(Perl_debug_log,"sv_2iuv_non '%s', IV=0x%"UVxf" NV=%g inttype=%"UVXf"\n", SvPVX(sv), SvIVX(sv), SvNVX(sv), (UV)numtype));
    if (SvNVX(sv) < (NV)IV_MIN) {
	(void)SvIOKp_on(sv);
	(void)SvNOK_on(sv);
	SvIVX(sv) = IV_MIN;
	return IS_NUMBER_UNDERFLOW_IV;
    }
    if (SvNVX(sv) > (NV)UV_MAX) {
	(void)SvIOKp_on(sv);
	(void)SvNOK_on(sv);
	SvIsUV_on(sv);
	SvUVX(sv) = UV_MAX;
	return IS_NUMBER_OVERFLOW_UV;
    }
    if (!(numtype & (IS_NUMBER_TO_INT_BY_ATOL | IS_NUMBER_TO_INT_BY_STRTOL))) {
	(void)SvIOKp_on(sv);
	(void)SvNOK_on(sv);
	/* Can't use strtol etc to convert this string */
	if (SvNVX(sv) <= (UV)IV_MAX) {
	    SvIVX(sv) = I_V(SvNVX(sv));
	    if ((NV)(SvIVX(sv)) == SvNVX(sv)) {
		SvIOK_on(sv); /* Integer is precise. NOK, IOK */
	    } else {
		/* Integer is imprecise. NOK, IOKp */
	    }
	    return SvNVX(sv) < 0 ? IS_NUMBER_UNDERFLOW_UV : IS_NUMBER_IV_AND_UV;
	}
	SvIsUV_on(sv);
	SvUVX(sv) = U_V(SvNVX(sv));
	if ((NV)(SvUVX(sv)) == SvNVX(sv)) {
	    if (SvUVX(sv) == UV_MAX) {
		/* As we know that NVs don't preserve UVs, UV_MAX cannot
		   possibly be preserved by NV. Hence, it must be overflow.
		   NOK, IOKp */
		return IS_NUMBER_OVERFLOW_UV;
	    }
	    SvIOK_on(sv); /* Integer is precise. NOK, UOK */
	} else {
	    /* Integer is imprecise. NOK, IOKp */
	}
	return IS_NUMBER_OVERFLOW_IV;
    }
    return S_sv_2inuv_non_preserve(aTHX_ sv, numtype);
}
#endif /* NV_PRESERVES_UV*/

IV
Perl_sv_2iv(pTHX_ 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)) {
		if (ckWARN(WARN_UNINITIALIZED) && !PL_localizing)
		    report_uninit();
	    }
	    return 0;
	}
    }
    if (SvTHINKFIRST(sv)) {
	if (SvROK(sv)) {
	  SV* tmpstr;
          if (SvAMAGIC(sv) && (tmpstr=AMG_CALLun(sv,numer)) &&
                  (SvRV(tmpstr) != SvRV(sv)))
	      return SvIV(tmpstr);
	  return PTR2IV(SvRV(sv));
	}
	if (SvREADONLY(sv) && SvFAKE(sv)) {
	    sv_force_normal(sv);
	}
	if (SvREADONLY(sv) && !SvOK(sv)) {
	    if (ckWARN(WARN_UNINITIALIZED))
		report_uninit();
	    return 0;
	}
    }
    if (SvIOKp(sv)) {
	if (SvIsUV(sv)) {
	    return (IV)(SvUVX(sv));
	}
	else {
	    return SvIVX(sv);
	}
    }
    if (SvNOKp(sv)) {
	/* erm. not sure. *should* never get NOKp (without NOK) from sv_2nv
	 * without also getting a cached IV/UV from it at the same time
	 * (ie PV->NV conversion should detect loss of accuracy and cache
	 * IV or UV at same time to avoid this.  NWC */

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

	(void)SvIOKp_on(sv);	/* Must do this first, to clear any SvOOK */
	/* < not <= as for NV doesn't preserve UV, ((NV)IV_MAX+1) will almost
	   certainly cast into the IV range at IV_MAX, whereas the correct
	   answer is the UV IV_MAX +1. Hence < ensures that dodgy boundary
	   cases go to UV */
	if (SvNVX(sv) < (NV)IV_MAX + 0.5) {
	    SvIVX(sv) = I_V(SvNVX(sv));
	    if (SvNVX(sv) == (NV) SvIVX(sv)
#ifndef NV_PRESERVES_UV
		&& (((UV)1 << NV_PRESERVES_UV_BITS) >
		    (UV)(SvIVX(sv) > 0 ? SvIVX(sv) : -SvIVX(sv)))
		/* Don't flag it as "accurately an integer" if the number
		   came from a (by definition imprecise) NV operation, and
		   we're outside the range of NV integer precision */
#endif
		) {
		SvIOK_on(sv);  /* Can this go wrong with rounding? NWC */
		DEBUG_c(PerlIO_printf(Perl_debug_log,
				      "0x%"UVxf" iv(%g => %"IVdf") (precise)\n",
				      PTR2UV(sv),
				      SvNVX(sv),
				      SvIVX(sv)));

	    } else {
		/* IV not precise.  No need to convert from PV, as NV
		   conversion would already have cached IV if it detected
		   that PV->IV would be better than PV->NV->IV
		   flags already correct - don't set public IOK.  */
		DEBUG_c(PerlIO_printf(Perl_debug_log,
				      "0x%"UVxf" iv(%g => %"IVdf") (imprecise)\n",
				      PTR2UV(sv),
				      SvNVX(sv),
				      SvIVX(sv)));
	    }
	    /* Can the above go wrong if SvIVX == IV_MIN and SvNVX < IV_MIN,
	       but the cast (NV)IV_MIN rounds to a the value less (more
	       negative) than IV_MIN which happens to be equal to SvNVX ??
	       Analogous to 0xFFFFFFFFFFFFFFFF rounding up to NV (2**64) and
	       NV rounding back to 0xFFFFFFFFFFFFFFFF, so UVX == UV(NVX) and
	       (NV)UVX == NVX are both true, but the values differ. :-(
	       Hopefully for 2s complement IV_MIN is something like
	       0x8000000000000000 which will be exact. NWC */
	}
	else {
	    SvUVX(sv) = U_V(SvNVX(sv));
	    if (
		(SvNVX(sv) == (NV) SvUVX(sv))
#ifndef  NV_PRESERVES_UV
		/* Make sure it's not 0xFFFFFFFFFFFFFFFF */
		/*&& (SvUVX(sv) != UV_MAX) irrelevant with code below */
		&& (((UV)1 << NV_PRESERVES_UV_BITS) > SvUVX(sv))
		/* Don't flag it as "accurately an integer" if the number
		   came from a (by definition imprecise) NV operation, and
		   we're outside the range of NV integer precision */
#endif
		)
		SvIOK_on(sv);
	    SvIsUV_on(sv);
	  ret_iv_max:
	    DEBUG_c(PerlIO_printf(Perl_debug_log,
				  "0x%"UVxf" 2iv(%"UVuf" => %"IVdf") (as unsigned)\n",
				  PTR2UV(sv),
				  SvUVX(sv),
				  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 we are sure it's not needed.
	 */

	if ((numtype & ~IS_NUMBER_NEG) == IS_NUMBER_TO_INT_BY_ATOL) {
	    /* The NV may be reconstructed from IV - safe to cache IV,
		which may be calculated by atol(). */
	    if (SvTYPE(sv) < SVt_PVIV)
		sv_upgrade(sv, SVt_PVIV);
	    (void)SvIOK_on(sv);
	    SvIVX(sv) = Atol(SvPVX(sv));
	} else {
#ifdef HAS_STRTOL
	    IV i;
	    int save_errno = errno;
	    /* Is it an integer that we could convert with strtol?
	       So try it, and if it doesn't set errno then it's pukka.
	       This should be faster than going atof and then thinking.  */
	    if (((numtype & (IS_NUMBER_TO_INT_BY_STRTOL | IS_NUMBER_NOT_INT))
		  == IS_NUMBER_TO_INT_BY_STRTOL)
		/* && is a sequence point. Without it not sure if I'm trying
		   to do too much between sequence points and hence going
		   undefined */
		&& ((errno = 0), 1) /* , 1 so always true */
		&& ((i = Strtol(SvPVX(sv), Null(char**), 10)), 1)
		&& (errno == 0)) {
		if (SvTYPE(sv) < SVt_PVIV)
		    sv_upgrade(sv, SVt_PVIV);
		(void)SvIOK_on(sv);
		SvIVX(sv) = i;
		errno = save_errno;
	    } else
#endif
	    {
		NV d;
#ifdef HAS_STRTOL
		/* Hopefully trace flow will optimise this away where possible
		 */
		errno = save_errno;
#endif
		/* It wasn't an integer, or it overflowed, or we don't have
		   strtol. Do things the slow way - check if it's a UV etc. */
		d = Atof(SvPVX(sv));

		if (SvTYPE(sv) < SVt_PVNV)
		    sv_upgrade(sv, SVt_PVNV);
		SvNVX(sv) = d;

		if (! numtype && ckWARN(WARN_NUMERIC))
		    not_a_number(sv);

#if defined(USE_LONG_DOUBLE)
		DEBUG_c(PerlIO_printf(Perl_debug_log, "0x%"UVxf" 2iv(%" PERL_PRIgldbl ")\n",
				      PTR2UV(sv), SvNVX(sv)));
#else
		DEBUG_c(PerlIO_printf(Perl_debug_log, "0x%"UVxf" 2iv(%g)\n",
				      PTR2UV(sv), SvNVX(sv)));
#endif


#ifdef NV_PRESERVES_UV
		(void)SvIOKp_on(sv);
		(void)SvNOK_on(sv);
		if (SvNVX(sv) < (NV)IV_MAX + 0.5) {
		    SvIVX(sv) = I_V(SvNVX(sv));
		    if ((NV)(SvIVX(sv)) == SvNVX(sv)) {
			SvIOK_on(sv);
		    } else {
			/* Integer is imprecise. NOK, IOKp */
		    }
		    /* UV will not work better than IV */
		} else {
		    if (SvNVX(sv) > (NV)UV_MAX) {
			SvIsUV_on(sv);
			/* Integer is inaccurate. NOK, IOKp, is UV */
			SvUVX(sv) = UV_MAX;
			SvIsUV_on(sv);
		    } else {
			SvUVX(sv) = U_V(SvNVX(sv));
			/* 0xFFFFFFFFFFFFFFFF not an issue in here */
			if ((NV)(SvUVX(sv)) == SvNVX(sv)) {
			    SvIOK_on(sv);
			    SvIsUV_on(sv);
			} else {
			    /* Integer is imprecise. NOK, IOKp, is UV */
			    SvIsUV_on(sv);
			}
		    }
		    goto ret_iv_max;
		}
#else /* NV_PRESERVES_UV */
		if (((UV)1 << NV_PRESERVES_UV_BITS) >
		    U_V(SvNVX(sv) > 0 ? SvNVX(sv) : -SvNVX(sv))) {
		    /* Small enough to preserve all bits. */
		    (void)SvIOKp_on(sv);
		    SvNOK_on(sv);
		    SvIVX(sv) = I_V(SvNVX(sv));
		    if ((NV)(SvIVX(sv)) == SvNVX(sv))
			SvIOK_on(sv);
		    /* Assumption: first non-preserved integer is < IV_MAX,
		       this NV is in the preserved range, therefore: */
		    if (!(U_V(SvNVX(sv) > 0 ? SvNVX(sv) : -SvNVX(sv))
			  < (UV)IV_MAX)) {
			Perl_croak(aTHX_ "sv_2iv assumed (U_V(fabs(SvNVX(sv))) < (UV)IV_MAX) but SvNVX(sv)=%g U_V is 0x%"UVxf", IV_MAX is 0x%"UVxf"\n", SvNVX(sv), U_V(SvNVX(sv)), (UV)IV_MAX);
		    }
		} else if (sv_2iuv_non_preserve (sv, numtype)
			   >= IS_NUMBER_OVERFLOW_IV)
		    goto ret_iv_max;
#endif /* NV_PRESERVES_UV */
	    }
	}
    } else  {
	if (ckWARN(WARN_UNINITIALIZED) && !PL_localizing && !(SvFLAGS(sv) & SVs_PADTMP))
	    report_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%"UVxf" 2iv(%"IVdf")\n",
	PTR2UV(sv),SvIVX(sv)));
    return SvIsUV(sv) ? (IV)SvUVX(sv) : SvIVX(sv);
}

UV
Perl_sv_2uv(pTHX_ 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)) {
		if (ckWARN(WARN_UNINITIALIZED) && !PL_localizing)
		    report_uninit();
	    }
	    return 0;
	}
    }
    if (SvTHINKFIRST(sv)) {
	if (SvROK(sv)) {
	  SV* tmpstr;
          if (SvAMAGIC(sv) && (tmpstr=AMG_CALLun(sv,numer)) &&
                  (SvRV(tmpstr) != SvRV(sv)))
	      return SvUV(tmpstr);
	  return PTR2UV(SvRV(sv));
	}
	if (SvREADONLY(sv) && SvFAKE(sv)) {
	    sv_force_normal(sv);
	}
	if (SvREADONLY(sv) && !SvOK(sv)) {
	    if (ckWARN(WARN_UNINITIALIZED))
		report_uninit();
	    return 0;
	}
    }
    if (SvIOKp(sv)) {
	if (SvIsUV(sv)) {
	    return SvUVX(sv);
	}
	else {
	    return (UV)SvIVX(sv);
	}
    }
    if (SvNOKp(sv)) {
	/* erm. not sure. *should* never get NOKp (without NOK) from sv_2nv
	 * without also getting a cached IV/UV from it at the same time
	 * (ie PV->NV conversion should detect loss of accuracy and cache
	 * IV or UV at same time to avoid this. */
	/* IV-over-UV optimisation - choose to cache IV if possible */

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

	(void)SvIOKp_on(sv);	/* Must do this first, to clear any SvOOK */
	if (SvNVX(sv) < (NV)IV_MAX + 0.5) {
	    SvIVX(sv) = I_V(SvNVX(sv));
	    if (SvNVX(sv) == (NV) SvIVX(sv)
#ifndef NV_PRESERVES_UV
		&& (((UV)1 << NV_PRESERVES_UV_BITS) >
		    (UV)(SvIVX(sv) > 0 ? SvIVX(sv) : -SvIVX(sv)))
		/* Don't flag it as "accurately an integer" if the number
		   came from a (by definition imprecise) NV operation, and
		   we're outside the range of NV integer precision */
#endif
		) {
		SvIOK_on(sv);  /* Can this go wrong with rounding? NWC */
		DEBUG_c(PerlIO_printf(Perl_debug_log,
				      "0x%"UVxf" uv(%g => %"IVdf") (precise)\n",
				      PTR2UV(sv),
				      SvNVX(sv),
				      SvIVX(sv)));

	    } else {
		/* IV not precise.  No need to convert from PV, as NV
		   conversion would already have cached IV if it detected
		   that PV->IV would be better than PV->NV->IV
		   flags already correct - don't set public IOK.  */
		DEBUG_c(PerlIO_printf(Perl_debug_log,
				      "0x%"UVxf" uv(%g => %"IVdf") (imprecise)\n",
				      PTR2UV(sv),
				      SvNVX(sv),
				      SvIVX(sv)));
	    }
	    /* Can the above go wrong if SvIVX == IV_MIN and SvNVX < IV_MIN,
	       but the cast (NV)IV_MIN rounds to a the value less (more
	       negative) than IV_MIN which happens to be equal to SvNVX ??
	       Analogous to 0xFFFFFFFFFFFFFFFF rounding up to NV (2**64) and
	       NV rounding back to 0xFFFFFFFFFFFFFFFF, so UVX == UV(NVX) and
	       (NV)UVX == NVX are both true, but the values differ. :-(
	       Hopefully for 2s complement IV_MIN is something like
	       0x8000000000000000 which will be exact. NWC */
	}
	else {
	    SvUVX(sv) = U_V(SvNVX(sv));
	    if (
		(SvNVX(sv) == (NV) SvUVX(sv))
#ifndef  NV_PRESERVES_UV
		/* Make sure it's not 0xFFFFFFFFFFFFFFFF */
		/*&& (SvUVX(sv) != UV_MAX) irrelevant with code below */
		&& (((UV)1 << NV_PRESERVES_UV_BITS) > SvUVX(sv))
		/* Don't flag it as "accurately an integer" if the number
		   came from a (by definition imprecise) NV operation, and
		   we're outside the range of NV integer precision */
#endif
		)
		SvIOK_on(sv);
	    SvIsUV_on(sv);
	    DEBUG_c(PerlIO_printf(Perl_debug_log,
				  "0x%"UVxf" 2uv(%"UVuf" => %"IVdf") (as unsigned)\n",
				  PTR2UV(sv),
				  SvUVX(sv),
				  SvUVX(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_NEG) == IS_NUMBER_TO_INT_BY_ATOL) {
	    /* The NV may be reconstructed from IV - safe to cache IV,
		which may be calculated by atol(). */
	    if (SvTYPE(sv) < SVt_PVIV)
		sv_upgrade(sv, SVt_PVIV);
	    (void)SvIOK_on(sv);
	    SvIVX(sv) = Atol(SvPVX(sv));
	} else {
#ifdef HAS_STRTOUL
	    UV u;
	    char *num_begin = SvPVX(sv);
	    int save_errno = errno;
	
	    /* seems that strtoul taking numbers that start with - is
	       implementation dependant, and can't be relied upon.  */
	    if (numtype & IS_NUMBER_NEG) {
		/* Not totally defensive. assumine that looks_like_num
		   didn't lie about a - sign */
		while (isSPACE(*num_begin))
		    num_begin++;
		if (*num_begin == '-')
		    num_begin++;
	    }

	    /* Is it an integer that we could convert with strtoul?
	       So try it, and if it doesn't set errno then it's pukka.
	       This should be faster than going atof and then thinking.  */
	    if (((numtype & (IS_NUMBER_TO_INT_BY_STRTOL | IS_NUMBER_NOT_INT))
		 == IS_NUMBER_TO_INT_BY_STRTOL)
		&& ((errno = 0), 1) /* always true */
		&& ((u = Strtoul(num_begin, Null(char**), 10)), 1) /* ditto */
		&& (errno == 0)
		/* If known to be negative, check it didn't undeflow IV
		   XXX possibly we should put more negative values as NVs
		   direct rather than go via atof below */
		&& ((numtype & IS_NUMBER_NEG) ? (u <= (UV)IV_MIN) : 1)) {
		errno = save_errno;

		if (SvTYPE(sv) < SVt_PVIV)
		    sv_upgrade(sv, SVt_PVIV);
		(void)SvIOK_on(sv);

		/* If it's negative must use IV.
		   IV-over-UV optimisation */
		if (numtype & IS_NUMBER_NEG) {
		    SvIVX(sv) = -(IV)u;
		} else if (u <= (UV) IV_MAX) {
		    SvIVX(sv) = (IV)u;
		} else {
		    /* it didn't overflow, and it was positive. */
		    SvUVX(sv) = u;
		    SvIsUV_on(sv);
		}
	    } else
#endif
	    {
		NV d;
#ifdef HAS_STRTOUL
		/* Hopefully trace flow will optimise this away where possible
		 */
		errno = save_errno;
#endif
		/* It wasn't an integer, or it overflowed, or we don't have
		   strtol. Do things the slow way - check if it's a IV etc. */
		d = Atof(SvPVX(sv));

		if (SvTYPE(sv) < SVt_PVNV)
		    sv_upgrade(sv, SVt_PVNV);
		SvNVX(sv) = d;

		if (! numtype && ckWARN(WARN_NUMERIC))
		    not_a_number(sv);

#if defined(USE_LONG_DOUBLE)
		DEBUG_c(PerlIO_printf(Perl_debug_log, "0x%"UVxf" 2uv(%" PERL_PRIgldbl ")\n",
				      PTR2UV(sv), SvNVX(sv)));
#else
		DEBUG_c(PerlIO_printf(Perl_debug_log, "0x%"UVxf" 2uv(%g)\n",
				      PTR2UV(sv), SvNVX(sv)));
#endif

#ifdef NV_PRESERVES_UV
		(void)SvIOKp_on(sv);
		(void)SvNOK_on(sv);
		if (SvNVX(sv) < (NV)IV_MAX + 0.5) {
		    SvIVX(sv) = I_V(SvNVX(sv));
		    if ((NV)(SvIVX(sv)) == SvNVX(sv)) {
			SvIOK_on(sv);
		    } else {
			/* Integer is imprecise. NOK, IOKp */
		    }
		    /* UV will not work better than IV */
		} else {
		    if (SvNVX(sv) > (NV)UV_MAX) {
			SvIsUV_on(sv);
			/* Integer is inaccurate. NOK, IOKp, is UV */
			SvUVX(sv) = UV_MAX;
			SvIsUV_on(sv);
		    } else {
			SvUVX(sv) = U_V(SvNVX(sv));
			/* 0xFFFFFFFFFFFFFFFF not an issue in here, NVs
			   NV preservse UV so can do correct comparison.  */
			if ((NV)(SvUVX(sv)) == SvNVX(sv)) {
			    SvIOK_on(sv);
			    SvIsUV_on(sv);
			} else {
			    /* Integer is imprecise. NOK, IOKp, is UV */
			    SvIsUV_on(sv);
			}
		    }
		}
#else /* NV_PRESERVES_UV */
		if (((UV)1 << NV_PRESERVES_UV_BITS) >
		    U_V(SvNVX(sv) > 0 ? SvNVX(sv) : -SvNVX(sv))) {
		    /* Small enough to preserve all bits. */
		    (void)SvIOKp_on(sv);
		    SvNOK_on(sv);
		    SvIVX(sv) = I_V(SvNVX(sv));
		    if ((NV)(SvIVX(sv)) == SvNVX(sv))
			SvIOK_on(sv);
		    /* Assumption: first non-preserved integer is < IV_MAX,
		       this NV is in the preserved range, therefore: */
		    if (!(U_V(SvNVX(sv) > 0 ? SvNVX(sv) : -SvNVX(sv))
			  < (UV)IV_MAX)) {
			Perl_croak(aTHX_ "sv_2uv assumed (U_V(fabs(SvNVX(sv))) < (UV)IV_MAX) but SvNVX(sv)=%g U_V is 0x%"UVxf", IV_MAX is 0x%"UVxf"\n", SvNVX(sv), U_V(SvNVX(sv)), (UV)IV_MAX);
		    }
		} else
		    sv_2iuv_non_preserve (sv, numtype);
#endif /* NV_PRESERVES_UV */
	    }
	}
    }
    else  {
	if (!(SvFLAGS(sv) & SVs_PADTMP)) {
	    if (ckWARN(WARN_UNINITIALIZED) && !PL_localizing)
		report_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%"UVxf" 2uv(%"UVuf")\n",
			  PTR2UV(sv),SvUVX(sv)));
    return SvIsUV(sv) ? SvUVX(sv) : (UV)SvIVX(sv);
}

NV
Perl_sv_2nv(pTHX_ 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)) {
	    if (ckWARN(WARN_NUMERIC) && !SvIOKp(sv) && !looks_like_number(sv))
		not_a_number(sv);
	    return Atof(SvPVX(sv));
	}
	if (SvIOKp(sv)) {
	    if (SvIsUV(sv))
		return (NV)SvUVX(sv);
	    else
		return (NV)SvIVX(sv);
	}	
        if (!SvROK(sv)) {
	    if (!(SvFLAGS(sv) & SVs_PADTMP)) {
		if (ckWARN(WARN_UNINITIALIZED) && !PL_localizing)
		    report_uninit();
	    }
            return 0;
        }
    }
    if (SvTHINKFIRST(sv)) {
	if (SvROK(sv)) {
	  SV* tmpstr;
          if (SvAMAGIC(sv) && (tmpstr=AMG_CALLun(sv,numer)) &&
                  (SvRV(tmpstr) != SvRV(sv)))
	      return SvNV(tmpstr);
	  return PTR2NV(SvRV(sv));
	}
	if (SvREADONLY(sv) && SvFAKE(sv)) {
	    sv_force_normal(sv);
	}
	if (SvREADONLY(sv) && !SvOK(sv)) {
	    if (ckWARN(WARN_UNINITIALIZED))
		report_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);
#if defined(USE_LONG_DOUBLE)
	DEBUG_c({
	    STORE_NUMERIC_LOCAL_SET_STANDARD();
	    PerlIO_printf(Perl_debug_log,
			  "0x%"UVxf" num(%" PERL_PRIgldbl ")\n",
			  PTR2UV(sv), SvNVX(sv));
	    RESTORE_NUMERIC_LOCAL();
	});
#else
	DEBUG_c({
	    STORE_NUMERIC_LOCAL_SET_STANDARD();
	    PerlIO_printf(Perl_debug_log, "0x%"UVxf" num(%g)\n",
			  PTR2UV(sv), SvNVX(sv));
	    RESTORE_NUMERIC_LOCAL();
	});
#endif
    }
    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) ? (NV)SvUVX(sv) : (NV)SvIVX(sv);
#ifdef NV_PRESERVES_UV
	SvNOK_on(sv);
#else
	/* Only set the public NV OK flag if this NV preserves the IV  */
	/* Check it's not 0xFFFFFFFFFFFFFFFF */
	if (SvIsUV(sv) ? ((SvUVX(sv) != UV_MAX)&&(SvUVX(sv) == U_V(SvNVX(sv))))
		       : (SvIVX(sv) == I_V(SvNVX(sv))))
	    SvNOK_on(sv);
	else
	    SvNOKp_on(sv);
#endif
    }
    else if (SvPOKp(sv) && SvLEN(sv)) {
	if (ckWARN(WARN_NUMERIC) && !SvIOKp(sv) && !looks_like_number(sv))
	    not_a_number(sv);
	SvNVX(sv) = Atof(SvPVX(sv));
#ifdef NV_PRESERVES_UV
	SvNOK_on(sv);
#else
	/* Only set the public NV OK flag if this NV preserves the value in
	   the PV at least as well as an IV/UV would.
	   Not sure how to do this 100% reliably. */
	/* if that shift count is out of range then Configure's test is
	   wonky. We shouldn't be in here with NV_PRESERVES_UV_BITS ==
	   UV_BITS */
	if (((UV)1 << NV_PRESERVES_UV_BITS) >
	    U_V(SvNVX(sv) > 0 ? SvNVX(sv) : -SvNVX(sv)))
	    SvNOK_on(sv); /* Definitely small enough to preserve all bits */
	else if (SvNVX(sv) < (NV)IV_MIN || SvNVX(sv) > (NV)UV_MAX) {
		/* Definitely too large/small to fit in an integer, so no loss
		   of precision going to integer in the future via NV */
	    SvNOK_on(sv);
	} else {
	    /* Is it something we can run through strtol etc (ie no
	       trailing exponent part)? */
	    int numtype = looks_like_number(sv);
	    /* XXX probably should cache this if called above */

	    if (!(numtype &
		  (IS_NUMBER_TO_INT_BY_ATOL | IS_NUMBER_TO_INT_BY_STRTOL))) {
		/* Can't use strtol etc to convert this string, so don't try */
		SvNOK_on(sv);
	    } else
		sv_2inuv_non_preserve (sv, numtype);
	}
#endif /* NV_PRESERVES_UV */
    }
    else  {
	if (ckWARN(WARN_UNINITIALIZED) && !PL_localizing && !(SvFLAGS(sv) & SVs_PADTMP))
	    report_uninit();
	if (SvTYPE(sv) < SVt_NV)
	    /* Typically the caller expects that sv_any is not NULL now.  */
	    /* XXX Ilya implies that this is a bug in callers that assume this
	       and ideally should be fixed.  */
	    sv_upgrade(sv, SVt_NV);
	return 0.0;
    }
#if defined(USE_LONG_DOUBLE)
    DEBUG_c({
	STORE_NUMERIC_LOCAL_SET_STANDARD();
	PerlIO_printf(Perl_debug_log, "0x%"UVxf" 2nv(%" PERL_PRIgldbl ")\n",
		      PTR2UV(sv), SvNVX(sv));
	RESTORE_NUMERIC_LOCAL();
    });
#else
    DEBUG_c({
	STORE_NUMERIC_LOCAL_SET_STANDARD();
	PerlIO_printf(Perl_debug_log, "0x%"UVxf" 1nv(%g)\n",
		      PTR2UV(sv), SvNVX(sv));
	RESTORE_NUMERIC_LOCAL();
    });
#endif
    return SvNVX(sv);
}

STATIC IV
S_asIV(pTHX_ SV *sv)
{
    I32 numtype = looks_like_number(sv);
    NV d;

    if (numtype & IS_NUMBER_TO_INT_BY_ATOL)
	return Atol(SvPVX(sv));
    if (!numtype) {
	if (ckWARN(WARN_NUMERIC))
	    not_a_number(sv);
    }
    d = Atof(SvPVX(sv));
    return I_V(d);
}

STATIC UV
S_asUV(pTHX_ 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) {
	if (ckWARN(WARN_NUMERIC))
	    not_a_number(sv);
    }
    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_LONGER_THAN_IV_MAX, IS_NUMBER_AS_LONG_AS_IV_MAX
 * IS_NUMBER_NOT_INT, IS_NUMBER_NEG, IS_NUMBER_INFINITY
 * 0 if does not look like number.
 *
 * (atol and strtol stop when they hit a decimal point. strtol will return
 * LONG_MAX and LONG_MIN when given out of range values. ANSI says they should
 * do this, and vendors have had 11 years to get it right.
 * However, will try to make it still work with only atol
 *
 * IS_NUMBER_TO_INT_BY_ATOL	123456789 or 123456789.3  definitely < IV_MAX
 * IS_NUMBER_TO_INT_BY_STRTOL	123456789 or 123456789.3  if digits = IV_MAX
 * IS_NUMBER_TO_INT_BY_ATOF	123456789e0               or >> IV_MAX
 * IS_NUMBER_LONGER_THAN_IV_MAX	  lots of digits, don't bother with atol
 * IS_NUMBER_AS_LONG_AS_IV_MAX	  atol might hit LONG_MAX, might not.
 * IS_NUMBER_NOT_INT		saw "." or "e"
 * IS_NUMBER_NEG
 * IS_NUMBER_INFINITY
 */

/*
=for apidoc looks_like_number

Test if an the content of an SV looks like a number (or is a
number). C<Inf> and C<Infinity> are treated as numbers (so will not
issue a non-numeric warning), even if your atof() doesn't grok them.

=cut
*/

I32
Perl_looks_like_number(pTHX_ SV *sv)
{
    register char *s;
    register char *send;
    register char *sbegin;
    register char *nbegin;
    I32 numtype = 0;
    I32 sawinf  = 0;
    STRLEN len;
#ifdef USE_LOCALE_NUMERIC
    bool specialradix = FALSE;
#endif

    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 IS_NUMBER_TO_INT_BY_ATOL if the number can converted to
     * integer with atol() without overflow, IS_NUMBER_TO_INT_BY_STRTOL if
     * possibly slightly larger than max int, IS_NUMBER_TO_INT_BY_ATOF if you
     * will need (int)atof().
     */

    /* next must be digit or the radix separator or beginning of infinity */
    if (isDIGIT(*s)) {
        do {
	    s++;
        } while (isDIGIT(*s));

	/* Aaargh. long long really is irritating.
	   In the gospel according to ANSI 1989, it is an axiom that "long"
	   is the longest integer type, and that if you don't know how long
	   something is you can cast it to long, and nothing will be lost
	   (except possibly speed of execution if long is slower than the
	   type is was).
	   Now, one can't be sure if the old rules apply, or long long
	   (or some other newfangled thing) is actually longer than the
	   (formerly) longest thing.
	*/
	/* This lot will work for 64 bit  *as long as* either
	   either long is 64 bit
	   or     we can find both strtol/strtoq and strtoul/strtouq
	   If not, we really should refuse to let the user use 64 bit IVs
	   By "64 bit" I really mean IVs that don't get preserved by NVs
	   It also should work for 128 bit IVs. Can any lend me a machine to
	   test this?
	*/
	if (s - nbegin > TYPE_DIGITS(UV)) /* Cannot cache ato[ul]() */
	    numtype |= IS_NUMBER_TO_INT_BY_ATOF | IS_NUMBER_LONGER_THAN_IV_MAX;
	else if (s - nbegin < BIT_DIGITS(((sizeof (IV)>sizeof (long))
					  ? sizeof(long) : sizeof (IV))*8-1))
	    numtype |= IS_NUMBER_TO_INT_BY_ATOL;
	else
	    /* Can't be sure either way. (For 64 bit UV, 63 bit IV is 1 decimal
	       digit less (IV_MAX=  9223372036854775807,
			   UV_MAX= 18446744073709551615) so be cautious  */
	    numtype |= IS_NUMBER_TO_INT_BY_STRTOL | IS_NUMBER_AS_LONG_AS_IV_MAX;

        if (*s == '.'
#ifdef USE_LOCALE_NUMERIC
	    || (specialradix = IS_NUMERIC_RADIX(s))
#endif
	    ) {
#ifdef USE_LOCALE_NUMERIC
	    if (specialradix)
		s += SvCUR(PL_numeric_radix);
	    else
#endif
		s++;
	    numtype |= IS_NUMBER_NOT_INT;
            while (isDIGIT(*s))  /* optional digits after the radix */
                s++;
        }
    }
    else if (*s == '.'
#ifdef USE_LOCALE_NUMERIC
	    || (specialradix = IS_NUMERIC_RADIX(s))
#endif
	    ) {
#ifdef USE_LOCALE_NUMERIC
	if (specialradix)
	    s += SvCUR(PL_numeric_radix);
	else
#endif
	    s++;
	numtype |= IS_NUMBER_TO_INT_BY_ATOL | IS_NUMBER_NOT_INT;
        /* no digits before the radix means we need digits after it */
        if (isDIGIT(*s)) {
	    do {
	        s++;
            } while (isDIGIT(*s));
        }
        else
	    return 0;
    }
    else if (*s == 'I' || *s == 'i') {
	s++; if (*s != 'N' && *s != 'n') return 0;
	s++; if (*s != 'F' && *s != 'f') return 0;
	s++; if (*s == 'I' || *s == 'i') {
	    s++; if (*s != 'N' && *s != 'n') return 0;
	    s++; if (*s != 'I' && *s != 'i') return 0;
	    s++; if (*s != 'T' && *s != 't') return 0;
	    s++; if (*s != 'Y' && *s != 'y') return 0;
	    s++;
	}
	sawinf = 1;
    }
    else
        return 0;

    if (sawinf)
	numtype = (numtype & IS_NUMBER_NEG) /* Keep track of sign  */
	  | IS_NUMBER_INFINITY | IS_NUMBER_NOT_INT;
    else {
	/* 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_INT;
	    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 *
Perl_sv_2pv_nolen(pTHX_ 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)
{
    char *ptr = buf + TYPE_CHARS(UV);
    char *ebuf = ptr;
    int sign;

    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 *
Perl_sv_2pv(pTHX_ 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)) {
	    if (SvIsUV(sv))
		(void)sprintf(tmpbuf,"%"UVuf, (UV)SvUVX(sv));
	    else
		(void)sprintf(tmpbuf,"%"IVdf, (IV)SvIVX(sv));
	    tsv = Nullsv;
	    goto tokensave;
	}
	if (SvNOKp(sv)) {
	    Gconvert(SvNVX(sv), NV_DIG, 0, tmpbuf);
	    tsv = Nullsv;
	    goto tokensave;
	}
        if (!SvROK(sv)) {
	    if (!(SvFLAGS(sv) & SVs_PADTMP)) {
		if (ckWARN(WARN_UNINITIALIZED) && !PL_localizing)
		    report_uninit();
	    }
            *lp = 0;
            return "";
        }
    }
    if (SvTHINKFIRST(sv)) {
	if (SvROK(sv)) {
	    SV* tmpstr;
            if (SvAMAGIC(sv) && (tmpstr=AMG_CALLun(sv,string)) &&
                    (SvRV(tmpstr) != SvRV(sv)))
		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'))) {
			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:	if (SvROK(sv))
				    s = "REF";
				else
				    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))
		    Perl_sv_setpvf(aTHX_ tsv, "%s=%s", HvNAME(SvSTASH(sv)), s);
		else
		    sv_setpv(tsv, s);
		Perl_sv_catpvf(aTHX_ tsv, "(0x%"UVxf")", PTR2UV(sv));
		goto tokensaveref;
	    }
	    *lp = strlen(s);
	    return s;
	}
	if (SvREADONLY(sv) && !SvOK(sv)) {
	    if (ckWARN(WARN_UNINITIALIZED))
		report_uninit();
	    *lp = 0;
	    return "";
	}
    }
    if (SvIOK(sv) || ((SvIOKp(sv) && !SvNOKp(sv)))) {
	/* I'm assuming that if both IV and NV are equally valid then
	   converting the IV is going to be more efficient */
	U32 isIOK = SvIOK(sv);
	U32 isUIOK = SvIsUV(sv);
	char buf[TYPE_CHARS(UV)];
	char *ebuf, *ptr;

	if (SvTYPE(sv) < SVt_PVIV)
	    sv_upgrade(sv, SVt_PVIV);
	if (isUIOK)
	    ptr = uiv_2buf(buf, 0, SvUVX(sv), 1, &ebuf);
	else
	    ptr = uiv_2buf(buf, SvIVX(sv), 0, 0, &ebuf);
	SvGROW(sv, ebuf - ptr + 1);	/* inlined from sv_setpvn */
	Move(ptr,SvPVX(sv),ebuf - ptr,char);
	SvCUR_set(sv, ebuf - ptr);
	s = SvEND(sv);
	*s = '\0';
	if (isIOK)
	    SvIOK_on(sv);
	else
	    SvIOKp_on(sv);
	if (isUIOK)
	    SvIsUV_on(sv);
    }
    else if (SvNOKp(sv)) {
	if (SvTYPE(sv) < SVt_PVNV)
	    sv_upgrade(sv, SVt_PVNV);
	/* The +20 is pure guesswork.  Configure test needed. --jhi */
	SvGROW(sv, NV_DIG + 20);
	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*/
	{
	    Gconvert(SvNVX(sv), NV_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 (ckWARN(WARN_UNINITIALIZED)
	    && !PL_localizing && !(SvFLAGS(sv) & SVs_PADTMP))
	    report_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%"UVxf" 2pv(%s)\n",
			  PTR2UV(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;
    }
}

char *
Perl_sv_2pvbyte_nolen(pTHX_ register SV *sv)
{
    STRLEN n_a;
    return sv_2pvbyte(sv, &n_a);
}

char *
Perl_sv_2pvbyte(pTHX_ register SV *sv, STRLEN *lp)
{
    sv_utf8_downgrade(sv,0);
    return SvPV(sv,*lp);
}

char *
Perl_sv_2pvutf8_nolen(pTHX_ register SV *sv)
{
    STRLEN n_a;
    return sv_2pvutf8(sv, &n_a);
}

char *
Perl_sv_2pvutf8(pTHX_ register SV *sv, STRLEN *lp)
{
    sv_utf8_upgrade(sv);
    return SvPV(sv,*lp);
}

/* This function is only called on magical items */
bool
Perl_sv_2bool(pTHX_ register SV *sv)
{
    if (SvGMAGICAL(sv))
	mg_get(sv);

    if (!SvOK(sv))
	return 0;
    if (SvROK(sv)) {
	SV* tmpsv;
        if (SvAMAGIC(sv) && (tmpsv=AMG_CALLun(sv,bool_)) &&
                (SvRV(tmpsv) != SvRV(sv)))
	    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;
	}
    }
}

/*
=for apidoc sv_utf8_upgrade

Convert the PV of an SV to its UTF8-encoded form.
Forces the SV to string form it it is not already.
Always sets the SvUTF8 flag to avoid future validity checks even
if all the bytes have hibit clear.

=cut
*/

STRLEN
Perl_sv_utf8_upgrade(pTHX_ register SV *sv)
{
    char *s, *t, *e;
    int  hibit = 0;

    if (!sv)
	return 0;

    if (!SvPOK(sv))
	(void) SvPV_nolen(sv);

    if (SvUTF8(sv))
	return SvCUR(sv);

    /* This function could be much more efficient if we had a FLAG in SVs
     * to signal if there are any hibit chars in the PV.
     * Given that there isn't make loop fast as possible
     */
    s = SvPVX(sv);
    e = SvEND(sv);
    t = s;
    while (t < e) {
	if ((hibit = UTF8_IS_CONTINUED(*t++)))
	    break;
    }

    if (hibit) {
	STRLEN len;

	if (SvREADONLY(sv) && SvFAKE(sv)) {
	    sv_force_normal(sv);
	    s = SvPVX(sv);
	}
	len = SvCUR(sv) + 1; /* Plus the \0 */
	SvPVX(sv) = (char*)bytes_to_utf8((U8*)s, &len);
	SvCUR(sv) = len - 1;
	if (SvLEN(sv) != 0)
	    Safefree(s); /* No longer using what was there before. */
	SvLEN(sv) = len; /* No longer know the real size. */
    }
    /* Mark as UTF-8 even if no hibit - saves scanning loop */
    SvUTF8_on(sv);
    return SvCUR(sv);
}

/*
=for apidoc sv_utf8_downgrade

Attempt to convert the PV of an SV from UTF8-encoded to byte encoding.
This may not be possible if the PV contains non-byte encoding characters;
if this is the case, either returns false or, if C<fail_ok> is not
true, croaks.

=cut
*/

bool
Perl_sv_utf8_downgrade(pTHX_ register SV* sv, bool fail_ok)
{
    if (SvPOK(sv) && SvUTF8(sv)) {
        if (SvCUR(sv)) {
	    char *s;
	    STRLEN len;

	    if (SvREADONLY(sv) && SvFAKE(sv))
		sv_force_normal(sv);
	    s = SvPV(sv, len);
	    if (!utf8_to_bytes((U8*)s, &len)) {
	        if (fail_ok)
		    return FALSE;
		else {
		    if (PL_op)
		        Perl_croak(aTHX_ "Wide character in %s",
				   PL_op_desc[PL_op->op_type]);
		    else
		        Perl_croak(aTHX_ "Wide character");
		}
	    }
	    SvCUR(sv) = len;
	}
    }
    SvUTF8_off(sv);
    return TRUE;
}

/*
=for apidoc sv_utf8_encode

Convert the PV of an SV to UTF8-encoded, but then turn off the C<SvUTF8>
flag so that it looks like octets again. Used as a building block
for encode_utf8 in Encode.xs

=cut
*/

void
Perl_sv_utf8_encode(pTHX_ register SV *sv)
{
    (void) sv_utf8_upgrade(sv);
    SvUTF8_off(sv);
}

/*
=for apidoc sv_utf8_decode

Convert the octets in the PV from UTF-8 to chars. Scan for validity and then
turn of SvUTF8 if needed so that we see characters. Used as a building block
for decode_utf8 in Encode.xs

=cut
*/



bool
Perl_sv_utf8_decode(pTHX_ register SV *sv)
{
    if (SvPOK(sv)) {
        char *c;
        char *e;

	/* The octets may have got themselves encoded - get them back as bytes */
        if (!sv_utf8_downgrade(sv, TRUE))
	    return FALSE;

        /* it is actually just a matter of turning the utf8 flag on, but
         * we want to make sure everything inside is valid utf8 first.
         */
        c = SvPVX(sv);
	if (!is_utf8_string((U8*)c, SvCUR(sv)+1))
	    return FALSE;
        e = SvEND(sv);
        while (c < e) {
            if (UTF8_IS_CONTINUED(*c++)) {
		SvUTF8_on(sv);
		break;
	    }
        }
    }
    return TRUE;
}


/* 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.
 */

/*
=for apidoc sv_setsv

Copies the contents of the source SV C<ssv> into the destination SV C<dsv>.
The source SV may be destroyed if it is mortal.  Does not handle 'set'
magic.  See the macro forms C<SvSetSV>, C<SvSetSV_nosteal> and
C<sv_setsv_mg>.

=cut
*/

void
Perl_sv_setsv(pTHX_ SV *dstr, register SV *sstr)
{
    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);
	    if (SvTAINTED(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);
	    if (SvTAINTED(sstr))
		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 (GvIMPORTED(dstr) != GVf_IMPORTED
		    && CopSTASH_ne(PL_curcop, 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)
	    Perl_croak(aTHX_ "Bizarre copy of %s in %s", sv_reftype(sstr, 0),
		PL_op_name[PL_op->op_type]);
	else
	    Perl_croak(aTHX_ "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, '*', Nullch, 0);
		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)))
		Perl_croak(aTHX_ "Can't redefine active sort subroutine %s",
		      GvNAME(dstr));

#ifdef GV_SHARED_CHECK
                if (GvSHARED((GV*)dstr)) {
                    Perl_croak(aTHX_ PL_no_modify);
                }
#endif

	    (void)SvOK_off(dstr);
	    GvINTRO_off(dstr);		/* one-shot flag */
	    gp_free((GV*)dstr);
	    GvGP(dstr) = gp_ref(GvGP(sstr));
	    if (SvTAINTED(sstr))
		SvTAINT(dstr);
	    if (GvIMPORTED(dstr) != GVf_IMPORTED
		&& CopSTASH_ne(PL_curcop, 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);

#ifdef GV_SHARED_CHECK
                if (GvSHARED((GV*)dstr)) {
                    Perl_croak(aTHX_ PL_no_modify);
                }
#endif

		if (intro) {
		    GP *gp;
		    gp_free((GV*)dstr);
		    GvINTRO_off(dstr);	/* one-shot flag */
		    Newz(602,gp, 1, GP);
		    GvGP(dstr) = gp_ref(gp);
		    GvSV(dstr) = NEWSV(72,0);
		    GvLINE(dstr) = CopLINE(PL_curcop);
		    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 (!GvIMPORTED_AV(dstr)
			&& CopSTASH_ne(PL_curcop, 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 (!GvIMPORTED_HV(dstr)
			&& CopSTASH_ne(PL_curcop, 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)))
			    {
				/* ahem, death to those who redefine
				 * active sort subs */
				if (PL_curstackinfo->si_type == PERLSI_SORT &&
				      PL_sortcop == CvSTART(cv))
				    Perl_croak(aTHX_
				    "Can't redefine active sort subroutine %s",
					  GvENAME((GV*)dstr));
 				/* Redefining a sub - warning is mandatory if
 				   it was a const and its value changed. */
 				if (ckWARN(WARN_REDEFINE)
 				    || (CvCONST(cv)
 					&& (!CvCONST((CV*)sref)
 					    || sv_cmp(cv_const_sv(cv),
 						      cv_const_sv((CV*)sref)))))
 				{
 				    Perl_warner(aTHX_ WARN_REDEFINE,
 					CvCONST(cv)
 					? "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 (!GvIMPORTED_CV(dstr)
			&& CopSTASH_ne(PL_curcop, 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;
		case SVt_PVFM:
		    if (intro)
			SAVESPTR(GvFORM(dstr));
		    else
			dref = (SV*)GvFORM(dstr);
		    GvFORM(dstr) = (CV*)sref;
		    break;
		default:
		    if (intro)
			SAVESPTR(GvSV(dstr));
		    else
			dref = (SV*)GvSV(dstr);
		    GvSV(dstr) = sref;
		    if (!GvIMPORTED_SV(dstr)
			&& CopSTASH_ne(PL_curcop, GvSTASH(dstr)))
		    {
			GvIMPORTED_SV_on(dstr);
		    }
		    break;
		}
		if (dref)
		    SvREFCNT_dec(dref);
		if (intro)
		    SAVEFREESV(sref);
		if (SvTAINTED(sstr))
		    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) {
	    SvNOKp_on(dstr);
	    /* Only set the public OK flag if the source has public OK.  */
	    if (sflags & SVf_NOK)
		SvFLAGS(dstr) |= SVf_NOK;
	    SvNVX(dstr) = SvNVX(sstr);
	}
	if (sflags & SVp_IOK) {
	    (void)SvIOKp_on(dstr);
	    if (sflags & SVf_IOK)
		SvFLAGS(dstr) |= SVf_IOK;
	    if (sflags & SVf_IVisUV)
		SvIsUV_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? */
	    SvLEN(sstr) 	&&	/* and really is a string */
	    !(PL_op && PL_op->op_type == OP_AASSIGN)) /* and won't be needed again, potentially */
	{
	    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);		/* NOTE: nukes most SvFLAGS on 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);
	}
	if (sflags & SVf_UTF8)
	    SvUTF8_on(dstr);
	/*SUPPRESS 560*/
	if (sflags & SVp_NOK) {
	    SvNOKp_on(dstr);
	    if (sflags & SVf_NOK)
		SvFLAGS(dstr) |= SVf_NOK;
	    SvNVX(dstr) = SvNVX(sstr);
	}
	if (sflags & SVp_IOK) {
	    (void)SvIOKp_on(dstr);
	    if (sflags & SVf_IOK)
		SvFLAGS(dstr) |= SVf_IOK;
	    if (sflags & SVf_IVisUV)
		SvIsUV_on(dstr);
	    SvIVX(dstr) = SvIVX(sstr);
	}
    }
    else if (sflags & SVp_IOK) {
	if (sflags & SVf_IOK)
	    (void)SvIOK_only(dstr);
	else {
	    (void)SvOK_off(dstr);
	    (void)SvIOKp_on(dstr);
	}
	/* XXXX Do we want to set IsUV for IV(ROK)?  Be extra safe... */
	if (sflags & SVf_IVisUV)
	    SvIsUV_on(dstr);
	SvIVX(dstr) = SvIVX(sstr);
	if (sflags & SVp_NOK) {
	    if (sflags & SVf_NOK)
		(void)SvNOK_on(dstr);
	    else
		(void)SvNOKp_on(dstr);
	    SvNVX(dstr) = SvNVX(sstr);
	}
    }
    else if (sflags & SVp_NOK) {
	if (sflags & SVf_NOK)
	    (void)SvNOK_only(dstr);
	else {
	    (void)SvOK_off(dstr);
	    SvNOKp_on(dstr);
	}
	SvNVX(dstr) = SvNVX(sstr);
    }
    else {
	if (dtype == SVt_PVGV) {
	    if (ckWARN(WARN_MISC))
		Perl_warner(aTHX_ WARN_MISC, "Undefined value assigned to typeglob");
	}
	else
	    (void)SvOK_off(dstr);
    }
    if (SvTAINTED(sstr))
	SvTAINT(dstr);
}

/*
=for apidoc sv_setsv_mg

Like C<sv_setsv>, but also handles 'set' magic.

=cut
*/

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

/*
=for apidoc sv_setpvn

Copies a string into an SV.  The C<len> parameter indicates the number of
bytes to be copied.  Does not handle 'set' magic.  See C<sv_setpvn_mg>.

=cut
*/

void
Perl_sv_setpvn(pTHX_ register SV *sv, register const char *ptr, register STRLEN len)
{
    register char *dptr;

    SV_CHECK_THINKFIRST(sv);
    if (!ptr) {
	(void)SvOK_off(sv);
	return;
    }
    else {
        /* len is STRLEN which is unsigned, need to copy to signed */
	IV iv = len;
	assert(iv >= 0);
    }
    (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_UTF8(sv);		/* validate pointer */
    SvTAINT(sv);
}

/*
=for apidoc sv_setpvn_mg

Like C<sv_setpvn>, but also handles 'set' magic.

=cut
*/

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

/*
=for apidoc sv_setpv

Copies a string into an SV.  The string must be null-terminated.  Does not
handle 'set' magic.  See C<sv_setpv_mg>.

=cut
*/

void
Perl_sv_setpv(pTHX_ 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_UTF8(sv);		/* validate pointer */
    SvTAINT(sv);
}

/*
=for apidoc sv_setpv_mg

Like C<sv_setpv>, but also handles 'set' magic.

=cut
*/

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

/*
=for apidoc sv_usepvn

Tells an SV to use C<ptr> to find its string value.  Normally the string is
stored inside the SV but sv_usepvn allows the SV to use an outside string.
The C<ptr> should point to memory that was allocated by C<malloc>.  The
string length, C<len>, must be supplied.  This function will realloc the
memory pointed to by C<ptr>, so that pointer should not be freed or used by
the programmer after giving it to sv_usepvn.  Does not handle 'set' magic.
See C<sv_usepvn_mg>.

=cut
*/

void
Perl_sv_usepvn(pTHX_ 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_UTF8(sv);		/* validate pointer */
    SvTAINT(sv);
}

/*
=for apidoc sv_usepvn_mg

Like C<sv_usepvn>, but also handles 'set' magic.

=cut
*/

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

void
Perl_sv_force_normal_flags(pTHX_ register SV *sv, U32 flags)
{
    if (SvREADONLY(sv)) {
	if (SvFAKE(sv)) {
	    char *pvx = SvPVX(sv);
	    STRLEN len = SvCUR(sv);
            U32 hash   = SvUVX(sv);
	    SvGROW(sv, len + 1);
	    Move(pvx,SvPVX(sv),len,char);
	    *SvEND(sv) = '\0';
	    SvFAKE_off(sv);
	    SvREADONLY_off(sv);
	    unsharepvn(pvx,SvUTF8(sv)?-len:len,hash);
	}
	else if (PL_curcop != &PL_compiling)
	    Perl_croak(aTHX_ PL_no_modify);
    }
    if (SvROK(sv))
	sv_unref_flags(sv, flags);
    else if (SvFAKE(sv) && SvTYPE(sv) == SVt_PVGV)
	sv_unglob(sv);
}

void
Perl_sv_force_normal(pTHX_ register SV *sv)
{
    sv_force_normal_flags(sv, 0);
}

/*
=for apidoc sv_chop

Efficient removal of characters from the beginning of the string buffer.
SvPOK(sv) must be true and the C<ptr> must be a pointer to somewhere inside
the string buffer.  The C<ptr> becomes the first character of the adjusted
string.

=cut
*/

void
Perl_sv_chop(pTHX_ 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;
}

/*
=for apidoc sv_catpvn

Concatenates the string onto the end of the string which is in the SV.  The
C<len> indicates number of bytes to copy.  Handles 'get' magic, but not
'set' magic.  See C<sv_catpvn_mg>.

=cut
*/

void
Perl_sv_catpvn(pTHX_ 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_UTF8(sv);		/* validate pointer */
    SvTAINT(sv);
}

/*
=for apidoc sv_catpvn_mg

Like C<sv_catpvn>, but also handles 'set' magic.

=cut
*/

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