/**************************************************************

 *

 *  giantsstack.c

 *

 *  Updates:

 *      1  Feb 99   JAK - creation.

 *

 *  This package is part of ongoing research in the

 *  Advanced Computation Group, Apple Computer.

 *  

 *  c. 1999 Apple Computer, Inc.

 *  All Rights Reserved.

 *

 *

 *************************************************************/

/*

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                The Apple Software is provided by Apple on an "AS IS" basis.  APPLE MAKES NO

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*/

#include "giantsstack.h"

#include "giantsdebug.h"

static Handle           gGiantStackHandle = nil;

static unsigned long    gCurrentStackIndex=0;

static unsigned long    gStackSize=0;

#define STACK_INCREMENT_SIZE    100

#define max(a, b) (a > b ? a : b)

static Handle GetStackHandle()

{

    if (gGiantStackHandle == nil) {

        gGiantStackHandle = NewHandle(0);

        GAssert(gGiantStackHandle != nil);

    }

    return gGiantStackHandle;

}

static void AddGiants(unsigned long addcount)

{

    Handle      stackhandle = GetStackHandle();

    SetHandleSize( stackhandle, GetHandleSize(stackhandle) + (addcount*sizeof(giant)) );    

    GAssert(!MemError());

    gStackSize += addcount;

    while (addcount--) {

        (*(giant**)stackhandle)[gCurrentStackIndex] = newgiant(DEFAULT_GIANT_BITS);

        GAssert((*(giant**)stackhandle)[gCurrentStackIndex] != nil);

        gCurrentStackIndex++;

    }

    GAssert(!MemError());

}

giant   popg()

{

    Handle      stackhandle = GetStackHandle();

    giant       g;

    if (gCurrentStackIndex == 0) {

        AddGiants(STACK_INCREMENT_SIZE);

    }

    g = ((*(giant**)stackhandle)[--gCurrentStackIndex]);

    g->giantDigits = 0;

    ASSERT_GVALID(g);

    return g;

}

void    pushg(unsigned long numgiants)

{

    GAssert(gGiantStackHandle != nil);

    GAssert(gCurrentStackIndex + numgiants <= gStackSize);

    gCurrentStackIndex += numgiants;

}