Desktop/xinu_mips-1.0.2.tar/xinu_mips-1.0.2/system/getstk.c

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/* Embedded XINU, Copyright (C) 2007.  All rights reserved. */

#include <kernel.h>

extern char *maxheap;
extern void *end;

void *getstk(ulong nbytes)
{
  /* NOTE: This is a completely broken implementation of getstk(),      */
  /*  intended only for introductory assignments before implementing    */
  /*  proper dynamic heap allocation.                                   */

        ulong newstk;

        if (nbytes == 0) 
        { return( (void *)SYSERR ); }
  
        nbytes = (nbytes + 15) & ~0x0F;

        if ((long)maxheap - nbytes < (int)&end)
        { return( (void *)SYSERR ); }

        newstk = (ulong)maxheap - 4;
        maxheap = (char *)(((int)maxheap) - nbytes);

        return ((void *)newstk);
}

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