heapinit.c

来自「开放源码的编译器open watcom 1.6.0版的源代码」· C语言 代码 · 共 65 行

/****************************************************************************
*
*                            Open Watcom Project
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*    Portions Copyright (c) 1983-2002 Sybase, Inc. All Rights Reserved.
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*    This file contains Original Code and/or Modifications of Original
*    Code as defined in and that are subject to the Sybase Open Watcom
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* Description:  WHEN YOU FIGURE OUT WHAT THIS FILE DOES, PLEASE
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#include "dll.h"        // needs to be first
#include "variety.h"
#include <stdlib.h>
#include <malloc.h>
#include "heap.h"

void _WCFAR __HeapInit( void _WCNEAR *start, unsigned int amount )
{
        mheapptr p1;
        tag *last_tag;

        p1 = start;
        amount -= sizeof( struct miniheapblkp ) + TAG_SIZE;
        __nheapbeg = p1;
        p1->len  = amount + sizeof( struct miniheapblkp );
        p1->prev = NULL;
        p1->next = NULL;
        p1->rover = &p1->freehead;
        p1->freehead.prev = &p1->freehead;
        p1->freehead.next = &p1->freehead;
        p1->numalloc = 0;
        p1->numfree = 0;
        ++p1;
        /* fix up end of heap links */
        last_tag = (tag *) ( (PTR)p1 + amount );
        last_tag[0] = END_TAG;
        /* build a block for _nfree() */
        ((frlptr)p1)->len = amount | 1;
        ++__nheapbeg->numalloc;                             /* 28-dec-90 */
        __nheapbeg->largest_blk = ~0;    /* set to largest value to be safe */
        _nfree( (PTR)p1 + TAG_SIZE );
}