heapinit.c

C标准库源代码

         */

        last = (_PBLKDESC) ((char *) first + _HEAP_EMPTYLIST_SIZE - 2 * sizeof(_BLKDESC));
        next = (_PBLKDESC) ((char *) first + sizeof(_BLKDESC));

        while ( first < last ) {

                /* Init this descriptor */
                first->pnextdesc = next;

                /* onto the next block */

                first = next++;

        }

        /*
         * Take care of the last descriptor (end of the empty list)
         */

        last->pnextdesc = NULL;


        return 1;
}


/***
*__getempty() - get an empty heap descriptor
*
*Purpose:
*       Get a descriptor from the list of empty heap descriptors. If the list
*       is empty, call _heap_grow_emptylist.
*
*Entry:
*       no arguments
*
*Exit:
*       If successful, a pointer to the descriptor is returned.
*       Otherwise, NULL is returned.
*
*Exceptions:
*
*******************************************************************************/

_PBLKDESC __cdecl __getempty(
        void
        )
{
        _PBLKDESC pdesc;

        if ( (_heap_desc.emptylist == NULL) && (_heap_grow_emptylist()
              == 0) )
                return NULL;

        pdesc = _heap_desc.emptylist;

        _heap_desc.emptylist = pdesc->pnextdesc;

        return pdesc;
}


#else  /* _WIN32 */

#if defined (_M_MPPC) || defined (_M_M68K)


#include <cruntime.h>
#include <dos.h>
#include <heap.h>
#include <malloc.h>
#include <stddef.h>
#include <stdio.h>
#include <string.h>
#include <dbgint.h>

#include <macos\types.h>
#include <macos\errors.h>
#include <macos\memory.h>               // Mac OS interface header
#include <macos\lowmem.h>
#include <macos\segload.h>

#define _HEAP_EMPTYLIST_SIZE    (1 * _PAGESIZE_)

#define DSErrCode   (*(short*)(0x0af0))

/*
 * Heap descriptor
 */

struct _heap_desc_ _heap_desc = {
        &_heap_desc.sentinel,           /* pfirstdesc */
        &_heap_desc.sentinel,           /* proverdesc */
        NULL,                           /* emptylist */
        NULL,                           /* sentinel.pnextdesc */
        NULL                            /* sentinel.pblock */
        };

/*
 * Array of region structures
 * [Note: We count on the fact that this is always initialized to zero
 * by the compiler.]
 */

Handle hHeapRegions = NULL;
int _heap_region_table_cur = 0;

/*
 * Control parameter locations
 */

unsigned int _heap_resetsize = 0xffffffff;

/* NOTE: Currenlty, _heap_growsize is a #define to _amblksiz */
unsigned int _heap_growsize   = _HEAP_GROWSIZE;         /* region inc size */
unsigned int _heap_regionsize = _HEAP_REGIONSIZE;       /* region size */


/***
*_heap_init() - Initialize the heap
*
*Purpose:
*       Setup the initial C library heap.  All necessary memory and
*       data bases are init'd appropriately so future requests work
*       correctly.
*
*       NOTES:
*       (1) This routine should only be called once!
*       (2) This routine must be called before any other heap requests.
*
*
*Entry:
*       <void>
*Exit:
*       <void>
*
*Exceptions:
*       If heap cannot be initialized, the program will be terminated
*       with a fatal runtime error.
*
*******************************************************************************/

void __cdecl _heap_init (
        void
        )
{

#define _INITREGIONSZ 0x1000

        /*LATER -- do we need to do anything to init heap? Yes, in case user not malloc first*/
        int oldregionsz = _heap_regionsize;     /* save current region size */

        struct _heap_region_ *pHeapRegions;
        void *p;
        void *p2;

        if (hHeapRegions == NULL)
                {
                hHeapRegions = NewHandle(sizeof(struct _heap_region_)*_HEAP_REGIONMAX);
                if (hHeapRegions == NULL)
                        {
                        DSErrCode = appMemFullErr;
                        ExitToShell();
                        }
                HLock(hHeapRegions);
                pHeapRegions = (struct _heap_region_ *)(*hHeapRegions);
                memset(pHeapRegions, 0, sizeof(struct _heap_region_)*_HEAP_REGIONMAX);
                _heap_region_table_cur = _HEAP_REGIONMAX;
                }


        _heap_regionsize = _INITREGIONSZ;       /* set region size to 64 Kb */

        /* make sure we have enough memory to do initialization */
        if ((p = NewPtr(_HEAP_EMPTYLIST_SIZE)) == NULL)
                {
                DSErrCode = appMemFullErr;
                ExitToShell();
                }

        if ((p2 = NewPtr(_heap_regionsize)) == NULL)
                {
                DSErrCode = appMemFullErr;
                ExitToShell();
                }

        if (p)
                {
                DisposePtr(p);
                }
        if (p2)
                {
                DisposePtr(p2);
                }

        p = _malloc_base(4);
        if (p == NULL)
                {
                DSErrCode = appMemFullErr;
                ExitToShell();
                }
        _free_base( p );                /* malloc, then free a block */
        _heap_regionsize = oldregionsz;         /* restore region size */

}



/***
* _heap_grow_emptylist() - Grow the empty heap descriptor list
*
*Purpose:
*       (1) Get memory from OS
*       (2) Form it into a linked list of empty heap descriptors
*       (3) Attach it to the master empty list
*
*       NOTE:  This routine assumes that the emptylist is NULL
*       when called (i.e., there are no available empty heap descriptors).
*
*Entry:
*       (void)
*
*Exit:
*       (void)
*
*Exceptions:
*
*******************************************************************************/

static int __cdecl _heap_grow_emptylist (
        void
        )
{
        REG1 _PBLKDESC first;
        REG2 _PBLKDESC next;
        _PBLKDESC last;


        /*
         * Get memory for the new empty heap descriptors
         *
         * Note that last is used to hold the returned pointer because
         * first (and next) are register class.
         */

        if ((last = (_PBLKDESC)NewPtr(_HEAP_EMPTYLIST_SIZE)) == NULL)
                {
                return 0;
                }

        /*
         * Init the empty heap descriptor list.
         */

        _heap_desc.emptylist = first = last;


        /*
         * Carve the memory into an empty list
         */

        last = (_PBLKDESC) ((char *) first + _HEAP_EMPTYLIST_SIZE - sizeof(_BLKDESC));
        next = (_PBLKDESC) ((char *) first + sizeof(_BLKDESC));

        while ( first < last ) {

                /* Init this descriptor */
                first->pnextdesc = next;

                /* onto the next block */

                first = next++;

        }

        /*
         * Take care of the last descriptor (end of the empty list)
         */

        last->pnextdesc = NULL;


        return 1;

}

/***
*__getempty() - get an empty heap descriptor
*
*Purpose:
*       Get a descriptor from the list of empty heap descriptors. If the list
*       is empty, call _heap_grow_emptylist.
*
*Entry:
*       no arguments
*
*Exit:
*       If successful, a pointer to the descriptor is returned.
*       Otherwise, NULL is returned.
*
*Exceptions:
*
*******************************************************************************/

_PBLKDESC __cdecl __getempty(
        void
        )
{
        _PBLKDESC pdesc;

        if ( (_heap_desc.emptylist == NULL) && (_heap_grow_emptylist()
              == 0) )
                return NULL;

        pdesc = _heap_desc.emptylist;

        _heap_desc.emptylist = pdesc->pnextdesc;

        return pdesc;
}


#endif  /* defined (_M_MPPC) || defined (_M_M68K) */

#endif  /* _WIN32 */

#endif  /* WINHEAP */