heapprm.c

C标准库源代码

/***
*heapprm.c - Set/report heap parameters
*
*       Copyright (c) 1991-1997, Microsoft Corporation. All rights reserved.
*
*Purpose:
*       Set or report the values of certain parameters in the heap.
*
*******************************************************************************/


#ifndef WINHEAP


#include <cruntime.h>
#include <heap.h>
#include <malloc.h>
#include <mtdll.h>

/***
*_heap_param(int flag, int param_id, void *pparam) - set or report the values
*       of the specified heap parameter.
*
*Purpose:
*       Get or set certain parameters which affect the behavior of the heap.
*       The supported parameters vary implementation to implementation and
*       version to version. See description of entry conditions for the
*       currently supported parameters.
*
*Entry:
*       int flag     - _HP_GETPARAM, to get a parameter value, or _HP_SETPARAM,
*                      to set a parameter value
*
*       int param_id - identifier for the heap parameter. values supported in
*                      this release are:
*
*                      _HP_AMBLKSIZ  - _amblksiz (aka _heap_growsize) parameter
*                      _HP_GROWSIZE  - same as _HP_AMBLKSIZ
*                      _HP_RESETSIZE - _heap_resetsize parameter
*
*       void *pparam - pointer to variable of appropriate type for the heap
*                      parameter to be fetched/set
*
*Exit:
*        0 = no error has occurred
*       -1 = an error has occurred (errno is set)
*
*Exceptions:
*
*******************************************************************************/

int __cdecl _heap_param (
        int flag,
        int param_id,
        void *pparam
        )
{

        switch ( param_id ) {

                case _HP_RESETSIZE:
                        if ( flag == _HP_SETPARAM ) {
                                _mlock(_HEAP_LOCK);
                                _heap_resetsize = *(unsigned *)pparam;
                                _munlock(_HEAP_LOCK);
                        }
                        else
                                *(unsigned *)pparam = _heap_resetsize;
                        break;

                case _HP_AMBLKSIZ:
                        if ( flag == _HP_SETPARAM )
                                /*
                                 * the only references to _amblksiz (aka
                                 * _heap_growsize) are atomic. therefore, the
                                 * heap does not need to be locked.
                                 */
                                _amblksiz = *(unsigned *)pparam;
                        else
                                *(unsigned *)pparam = _amblksiz;
                        break;

                default:
                        return -1;
        }

        return 0;
}


#endif  /* WINHEAP */