frealloc.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 111 行

/****************************************************************************
*
*                            Open Watcom Project
*
*    Portions Copyright (c) 1983-2002 Sybase, Inc. All Rights Reserved.
*
*  ========================================================================
*
*    This file contains Original Code and/or Modifications of Original
*    Code as defined in and that are subject to the Sybase Open Watcom
*    Public License version 1.0 (the 'License'). You may not use this file
*    except in compliance with the License. BY USING THIS FILE YOU AGREE TO
*    ALL TERMS AND CONDITIONS OF THE LICENSE. A copy of the License is
*    provided with the Original Code and Modifications, and is also
*    available at www.sybase.com/developer/opensource.
*
*    The Original Code and all software distributed under the License are
*    distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
*    EXPRESS OR IMPLIED, AND SYBASE AND ALL CONTRIBUTORS HEREBY DISCLAIM
*    ALL SUCH WARRANTIES, INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF
*    MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR
*    NON-INFRINGEMENT. Please see the License for the specific language
*    governing rights and limitations under the License.
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*  ========================================================================
*
* Description:  WHEN YOU FIGURE OUT WHAT THIS FILE DOES, PLEASE
*               DESCRIBE IT HERE!
*
****************************************************************************/


#include "dll.h"        // needs to be first
#include "variety.h"
#include <stddef.h>
#include <malloc.h>
#include <string.h>
#include "heap.h"

#if defined(__386__)
#define MOVSW   0x66 0xa5
#define _DI     edi
#define _SI     esi
#define _CX     ecx
#else
#define MOVSW   0xa5
#define _DI     di
#define _SI     si
#define _CX     cx
#endif


extern void _WCNEAR *_mymemcpy( void _WCFAR *, void _WCFAR *, size_t );
#pragma aux _mymemcpy = \
        0x1e            /* push ds */ \
        0x8e 0xda       /* mov ds,dx */ \
        0xd1 0xe9       /* shr cx,1 */ \
        0xf3 MOVSW      /* rep movsw */ \
        0x11 0xc9       /* adc cx,cx */ \
        0xf3 0xa4       /* rep movsb */ \
        0x1f            /* pop ds */ \
        parm caller     [es _DI] [dx _SI] [_CX] \
        value           [_SI] \
        modify exact    [_SI _DI _CX];


#if defined(__BIG_DATA__)

_WCRTLINK void *realloc( void *stg, size_t amount )
    {
        return( _frealloc( stg, amount ) );
    }

#endif


_WCRTLINK void _WCFAR *_frealloc( void _WCFAR *stg, size_t req_size )
    {
        size_t    old_size;
        void _WCFAR *p;

        if( stg == NULL ) {
            return( _fmalloc( req_size ) );
        }
        if( req_size == 0 ) {
            _ffree( stg );
            return( NULL );
        }
        old_size = _fmsize( stg );
        if( FP_SEG(stg) == _DGroup() ) {
            p = stg;
            if( _nexpand( (void _WCNEAR *) stg, req_size ) == NULL ) p = NULL;
        } else {
            p = _fexpand( stg, req_size );
        }
        if( p == NULL ) {       /* couldn't be expanded inline */
            p = _fmalloc( req_size );
            if( p != NULL ) {
                _mymemcpy( p, stg, old_size );
                _ffree( stg );
            } else {
                if( FP_SEG(stg) == _DGroup() ) {
                    _nexpand( (void _WCNEAR *) stg, old_size );
                } else {
                    _fexpand( stg, old_size );
                }
            }
        }
        return( p );
    }