__copy.asm

来自「开放源码的编译器open watcom 1.6.0版的源代码」· 汇编 代码 · 共 69 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
;*               DESCRIBE IT HERE!
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;*****************************************************************************


;
;  char *__COPY( char *dst, char *src, unsigned len );
;
;
include mdef.inc

        name    __copy
_TEXT   segment use32 para public 'CODE'
        assume  cs:_TEXT

        public  __COPY
        public  __COPY_

__COPY  proc    near
__COPY_ proc    near
        push    edi                     ; save regs
        push    esi                     ; ...
        push    ecx                     ; ...
        mov     edi,16+0[esp]           ; get dst
        mov     esi,16+4[esp]           ; get src
        mov     ecx,16+8[esp]           ; get len
        mov     eax,edi                 ; return with dst ptr in eax
        shr     ecx,2                   ; calc. # of dwords
        rep     movsd                   ; do the copy
        mov     ecx,16+8[esp]           ; get len
        and     ecx,3                   ; plus extra bytes
        rep     movsb                   ; do the copy
        pop     ecx                     ; restore regs
        pop     esi                     ; ...
        pop     edi                     ; ...
        ret     12                      ; return and remove parms
__COPY_ endp
__COPY  endp

_TEXT   ends
        end