rmemmove.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 59 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
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*    except in compliance with the License. BY USING THIS FILE YOU AGREE TO
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*    available at www.sybase.com/developer/opensource.
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* Description:  WHEN YOU FIGURE OUT WHAT THIS FILE DOES, PLEASE
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****************************************************************************/


#include <string.h>
#include "riscstr.h"


void *memmove( void *dest, const void *src, size_t n )
/****************************************************/
{
    const char *        from = src;
    char *              to = dest;

    if( from == to )  return( dest );

    if( ( to<from && to+n<from )  ||  ( from<to && from+n<to ) ) {
        memcpy( to, from, n );          /* no overlap between regions */
    } else if( from < to  &&  from + n > to ) {
        to += n;
        from += n;
        while( n != 0 ) {               /* tread softly */
            *--to = *--from;
            n--;
        }
    } else {
        memcpy( to, from, n );          /* permissible overlap */
    }
    return( to );
}