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      1 /*
      2  *	memmove.c: memmove compat implementation.
      3  *
      4  *	Copyright (c) 2001-2006, NLnet Labs. All rights reserved.
      5  *
      6  * See LICENSE for the license.
      7 */
      8 
      9 #include <config.h>
     10 #include <stdlib.h>
     11 
     12 void *memmove(void *dest, const void *src, size_t n);
     13 
     14 void *memmove(void *dest, const void *src, size_t n)
     15 {
     16 	uint8_t* from = (uint8_t*) src;
     17 	uint8_t* to = (uint8_t*) dest;
     18 
     19 	if (from == to || n == 0)
     20 		return dest;
     21 	if (to > from && to-from < (int)n) {
     22 		/* to overlaps with from */
     23 		/*  <from......>         */
     24 		/*         <to........>  */
     25 		/* copy in reverse, to avoid overwriting from */
     26 		int i;
     27 		for(i=n-1; i>=0; i--)
     28 			to[i] = from[i];
     29 		return dest;
     30 	}
     31 	if (from > to && from-to < (int)n) {
     32 		/* to overlaps with from */
     33 		/*        <from......>   */
     34 		/*  <to........>         */
     35 		/* copy forwards, to avoid overwriting from */
     36 		size_t i;
     37 		for(i=0; i<n; i++)
     38 			to[i] = from[i];
     39 		return dest;
     40 	}
     41 	memcpy(dest, src, n);
     42 	return dest;
     43 }
     44