memmove.c

  1/*
  2 * This file is subject to the terms and conditions of the GNU General Public
  3 * License.  See the file COPYING in the main directory of this archive
  4 * for more details.
  5 */
  6
  7#include <linux/module.h>
  8#include <linux/string.h>
  9
 10void *memmove(void *dest, const void *src, size_t n)
 11{
 12	void *xdest = dest;
 13	size_t temp;
 14
 15	if (!n)
 16		return xdest;
 17
 18	if (dest < src) {
 19		if ((long)dest & 1) {
 20			char *cdest = dest;
 21			const char *csrc = src;
 22			*cdest++ = *csrc++;
 23			dest = cdest;
 24			src = csrc;
 25			n--;
 26		}
 27#if defined(CONFIG_M68000)
 28		if ((long)src & 1) {
 29			char *cdest = dest;
 30			const char *csrc = src;
 31			for (; n; n--)
 32				*cdest++ = *csrc++;
 33			return xdest;
 34		}
 35#endif
 36		if (n > 2 && (long)dest & 2) {
 37			short *sdest = dest;
 38			const short *ssrc = src;
 39			*sdest++ = *ssrc++;
 40			dest = sdest;
 41			src = ssrc;
 42			n -= 2;
 43		}
 44		temp = n >> 2;
 45		if (temp) {
 46			long *ldest = dest;
 47			const long *lsrc = src;
 48			temp--;
 49			do
 50				*ldest++ = *lsrc++;
 51			while (temp--);
 52			dest = ldest;
 53			src = lsrc;
 54		}
 55		if (n & 2) {
 56			short *sdest = dest;
 57			const short *ssrc = src;
 58			*sdest++ = *ssrc++;
 59			dest = sdest;
 60			src = ssrc;
 61		}
 62		if (n & 1) {
 63			char *cdest = dest;
 64			const char *csrc = src;
 65			*cdest = *csrc;
 66		}
 67	} else {
 68		dest = (char *)dest + n;
 69		src = (const char *)src + n;
 70		if ((long)dest & 1) {
 71			char *cdest = dest;
 72			const char *csrc = src;
 73			*--cdest = *--csrc;
 74			dest = cdest;
 75			src = csrc;
 76			n--;
 77		}
 78#if defined(CONFIG_M68000)
 79		if ((long)src & 1) {
 80			char *cdest = dest;
 81			const char *csrc = src;
 82			for (; n; n--)
 83				*--cdest = *--csrc;
 84			return xdest;
 85		}
 86#endif
 87		if (n > 2 && (long)dest & 2) {
 88			short *sdest = dest;
 89			const short *ssrc = src;
 90			*--sdest = *--ssrc;
 91			dest = sdest;
 92			src = ssrc;
 93			n -= 2;
 94		}
 95		temp = n >> 2;
 96		if (temp) {
 97			long *ldest = dest;
 98			const long *lsrc = src;
 99			temp--;
100			do
101				*--ldest = *--lsrc;
102			while (temp--);
103			dest = ldest;
104			src = lsrc;
105		}
106		if (n & 2) {
107			short *sdest = dest;
108			const short *ssrc = src;
109			*--sdest = *--ssrc;
110			dest = sdest;
111			src = ssrc;
112		}
113		if (n & 1) {
114			char *cdest = dest;
115			const char *csrc = src;
116			*--cdest = *--csrc;
117		}
118	}
119	return xdest;
120}
121EXPORT_SYMBOL(memmove);