memmove.c

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/*
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file COPYING in the main directory of this archive
 * for more details.
 */

#include <linux/module.h>
#include <linux/string.h>

void *memmove(void *dest, const void *src, size_t n)
{
    void *xdest = dest;
    size_t temp;

    if (!n)
        return xdest;

    if (dest < src) {
        if ((long)dest & 1) {
            char *cdest = dest;
            const char *csrc = src;
            *cdest++ = *csrc++;
            dest = cdest;
            src = csrc;
            n--;
        }
        if (n > 2 && (long)dest & 2) {
            short *sdest = dest;
            const short *ssrc = src;
            *sdest++ = *ssrc++;
            dest = sdest;
            src = ssrc;
            n -= 2;
        }
        temp = n >> 2;
        if (temp) {
            long *ldest = dest;
            const long *lsrc = src;
            temp--;
            do
                *ldest++ = *lsrc++;
            while (temp--);
            dest = ldest;
            src = lsrc;
        }
        if (n & 2) {
            short *sdest = dest;
            const short *ssrc = src;
            *sdest++ = *ssrc++;
            dest = sdest;
            src = ssrc;
        }
        if (n & 1) {
            char *cdest = dest;
            const char *csrc = src;
            *cdest = *csrc;
        }
    } else {
        dest = (char *)dest + n;
        src = (const char *)src + n;
        if ((long)dest & 1) {
            char *cdest = dest;
            const char *csrc = src;
            *--cdest = *--csrc;
            dest = cdest;
            src = csrc;
            n--;
        }
        if (n > 2 && (long)dest & 2) {
            short *sdest = dest;
            const short *ssrc = src;
            *--sdest = *--ssrc;
            dest = sdest;
            src = ssrc;
            n -= 2;
        }
        temp = n >> 2;
        if (temp) {
            long *ldest = dest;
            const long *lsrc = src;
            temp--;
            do
                *--ldest = *--lsrc;
            while (temp--);
            dest = ldest;
            src = lsrc;
        }
        if (n & 2) {
            short *sdest = dest;
            const short *ssrc = src;
            *--sdest = *--ssrc;
            dest = sdest;
            src = ssrc;
        }
        if (n & 1) {
            char *cdest = dest;
            const char *csrc = src;
            *--cdest = *--csrc;
        }
    }
    return xdest;
}
EXPORT_SYMBOL(memmove);