memcmp.c

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#include <sys/types.h>
#include <stdio.h>
#include <string.h>

int memcmp(void *dest, void *src, size_t size)
{
        register unsigned long * __restrict__ word_dest;
        register unsigned long * __restrict__ word_src;
        register unsigned char * __restrict__ byte_dest;
        register unsigned char * __restrict__ byte_src;

        word_dest = dest;
        word_src = src;
        while (size > sizeof(*word_dest)) {
                if (*word_dest != *word_src) {
                        return (int)(*word_dest - *word_src);
                }
                word_dest++;
                word_src++;
                size -= sizeof(*word_dest);
        }

        byte_dest = (unsigned char*)word_dest;
        byte_src = (unsigned char*)word_src;
        while (size-- > 0) {
                if (*byte_dest != *byte_src) {
                        return (int)(*byte_dest - *byte_src);
                }
                byte_dest++;
                byte_src++;
        }

        return 0;
}

/* End of a file */