#define lsize sizeof(word)#define lmask (lsize - 1)void *memcpy(void *dest, const void *src, size_t count){char *d = (char *)dest;const char *s = (const char *)src;int len;if(count == 0 || dest == src)return dest;if(((long)d | (long)s) & lmask) {// src and/or dest do not align on word boundaryif((((long)d ^ (long)s) & lmask) || (count < lsize))len = count; // copy the rest of the buffer with the byte moverelselen = lsize - ((long)d & lmask); // move the ptrs up to a word boundarycount -= len;for(; len > 0; len--)*d++ = *s++;}for(len = count / lsize; len > 0; len--) {*(word *)d = *(word *)s;d += lsize;s += lsize;}for(len = count & lmask; len > 0; len--)*d++ = *s++;return dest;}