memcpy_noalign.c

   1 #include <string.h>
   2 #include <stdlib.h>
   3 #include <stdint.h>
   4
   5 #define SS (sizeof(size_t))
   6 #define ALIGN (sizeof(size_t)-1)
   7 #define ONES ((size_t)-1/UCHAR_MAX)
   8
   9 typedef struct block { unsigned char data[4*SS]; } block;
  10
  11 void *mymemcpy(void *restrict dest, const void *restrict src, size_t n)
  12 {
  13         unsigned char *d = dest;
  14         const unsigned char *s = src;
  15
  16         for (; n>=4*SS; n-=4*SS, s+=4*SS, d+=4*SS)
  17                 *(block *)d = *(block *)s;
  18         for (; n; n--) *d++ = *s++;
  19
  20         return dest;
  21 }