memdisk/memset.c

   1 /*
   2  * memset.c
   3  */
   4
   5 #include <string.h>
   6 #include <stdint.h>
   7
   8 void *memset(void *dst, int c, size_t n)
   9 {
  10         char *q = dst;
  11
  12 #if defined(__i386__)
  13         size_t nl = n >> 2;
  14         asm volatile ("cld ; rep ; stosl ; movl %3,%0 ; rep ; stosb"
  15                       : "+c" (nl), "+D" (q)
  16                       : "a" ((unsigned char)c * 0x01010101U), "r" (n & 3));
  17 #elif defined(__x86_64__)
  18         size_t nq = n >> 3;
  19         asm volatile ("cld ; rep ; stosq ; movl %3,%%ecx ; rep ; stosb"
  20                       :"+c" (nq), "+D" (q)
  21                       : "a" ((unsigned char)c * 0x0101010101010101U),
  22                         "r" ((uint32_t) n & 7));
  23 #else
  24         while (n--) {
  25                 *q++ = c;
  26         }
  27 #endif
  28
  29         return dst;
  30 }