44 lines
1.1 KiB
C
44 lines
1.1 KiB
C
|
#include <stddef.h>
|
||
|
|
|
||
|
|
#define ALIGNED(p) (!((long)p & (sizeof(long) - 1)))
|
||
|
|
#define QUADBLOCKSIZE (sizeof(long) << 2)
|
||
|
|
#define BLOCKSIZE (sizeof(long))
|
||
|
|
|
||
|
|
void *memcpy(void *dest, const void *src, size_t sz)
|
||
|
|
{
|
||
|
|
/* Only try word-writing if the pointers are aligned and
|
||
|
|
* the buffer is big enough */
|
||
|
|
if (sz >= BLOCKSIZE && ALIGNED(dest) && ALIGNED(src)) {
|
||
|
|
long *dest_word = dest;
|
||
|
|
const long *src_word = src;
|
||
|
|
|
||
|
|
/* First try copying 4x blocks per iteration */
|
||
|
|
while (sz >= QUADBLOCKSIZE) {
|
||
|
|
*dest_word++ = *src_word++;
|
||
|
|
*dest_word++ = *src_word++;
|
||
|
|
*dest_word++ = *src_word++;
|
||
|
|
*dest_word++ = *src_word++;
|
||
|
|
sz -= QUADBLOCKSIZE;
|
||
|
|
}
|
||
|
|
|
||
|
|
/* Then try copying 1x words per iteration */
|
||
|
|
while (sz >= BLOCKSIZE) {
|
||
|
|
*dest_word++ = *src_word++;
|
||
|
|
sz -= BLOCKSIZE;
|
||
|
|
}
|
||
|
|
|
||
|
|
/* Then go back to the byte-level copying */
|
||
|
|
dest = dest_word;
|
||
|
|
src = src_word;
|
||
|
|
}
|
||
|
|
|
||
|
|
char *dest0 = dest;
|
||
|
|
const char *src0 = src;
|
||
|
|
|
||
|
|
while (sz-- > 0) {
|
||
|
|
*dest0++ = *src0++;
|
||
|
|
}
|
||
|
|
|
||
|
|
return dest;
|
||
|
|
}
|