In message 003101c7f37f$1fcb6cd0$e1ac580a@swcenter.sec.samsung.co.kr you wrote:
+static void *memcpy(void *dest, const void *src, size_t count) +{
- if (count < 32) {
unsigned short *_s = (unsigned short *)(src);unsigned short *_d = (unsigned short *)(dest);count >>= 1;while (count--)*_d++ = *_s++;return _d;- }
...
How much difference does this optimization make in real life? Do you have any time measurements at hand?
It's also discuss the at previous time http://sourceforge.net/mailarchive/message.php?msg_id=f3f1b91a0703141856n180...
Now I remember, thanks for the link.
I'm concerned about correctness. What happens in your coide when I write
memcpy (dst, src, 5);
How many bytes will be copied?
What happens when src or dst or both are pointing to odd addresses, i. e. in case of unaligned accesses?
Agreed
If my interpretation is right, that above implementation will copy only 4 bytes when I ask for 5 to be copied, then the answer is simple: fix it, or dump it.
I remember that ARM is terribly broken there... :-(
Memcpy32 is 32-bytes aligned optimized. Since we know the memcpy usages in OneNAND driver, we
guarantee the usage of memcpy32.
But the memcpy() you provide will also be used in all other partrs of U-Boot, won't it?
If you concern the portability issues, I can omit it at this time. How do you think about it?
Portability is one thing, but it seems to be not correct, which is a strict No, No to me.
Best regards,
Wolfgang Denk