lkml.org 
[lkml]   [2007]   [Aug]   [24]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH] memchr (trivial) optimization

On Aug 23 2007 19:13, Matt Mackall wrote:
>
>And you can do even better with this:
>
>void *memchr(const void *s, int c, size_t n)
>{
> const unsigned char *p = s, *e = s + n;
> const unsigned char *e = p + n;

Uhm, you have two "e"s in there.

> for (; p < e ; p++)
> if ((unsigned char)c == *p)
> return (void *)p;
>
> return NULL;
>}

Or do it glibc-style

void *memchr(const void *s, unsigned char c, size_t n)
{
...
for (; p + 3 < e; p += 4) {
if (c == p[0])
return (void *)&p[0];
if (c == p[1])
return (void *)&p[1];
if (c == p[2])
return (void *)&p[2];
if (c == p[3])
return (void *)&p[3];
}
... /* check the rest */
}


Jan
--
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2007-08-24 14:59    [W:0.061 / U:0.064 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site