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 Fri, Aug 24, 2007 at 02:54:48PM +0200, Jan Engelhardt wrote:
    >
    > 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.

    Yep, that's what I get for editing in email.

    > 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 */
    > }

    Yes, very funny.

    --
    Mathematics is the supreme nostalgia of our time.
    -
    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 17:59    [W:0.022 / U:64.612 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site