From: Joshua Wise Date: Sat, 6 Dec 2008 11:09:23 +0000 (-0500) Subject: An optimized memcpy() is fine too. X-Git-Url: http://git.joshuawise.com/netwatch.git/commitdiff_plain/90122e523ed5d77a6951ec7332c7d5e72eec802c?ds=inline;hp=-c An optimized memcpy() is fine too. --- 90122e523ed5d77a6951ec7332c7d5e72eec802c diff --git a/lib/minilib.c b/lib/minilib.c index 664a0b4..56090ed 100644 --- a/lib/minilib.c +++ b/lib/minilib.c @@ -1,12 +1,59 @@ #include "console.h" #include +#include -void memcpy(void *dest, const void *src, int bytes) +/* We have both _memcpy and memcpy, because gcc might be able to do better in lwip. + * For small things, gcc inlines its memcpy, but for large things, we call out + * to this memcpy. + */ +inline void _memcpy(void *dest, const void *src, int bytes) { + /* I hate everyone */ + /* Since we otherwise compile with -O0, we might as well manually speed this up a bit. */ + char *cdest = dest; const char *csrc = src; - while (bytes--) + int *idest; + const int *isrc; + int nwords; + + /* Align to src (picked arbitrarily; might as well align to something) */ + while (bytes && ((unsigned int)csrc & 3)) + { + *(cdest++) = *(csrc++); + bytes--; + } + + idest = (int *)cdest; + isrc = (const int *)csrc; + + nwords = bytes / 4; + bytes -= bytes & ~3; + if (nwords != 0) + switch(nwords % 8) /* They see me Duff'sin'. They hatin'. */ + do { + case 0: nwords--; *(idest++) = *(isrc++); + case 7: nwords--; *(idest++) = *(isrc++); + case 6: nwords--; *(idest++) = *(isrc++); + case 5: nwords--; *(idest++) = *(isrc++); + case 4: nwords--; *(idest++) = *(isrc++); + case 3: nwords--; *(idest++) = *(isrc++); + case 2: nwords--; *(idest++) = *(isrc++); + case 1: nwords--; *(idest++) = *(isrc++); + } while (nwords); + + cdest = (char *)idest; + csrc = (const char *)isrc; + while (bytes) /* Clean up the remainder */ + { *(cdest++) = *(csrc++); + bytes--; + } +} + +void memcpy(void *dest, const void *src, int bytes) +{ + _memcpy(dest, src, bytes); } void memset(void *dest, int data, int bytes) @@ -28,8 +75,7 @@ void memmove(void *dest, void *src, int bytes) while (bytes--) *(--cdest) = *(--csrc); } else - while (bytes--) - *(cdest++) = *(csrc++); + memcpy(dest, src, bytes); } int memcmp (const char *a2, const char *a1, int bytes) {