From 1a00d99c2f1f4006ccad3b2289839676d0b282de Mon Sep 17 00:00:00 2001 From: Paul Eggert Date: Mon, 14 Aug 2006 16:20:49 +0000 Subject: [PATCH] (memcoll): Optimize for the common case where the arguments are bytewise equal. --- lib/ChangeLog | 5 ++++ lib/memcoll.c | 65 +++++++++++++++++++++++++++++---------------------- 2 files changed, 42 insertions(+), 28 deletions(-) diff --git a/lib/ChangeLog b/lib/ChangeLog index 9fa61ac7b..2d2203ea8 100644 --- a/lib/ChangeLog +++ b/lib/ChangeLog @@ -1,3 +1,8 @@ +2006-08-14 Paul Eggert + + * memcoll.c (memcoll): Optimize for the common case where the + arguments are bytewise equal. + 2006-08-11 Paul Eggert * pipe-safer.c (pipe_safer): Fix misspelling: HAVE_FUNC_PIPE -> diff --git a/lib/memcoll.c b/lib/memcoll.c index 82d889f40..7f61a6b58 100644 --- a/lib/memcoll.c +++ b/lib/memcoll.c @@ -38,39 +38,48 @@ memcoll (char *s1, size_t s1len, char *s2, size_t s2len) #if HAVE_STRCOLL - char n1 = s1[s1len]; - char n2 = s2[s2len]; + /* strcoll is slow on many platforms, so check for the common case + where the arguments are bytewise equal. Otherwise, walk through + the buffers using strcoll on each substring. */ - s1[s1len++] = '\0'; - s2[s2len++] = '\0'; - - while (! (errno = 0, (diff = strcoll (s1, s2)) || errno)) + if (s1len == s2len && memcmp (s1, s2, s1len) == 0) + diff = 0; + else { - /* strcoll found no difference, but perhaps it was fooled by NUL - characters in the data. Work around this problem by advancing - past the NUL chars. */ - size_t size1 = strlen (s1) + 1; - size_t size2 = strlen (s2) + 1; - s1 += size1; - s2 += size2; - s1len -= size1; - s2len -= size2; - - if (s1len == 0) - { - if (s2len != 0) - diff = -1; - break; - } - else if (s2len == 0) + char n1 = s1[s1len]; + char n2 = s2[s2len]; + + s1[s1len++] = '\0'; + s2[s2len++] = '\0'; + + while (! (errno = 0, (diff = strcoll (s1, s2)) || errno)) { - diff = 1; - break; + /* strcoll found no difference, but perhaps it was fooled by NUL + characters in the data. Work around this problem by advancing + past the NUL chars. */ + size_t size1 = strlen (s1) + 1; + size_t size2 = strlen (s2) + 1; + s1 += size1; + s2 += size2; + s1len -= size1; + s2len -= size2; + + if (s1len == 0) + { + if (s2len != 0) + diff = -1; + break; + } + else if (s2len == 0) + { + diff = 1; + break; + } } - } - s1[s1len - 1] = n1; - s2[s2len - 1] = n2; + s1[s1len - 1] = n1; + s2[s2len - 1] = n2; + } #else -- 2.34.1