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xdiff/xutils.c(xdl_hash_record): factor out whitespace handling

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Since in at least one use case, xdl_hash_record() takes over 15% of the
CPU time, it makes sense to even micro-optimize it. For many cases, no
whitespace special handling is needed, and in these cases we should not
even bother to check for whitespace in _every_ iteration of the loop.

Signed-off-by: Johannes Schindelin <Johannes.Schindelin@gmx.de>
Signed-off-by: Junio C Hamano <junkio@cox.net>
This commit is contained in:
Johannes Schindelin 2007-03-20 04:05:10 +01:00 committed by Junio C Hamano
parent 57584d9edd
commit 824f782c3f
1 changed files with 20 additions and 2 deletions
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22
xdiff/xutils.c
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@ -236,12 +236,13 @@ int xdl_recmatch(const char *l1, long s1, const char *l2, long s2, long flags)
return 0;
}
unsigned long xdl_hash_record(char const **data, char const *top, long flags) {
static unsigned long xdl_hash_record_with_whitespace(char const **data,
char const *top, long flags) {
unsigned long ha = 5381;
char const *ptr = *data;
for (; ptr < top && *ptr != '\n'; ptr++) {
if (isspace(*ptr) && (flags & XDF_WHITESPACE_FLAGS)) {
if (isspace(*ptr)) {
const char *ptr2 = ptr;
while (ptr + 1 < top && isspace(ptr[1])
&& ptr[1] != '\n')
@ -270,6 +271,23 @@ unsigned long xdl_hash_record(char const **data, char const *top, long flags) {
}
unsigned long xdl_hash_record(char const **data, char const *top, long flags) {
unsigned long ha = 5381;
char const *ptr = *data;
if (flags & XDF_WHITESPACE_FLAGS)
return xdl_hash_record_with_whitespace(data, top, flags);
for (; ptr < top && *ptr != '\n'; ptr++) {
ha += (ha << 5);
ha ^= (unsigned long) *ptr;
}
*data = ptr < top ? ptr + 1: ptr;
return ha;
}
unsigned int xdl_hashbits(unsigned int size) {
unsigned int val = 1, bits = 0;