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Reduce time of __collate_substitute() from O(strlen(s)^2) to O(strlen(s)).

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Other minor optimizations. I got ~30% speedup in strcoll() for 50 char strings,
~40% speedup for 100 char strings, and unmeasurable speedup for 1M strings.

Collates are still terribly slow. To make them reasonable fast,
__collate_substitute() should be killed.
This commit is contained in:
dt 1999-09-12 19:42:38 +00:00
parent d9de85e5aa
commit 78e49a27cc
1 changed files with 11 additions and 8 deletions
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19
lib/libc/locale/collate.c
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@ -102,23 +102,26 @@ u_char *
__collate_substitute(s)
const u_char *s;
{
int dest_len = 0, len = 0;
int dest_len, len, nlen;
int delta = strlen(s);
u_char *dest_str = NULL;
if(s == NULL || *s == '\0')
return __collate_strdup("");
delta += delta / 8;
dest_str = malloc(dest_len = delta);
if(dest_str == NULL)
__collate_err(EX_OSERR, __FUNCTION__);
len = 0;
while(*s) {
len += strlen(__collate_substitute_table[*s]);
while(dest_len <= len) {
if(!dest_str)
dest_str = calloc(dest_len = delta, 1);
else
dest_str = reallocf(dest_str, dest_len += delta);
nlen = len + strlen(__collate_substitute_table[*s]);
if (dest_len <= nlen) {
dest_str = reallocf(dest_str, dest_len = nlen + delta);
if(dest_str == NULL)
__collate_err(EX_OSERR, __FUNCTION__);
}
strcat(dest_str, __collate_substitute_table[*s++]);
strcpy(dest_str + len, __collate_substitute_table[*s++]);
len = nlen;
}
return dest_str;
}