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saw commit of vapier@busybox.net (thanks!),

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decided to stop doing FOUR memcmp's per each input character.
I should have fixed this much earlier...
This commit is contained in:
Denis Vlasenko 2006-12-30 19:52:28 +00:00
parent 1b3e8179a2
commit 80602a98bc
1 changed files with 23 additions and 18 deletions
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41
scripts/basic/fixdep.c
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@ -225,31 +225,36 @@ void use_config(char *m, int slen)
void parse_config_file(char *map, size_t len) void parse_config_file(char *map, size_t len)
{ {
/* modified for bbox */ /* modified for bbox */
char *end = map + len; char *end_4 = map + len - 4; /* 4 == length of "USE_" */
char *end_7 = map + len - 7;
char *p = map; char *p = map;
char *q; char *q;
int off; int off;
for (; p < end; p++) { for (; p < end_4; p++) {
if (p<end-7 && !memcmp(p, "CONFIG_", 7)) goto conf7; if (p < end_7 && p[6] == '_') {
if (p<end-7 && !memcmp(p, "ENABLE_", 7)) goto conf7; if (!memcmp(p, "CONFIG", 6)) goto conf7;
if (p<end-4 && !memcmp(p, "USE_", 4)) goto conf4; if (!memcmp(p, "ENABLE", 6)) goto conf7;
if (p<end-5 && !memcmp(p, "SKIP_", 5)) goto conf5;
continue;
conf4: off = 4; goto conf;
conf5: off = 5; goto conf;
conf7: off = 7;
conf:
if (p > map + len - off)
continue;
for (q = p + off; q < map + len; q++) {
if (!(isalnum(*q) || *q == '_'))
goto found;
} }
/* We have at least 5 chars: for() has
* "p < end-4", not "p <= end-4"
* therefore we don't need to check p <= end-5 here */
if (p[4] == '_') {
if (!memcmp(p, "SKIP", 4)) goto conf5;
}
/* Ehhh, gcc is too stupid to just compare it as 32bit int */
if (!memcmp(p, "USE_", 4)) goto conf4;
continue; continue;
found: conf4: off = 4;
use_config(p+off, q-p-off); conf5: off = 5;
conf7: off = 7;
p += off;
for (q = p; q < end_4+4; q++) {
if (!(isalnum(*q) || *q == '_'))
break;
}
use_config(p, q-p);
} }
} }