Messages in this thread | | | From | "Ulrich Windl" <> | Date | Fri, 08 Dec 2006 14:24:45 +0100 | Subject | 2.6.19: slight performance optimization for lib/string.c's strstrip() |
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Hi,
my apologies for disobeying all the rules for submitting patches, but I'll suggest a performance optimization for strstrip() in lib/string.c:
Original routine: char *strstrip(char *s) { size_t size; char *end;
size = strlen(s);
if (!size) return s;
end = s + size - 1; while (end >= s && isspace(*end)) end--; *(end + 1) = '\0';
while (*s && isspace(*s)) s++;
return s; } EXPORT_SYMBOL(strstrip);
Suggested replacement:
char *strstrip(char *s) { size_t size; char *end;
while (*s && isspace(*s)) s++; if (!*s) return s; size = strlen(s);
end = s + size - 1; while (end > s && isspace(*end)) end--; *(end + 1) = '\0';
return s; } EXPORT_SYMBOL(strstrip);
Comments: There's no need to scan the initial banks at the start of the string twice (using strlen(), and then looking for initial blanks), and we know that the first character of the string cannot be a blank when we are removing trailing blanks after having removed leading blanks. Also we do not need to call strlen() to detect an empty string.
Regards, Ulrich
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