Messages in this thread | | | Date | Sun, 10 Dec 2006 16:02:54 -0800 (PST) | From | Amit Choudhary <> | Subject | Re: 2.6.19: slight performance optimization for lib/string.c's strstrip() |
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> 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);
How about this:
char *strstrip(char *s) { size_t less = 0; char c = 0; char *e = NULL;
while ((c=*s) && isspace(c)) s++; if (!c) return s;
e = s;
while (c=*e) { less = isspace(c) ? (less + 1) : 0; e++; }
*(e-less) = 0;
return s; }
1. no need to scan trailing spaces twice (once in strlen and then again). 2. pointer dereference only once per loop rather than multiple times.
Regards, Amit
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