[PATCH] libbb/last_char_is: rewrite for smaller and faster code
Tito
farmatito at tiscali.it
Fri Jul 3 19:15:07 UTC 2020
On 7/3/20 6:13 PM, Xabier Oneca -- xOneca wrote:
> Hi all,
>
>>> On Fri, 2020-07-03 at 08:12 +0200, Tito wrote:
>>> [...]
>>>> Improved version:
>>>>
>>>> char* last_char_is(const char *s, int c) {
>>>> if (!s || !*s) return NULL;
>>>> while (*(s + 1))s++;
>>>> return (c == *s) ? (char *)s : NULL;
>>>> }
>
> Let me "improve" the Tito's -11 bytes, probably introducing some subtle bug :)
>
> char* FAST_FUNC last_char_is(const char *s, int c)
> {
> if (!s || !*s) return NULL;
> while (*(++s));
> return (*(--s) == c) ? s : NULL;
> }
>
> function old new delta
> last_char_is 58 42 -16
> ------------------------------------------------------------------------------
> (add/remove: 0/0 grow/shrink: 0/1 up/down: 0/-16) Total: -16 bytes
> text data bss dec hex filename
> 956449 4235 1904 962588 eb01c busybox_old
> 956433 4235 1904 962572 eb00c busybox_unstripped
>
> Also, there's a warning compiling this function: return discards
> ‘const’ qualifier from pointer target type
Hi,
cast it?
char* FAST_FUNC last_char_is(const char *s, int c)
{
if (!s || !*s) return NULL;
while (*(++s));
return (*(--s) == c) ? (char *)s : NULL;
}
> Fun to play with you.
>
> Cheers,
>
> Xabier Oneca_,,_
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