On 2016/6/30 6:06, Alexey Dobriyan wrote:
> On Thu, Jun 30, 2016 at 12:22:13AM +0800, zengzhao...@163.com wrote:
>> --- a/lib/kstrtox.c
>> +++ b/lib/kstrtox.c
>> @@ -48,38 +48,26 @@ unsigned int _parse_integer(const char *s, unsigned int
>> base, unsigned long long
>> {
>> unsigned long long res;
>> unsigned int rv;
>> - int overflow;
>> + unsigned int overflow;
>> + unsigned int val;
>>
>> res = 0;
>> rv = 0;
>> overflow = 0;
>> - while (*s) {
>> - unsigned int val;
>> -
>> - if ('0' <= *s && *s <= '9')
>> - val = *s - '0';
>> - else if ('a' <= _tolower(*s) && _tolower(*s) <= 'f')
>> - val = _tolower(*s) - 'a' + 10;
>> - else
>> - break;
>> -
>> - if (val >= base)
>> - break;
>> + while ((val = hex_to_bin(*s++)) < base) {
> I hate this function. And it has a branch if your table patch doesn't
> go it. And it is beartrap (unsigned int = -1 < base).
How about this?
for (;;) {
unsigned int val = hex_to_bin(*s++);
if (val >= base)
break;
> ACK *s++ bit, though. Should make code smaller in my experience.
> Please, change to "unsigned char c; while ((c = *s++)".
> This is about maximum code compression I can understand.
The previous tests are useless until reach the end of s.
The '\0' will be caught by "if (val >= base)" too.
>> /*
>> * Check for overflow only if we are within range of
>> * it in the max base we support (16)
>> */
>> if (unlikely(res & (~0ull << 60))) {
>> if (res > div_u64(ULLONG_MAX - val, base))
>> - overflow = 1;
>> + overflow = KSTRTOX_OVERFLOW;
> Just do |= KSTRTOX_OVERFLOW here directly, it is the leftmost bit.
I thought so too at first， but finally I decided to reserve the varaible
"overflow",
because this hack depend on the definition of KSTRTOX_OVERFLOW.
