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SubjectRe: [PATCHv3 1/2] lib: vsprintf: optimised put_dec() function
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On Wednesday 11 August 2010 23:58, Michal Nazarewicz wrote:
> +static noinline_for_stack
> +char *put_dec(char *buf, unsigned long long n)
> +{
> + uint32_t d3, d2, d1, q;
> +
> + if (n < 10) {
> + *buf++ = '0' + (unsigned)n;
> + return buf;
> + }

I looked at it and discovered that 0 is already special-cased
at put_dec() callsite. You can drop the above if() block
(or better comment it out, explaining that caller does it),
and while at it, improve special-case code in number():
replace

/* generate full string in tmp[], in reverse order */
i = 0;
if (num == 0)
tmp[i++] = '0';

with

if (num <= 7)
tmp[i++] = '0' + num;

(7, not 9, because it can be an octal conversion).


> + q = q / 10000;
> + buf = put_dec_full4(buf, q % 10000);

Bug. You need to use temporary variable to store q / 10000 result.

--
vda


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