[FFmpeg-devel] [PATCH]Lagarith decoder.

Loren Merritt lorenm
Fri Oct 16 14:46:06 CEST 2009


On Thu, 15 Oct 2009, Nathan Caldwell wrote:
> On Tue, Oct 13, 2009 at 3:28 AM, Michael Niedermayer <michaelni at gmx.at> wrote:
>>
>>> +/* compute the 52bit mantissa of 1/(double)denom */
>>> +static uint64_t softfloat_reciprocal(uint32_t denom)
>>
>> comment not doxygen compatible
>> and this really needs some explanation of why it is used instead of
>> 1.0/denom in the doxy
>
> Updated. It would be nice if Loren could comment on these descriptions.
>
> + This is used because it is more portable across architectures and
> + toolchains than using floats.

I wouldn't say that explains anything. How about:

This crazy format uses floats in an entropy coder, thus we have to match 
x86's rounding exactly, thus ordinary floats aren't portable enough.

--Loren Merritt



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