[FFmpeg-devel] [PATCH] Remove MULL macro from lsp.c
Tue Aug 26 21:22:58 CEST 2008
Loren Merritt <lorenm at u.washington.edu> writes:
> On Tue, 26 Aug 2008, M?ns Rullg?rd wrote:
>> "Vladimir Voroshilov" <voroshil at gmail.com> writes:
>>> Please look into attached patch and tell what chunks are ok.
>>> I used (and tested) only MULL macro but others (due to used "l"
>>> suffix) can have the same bug.
>>> Unfortunately, i'm not know asm enough good to be sure.
>>> Index: libavcodec/i386/mathops.h
>>> --- libavcodec/i386/mathops.h (revision 14975)
>>> +++ libavcodec/i386/mathops.h (working copy)
>>> @@ -28,18 +28,18 @@
>>> "imull %3 \n\t"\
>>> "shrdl %4, %%edx, %%eax \n\t"\
>>> : "=a"(rt), "=d"(dummy)\
>>> - : "a" (ra), "rm" (rb), "i"(FRAC_BITS));\
>>> + : "a" ((int)ra), "rm" ((int)rb), "i"(FRAC_BITS));\
>>> rt; })
>> I think only the potential memory operands need the cast. Here it
>> would be the "rb" parameter.
> ra needs to be sign-extended too.
> gcc defaults to zero-extend when loading 16bit values from memory. Or
> if it's computed, then the msbs will be junk.
What a twisted compiler. Thanks for the correction, anyway. I should
know better than to speak about x86.
mans at mansr.com
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