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authorAndreas Rheinhardt <andreas.rheinhardt@outlook.com>2024-02-13 12:30:05 +0100
committerAndreas Rheinhardt <andreas.rheinhardt@outlook.com>2024-02-16 14:58:12 +0100
commit7ed1e806e76092df27d7f984a554546a1cf1a175 (patch)
tree1bc2850d3ade82b4b8d4482c7e380a673bb30ca9 /libavcodec/ppc/audiodsp.c
parentacacf8a313f74d0cc83ae790d39341f471ef47b8 (diff)
downloadffmpeg-7ed1e806e76092df27d7f984a554546a1cf1a175.tar.gz
avcodec/x86/simple_idct: Empty MMX state in ff_simple_idct_mmx
We currently mostly do not empty the MMX state in our MMX DSP functions; instead we only do so before code that might be using x87 code. This is a violation of the System V i386 ABI (and maybe of other ABIs, too): "The CPU shall be in x87 mode upon entry to a function. Therefore, every function that uses the MMX registers is required to issue an emms or femms instruction after using MMX registers, before returning or calling another function." (See 2.2.1 in [1]) This patch does not intend to change all these functions to abide by the ABI; it only does so for ff_simple_idct_mmx, as this function can by called by external users, because it is exported via the avdct API. Without this, the following fragment will assert (on x86_32, as ff_simple_idct_mmx is not used on x64): int16_t __attribute__ ((aligned (16))) block[64]; AVDCT *dct = avcodec_dct_alloc(); dct->idct_algo = FF_IDCT_AUTO; avcodec_dct_init(dct); dct->idct(block); av_assert0_fpu(); [1]: https://raw.githubusercontent.com/wiki/hjl-tools/x86-psABI/intel386-psABI-1.1.pdf Reviewed-by: Kieran Kunhya <kierank@obe.tv> Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
Diffstat (limited to 'libavcodec/ppc/audiodsp.c')
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