Hi, 2011/7/10 Måns Rullgård <[email protected]>: > "Ronald S. Bultje" <[email protected]> writes: >> 2011/7/10 Måns Rullgård <[email protected]>: >>> "Ronald S. Bultje" <[email protected]> writes: >>> >>>> From: Anton Mitrofanov <[email protected]> >>>> >>>> ptrdiff_t can be 4 bytes, which leads to the next element being 4-byte >>>> aligned and thus at a different offset than intended. Using a fixed 8-byte >>>> element for uv_off_px/byte fixes that. >>>> >>>> Signed-off-by: Ronald S. Bultje <[email protected]> >>>> --- >>>> libswscale/swscale_internal.h | 4 ++-- >>>> 1 files changed, 2 insertions(+), 2 deletions(-) >>>> >>>> diff --git a/libswscale/swscale_internal.h b/libswscale/swscale_internal.h >>>> index b602541..7166667 100644 >>>> --- a/libswscale/swscale_internal.h >>>> +++ b/libswscale/swscale_internal.h >>>> @@ -345,8 +345,8 @@ typedef struct SwsContext { >>>> DECLARE_ALIGNED(8, uint64_t, v_temp); >>>> DECLARE_ALIGNED(8, uint64_t, y_temp); >>>> int32_t alpMmxFilter[4*MAX_FILTER_SIZE]; >>>> - DECLARE_ALIGNED(8, ptrdiff_t, uv_off_px); ///< offset (in pixels) >>>> between u and v planes >>>> - DECLARE_ALIGNED(8, ptrdiff_t, uv_off_byte); ///< offset (in bytes) >>>> between u and v planes >>>> + DECLARE_ALIGNED(8, int64_t, uv_off_px); ///< offset (in pixels) >>>> between u and v planes >>>> + DECLARE_ALIGNED(8, int64_t, uv_off_byte); ///< offset (in bytes) >>>> between u and v planes >>>> uint16_t dither16[8]; >>>> uint32_t dither32[8]; >>>> >>>> -- >>> >>> What is this supposed to fix, and why are those things declared with >>> extra alignment at all? It makes no sense. >> >> It fixes ptrdiff_t being 4 bytes on x86-32, and then dither16 being at >> a different address. We hardcode the offset from dither16 somewhere >> for use in assembly. > > Don't do that then. If you must hardcode offsets, put those early in > the struct, before any variably sized elements.
That wouldn't fix anything, we use uv_off_px/byte in asm also. Ronald _______________________________________________ libav-devel mailing list [email protected] https://lists.libav.org/mailman/listinfo/libav-devel
