"Ronald S. Bultje" <[email protected]> writes: > 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.
So fix the asm. -- Måns Rullgård [email protected] _______________________________________________ libav-devel mailing list [email protected] https://lists.libav.org/mailman/listinfo/libav-devel
