diff options
| author | Katerina Barone-Adesi <katerinab@gmail.com> | 2016-03-02 18:52:25 -0500 |
|---|---|---|
| committer | Vittorio Giovara <vittorio.giovara@gmail.com> | 2016-03-05 08:26:36 -0500 |
| commit | 1389b4c18d1042c196603ba66c25113bcee1738b (patch) | |
| tree | e7a6f5258a868a4e6b854f986773431debe6eb38 /libavcodec/jfdctint_template.c | |
| parent | e10b7ef2fe56603fb1baac6b20fd6bd0a3fdd0d0 (diff) | |
| download | ffmpeg-1389b4c18d1042c196603ba66c25113bcee1738b.tar.gz | |
idct8x8: Fix undefined negative shifts
The original code left-shifts negative values, which is undefined
in the C99 specification (the one used during normal Libav compilation).
This change multiplies by (1 << shift), which is functionally equivalent,
but has defined behavior.
With this change, fate-idct8x8 compiled with --fsanitize=undefined works.
Bug-Id: 686
Diffstat (limited to 'libavcodec/jfdctint_template.c')
| -rw-r--r-- | libavcodec/jfdctint_template.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/libavcodec/jfdctint_template.c b/libavcodec/jfdctint_template.c index c6a1638107..3ea2f5dadc 100644 --- a/libavcodec/jfdctint_template.c +++ b/libavcodec/jfdctint_template.c @@ -216,8 +216,8 @@ static av_always_inline void FUNC(row_fdct)(int16_t *data) tmp11 = tmp1 + tmp2; tmp12 = tmp1 - tmp2; - dataptr[0] = (int16_t) ((tmp10 + tmp11) << PASS1_BITS); - dataptr[4] = (int16_t) ((tmp10 - tmp11) << PASS1_BITS); + dataptr[0] = (int16_t) ((tmp10 + tmp11) * (1 << PASS1_BITS)); + dataptr[4] = (int16_t) ((tmp10 - tmp11) * (1 << PASS1_BITS)); z1 = MULTIPLY(tmp12 + tmp13, FIX_0_541196100); dataptr[2] = (int16_t) DESCALE(z1 + MULTIPLY(tmp13, FIX_0_765366865), |