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/jrevdct.c | |
| parent | e10b7ef2fe56603fb1baac6b20fd6bd0a3fdd0d0 (diff) | |
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/jrevdct.c')
| -rw-r--r-- | libavcodec/jrevdct.c | 36 |
1 files changed, 18 insertions, 18 deletions
diff --git a/libavcodec/jrevdct.c b/libavcodec/jrevdct.c index 8261269b25..96a884ae87 100644 --- a/libavcodec/jrevdct.c +++ b/libavcodec/jrevdct.c @@ -251,8 +251,8 @@ void ff_j_rev_dct(DCTBLOCK data) /* AC terms all zero */ if (d0) { /* Compute a 32 bit value to assign. */ - int16_t dcval = (int16_t) (d0 << PASS1_BITS); - register int v = (dcval & 0xffff) | ((dcval << 16) & 0xffff0000); + int16_t dcval = (int16_t) (d0 * (1 << PASS1_BITS)); + register int v = (dcval & 0xffff) | ((dcval * (1 << 16)) & 0xffff0000); idataptr[0] = v; idataptr[1] = v; @@ -274,8 +274,8 @@ void ff_j_rev_dct(DCTBLOCK data) tmp2 = z1 + MULTIPLY(-d6, FIX_1_847759065); tmp3 = z1 + MULTIPLY(d2, FIX_0_765366865); - tmp0 = (d0 + d4) << CONST_BITS; - tmp1 = (d0 - d4) << CONST_BITS; + tmp0 = (d0 + d4) * CONST_SCALE; + tmp1 = (d0 - d4) * CONST_SCALE; tmp10 = tmp0 + tmp3; tmp13 = tmp0 - tmp3; @@ -286,8 +286,8 @@ void ff_j_rev_dct(DCTBLOCK data) tmp2 = MULTIPLY(-d6, FIX_1_306562965); tmp3 = MULTIPLY(d6, FIX_0_541196100); - tmp0 = (d0 + d4) << CONST_BITS; - tmp1 = (d0 - d4) << CONST_BITS; + tmp0 = (d0 + d4) * CONST_SCALE; + tmp1 = (d0 - d4) * CONST_SCALE; tmp10 = tmp0 + tmp3; tmp13 = tmp0 - tmp3; @@ -300,8 +300,8 @@ void ff_j_rev_dct(DCTBLOCK data) tmp2 = MULTIPLY(d2, FIX_0_541196100); tmp3 = MULTIPLY(d2, FIX_1_306562965); - tmp0 = (d0 + d4) << CONST_BITS; - tmp1 = (d0 - d4) << CONST_BITS; + tmp0 = (d0 + d4) * CONST_SCALE; + tmp1 = (d0 - d4) * CONST_SCALE; tmp10 = tmp0 + tmp3; tmp13 = tmp0 - tmp3; @@ -309,8 +309,8 @@ void ff_j_rev_dct(DCTBLOCK data) tmp12 = tmp1 - tmp2; } else { /* d0 != 0, d2 == 0, d4 != 0, d6 == 0 */ - tmp10 = tmp13 = (d0 + d4) << CONST_BITS; - tmp11 = tmp12 = (d0 - d4) << CONST_BITS; + tmp10 = tmp13 = (d0 + d4) * CONST_SCALE; + tmp11 = tmp12 = (d0 - d4) * CONST_SCALE; } } @@ -620,8 +620,8 @@ void ff_j_rev_dct(DCTBLOCK data) tmp2 = z1 + MULTIPLY(-d6, FIX_1_847759065); tmp3 = z1 + MULTIPLY(d2, FIX_0_765366865); - tmp0 = (d0 + d4) << CONST_BITS; - tmp1 = (d0 - d4) << CONST_BITS; + tmp0 = (d0 + d4) * CONST_SCALE; + tmp1 = (d0 - d4) * CONST_SCALE; tmp10 = tmp0 + tmp3; tmp13 = tmp0 - tmp3; @@ -632,8 +632,8 @@ void ff_j_rev_dct(DCTBLOCK data) tmp2 = MULTIPLY(-d6, FIX_1_306562965); tmp3 = MULTIPLY(d6, FIX_0_541196100); - tmp0 = (d0 + d4) << CONST_BITS; - tmp1 = (d0 - d4) << CONST_BITS; + tmp0 = (d0 + d4) * CONST_SCALE; + tmp1 = (d0 - d4) * CONST_SCALE; tmp10 = tmp0 + tmp3; tmp13 = tmp0 - tmp3; @@ -646,8 +646,8 @@ void ff_j_rev_dct(DCTBLOCK data) tmp2 = MULTIPLY(d2, FIX_0_541196100); tmp3 = MULTIPLY(d2, FIX_1_306562965); - tmp0 = (d0 + d4) << CONST_BITS; - tmp1 = (d0 - d4) << CONST_BITS; + tmp0 = (d0 + d4) * CONST_SCALE; + tmp1 = (d0 - d4) * CONST_SCALE; tmp10 = tmp0 + tmp3; tmp13 = tmp0 - tmp3; @@ -655,8 +655,8 @@ void ff_j_rev_dct(DCTBLOCK data) tmp12 = tmp1 - tmp2; } else { /* d0 != 0, d2 == 0, d4 != 0, d6 == 0 */ - tmp10 = tmp13 = (d0 + d4) << CONST_BITS; - tmp11 = tmp12 = (d0 - d4) << CONST_BITS; + tmp10 = tmp13 = (d0 + d4) * CONST_SCALE; + tmp11 = tmp12 = (d0 - d4) * CONST_SCALE; } } |