[FFmpeg-cvslog] idct8x8: Fix undefined negative shifts
Katerina Barone-Adesi
git at videolan.org
Wed Apr 13 17:26:10 CEST 2016
ffmpeg | branch: master | Katerina Barone-Adesi <katerinab at gmail.com> | Wed Mar 2 18:52:25 2016 -0500| [1389b4c18d1042c196603ba66c25113bcee1738b] | committer: Vittorio Giovara
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
> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=1389b4c18d1042c196603ba66c25113bcee1738b
---
libavcodec/jfdctint_template.c | 4 ++--
libavcodec/jrevdct.c | 36 ++++++++++++++++++------------------
libavcodec/simple_idct_template.c | 10 +++++-----
3 files changed, 25 insertions(+), 25 deletions(-)
diff --git a/libavcodec/jfdctint_template.c b/libavcodec/jfdctint_template.c
index c6a1638..3ea2f5d 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),
diff --git a/libavcodec/jrevdct.c b/libavcodec/jrevdct.c
index 8261269..96a884a 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;
}
}
diff --git a/libavcodec/simple_idct_template.c b/libavcodec/simple_idct_template.c
index b287c4f..171ae08 100644
--- a/libavcodec/simple_idct_template.c
+++ b/libavcodec/simple_idct_template.c
@@ -96,12 +96,12 @@ static inline void FUNC(idctRowCondDC)(int16_t *row, int extra_shift)
if (((((uint64_t *)row)[0] & ~ROW0_MASK) | ((uint64_t *)row)[1]) == 0) {
uint64_t temp;
if (DC_SHIFT - extra_shift > 0) {
- temp = (row[0] << (DC_SHIFT - extra_shift)) & 0xffff;
+ temp = (row[0] * (1 << (DC_SHIFT - extra_shift))) & 0xffff;
} else {
temp = (row[0] >> (extra_shift - DC_SHIFT)) & 0xffff;
}
- temp += temp << 16;
- temp += temp << 32;
+ temp += temp * (1 << 16);
+ temp += temp * ((uint64_t) 1 << 32);
((uint64_t *)row)[0] = temp;
((uint64_t *)row)[1] = temp;
return;
@@ -113,11 +113,11 @@ static inline void FUNC(idctRowCondDC)(int16_t *row, int extra_shift)
row[1])) {
uint32_t temp;
if (DC_SHIFT - extra_shift > 0) {
- temp = (row[0] << (DC_SHIFT - extra_shift)) & 0xffff;
+ temp = (row[0] * (1 << (DC_SHIFT - extra_shift))) & 0xffff;
} else {
temp = (row[0] >> (extra_shift - DC_SHIFT)) & 0xffff;
}
- temp += temp << 16;
+ temp += temp * (1 << 16);
((uint32_t*)row)[0]=((uint32_t*)row)[1] =
((uint32_t*)row)[2]=((uint32_t*)row)[3] = temp;
return;
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