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authorKaterina Barone-Adesi <katerinab@gmail.com>2014-05-19 17:27:52 +0200
committerMichael Niedermayer <michaelni@gmx.at>2014-05-20 04:21:06 +0200
commite50ae60d46181814245f70b61b70394311e10373 (patch)
tree84197bc05af463440414de72ca6620299e564586 /libavcodec/jrevdct.c
parent7d25af1547f8d97231f1c6e4cab7ad2bbf1dd071 (diff)
downloadffmpeg-e50ae60d46181814245f70b61b70394311e10373.tar.gz
avcodec/fate-idct8x8: Defined behavior: eliminate negative left-shifts.
The original code left-shifts negative values, which is undefined in the C99 specification (the one used during normal FFmpeg 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 Signed-off-by: Michael Niedermayer <michaelni@gmx.at> The assembly generated by gcc is unchanged by this commit
Diffstat (limited to 'libavcodec/jrevdct.c')
-rw-r--r--libavcodec/jrevdct.c36
1 files changed, 18 insertions, 18 deletions
diff --git a/libavcodec/jrevdct.c b/libavcodec/jrevdct.c
index 91780b2e44..d4e6571acc 100644
--- a/libavcodec/jrevdct.c
+++ b/libavcodec/jrevdct.c
@@ -249,8 +249,8 @@ 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;
@@ -272,8 +272,8 @@ 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;
@@ -284,8 +284,8 @@ 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;
@@ -298,8 +298,8 @@ 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;
@@ -307,8 +307,8 @@ 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;
}
}
@@ -618,8 +618,8 @@ 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;
@@ -630,8 +630,8 @@ 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;
@@ -644,8 +644,8 @@ 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;
@@ -653,8 +653,8 @@ 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;
}
}