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avcodec/adxdec: Remove unnecessary left-shift 

Replace "(a * (1 << shift) * b + c) >> shift" by "a * b + (c >> shift)".
It is equivalent to the old code because a is in the range of uint16_t,
shift is 12 and b is effectively a signed 4-bit number, so that no
overflow/truncation of high bits happens during the multiplication
(overflow would be undefined anyway).

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
This commit is contained in:
Andreas Rheinhardt 2020-01-20 20:20:43 +01:00 committed by Michael Niedermayer
parent 59a9d65e0d
commit 340e6b0185
1 changed files with 1 additions and 1 deletions
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libavcodec/adxdec.c
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@ -81,7 +81,7 @@ static int adx_decode(ADXContext *c, int16_t *out, int offset,
s2 = prev->s2;
for (i = 0; i < BLOCK_SAMPLES; i++) {
d = get_sbits(&gb, 4);
s0 = ((d * (1 << COEFF_BITS)) * scale + c->coeff[0] * s1 + c->coeff[1] * s2) >> COEFF_BITS;
s0 = d * scale + ((c->coeff[0] * s1 + c->coeff[1] * s2) >> COEFF_BITS);
s2 = s1;
s1 = av_clip_int16(s0);
*out++ = s1;