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avoid an unpredictable branch

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20% faster predictor_update_filter, .4-4% faster ape decoding on core2

Originally committed as revision 20720 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Loren Merritt 2009-12-03 17:48:54 +00:00
parent 36373cde20
commit 2ae87a6d5a
1 changed files with 17 additions and 38 deletions
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55
libavcodec/apedec.c
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@ -519,7 +519,7 @@ static inline int APESIGN(int32_t x) {
static av_always_inline int predictor_update_filter(APEPredictor *p, const int decoded, const int filter, const int delayA, const int delayB, const int adaptA, const int adaptB)
{
int32_t predictionA, predictionB;
int32_t predictionA, predictionB, sign;
p->buf[delayA] = p->lastA[filter];
p->buf[adaptA] = APESIGN(p->buf[delayA]);
@ -547,32 +547,17 @@ static av_always_inline int predictor_update_filter(APEPredictor *p, const int d
p->lastA[filter] = decoded + ((predictionA + (predictionB >> 1)) >> 10);
p->filterA[filter] = p->lastA[filter] + ((p->filterA[filter] * 31) >> 5);
if (!decoded) // no need updating filter coefficients
return p->filterA[filter];
sign = APESIGN(decoded);
p->coeffsA[filter][0] += p->buf[adaptA ] * sign;
p->coeffsA[filter][1] += p->buf[adaptA - 1] * sign;
p->coeffsA[filter][2] += p->buf[adaptA - 2] * sign;
p->coeffsA[filter][3] += p->buf[adaptA - 3] * sign;
p->coeffsB[filter][0] += p->buf[adaptB ] * sign;
p->coeffsB[filter][1] += p->buf[adaptB - 1] * sign;
p->coeffsB[filter][2] += p->buf[adaptB - 2] * sign;
p->coeffsB[filter][3] += p->buf[adaptB - 3] * sign;
p->coeffsB[filter][4] += p->buf[adaptB - 4] * sign;
if (decoded > 0) {
p->coeffsA[filter][0] -= p->buf[adaptA ];
p->coeffsA[filter][1] -= p->buf[adaptA - 1];
p->coeffsA[filter][2] -= p->buf[adaptA - 2];
p->coeffsA[filter][3] -= p->buf[adaptA - 3];
p->coeffsB[filter][0] -= p->buf[adaptB ];
p->coeffsB[filter][1] -= p->buf[adaptB - 1];
p->coeffsB[filter][2] -= p->buf[adaptB - 2];
p->coeffsB[filter][3] -= p->buf[adaptB - 3];
p->coeffsB[filter][4] -= p->buf[adaptB - 4];
} else {
p->coeffsA[filter][0] += p->buf[adaptA ];
p->coeffsA[filter][1] += p->buf[adaptA - 1];
p->coeffsA[filter][2] += p->buf[adaptA - 2];
p->coeffsA[filter][3] += p->buf[adaptA - 3];
p->coeffsB[filter][0] += p->buf[adaptB ];
p->coeffsB[filter][1] += p->buf[adaptB - 1];
p->coeffsB[filter][2] += p->buf[adaptB - 2];
p->coeffsB[filter][3] += p->buf[adaptB - 3];
p->coeffsB[filter][4] += p->buf[adaptB - 4];
}
return p->filterA[filter];
}
@ -604,7 +589,7 @@ static void predictor_decode_mono(APEContext * ctx, int count)
{
APEPredictor *p = &ctx->predictor;
int32_t *decoded0 = ctx->decoded0;
int32_t predictionA, currentA, A;
int32_t predictionA, currentA, A, sign;
currentA = p->lastA[0];
@ -624,17 +609,11 @@ static void predictor_decode_mono(APEContext * ctx, int count)
p->buf[YADAPTCOEFFSA] = APESIGN(p->buf[YDELAYA ]);
p->buf[YADAPTCOEFFSA - 1] = APESIGN(p->buf[YDELAYA - 1]);
if (A > 0) {
p->coeffsA[0][0] -= p->buf[YADAPTCOEFFSA ];
p->coeffsA[0][1] -= p->buf[YADAPTCOEFFSA - 1];
p->coeffsA[0][2] -= p->buf[YADAPTCOEFFSA - 2];
p->coeffsA[0][3] -= p->buf[YADAPTCOEFFSA - 3];
} else if (A < 0) {
p->coeffsA[0][0] += p->buf[YADAPTCOEFFSA ];
p->coeffsA[0][1] += p->buf[YADAPTCOEFFSA - 1];
p->coeffsA[0][2] += p->buf[YADAPTCOEFFSA - 2];
p->coeffsA[0][3] += p->buf[YADAPTCOEFFSA - 3];
}
sign = APESIGN(A);
p->coeffsA[0][0] += p->buf[YADAPTCOEFFSA ] * sign;
p->coeffsA[0][1] += p->buf[YADAPTCOEFFSA - 1] * sign;
p->coeffsA[0][2] += p->buf[YADAPTCOEFFSA - 2] * sign;
p->coeffsA[0][3] += p->buf[YADAPTCOEFFSA - 3] * sign;
p->buf++;