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CMOV-ify vp56 arithcoder
This incantation causes gcc 4.3 to generate cmov on x86, a vastly better option than a completely unpredictable branch. Hopefully this carries over to newer versions and other CPUs with conditionals. ~5 cycles saved per call on a Core i7. Originally committed as revision 23921 to svn://svn.ffmpeg.org/ffmpeg/trunk
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@ -199,12 +199,8 @@ static inline int vp56_rac_get_prob(VP56RangeCoder *c, uint8_t prob)
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int bit = c->code_word >= low_shift;
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int shift;
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if (bit) {
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c->high -= low;
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c->code_word -= low_shift;
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} else {
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c->high = low;
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}
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c->high = bit ? c->high - low : low;
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c->code_word = bit ? c->code_word - low_shift : c->code_word;
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/* normalize */
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shift = ff_h264_norm_shift[c->high] - 1;
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