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| author | Alberto Delmás <adelmas@gmail.com> | 2012-09-03 17:32:01 +0200 |
|---|---|---|
| committer | Kostya Shishkov <kostya.shishkov@gmail.com> | 2012-09-06 20:44:04 +0200 |
| commit | 9699b3a2d7ebc62ae58c4e70997190f5f7b45d27 (patch) | |
| tree | 7c4d1aa78b53c3edf474eb52d7ca331d751186bc | |
| parent | 6ceef07b21a6b828d98f25edefb66e322a628667 (diff) | |
| download | ffmpeg-9699b3a2d7ebc62ae58c4e70997190f5f7b45d27.tar.gz | |
mss12: avoid unnecessary division in arith*_get_bit()
That division can be replaced with a comparison:
((c->value - c->low) << 1) + 1 >= range
By expanding 'range' definition and simplifying this inequation we obtain
the final expression.
Suggested by Michael Niedermayer <michaelni@gmx.at>
Signed-off-by: Kostya Shishkov <kostya.shishkov@gmail.com>
| -rw-r--r-- | libavcodec/mss12.h | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/libavcodec/mss12.h b/libavcodec/mss12.h index 678a0c0dfb..f5d03662b8 100644 --- a/libavcodec/mss12.h +++ b/libavcodec/mss12.h @@ -103,7 +103,7 @@ av_cold int ff_mss12_decode_end(MSS12Context *ctx); static int arith ## VERSION ## _get_bit(ArithCoder *c) \ { \ int range = c->high - c->low + 1; \ - int bit = (((c->value - c->low) << 1) + 1) / range; \ + int bit = 2 * c->value - c->low >= c->high; \ \ if (bit) \ c->low += range >> 1; \ |