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avcodec/smacker: Remove redundant check when decoding header trees 

When length is zero for a leaf node (which happens iff the Huffman tree
consists of one leaf node only), prefix is also automatically zero.

Performance impact is negligible: For GCC 9 and the sample from #2425,
the time for one call to smka_decode_frame() decreased from 2053758 to
2053671 decicycles; for Clang 9 it went from 1523153 to 1521288.

Reviewed-by: Paul B Mahol <onemda@gmail.com>
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
This commit is contained in:
Andreas Rheinhardt 2020-07-24 20:56:46 +02:00
parent 77c9507253
commit 943a458157
1 changed files with 2 additions and 7 deletions
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9
libavcodec/smacker.c
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@ -105,13 +105,8 @@ static int smacker_decode_tree(GetBitContext *gb, HuffContext *hc, uint32_t pref
av_log(NULL, AV_LOG_ERROR, "Tree size exceeded!\n");
return AVERROR_INVALIDDATA;
}
if(length){
hc->bits[hc->current] = prefix;
hc->lengths[hc->current] = length;
} else {
hc->bits[hc->current] = 0;
hc->lengths[hc->current] = 0;
}
hc->bits[hc->current] = prefix;
hc->lengths[hc->current] = length;
hc->values[hc->current] = get_bits(gb, 8);
hc->current++;
return 0;