Module: libav
Branch: master
Commit: 714508bcb91057868a96588b9fba4d29c6c4fc77
Author: Luca Barbato <lu_z...@gentoo.org>
Committer: Luca Barbato <lu_z...@gentoo.org>
Date: Thu Sep 13 19:45:21 2012 +0200
vorbisdec: ensure FASTDIV denominator is never 1
In both usages of FASTDIV the denominator might be 1.
Using a branch could make the function slower than using a normal
division.
Both denominator and numerator can be multiplied by 2 safely and
using shifts is faster than using a branch.
---
libavcodec/vorbisdec.c | 5 ++---
1 files changed, 2 insertions(+), 3 deletions(-)
diff --git a/libavcodec/vorbisdec.c b/libavcodec/vorbisdec.c
index f11e2f5..f5a541a 100644
--- a/libavcodec/vorbisdec.c
+++ b/libavcodec/vorbisdec.c
@@ -1354,8 +1354,7 @@ static av_always_inline int
vorbis_residue_decode_internal(vorbis_context *vc,
if (vqbook >= 0 && vc->codebooks[vqbook].codevectors) {
unsigned coffs;
unsigned dim = vc->codebooks[vqbook].dimensions;
- unsigned step = dim == 1 ? vr->partition_size
- :
FASTDIV(vr->partition_size, dim);
+ unsigned step = FASTDIV(vr->partition_size << 1,
dim << 1);
vorbis_codebook codebook = vc->codebooks[vqbook];
if (vr_type == 0) {
@@ -1409,7 +1408,7 @@ static av_always_inline int
vorbis_residue_decode_internal(vorbis_context *vc,
}
} else if (vr_type == 2) {
- unsigned voffs_div = FASTDIV(voffset, ch);
+ unsigned voffs_div = FASTDIV(voffset << 1, ch
<<1);
unsigned voffs_mod = voffset - voffs_div * ch;
for (k = 0; k < step; ++k) {
_______________________________________________
libav-commits mailing list
libav-commits@libav.org
https://lists.libav.org/mailman/listinfo/libav-commits
