From fd9451c68fa59ecc1cddc2f2faaedfa7675218ad Mon Sep 17 00:00:00 2001
From: Michael Niedermayer <michaelni@gmx.at>
Date: Tue, 11 May 2010 20:33:48 +0000
Subject: [PATCH] Make lsf_sf_expand() 4 times faster.
Originally committed as revision 23096 to svn://svn.ffmpeg.org/ffmpeg/trunk
---
libavcodec/mpegaudiodec.c | 40 +++++++++++++++++++++++----------------
1 file changed, 24 insertions(+), 16 deletions(-)
diff --git a/libavcodec/mpegaudiodec.c b/libavcodec/mpegaudiodec.c
index 185db6c60b7..31aa92e2350 100644
--- a/libavcodec/mpegaudiodec.c
+++ b/libavcodec/mpegaudiodec.c
@@ -1318,24 +1318,32 @@ static int mp_decode_layer2(MPADecodeContext *s)
return 3 * 12;
}
-//FIXME optimze this shit
-static inline void lsf_sf_expand(int *slen,
+#define SPLIT(dst,sf,n)\
+ if(n==3){\
+ int m= (sf*171)>>9;\
+ dst= sf - 3*m;\
+ sf=m;\
+ }else if(n==4){\
+ dst= sf&3;\
+ sf>>=2;\
+ }else if(n==5){\
+ int m= (sf*205)>>10;\
+ dst= sf - 5*m;\
+ sf=m;\
+ }else if(n==6){\
+ int m= (sf*171)>>10;\
+ dst= sf - 6*m;\
+ sf=m;\
+ }else{\
+ dst=0;\
+ }
+
+static av_always_inline void lsf_sf_expand(int *slen,
int sf, int n1, int n2, int n3)
{
- if (n3) {
- slen[3] = sf % n3;
- sf /= n3;
- } else {
- slen[3] = 0;
- }
- if (n2) {
- slen[2] = sf % n2;
- sf /= n2;
- } else {
- slen[2] = 0;
- }
- slen[1] = sf % n1;
- sf /= n1;
+ SPLIT(slen[3], sf, n3)
+ SPLIT(slen[2], sf, n2)
+ SPLIT(slen[1], sf, n1)
slen[0] = sf;
}
--
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