From 1bc873acd6e15eaca8c2aebfd7dc6472b0429c50 Mon Sep 17 00:00:00 2001
From: Michael Niedermayer <michael@niedermayer.cc>
Date: Wed, 7 Oct 2015 17:57:58 +0200
Subject: [PATCH] swresample/resample: manually unroll the main loop in
bessel()
About 10% faster
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
---
libswresample/resample.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)
diff --git a/libswresample/resample.c b/libswresample/resample.c
index d6737d956a0..036eff391fd 100644
--- a/libswresample/resample.c
+++ b/libswresample/resample.c
@@ -51,11 +51,13 @@ static double bessel(double x){
x= x*x/4;
t = x;
v = 1 + x;
- for(i=1; v != lastv; i++){
- lastv=v;
+ for(i=1; v != lastv; i+=2){
t *= x*inv[i];
v += t;
- av_assert2(i<99);
+ lastv=v;
+ t *= x*inv[i + 1];
+ v += t;
+ av_assert2(i<98);
}
return v;
}
--
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