From ce15e6531932624387b5c49bb1fbfccd19710bca Mon Sep 17 00:00:00 2001
From: "Timothy B. Terriberry" <tterribe@xiph.org>
Date: Fri, 14 Jun 2013 23:57:19 -0700
Subject: [PATCH] Split cwrsi() by pulses vs. dimensions.
This lets us cut out a bunch of work in the large _n, small _k case
where most of the dimensions won't have any pulses.
It also gets rid of all remaining usage of CELT_PVQ_U() in cwrsi(),
leaving just a single test instead of lots of mins and maxes, and
makes a bunch of the jump threading more obvious.
This is a 1.6% decoder speedup on a 96 kbps comp48-stereo encode on
a Cortex A8.
---
celt/cwrs.c | 55 ++++++++++++++++++++++++++++++++++-------------------
1 file changed, 35 insertions(+), 20 deletions(-)
diff --git a/celt/cwrs.c b/celt/cwrs.c
index d384dfe2..029232c8 100644
--- a/celt/cwrs.c
+++ b/celt/cwrs.c
@@ -467,34 +467,49 @@ static void cwrsi(int _n,int _k,opus_uint32 _i,int *_y){
celt_assert(_k>0);
celt_assert(_n>1);
while(_n>2){
- /*Are the pulses in this dimension negative?*/
- p=CELT_PVQ_U(_n,_k+1);
- s=-(_i>=p);
- _i-=p&s;
- /*Count how many pulses were placed in this dimension.*/
- k0=_k;
- p=CELT_PVQ_U(_n,_k);
- if(_k>_n){
+ opus_uint32 q;
+ /*Lots of pulses case:*/
+ if(_k>=_n){
const opus_uint32 *row;
- opus_uint32 q;
row=CELT_PVQ_U_ROW[_n];
+ /*Are the pulses in this dimension negative?*/
+ p=row[_k+1];
+ s=-(_i>=p);
+ _i-=p&s;
+ /*Count how many pulses were placed in this dimension.*/
+ k0=_k;
q=row[_n];
if(q>_i){
celt_assert(p>q);
- /*Setting p=q is unnecessary, but it helps the optimizer prove p>_i,
- allowing it to jump straight past the initial test in the second
- loop below.
- Once it's removed that first comparison, a smart compiler should be
- able to figure out that the result of this assignment isn't used and
- optimize it away anyway.*/
- p=q;
_k=_n;
+ do p=CELT_PVQ_U_ROW[--_k][_n];
+ while(p>_i);
+ }
+ else for(p=row[_k];p>_i;p=row[_k])_k--;
+ _i-=p;
+ *_y++=(k0-_k+s)^s;
+ }
+ /*Lots of dimensions case:*/
+ else{
+ /*Are there any pulses in this dimension at all?*/
+ p=CELT_PVQ_U_ROW[_k][_n];
+ q=CELT_PVQ_U_ROW[_k+1][_n];
+ if(p<=_i&&_i<q){
+ _i-=p;
+ *_y++=0;
+ }
+ else{
+ /*Are the pulses in this dimension negative?*/
+ s=-(_i>=q);
+ _i-=q&s;
+ /*Count how many pulses were placed in this dimension.*/
+ k0=_k;
+ do p=CELT_PVQ_U_ROW[--_k][_n];
+ while(p>_i);
+ _i-=p;
+ *_y++=(k0-_k+s)^s;
}
- else for(;p>_i;p=row[_k])_k--;
}
- for(;p>_i;p=CELT_PVQ_U_ROW[_k][_n])_k--;
- _i-=p;
- *_y++=(k0-_k+s)^s;
_n--;
}
/*_n==2*/
--
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