From ed317c94c310d50e48f55f0504c4d3e06b4f96da Mon Sep 17 00:00:00 2001
From: Jean-Marc Valin <Jean-Marc.Valin@csiro.au>
Date: Tue, 15 Apr 2008 17:31:23 +1000
Subject: [PATCH] optimisation: another bunch of simplifications to the "simple
case" of the alg_quant() search.
---
libcelt/cwrs.c | 1 +
libcelt/vq.c | 66 ++++++++++++++++++++++++++++----------------------
2 files changed, 38 insertions(+), 29 deletions(-)
diff --git a/libcelt/cwrs.c b/libcelt/cwrs.c
index 9ed3d7336..c8a2ac65e 100644
--- a/libcelt/cwrs.c
+++ b/libcelt/cwrs.c
@@ -42,6 +42,7 @@
#include "config.h"
#endif
+#include "os_support.h"
#include <stdlib.h>
#include <string.h>
#include "cwrs.h"
diff --git a/libcelt/vq.c b/libcelt/vq.c
index b071cdd74..b9a91bab4 100644
--- a/libcelt/vq.c
+++ b/libcelt/vq.c
@@ -137,61 +137,67 @@ void alg_quant(celt_norm_t *X, celt_mask_t *W, int N, int K, const celt_norm_t *
while (pulsesLeft > 0)
{
int pulsesAtOnce=1;
- int sign;
- celt_word32_t Rxy, Ryy, Ryp;
- celt_word32_t g;
- celt_word32_t best_num;
- celt_word16_t best_den;
int best_id;
-
+ celt_word16_t magnitude;
+#ifdef FIXED_POINT
+ int rshift;
+#endif
/* Decide on how many pulses to find at once */
pulsesAtOnce = (pulsesLeft*N_1)>>9; /* pulsesLeft/N */
if (pulsesAtOnce<1)
pulsesAtOnce = 1;
+#ifdef FIXED_POINT
+ rshift = yshift+1+celt_ilog2(K-pulsesLeft+pulsesAtOnce);
+#endif
+ magnitude = SHL16(pulsesAtOnce, yshift);
- /* This should ensure that anything we can process will have a better score */
- best_num = -SHR32(VERY_LARGE32,4);
- best_den = 0;
best_id = 0;
+ /* The squared magnitude term gets added anyway, so we might as well
+ add it outside the loop */
+ yy = ADD32(yy, MULT16_16(magnitude,magnitude));
/* Choose between fast and accurate strategy depending on where we are in the search */
if (pulsesLeft>1)
{
- /* OPT: This loop is very CPU-intensive */
+ /* This should ensure that anything we can process will have a better score */
+ celt_word32_t best_num = -VERY_LARGE16;
+ celt_word16_t best_den = 0;
j=0;
do {
- celt_word32_t num;
- celt_word16_t den;
+ celt_word16_t Rxy, Ryy;
/* Select sign based on X[j] alone */
- sign = signx[j];
- s = SHL16(sign*pulsesAtOnce, yshift);
+ s = signx[j]*magnitude;
/* Temporary sums of the new pulse(s) */
- Rxy = xy + MULT16_16(s,X[j]);
- Ryy = yy + 2*MULT16_16(s,y[j]) + MULT16_16(s,s);
+ Rxy = SHR32(xy + MULT16_16(s,X[j]),rshift);
+ /* We're multiplying y[j] by two so we don't have to do it here */
+ Ryy = SHR32(yy + MULT16_16(s,y[j]),rshift);
- /* Approximate score: we maximise Rxy/sqrt(Ryy) */
- num = MULT16_16(ROUND16(Rxy,14),ABS16(ROUND16(Rxy,14)));
- den = ROUND16(Ryy,14);
+ /* Approximate score: we maximise Rxy/sqrt(Ryy) (we're guaranteed that
+ Rxy is positive because the sign is pre-computed) */
+ Rxy = MULT16_16_Q15(Rxy,Rxy);
/* The idea is to check for num/den >= best_num/best_den, but that way
we can do it without any division */
- /* OPT: Make sure to use a conditional move here */
- if (MULT16_32_Q15(best_den, num) > MULT16_32_Q15(den, best_num))
+ /* OPT: Make sure to use conditional moves here */
+ if (MULT16_16(best_den, Rxy) > MULT16_16(Ryy, best_num))
{
- best_den = den;
- best_num = num;
+ best_den = Ryy;
+ best_num = Rxy;
best_id = j;
}
} while (++j<N); /* Promises we loop at least once */
} else {
+ celt_word32_t g;
+ celt_word32_t best_num = -VERY_LARGE32;
for (j=0;j<N;j++)
{
+ celt_word32_t Rxy, Ryy, Ryp;
celt_word32_t num;
/* Select sign based on X[j] alone */
- sign = signx[j];
- s = SHL16(sign*pulsesAtOnce, yshift);
+ s = signx[j]*magnitude;
/* Temporary sums of the new pulse(s) */
Rxy = xy + MULT16_16(s,X[j]);
- Ryy = yy + 2*MULT16_16(s,y[j]) + MULT16_16(s,s);
- Ryp = yp + MULT16_16(s, P[j]);
+ /* We're multiplying y[j] by two so we don't have to do it here */
+ Ryy = yy + MULT16_16(s,y[j]);
+ Ryp = yp + MULT16_16(s,P[j]);
/* Compute the gain such that ||p + g*y|| = 1 */
g = MULT16_32_Q15(
@@ -218,11 +224,13 @@ void alg_quant(celt_norm_t *X, celt_mask_t *W, int N, int K, const celt_norm_t *
/* Updating the sums of the new pulse(s) */
xy = xy + MULT16_16(s,X[j]);
- yy = yy + 2*MULT16_16(s,y[j]) + MULT16_16(s,s);
+ /* We're multiplying y[j] by two so we don't have to do it here */
+ yy = yy + MULT16_16(s,y[j]);
yp = yp + MULT16_16(s, P[j]);
/* Only now that we've made the final choice, update y/iy */
- y[j] += s;
+ /* Multiplying y[j] by 2 so we don't have to do it everywhere else */
+ y[j] += 2*s;
iy[j] += is;
pulsesLeft -= pulsesAtOnce;
}
--
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