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sbrdsp: unroll and use integer operations 

This patch can be controversial, by assuming floats are IEEE-754 and
particular behaviour of the FPU will get in the way.
Timing on Arrandale and Win32 (thus, x87 FPU is used in the reference).

sbr_qmf_pre_shuffle_c: 115 to 76
sbr_neg_odd_64_c: 84 to 55
sbr_qmf_post_shuffle_c: 112 to 83

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
This commit is contained in:
Christophe Gisquet 2013-04-06 10:52:13 +00:00 committed by Michael Niedermayer
parent f4ac80227b
commit 11774169ae
1 changed files with 28 additions and 12 deletions
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40
libavcodec/sbrdsp.c
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@ -22,6 +22,7 @@
#include "config.h"
#include "libavutil/attributes.h"
#include "libavutil/intfloat.h"
#include "sbrdsp.h"
static void sbr_sum64x5_c(float *z)
@ -51,37 +52,52 @@ static float sbr_sum_square_c(float (*x)[2], int n)
static void sbr_neg_odd_64_c(float *x)
{
union av_intfloat32 *xi = (union av_intfloat32*)x;
int i;
for (i = 1; i < 64; i += 2)
x[i] = -x[i];
for (i = 1; i < 64; i += 4)
{
xi[i+0].i ^= 1U<<31;
xi[i+2].i ^= 1U<<31;
}
}
static void sbr_qmf_pre_shuffle_c(float *z)
{
union av_intfloat32 *zi = (union av_intfloat32*)z;
int k;
z[64] = z[0];
z[65] = z[1];
for (k = 1; k < 32; k++) {
z[64+2*k ] = -z[64 - k];
z[64+2*k+1] = z[ k + 1];
zi[64].i = zi[0].i;
zi[65].i = zi[1].i;
for (k = 1; k < 31; k+=2) {
zi[64+2*k+0].i = zi[64 - k].i ^ (1U<<31);
zi[64+2*k+1].i = zi[ k + 1].i;
zi[64+2*k+2].i = zi[63 - k].i ^ (1U<<31);
zi[64+2*k+3].i = zi[ k + 2].i;
}
zi[64+2*31+0].i = zi[64 - 31].i ^ (1U<<31);
zi[64+2*31+1].i = zi[31 + 1].i;
}
static void sbr_qmf_post_shuffle_c(float W[32][2], const float *z)
{
const union av_intfloat32 *zi = (const union av_intfloat32*)z;
union av_intfloat32 *Wi = (union av_intfloat32*)W;
int k;
for (k = 0; k < 32; k++) {
W[k][0] = -z[63-k];
W[k][1] = z[k];
for (k = 0; k < 32; k+=2) {
Wi[2*k+0].i = zi[63-k].i ^ (1U<<31);
Wi[2*k+1].i = zi[k+0].i;
Wi[2*k+2].i = zi[62-k].i ^ (1U<<31);
Wi[2*k+3].i = zi[k+1].i;
}
}
static void sbr_qmf_deint_neg_c(float *v, const float *src)
{
const union av_intfloat32 *si = (const union av_intfloat32*)src;
union av_intfloat32 *vi = (union av_intfloat32*)v;
int i;
for (i = 0; i < 32; i++) {
v[ i] = src[63 - 2*i ];
v[63 - i] = -src[63 - 2*i - 1];
vi[ i].i = si[63 - 2*i ].i;
vi[63 - i].i = si[63 - 2*i - 1].i ^ (1U<<31);
}
}