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
---
libavcodec/sbrdsp.c | 50 +++++++++++++++++++++++++++++++++-----------------
1 file changed, 33 insertions(+), 17 deletions(-)
diff --git a/libavcodec/sbrdsp.c b/libavcodec/sbrdsp.c
index 9a9b950..41b1c0d 100644
--- a/libavcodec/sbrdsp.c
+++ b/libavcodec/sbrdsp.c
@@ -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);
}
}
@@ -135,11 +151,11 @@ static void sbr_autocorrelate_c(const float x[40][2],
float phi[3][2][2])
float real_sum1 = 0.f, imag_sum1 = 0.f, real_sum0 = 0.0f;
int i;
for (i = 1; i < 38; i++) {
- real_sum0 += x[i][0] * x[i ][0] + x[i][1] * x[i ][1];
- real_sum1 += x[i][0] * x[i+1][0] + x[i][1] * x[i+1][1];
- imag_sum1 += x[i][0] * x[i+1][1] - x[i][1] * x[i+1][0];
- real_sum2 += x[i][0] * x[i+2][0] + x[i][1] * x[i+2][1];
- imag_sum2 += x[i][0] * x[i+2][1] - x[i][1] * x[i+2][0];
+ real_sum0 += x[i][0] * x[i ][0] + x[i][1] * x[i ][1];
+ real_sum1 += x[i][0] * x[i + 1][0] + x[i][1] * x[i + 1][1];
+ imag_sum1 += x[i][0] * x[i + 1][1] - x[i][1] * x[i + 1][0];
+ real_sum2 += x[i][0] * x[i + 2][0] + x[i][1] * x[i + 2][1];
+ imag_sum2 += x[i][0] * x[i + 2][1] - x[i][1] * x[i + 2][0];
}
phi[2-2][1][0] = real_sum2;
phi[2-2][1][1] = imag_sum2;
--
1.8.0.msysgit.0
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