From 11774169ae22b2818536551067668141c2f62a0c Mon Sep 17 00:00:00 2001 From: Christophe Gisquet Date: Sat, 6 Apr 2013 10:52:13 +0000 Subject: [PATCH] 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 --- libavcodec/sbrdsp.c | 40 ++++++++++++++++++++++++++++------------ 1 file changed, 28 insertions(+), 12 deletions(-) diff --git a/libavcodec/sbrdsp.c b/libavcodec/sbrdsp.c index e2280cc88d..7207f3bc54 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); } }