From 8394d9a676db1ffa1c8e4f6dd239e154d051ce03 Mon Sep 17 00:00:00 2001 From: Christophe Gisquet Date: Tue, 9 Apr 2013 21:57:09 +0000 Subject: [PATCH] sbrdsp: Unroll sbr_autocorrelate_c 1410 cycles to 1148 on Arrandale/Win64 Signed-off-by: Diego Biurrun --- libavcodec/sbrdsp.c | 25 +++++++++++++++++++++++++ 1 file changed, 25 insertions(+) diff --git a/libavcodec/sbrdsp.c b/libavcodec/sbrdsp.c index 781ec83fe8..85b4ebefb4 100644 --- a/libavcodec/sbrdsp.c +++ b/libavcodec/sbrdsp.c @@ -122,9 +122,34 @@ static av_always_inline void autocorrelate(const float x[40][2], static void sbr_autocorrelate_c(const float x[40][2], float phi[3][2][2]) { +#if 0 + /* This code is slower because it multiplies memory accesses. + * It is left for educational purposes and because it may offer + * a better reference for writing arch-specific DSP functions. */ autocorrelate(x, phi, 0); autocorrelate(x, phi, 1); autocorrelate(x, phi, 2); +#else + float real_sum2 = x[0][0] * x[2][0] + x[0][1] * x[2][1]; + float imag_sum2 = x[0][0] * x[2][1] - x[0][1] * x[2][0]; + float real_sum1 = 0.0f, imag_sum1 = 0.0f, 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]; + } + phi[2 - 2][1][0] = real_sum2; + phi[2 - 2][1][1] = imag_sum2; + phi[2 ][1][0] = real_sum0 + x[ 0][0] * x[ 0][0] + x[ 0][1] * x[ 0][1]; + phi[1 ][0][0] = real_sum0 + x[38][0] * x[38][0] + x[38][1] * x[38][1]; + phi[2 - 1][1][0] = real_sum1 + x[ 0][0] * x[ 1][0] + x[ 0][1] * x[ 1][1]; + phi[2 - 1][1][1] = imag_sum1 + x[ 0][0] * x[ 1][1] - x[ 0][1] * x[ 1][0]; + phi[0 ][0][0] = real_sum1 + x[38][0] * x[39][0] + x[38][1] * x[39][1]; + phi[0 ][0][1] = imag_sum1 + x[38][0] * x[39][1] - x[38][1] * x[39][0]; +#endif } static void sbr_hf_gen_c(float (*X_high)[2], const float (*X_low)[2],