From 518f07d04668837269dd80f5443defb8ea310b9a Mon Sep 17 00:00:00 2001 From: Christophe GISQUET Date: Wed, 18 Jan 2012 22:34:29 +0100 Subject: [PATCH 3/3] mpegaudio: replace memcpy by SIMD code By replacing memcpy with an unrolled loop using the alignment knowledge it has, some speedup can be obtained. Before (gcc 4.6.1): ~400 cycles After: ~370 cycles Overall, around 2% speed increase when decoding a 2400s mp3 to f32le. --- libavcodec/x86/mpegaudiodec_mmx.c | 21 ++++++++++++++++++++- 1 files changed, 20 insertions(+), 1 deletions(-) diff --git a/libavcodec/x86/mpegaudiodec_mmx.c b/libavcodec/x86/mpegaudiodec_mmx.c index 06ffbca..f51a06d 100644 --- a/libavcodec/x86/mpegaudiodec_mmx.c +++ b/libavcodec/x86/mpegaudiodec_mmx.c @@ -106,7 +106,26 @@ static void apply_window_mp3(float *in, float *win, int *unused, float *out, float sum; /* copy to avoid wrap */ - memcpy(in + 512, in, 32 * sizeof(*in)); + __asm__ volatile( + "movaps 0(%0), %%xmm0 \n\t" \ + "movaps 16(%0), %%xmm1 \n\t" \ + "movaps 32(%0), %%xmm2 \n\t" \ + "movaps 48(%0), %%xmm3 \n\t" \ + "movaps %%xmm0, 0(%1) \n\t" \ + "movaps %%xmm1, 16(%1) \n\t" \ + "movaps %%xmm2, 32(%1) \n\t" \ + "movaps %%xmm3, 48(%1) \n\t" \ + "movaps 64(%0), %%xmm0 \n\t" \ + "movaps 80(%0), %%xmm1 \n\t" \ + "movaps 96(%0), %%xmm2 \n\t" \ + "movaps 112(%0), %%xmm3 \n\t" \ + "movaps %%xmm0, 64(%1) \n\t" \ + "movaps %%xmm1, 80(%1) \n\t" \ + "movaps %%xmm2, 96(%1) \n\t" \ + "movaps %%xmm3, 112(%1) \n\t" + ::"r"(in), "r"(in+512) + :"memory" + ); apply_window(in + 16, win , win + 512, suma, sumc, 16); apply_window(in + 32, win + 48, win + 640, sumb, sumd, 16); -- 1.7.7.msysgit.0