From 67209b9ecccc6578fb3996a5e6dc42dbec1753bd Mon Sep 17 00:00:00 2001 From: Wim Taymans Date: Mon, 18 Oct 2021 21:17:36 +0200 Subject: [PATCH] resample: add some float math optimization Multiplying and adding the smaller floats first will reduce the amount of rounding errors. --- spa/plugins/audioconvert/resample-native.c | 16 ++++++++++++++-- 1 file changed, 14 insertions(+), 2 deletions(-) diff --git a/spa/plugins/audioconvert/resample-native.c b/spa/plugins/audioconvert/resample-native.c index d66bacd00..f522d67e2 100644 --- a/spa/plugins/audioconvert/resample-native.c +++ b/spa/plugins/audioconvert/resample-native.c @@ -87,10 +87,15 @@ static void inner_product_c(float *d, const float * SPA_RESTRICT s, const float * SPA_RESTRICT taps, uint32_t n_taps) { float sum = 0.0f; +#if 1 + uint32_t i, j, nt2 = n_taps/2; + for (i = 0, j = n_taps-1; i < nt2; i++, j--) + sum += s[i] * taps[i] + s[j] * taps[j]; +#else uint32_t i; - for (i = 0; i < n_taps; i++) sum += s[i] * taps[i]; +#endif *d = sum; } @@ -100,11 +105,18 @@ static void inner_product_ip_c(float *d, const float * SPA_RESTRICT s, { float sum[2] = { 0.0f, 0.0f }; uint32_t i; - +#if 1 + uint32_t j, nt2 = n_taps/2; + for (i = 0, j = n_taps-1; i < nt2; i++, j--) { + sum[0] += s[i] * t0[i] + s[j] * t0[j]; + sum[1] += s[i] * t1[i] + s[j] * t1[j]; + } +#else for (i = 0; i < n_taps; i++) { sum[0] += s[i] * t0[i]; sum[1] += s[i] * t1[i]; } +#endif *d = (sum[1] - sum[0]) * x + sum[0]; }