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resample: add some float math optimization

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Multiplying and adding the smaller floats first will reduce the amount
of rounding errors.
This commit is contained in:
Wim Taymans 2021-10-18 21:17:36 +02:00
parent cc996b6292
commit 67209b9ecc
1 changed files with 14 additions and 2 deletions
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16
spa/plugins/audioconvert/resample-native.c
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@ -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) const float * SPA_RESTRICT taps, uint32_t n_taps)
{ {
float sum = 0.0f; 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; uint32_t i;
for (i = 0; i < n_taps; i++) for (i = 0; i < n_taps; i++)
sum += s[i] * taps[i]; sum += s[i] * taps[i];
#endif
*d = sum; *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 }; float sum[2] = { 0.0f, 0.0f };
uint32_t i; 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++) { for (i = 0; i < n_taps; i++) {
sum[0] += s[i] * t0[i]; sum[0] += s[i] * t0[i];
sum[1] += s[i] * t1[i]; sum[1] += s[i] * t1[i];
} }
#endif
*d = (sum[1] - sum[0]) * x + sum[0]; *d = (sum[1] - sum[0]) * x + sum[0];
} }