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Early calculation to reduce pressure on registers.

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Jared Boone 2015-11-03 17:02:46 -08:00
parent a074e7d8d8
commit 86b068be62
1 changed files with 10 additions and 3 deletions
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15
firmware/baseband/dsp_decimate.cpp
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@ -205,10 +205,15 @@ buffer_c16_t FIRAndDecimateComplex::execute(
* -> int16_t output, decimated by decimation_factor. * -> int16_t output, decimated by decimation_factor.
* taps are normalized to 1 << 16 == 1.0. * taps are normalized to 1 << 16 == 1.0.
*/ */
const sample_t* src_p = src.p; const auto output_sampling_rate = src.sampling_rate / decimation_factor_;
sample_t* dst_p = dst.p; const size_t output_samples = src.count / decimation_factor_;
while(src_p < &src.p[src.count]) { sample_t* dst_p = dst.p;
const buffer_c16_t result { dst.p, output_samples, output_sampling_rate };
const sample_t* src_p = src.p;
size_t outer_count = output_samples;
while(outer_count > 0) {
/* Put two new samples into delay buffer */ /* Put two new samples into delay buffer */
auto z_new_p = &samples_[taps_count_ - decimation_factor_]; auto z_new_p = &samples_[taps_count_ - decimation_factor_];
for(size_t i=0; i<decimation_factor_; i++) { for(size_t i=0; i<decimation_factor_; i++) {
@ -295,9 +300,11 @@ buffer_c16_t FIRAndDecimateComplex::execute(
*(t++) = *(s++); *(t++) = *(s++);
shift_count--; shift_count--;
} }
outer_count--;
} }
return { dst.p, src.count / decimation_factor_, src.sampling_rate / decimation_factor_ }; return result;
} }
buffer_s16_t DecimateBy2CIC4Real::execute( buffer_s16_t DecimateBy2CIC4Real::execute(