From be78ed657fc23dfdbb41c2a595af4945db0219e7 Mon Sep 17 00:00:00 2001
From: Jared Boone <jboone@earfeast.com>
Date: Tue, 3 Nov 2015 12:11:32 -0800
Subject: [PATCH] Remove taps_count template arg for FIRAndDecimateBy2Complex.

Use heap to allocate samples and taps buffers, so filters of different lengths can be supported.
---
 firmware/baseband/dsp_decimate.hpp   | 42 ++++++++++++++++++++--------
 firmware/baseband/proc_am_audio.hpp  |  2 +-
 firmware/baseband/proc_fsk.hpp       |  2 +-
 firmware/baseband/proc_nfm_audio.hpp |  2 +-
 4 files changed, 34 insertions(+), 14 deletions(-)

diff --git a/firmware/baseband/dsp_decimate.hpp b/firmware/baseband/dsp_decimate.hpp
index d34034e19..aed3dcc61 100644
--- a/firmware/baseband/dsp_decimate.hpp
+++ b/firmware/baseband/dsp_decimate.hpp
@@ -24,6 +24,10 @@
 
 #include <cstdint>
 #include <array>
+#include <memory>
+#include <algorithm>
+
+#include "utility.hpp"
 
 #include "dsp_types.hpp"
 
@@ -83,32 +87,48 @@ size_t fir_and_decimate_by_2_complex_fast(
 	const size_t taps_count
 );
 
-template<size_t taps_count>
 class FIRAndDecimateBy2Complex {
 public:
+	using sample_t = complex16_t;
+	using tap_t = complex16_t;
+
+	using taps_t = tap_t[];
+
 	/* NOTE! Current code makes an assumption that block of samples to be
 	 * processed will be a multiple of the taps_count.
 	 */
 	FIRAndDecimateBy2Complex(
-		const std::array<int16_t, taps_count>& real_taps
-	) {
-		for(size_t i=0; i<taps_count; i++) {
-			taps[             i] = real_taps[i];
-			taps[taps_count + i] = real_taps[i];
-		}
+	 	const size_t taps_count
+	) : samples_ { std::make_unique<samples_t>(taps_count) },
+		taps_reversed_ { std::make_unique<taps_t>(taps_count * 2) },
+		taps_count_ { taps_count }
+	{
+	}
+
+	template<typename T>
+	FIRAndDecimateBy2Complex(
+		const T& taps
+	) : FIRAndDecimateBy2Complex(taps.size())
+	{
+		std::reverse_copy(taps.cbegin(), taps.cend(), &taps_reversed_[0]);
+		std::reverse_copy(taps.cbegin(), taps.cend(), &taps_reversed_[taps.size()]);
 	}
 
 	buffer_c16_t execute(
 		buffer_c16_t src,
 		buffer_c16_t dst
 	) {
-		const auto dst_count = fir_and_decimate_by_2_complex_fast(src.p, src.count, dst.p, z.data(), taps.data(), taps_count);
-		return { dst.p, dst_count, src.sampling_rate / 2 };
+		const auto dst_count = fir_and_decimate_by_2_complex_fast(src.p, src.count, dst.p, &samples_[0], &taps_reversed_[0], taps_count_);
+		return { dst.p, dst_count, src.sampling_rate / decimation_factor };
 	}
 
 private:
-	std::array<complex16_t, taps_count * 2> taps;
-	std::array<complex16_t, taps_count> z;
+	using samples_t = sample_t[];
+
+	const std::unique_ptr<samples_t> samples_;
+	const std::unique_ptr<taps_t> taps_reversed_;
+	const size_t taps_count_;
+	const size_t decimation_factor { 2 };
 };
 
 class DecimateBy2CIC4Real {
diff --git a/firmware/baseband/proc_am_audio.hpp b/firmware/baseband/proc_am_audio.hpp
index 5ba413026..1302a2eab 100644
--- a/firmware/baseband/proc_am_audio.hpp
+++ b/firmware/baseband/proc_am_audio.hpp
@@ -38,7 +38,7 @@ public:
 private:
 	ChannelDecimator decimator { ChannelDecimator::DecimationFactor::By32 };
 	const fir_taps_real<64>& channel_filter_taps = taps_64_lp_031_070_tfilter;
-	dsp::decimate::FIRAndDecimateBy2Complex<64> channel_filter { channel_filter_taps.taps };
+	dsp::decimate::FIRAndDecimateBy2Complex channel_filter { channel_filter_taps.taps };
 	dsp::demodulate::AM demod;
 	IIRBiquadFilter audio_hpf { audio_hpf_config };
 };
diff --git a/firmware/baseband/proc_fsk.hpp b/firmware/baseband/proc_fsk.hpp
index c8515fac4..4af865924 100644
--- a/firmware/baseband/proc_fsk.hpp
+++ b/firmware/baseband/proc_fsk.hpp
@@ -55,7 +55,7 @@ private:
 	
 	ChannelDecimator decimator { ChannelDecimator::DecimationFactor::By16 };
 	const fir_taps_real<64>& channel_filter_taps = taps_64_lp_031_070_tfilter;
-	dsp::decimate::FIRAndDecimateBy2Complex<64> channel_filter { channel_filter_taps.taps };
+	dsp::decimate::FIRAndDecimateBy2Complex channel_filter { channel_filter_taps.taps };
 
 	dsp::matched_filter::MatchedFilter mf { baseband::ais::rrc_taps_128_decim_4_p, 1 };
 
diff --git a/firmware/baseband/proc_nfm_audio.hpp b/firmware/baseband/proc_nfm_audio.hpp
index 9ecd0fa70..72437adce 100644
--- a/firmware/baseband/proc_nfm_audio.hpp
+++ b/firmware/baseband/proc_nfm_audio.hpp
@@ -39,7 +39,7 @@ public:
 private:
 	ChannelDecimator decimator { ChannelDecimator::DecimationFactor::By32 };
 	const fir_taps_real<64>& channel_filter_taps = taps_64_lp_042_078_tfilter;
-	dsp::decimate::FIRAndDecimateBy2Complex<64> channel_filter { channel_filter_taps.taps };
+	dsp::decimate::FIRAndDecimateBy2Complex channel_filter { channel_filter_taps.taps };
 	dsp::demodulate::FM demod { 48000, 7500 };
 
 	IIRBiquadFilter audio_hpf { audio_hpf_config };