From 060da5d22762f7ab28023c49ae6caab82a93d834 Mon Sep 17 00:00:00 2001
From: Jared Boone <jboone@earfeast.com>
Date: Thu, 19 Nov 2015 12:24:20 -0800
Subject: [PATCH] Add ChannelDecimator decimate by 2 and no-shift options.

---
 firmware/baseband/channel_decimator.cpp | 23 +++++++++++++++--------
 firmware/baseband/channel_decimator.hpp | 20 ++++++++++++++------
 2 files changed, 29 insertions(+), 14 deletions(-)

diff --git a/firmware/baseband/channel_decimator.cpp b/firmware/baseband/channel_decimator.cpp
index a7e7edf7..80bd136b 100644
--- a/firmware/baseband/channel_decimator.cpp
+++ b/firmware/baseband/channel_decimator.cpp
@@ -39,14 +39,10 @@ buffer_c16_t ChannelDecimator::execute_decimation(buffer_c8_t buffer) {
 	 * -> gain of 256
 	 * -> decimation by 2
 	 * -> 1.544MHz complex<int16_t>[1024], [-32768, 32512] */
-	const auto stage_0_out = translate.execute(buffer, work_baseband_buffer);
-
-	//if( fs_over_4_downconvert ) {
-	//	// TODO:
-	//} else {
-	// Won't work until cic_0 will accept input type of buffer_c8_t.
-	//	stage_0_out = cic_0.execute(buffer, work_baseband_buffer);
-	//}
+	auto stage_0_out = execute_stage_0(buffer, work_baseband_buffer);
+	if( decimation_factor == DecimationFactor::By2 ) {
+		return stage_0_out;
+	}
 
 	/* 1.536MHz complex<int16_t>[1024], [-32768, 32512]
 	 * -> 3rd order CIC: -0.1dB @ 0.028fs, -1dB @ 0.088fs, -60dB @ 0.468fs
@@ -82,3 +78,14 @@ buffer_c16_t ChannelDecimator::execute_decimation(buffer_c8_t buffer) {
 
 	return cic_4_out;
 }
+
+buffer_c16_t ChannelDecimator::execute_stage_0(
+	buffer_c8_t buffer,
+	buffer_c16_t work_baseband_buffer
+) {
+	if( fs_over_4_downconvert ) {
+		return translate.execute(buffer, work_baseband_buffer);
+	} else {
+		return cic_0.execute(buffer, work_baseband_buffer);
+	}
+}
diff --git a/firmware/baseband/channel_decimator.hpp b/firmware/baseband/channel_decimator.hpp
index 3e20c0df..10a65033 100644
--- a/firmware/baseband/channel_decimator.hpp
+++ b/firmware/baseband/channel_decimator.hpp
@@ -32,6 +32,7 @@
 class ChannelDecimator {
 public:
 	enum class DecimationFactor {
+		By2,
 		By4,
 		By8,
 		By16,
@@ -39,13 +40,16 @@ public:
 	};
 
 	constexpr ChannelDecimator(
-	) : decimation_factor { DecimationFactor::By32 }
+	) : decimation_factor { DecimationFactor::By32 },
+		fs_over_4_downconvert { true }
 	{
 	}
 	
 	constexpr ChannelDecimator(
-		const DecimationFactor decimation_factor
-	) : decimation_factor { decimation_factor }
+		const DecimationFactor decimation_factor,
+		const bool fs_over_4_downconvert = true
+	) : decimation_factor { decimation_factor },
+		fs_over_4_downconvert { fs_over_4_downconvert }
 	{
 	}
 
@@ -62,18 +66,22 @@ public:
 private:
 	std::array<complex16_t, 1024> work_baseband;
 
-	//const bool fs_over_4_downconvert = true;
-
 	dsp::decimate::TranslateByFSOver4AndDecimateBy2CIC3 translate;
-	//dsp::decimate::DecimateBy2CIC3 cic_0;
+	dsp::decimate::Complex8DecimateBy2CIC3 cic_0;
 	dsp::decimate::DecimateBy2CIC3 cic_1;
 	dsp::decimate::DecimateBy2CIC3 cic_2;
 	dsp::decimate::DecimateBy2CIC3 cic_3;
 	dsp::decimate::DecimateBy2CIC3 cic_4;
 
 	DecimationFactor decimation_factor;
+	const bool fs_over_4_downconvert;
 
 	buffer_c16_t execute_decimation(buffer_c8_t buffer);
+
+	buffer_c16_t execute_stage_0(
+		buffer_c8_t buffer,
+		buffer_c16_t work_baseband_buffer
+	);
 };
 
 #endif/*__CHANNEL_DECIMATOR_H__*/