Transmit ChannelSpectrum data through separate FIFO.

Allows handling of data during LCD "vertical retrace", independent of other baseband->application messages. A bit kludgy still...

firmware/application/ui_spectrum.cpp

@@ -237,15 +237,20 @@ WaterfallWidget::WaterfallWidget() {
 }
 
 void WaterfallWidget::on_show() {
-	context().message_map().register_handler(Message::ID::ChannelSpectrum,
+	context().message_map().register_handler(Message::ID::FIFONotify,
 		[this](const Message* const p) {
-			this->on_channel_spectrum(reinterpret_cast<const ChannelSpectrumMessage*>(p)->spectrum);
+			const auto message = reinterpret_cast<const FIFONotifyMessage*>(p);
+			auto fifo = reinterpret_cast<ChannelSpectrumFIFO*>(message->fifo);
+			ChannelSpectrum channel_spectrum;
+			if( fifo->out(channel_spectrum) ) {
+				this->on_channel_spectrum(channel_spectrum);
+			}
 		}
 	);
 }
 
 void WaterfallWidget::on_hide() {
-	context().message_map().unregister_handler(Message::ID::ChannelSpectrum);
+	context().message_map().unregister_handler(Message::ID::FIFONotify);
 }
 
 void WaterfallWidget::set_parent_rect(const Rect new_parent_rect) {

firmware/baseband/spectrum_collector.cpp

@@ -73,8 +73,8 @@ void SpectrumCollector::update() {
 		channel_spectrum_request_update = false;
 		fft_c_preswapped(channel_spectrum);
 
-		ChannelSpectrumMessage spectrum_message;
-		for(size_t i=0; i<spectrum_message.spectrum.db.size(); i++) {
+		ChannelSpectrum spectrum;
+		for(size_t i=0; i<spectrum.db.size(); i++) {
 			// Three point Hamming window.
 			const auto corrected_sample = channel_spectrum[i] * 0.54f
 				+ (channel_spectrum[(i-1) & 0xff] + channel_spectrum[(i+1) & 0xff]) * -0.23f;
@@ -82,14 +82,16 @@ void SpectrumCollector::update() {
 			const float db = complex16_mag_squared_to_dbv_norm(mag2);
 			constexpr float mag_scale = 5.0f;
 			const unsigned int v = (db * mag_scale) + 255.0f;
-			spectrum_message.spectrum.db[i] = std::max(0U, std::min(255U, v));
+			spectrum.db[i] = std::max(0U, std::min(255U, v));
 		}
 
 		/* TODO: Rename .db -> .magnitude, or something more (less!) accurate. */
-		spectrum_message.spectrum.db_count = spectrum_message.spectrum.db.size();
-		spectrum_message.spectrum.sampling_rate = channel_spectrum_sampling_rate;
-		spectrum_message.spectrum.channel_filter_pass_frequency = channel_filter_pass_frequency;
-		spectrum_message.spectrum.channel_filter_stop_frequency = channel_filter_stop_frequency;
-		shared_memory.application_queue.push(spectrum_message);
+		spectrum.db_count = spectrum.db.size();
+		spectrum.sampling_rate = channel_spectrum_sampling_rate;
+		spectrum.channel_filter_pass_frequency = channel_filter_pass_frequency;
+		spectrum.channel_filter_stop_frequency = channel_filter_stop_frequency;
+		fifo.in(spectrum);
+		FIFONotifyMessage message { &fifo };
+		shared_memory.application_queue.push(message);
 	}
 }

firmware/baseband/spectrum_collector.hpp

@@ -30,6 +30,8 @@
 #include <cstdint>
 #include <array>
 
+#include "message.hpp"
+
 class SpectrumCollector {
 public:
 	constexpr SpectrumCollector(
@@ -49,6 +51,7 @@ public:
 
 private:
 	BlockDecimator<256> channel_spectrum_decimator;
+	ChannelSpectrumFIFO fifo;
 
 	volatile bool channel_spectrum_request_update { false };
 	std::array<std::complex<float>, 256> channel_spectrum;

firmware/common/message.hpp

@@ -30,6 +30,7 @@
 #include "baseband_packet.hpp"
 #include "ert_packet.hpp"
 #include "dsp_fir_taps.hpp"
+#include "fifo.hpp"
 
 #include "utility.hpp"
 
@@ -44,7 +45,7 @@ public:
 		RSSIStatistics = 0,
 		BasebandStatistics = 1,
 		ChannelStatistics = 2,
-		ChannelSpectrum = 3,
+
 		AudioStatistics = 4,
 		BasebandConfiguration = 5,
 		TPMSPacket = 6,
@@ -55,6 +56,7 @@ public:
 		NBFMConfigure = 11,
 		WFMConfigure = 12,
 		AMConfigure = 13,
+		FIFONotify = 14,
 		MAX
 	};
 
@@ -207,15 +209,7 @@ struct ChannelSpectrum {
 	uint32_t channel_filter_stop_frequency { 0 };
 };
 
-class ChannelSpectrumMessage : public Message {
-public:
-	constexpr ChannelSpectrumMessage(
-	) : Message { ID::ChannelSpectrum }
-	{
-	}
-
-	ChannelSpectrum spectrum;
-};
+using ChannelSpectrumFIFO = FIFO<ChannelSpectrum, 2>;
 
 class AISPacketMessage : public Message {
 public:
@@ -333,6 +327,18 @@ public:
 	const fir_taps_real<32> channel_filter;
 };
 
+class FIFONotifyMessage : public Message {
+public:
+	constexpr FIFONotifyMessage(
+		void* const fifo
+	) : Message { ID::FIFONotify },
+		fifo { fifo }
+	{
+	}
+
+	void* const fifo;
+};
+
 class MessageHandlerMap {
 public:
 	using MessageHandler = std::function<void(Message* const p)>;