Refactor of capture buffer management between cores.

Instead of copying data into and out of FIFO, passing buffer pointers between cores that are sized to match preferred/ideal SD card write size.

firmware/baseband/Makefile

@@ -146,6 +146,7 @@ CPPSRC = main.cpp \
          proc_tpms.cpp \
          proc_ert.cpp \
          proc_capture.cpp \
+         stream_input.cpp \
          dsp_squelch.cpp \
          clock_recovery.cpp \
          packet_builder.cpp \

firmware/baseband/stream_input.cpp

@@ -0,0 +1,76 @@
+/*
+ * Copyright (C) 2016 Jared Boone, ShareBrained Technology, Inc.
+ *
+ * This file is part of PortaPack.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2, or (at your option)
+ * any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; see the file COPYING.  If not, write to
+ * the Free Software Foundation, Inc., 51 Franklin Street,
+ * Boston, MA 02110-1301, USA.
+ */
+
+#include "stream_input.hpp"
+
+#include "lpc43xx_cpp.hpp"
+using namespace lpc43xx;
+
+StreamInput::StreamInput(CaptureConfig* const config) :
+	fifo_buffers_empty { buffers_empty.data(), buffer_count_max_log2 },
+	fifo_buffers_full { buffers_full.data(), buffer_count_max_log2 },
+	config { config },
+	data { std::make_unique<uint8_t[]>(config->write_size * config->buffer_count) }
+{
+	config->fifo_buffers_empty = &fifo_buffers_empty;
+	config->fifo_buffers_full = &fifo_buffers_full;
+
+	for(size_t i=0; i<config->buffer_count; i++) {
+		buffers[i] = { &(data.get()[i * config->write_size]), config->write_size };
+		fifo_buffers_empty.in(&buffers[i]);
+	}
+}
+
+size_t StreamInput::write(const void* const data, const size_t length) {
+	const uint8_t* p = static_cast<const uint8_t*>(data);
+	size_t written = 0;
+
+	while( written < length ) {
+		if( !active_buffer ) {
+			// We need an empty buffer...
+			if( !fifo_buffers_empty.out(active_buffer) ) {
+				// ...but none are available. Samples were dropped.
+				break;
+			}
+		}
+		
+		const auto remaining = length - written;
+		written += active_buffer->write(&p[written], remaining);
+
+		if( active_buffer->is_full() ) {
+			if( !fifo_buffers_full.in(active_buffer) ) {
+				// FIFO is fuil of buffers, there's no place for this one.
+				// Bail out of the loop, and try submitting the buffer in the
+				// next pass.
+				// This should never happen if the number of buffers is less
+				// than the capacity of the FIFO.
+				break;
+			}
+			active_buffer = nullptr;
+			creg::m4txevent::assert();
+		}
+	}
+
+	config->baseband_bytes_received += length;
+	config->baseband_bytes_dropped += (length - written);
+
+	return written;
+}

firmware/baseband/stream_input.hpp

@@ -25,46 +25,29 @@
 #include "message.hpp"
 #include "fifo.hpp"
 
-#include "lpc43xx_cpp.hpp"
-using namespace lpc43xx;
-
 #include <cstdint>
 #include <cstddef>
+#include <array>
 #include <memory>
 
 class StreamInput {
 public:
-	StreamInput(CaptureConfig* const config) :
-		config { config },
-		K { config->write_size_log2 + config->buffer_count_log2 },
-		event_bytes_mask { (1UL << config->write_size_log2) - 1 },
-		data { std::make_unique<uint8_t[]>(1UL << K) },
-		fifo { data.get(), K }
-	{
-		config->fifo = &fifo;
-	}
+	StreamInput(CaptureConfig* const config);
 
-	size_t write(const void* const data, const size_t length) {
-		const auto written = fifo.in(reinterpret_cast<const uint8_t*>(data), length);
-
-		const auto last_bytes_written = bytes_written;
-		bytes_written += written;
-		if( (bytes_written & event_bytes_mask) < (last_bytes_written & event_bytes_mask) ) {
-			creg::m4txevent::assert();
-		}
-		config->baseband_bytes_received += length;
-		config->baseband_bytes_dropped = config->baseband_bytes_received - bytes_written;
-
-		return written;
-	}
+	size_t write(const void* const data, const size_t length);
 
 private:
-	CaptureConfig* const config;
-	const size_t K;
-	const uint64_t event_bytes_mask;
-	uint64_t bytes_written = 0;
+	static constexpr size_t buffer_count_max_log2 = 3;
+	static constexpr size_t buffer_count_max = 1U << buffer_count_max_log2;
+	
+	FIFO<StreamBuffer*> fifo_buffers_empty;
+	FIFO<StreamBuffer*> fifo_buffers_full;
+	std::array<StreamBuffer, buffer_count_max> buffers;
+	std::array<StreamBuffer*, buffer_count_max> buffers_empty;
+	std::array<StreamBuffer*, buffer_count_max> buffers_full;
+	StreamBuffer* active_buffer { nullptr };
+	CaptureConfig* const config { nullptr };
 	std::unique_ptr<uint8_t[]> data;
-	FIFO<uint8_t> fifo;
 };
 
 #endif/*__STREAM_INPUT_H__*/