Simplify RSSI/BB DMA, extract to ThreadWait class.

Also saved 688 bytes of code.

firmware/baseband/Makefile

@@ -126,6 +126,7 @@ CPPSRC = main.cpp \
          message_queue.cpp \
          event.cpp \
          event_m4.cpp \
+         thread_wait.cpp \
          gpdma.cpp \
          baseband_dma.cpp \
          baseband_sgpio.cpp \

firmware/baseband/baseband_dma.cpp

@@ -32,6 +32,8 @@ using namespace lpc43xx;
 
 #include "portapack_dma.hpp"
 
+#include "thread_wait.hpp"
+
 namespace baseband {
 namespace dma {
 
@@ -99,21 +101,19 @@ constexpr size_t msg_count = transfers_per_buffer - 1;
 static std::array<gpdma::channel::LLI, transfers_per_buffer> lli_loop;
 static constexpr auto& gpdma_channel_sgpio = gpdma::channels[portapack::sgpio_gpdma_channel_number];
 
-static Semaphore semaphore;
-
-static volatile const gpdma::channel::LLI* next_lli = nullptr;
+static ThreadWait thread_wait;
 
 static void transfer_complete() {
-	next_lli = gpdma_channel_sgpio.next_lli();
-	chSemSignalI(&semaphore);
+	const auto next_lli_index = gpdma_channel_sgpio.next_lli() - &lli_loop[0];
+	thread_wait.wake_from_interrupt(next_lli_index);
 }
 
 static void dma_error() {
+	thread_wait.wake_from_interrupt(-1);
 	disable();
 }
 
 void init() {
-	chSemInit(&semaphore, 0);
 	gpdma_channel_sgpio.set_handlers(transfer_complete, dma_error);
 
 	// LPC_GPDMA->SYNC |= (1 << gpdma_src_peripheral);
@@ -138,9 +138,6 @@ void configure(
 void enable(const baseband::Direction direction) {
 	const auto gpdma_config = config(direction);
 	gpdma_channel_sgpio.configure(lli_loop[0], gpdma_config);
-
-	chSemReset(&semaphore, 0);
-
 	gpdma_channel_sgpio.enable();
 }
 
@@ -153,16 +150,11 @@ void disable() {
 }
 
 baseband::buffer_t wait_for_rx_buffer() {
-	const auto status = chSemWait(&semaphore);
-	if( status == RDY_OK ) {
-		const auto next = next_lli;
-		if( next ) {
-			const size_t next_index = next - &lli_loop[0];
-			const size_t free_index = (next_index + transfers_per_buffer - 2) & transfers_mask;
-			return { reinterpret_cast<sample_t*>(lli_loop[free_index].destaddr), transfer_samples };
-		} else {
-			return { };
-		}
+	const auto next_index = thread_wait.sleep();
+	
+	if( next_index >= 0 ) {
+		const size_t free_index = (next_index + transfers_per_buffer - 2) & transfers_mask;
+		return { reinterpret_cast<sample_t*>(lli_loop[free_index].destaddr), transfer_samples };
 	} else {
 		return { };
 	}

firmware/baseband/rssi_dma.cpp

@@ -33,6 +33,8 @@ using namespace lpc43xx;
 #include "portapack_dma.hpp"
 #include "portapack_adc.hpp"
 
+#include "thread_wait.hpp"
+
 namespace rf {
 namespace rssi {
 namespace dma {
@@ -99,20 +101,19 @@ static buffers_config_t			buffers_config;
 static sample_t				*samples	{ nullptr };
 static gpdma::channel::LLI	*lli		{ nullptr };
 
-static Semaphore semaphore;
-static volatile const gpdma::channel::LLI* next_lli = nullptr;
+static ThreadWait thread_wait;
 
 static void transfer_complete() {
-	next_lli = gpdma_channel.next_lli();
-	chSemSignalI(&semaphore);
+	const auto next_lli_index = gpdma_channel.next_lli() - &lli[0];
+	thread_wait.wake_from_interrupt(next_lli_index);
 }
 
 static void dma_error() {
+	thread_wait.wake_from_interrupt(-1);
 	disable();
 }
 
 void init() {
-	chSemInit(&semaphore, 0);
 	gpdma_channel.set_handlers(transfer_complete, dma_error);
 
 	// LPC_GPDMA->SYNC |= (1 << gpdma_peripheral);
@@ -147,8 +148,6 @@ void free() {
 void enable() {
 	const auto gpdma_config = config();
 	gpdma_channel.configure(lli[0], gpdma_config);
-
-	chSemReset(&semaphore, 0);
 	gpdma_channel.enable();
 }
 
@@ -161,16 +160,11 @@ void disable() {
 }
 
 rf::rssi::buffer_t wait_for_buffer() {
-	const auto status = chSemWait(&semaphore);
-	if( status == RDY_OK ) {
-		const auto next = next_lli;
-		if( next ) {
-			const size_t next_index = next - &lli[0];
-			const size_t free_index = (next_index + buffers_config.count - 2) % buffers_config.count;
-			return { reinterpret_cast<sample_t*>(lli[free_index].destaddr), buffers_config.items_per_buffer };
-		} else {
-			return { nullptr, 0 };
-		}
+	const auto next_index = thread_wait.sleep();
+
+	if( next_index >= 0 ) {
+		const size_t free_index = (next_index + buffers_config.count - 2) % buffers_config.count;
+		return { reinterpret_cast<sample_t*>(lli[free_index].destaddr), buffers_config.items_per_buffer };
 	} else {
 		// TODO: Should I return here, or loop if RDY_RESET?
 		return { nullptr, 0 };

firmware/common/thread_wait.cpp

@@ -0,0 +1,42 @@
+/*
+ * 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 "thread_wait.hpp"
+
+int ThreadWait::sleep() {
+	chSysLock();
+	thread_to_wake = chThdSelf();
+	chSchGoSleepS(THD_STATE_SUSPENDED);
+	const auto result = chThdSelf()->p_u.rdymsg;
+	chSysUnlock();
+	return result;
+}
+
+bool ThreadWait::wake_from_interrupt(const int value) {
+	if( thread_to_wake ) {
+		thread_to_wake->p_u.rdymsg = value;
+		chSchReadyI(thread_to_wake);
+		thread_to_wake = nullptr;
+		return true;
+	} else {
+		return false;
+	}
+}

firmware/common/thread_wait.hpp

@@ -0,0 +1,36 @@
+/*
+ * 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.
+ */
+
+#ifndef __THREAD_WAIT_H__
+#define __THREAD_WAIT_H__
+
+#include <ch.h>
+
+class ThreadWait {
+public:
+	int sleep();
+	bool wake_from_interrupt(const int value);
+
+private:
+	Thread* thread_to_wake { nullptr };
+};
+
+#endif/*__THREAD_WAIT_H__*/