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audio/softsynth/pcspk.cpp

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+/* ScummVM - Graphic Adventure Engine
+ *
+ * ScummVM is the legal property of its developers, whose names
+ * are too numerous to list here. Please refer to the COPYRIGHT
+ * file distributed with this source distribution.
+ *
+ * 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 3 of the License, 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.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include "audio/softsynth/pcspk.h"
+#include "audio/null.h"
+
+#include "common/queue.h"
+#include "common/translation.h"
+
+namespace Audio {
+
+PCSpeakerStream::Command::Command(PCSpeaker::WaveForm aWaveForm, float aFrequency, uint32 aLength) :
+	waveForm(aWaveForm), frequency(aFrequency), length(aLength) { }
+
+const PCSpeakerStream::generatorFunc PCSpeakerStream::generateWave[] =
+	{&PCSpeakerStream::generateSquare, &PCSpeakerStream::generateSine,
+	 &PCSpeakerStream::generateSaw,    &PCSpeakerStream::generateTriangle,
+	 &PCSpeakerStream::generateSilence};
+
+PCSpeakerStream::PCSpeakerStream(int rate) {
+	_rate = rate;
+	_wave = PCSpeaker::kWaveFormSquare;
+	_playForever = false;
+	_oscLength = 0;
+	_oscSamples = 0;
+	_remainingSamples = 0;
+	_mixedSamples = 0;
+	_volume = 20; // The maximum volume is 255
+	_commandQueue = new Common::Queue<Command>();
+	_commandActive = false;
+}
+
+PCSpeakerStream::~PCSpeakerStream() {
+	delete _commandQueue;
+}
+
+void PCSpeakerStream::play(PCSpeaker::WaveForm wave, int freq, int32 length) {
+	Common::StackLock lock(_mutex);
+
+	assert((wave >= PCSpeaker::kWaveFormSquare) && (wave <= PCSpeaker::kWaveFormTriangle));
+
+	if (_commandActive || !_commandQueue->empty())
+		// Currently playing back a queued instruction. Stop playback and clear
+		// the instruction queue.
+		stop(0);
+
+	_wave = wave;
+	_oscLength = _rate / freq;
+	_oscSamples = 0;
+	if (length == -1) {
+		_remainingSamples = 1;
+		_playForever = true;
+	} else {
+		_remainingSamples = (_rate * length) / 1000;
+		_playForever = false;
+	}
+	_mixedSamples = 0;
+}
+
+void PCSpeakerStream::playQueue(PCSpeaker::WaveForm wave, float freq, uint32 lengthus) {
+	Common::StackLock lock(_mutex);
+
+	// Put the new instruction in the queue. This will be picked up by the
+	// readBuffer method.
+	_commandQueue->push(Command(wave, freq, lengthus));
+}
+
+void PCSpeakerStream::stop(int32 delay) {
+	Common::StackLock lock(_mutex);
+
+	_commandQueue->clear();
+	uint32 delaySamples = (_rate * delay) / 1000;
+	if (_commandActive) {
+		_remainingSamples = MIN(_remainingSamples, delaySamples);
+	} else {
+		_remainingSamples = delaySamples;
+	}
+	_playForever = false;
+}
+
+bool PCSpeakerStream::isPlaying() const {
+	Common::StackLock lock(_mutex);
+
+	return _remainingSamples != 0 || !_commandQueue->empty();
+}
+
+int PCSpeakerStream::readBuffer(int16 *buffer, const int numSamples) {
+	Common::StackLock lock(_mutex);
+
+	// The total number of samples generated.
+	int generatedSamples = 0;
+	// Keep generating samples when not enough have been generated and either
+	// the current instruction has not yet finished, or there are more
+	// instructions in the queue.
+	while (generatedSamples < numSamples && (_remainingSamples > 0 || !_commandQueue->empty())) {
+		if (!_commandActive && !_commandQueue->empty()) {
+			// No playback instruction is currently being processed, but there
+			// are instructions in the queue. Start processing the first queued
+			// instruction.
+			// Note that this will end playback started by the play method.
+			Command command = _commandQueue->pop();
+			_wave = command.waveForm;
+			_oscLength = (uint32)(_rate / command.frequency);
+			_oscSamples = 0;
+			// Length is in microseconds.
+			_remainingSamples = ((uint64)_rate * (uint64)command.length) / 1000000;
+			_playForever = false;
+			_commandActive = true;
+		}
+
+		// The number of samples generated by this playback instruction.
+		int commandSamples;
+
+		// Offset the samples for this command by the number of previously
+		// generated samples.
+		for (commandSamples = 0; _remainingSamples && ((generatedSamples + commandSamples) < numSamples); commandSamples++) {
+			buffer[generatedSamples + commandSamples] = generateWave[_wave](_oscSamples, _oscLength) * _volume;
+			if (_oscSamples++ >= _oscLength)
+				_oscSamples = 0;
+			if (!_playForever)
+				_remainingSamples--;
+			_mixedSamples++;
+		}
+
+		generatedSamples += commandSamples;
+
+		if (_remainingSamples == 0)
+			// Current playback instruction has finished.
+			_commandActive = false;
+	}
+
+	// Clear the rest of the buffer
+	if (generatedSamples < numSamples)
+		memset(buffer + generatedSamples, 0, (numSamples - generatedSamples) * sizeof(int16));
+
+	return numSamples;
+}
+
+int8 PCSpeakerStream::generateSquare(uint32 x, uint32 oscLength) {
+	return (x < (oscLength / 2)) ? 127 : -128;
+}
+
+int8 PCSpeakerStream::generateSine(uint32 x, uint32 oscLength) {
+	if (oscLength == 0)
+		return 0;
+
+	// TODO: Maybe using a look-up-table would be better?
+	return CLIP<int16>((int16) (128 * sin(2.0 * M_PI * x / oscLength)), -128, 127);
+}
+
+int8 PCSpeakerStream::generateSaw(uint32 x, uint32 oscLength) {
+	if (oscLength == 0)
+		return 0;
+
+	return ((x * (65536 / oscLength)) >> 8) - 128;
+}
+
+int8 PCSpeakerStream::generateTriangle(uint32 x, uint32 oscLength) {
+	if (oscLength == 0)
+		return 0;
+
+	int y = ((x * (65536 / (oscLength / 2))) >> 8) - 128;
+
+	return (x <= (oscLength / 2)) ? y : (256 - y);
+}
+
+int8 PCSpeakerStream::generateSilence(uint32 x, uint32 oscLength) {
+	return 0;
+}
+
+PCSpeaker::PCSpeaker() : _speakerStream(nullptr) {
+}
+
+PCSpeaker::~PCSpeaker() {
+	quit();
+}
+
+bool PCSpeaker::init() {
+	quit();
+
+	Mixer *mixer = g_system->getMixer();
+	if (!mixer || !mixer->isReady())
+		return false;
+
+	_speakerStream = new Audio::PCSpeakerStream(mixer->getOutputRate());
+	mixer->playStream(Audio::Mixer::kSFXSoundType, &_speakerHandle,
+	                  _speakerStream, -1, Audio::Mixer::kMaxChannelVolume, 0, DisposeAfterUse::NO, true);
+	return true;
+}
+
+void PCSpeaker::quit() {
+	Mixer *mixer = g_system->getMixer();
+	if (!mixer)
+		return;
+
+	mixer->stopHandle(_speakerHandle);
+	delete _speakerStream;
+	_speakerStream = nullptr;
+}
+
+void PCSpeaker::play(WaveForm wave, int freq, int32 length) {
+	assert(_speakerStream);
+	_speakerStream->play(wave, freq, length);
+}
+
+void PCSpeaker::playQueue(WaveForm wave, float freq, uint32 lengthus) {
+	assert(_speakerStream);
+	_speakerStream->playQueue(wave, freq, lengthus);
+}
+
+void PCSpeaker::stop(int32 delay) {
+	assert(_speakerStream);
+	_speakerStream->stop(delay);
+}
+
+bool PCSpeaker::isPlaying() const {
+	assert(_speakerStream);
+	return _speakerStream->isPlaying();
+}
+
+} // End of namespace Audio
+
+
+//	Plugin interface
+//	(This can only create a null driver since pc speaker support is not part of the
+//	midi driver architecture. But we need the plugin for the options menu in the launcher
+//	and for MidiDriver::detectDevice() which is more or less used by all engines.)
+
+class PCSpeakerMusicPlugin : public NullMusicPlugin {
+public:
+	const char *getName() const override {
+		return _s("PC Speaker emulator");
+	}
+
+	const char *getId() const override {
+		return "pcspk";
+	}
+
+	MusicDevices getDevices() const override;
+};
+
+MusicDevices PCSpeakerMusicPlugin::getDevices() const {
+	MusicDevices devices;
+	devices.push_back(MusicDevice(this, "", MT_PCSPK));
+	return devices;
+}
+
+class PCjrMusicPlugin : public NullMusicPlugin {
+public:
+	const char *getName() const override {
+		return _s("IBM PCjr emulator");
+	}
+
+	const char *getId() const override {
+		return "pcjr";
+	}
+
+	MusicDevices getDevices() const override;
+};
+
+MusicDevices PCjrMusicPlugin::getDevices() const {
+	MusicDevices devices;
+	devices.push_back(MusicDevice(this, "", MT_PCJR));
+	return devices;
+}
+
+//#if PLUGIN_ENABLED_DYNAMIC(PCSPK)
+	//REGISTER_PLUGIN_DYNAMIC(PCSPK, PLUGIN_TYPE_MUSIC, PCSpeakerMusicPlugin);
+//#else
+	REGISTER_PLUGIN_STATIC(PCSPK, PLUGIN_TYPE_MUSIC, PCSpeakerMusicPlugin);
+//#endif
+
+//#if PLUGIN_ENABLED_DYNAMIC(PCJR)
+	//REGISTER_PLUGIN_DYNAMIC(PCJR, PLUGIN_TYPE_MUSIC, PCjrMusicPlugin);
+//#else
+	REGISTER_PLUGIN_STATIC(PCJR, PLUGIN_TYPE_MUSIC, PCjrMusicPlugin);
+//#endif