Initial commit

backends/mixer/null/null-mixer.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 "backends/mixer/null/null-mixer.h"
+#include "common/savefile.h"
+
+NullMixerManager::NullMixerManager() : MixerManager() {
+	_outputRate = 22050;
+	_callsCounter = 0;
+	_samples = 8192;
+	while (_samples * 16 > _outputRate * 2)
+		_samples >>= 1;
+	_samplesBuf = new uint8[_samples * 4];
+}
+
+NullMixerManager::~NullMixerManager() {
+	delete[] _samplesBuf;
+}
+
+void NullMixerManager::init() {
+	_mixer = new Audio::MixerImpl(_outputRate, true, _samples);
+	assert(_mixer);
+	_mixer->setReady(true);
+}
+
+void NullMixerManager::suspendAudio() {
+	_audioSuspended = true;
+}
+
+int NullMixerManager::resumeAudio() {
+	if (!_audioSuspended) {
+		return -2;
+	}
+	_audioSuspended = false;
+	return 0;
+}
+
+bool NullMixerManager::isNullDevice() const {
+	return true;
+}
+
+void NullMixerManager::update(uint8 callbackPeriod) {
+	if (_audioSuspended) {
+		return;
+	}
+	_callsCounter++;
+	if ((_callsCounter % callbackPeriod) == 0) {
+		assert(_mixer);
+		_mixer->mixCallback(_samplesBuf, _samples);
+	}
+}

backends/mixer/null/null-mixer.h

@@ -0,0 +1,56 @@
+/* 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/>.
+ *
+ */
+
+#ifndef BACKENDS_MIXER_NULL_H
+#define BACKENDS_MIXER_NULL_H
+
+#include "backends/mixer/mixer.h"
+
+/** Audio mixer which in fact does not output audio.
+ *
+ *  It is used by events recorder since the recorder is intentionally
+ *  turning sound off to avoid stuttering.
+ *
+ *  It returns correct output and shoots callbacks, so all OSystem
+ *  users could work without modifications.
+ */
+
+class NullMixerManager : public MixerManager {
+public:
+	NullMixerManager();
+	virtual ~NullMixerManager();
+
+	void init() override;
+	void update(uint8 callbackPeriod = 10);
+
+	void suspendAudio() override;
+	int resumeAudio() override;
+
+	bool isNullDevice() const override;
+
+private:
+	uint32 _outputRate;
+	uint32 _callsCounter;
+	uint32 _samples;
+	uint8 *_samplesBuf;
+};
+
+#endif