Added AlsaOutputEngine

1 files changed, 141 insertions, 0 deletions

diff --git a/drumgizmo/output/alsa.cc b/drumgizmo/output/alsa.cc
new file mode 100644
index 0000000..d6a2f19
--- /dev/null
+++ b/drumgizmo/output/alsa.cc
@@ -0,0 +1,141 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/***************************************************************************
+ *            alsa.cc
+ *
+ *  Do 21. Jan 16:48:32 CET 2016
+ *  Copyright 2016 Christian Glöckner
+ *  cgloeckner@freenet.de
+ ****************************************************************************/
+
+/*
+ *  This file is part of DrumGizmo.
+ *
+ *  DrumGizmo 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 of the License, or
+ *  (at your option) any later version.
+ *
+ *  DrumGizmo 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 DrumGizmo; if not, write to the Free Software
+ *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA.
+ */
+#include "alsa.h"
+
+int const BUFFER_SIZE = 40960;
+
+struct AlsaInitError {
+	int const code;
+	std::string const msg;
+	
+	AlsaInitError(int op_code, std::string const & msg)
+		: code{code}
+		, msg{msg} {
+	}
+	
+	static inline void test(int code, std::string const & msg) {
+		if (code < 0) {
+			throw AlsaInitError(code, msg);
+		}
+	}
+};
+
+AlsaOutputEngine::AlsaOutputEngine()
+	: handle{nullptr}
+	, params{nullptr}
+	, data{}
+	, num_channels{0u}
+	, dev{"default"}
+	, srate{44100}
+	, frames{32} {
+}
+
+AlsaOutputEngine::~AlsaOutputEngine() {
+	if (params) {
+		// snd_pcm_hw_params_alloca uses std alloc
+		free(params);
+	}
+	if (handle != nullptr) {
+		snd_pcm_close(handle);
+	}
+}
+
+bool AlsaOutputEngine::init(Channels channels) {
+	// try to initialize alsa
+	try {
+		int value = snd_pcm_open(&handle, dev.c_str(), SND_PCM_STREAM_PLAYBACK, 0);
+		AlsaInitError::test(value, "snd_pcm_open");
+		num_channels = channels.size();
+		if (handle == nullptr) {
+			printf("No handle!\n");
+			return false;
+		}
+		// Allocate and init a hardware parameters object
+		snd_pcm_hw_params_alloca(&params);
+		value = snd_pcm_hw_params_any(handle, params);
+		AlsaInitError::test(value, "snd_pcm_hw_params_any");
+		
+		value = snd_pcm_hw_params_set_access(handle, params, SND_PCM_ACCESS_RW_INTERLEAVED);
+		AlsaInitError::test(value, "snd_pcm_hw_params_set_access");
+		value = snd_pcm_hw_params_set_format(handle, params, SND_PCM_FORMAT_FLOAT);
+		AlsaInitError::test(value, "snd_pcm_hw_params_set_format");
+		value = snd_pcm_hw_params_set_channels(handle, params, num_channels);
+		AlsaInitError::test(value, "snd_pcm_hw_params_set_channels");
+		value = snd_pcm_hw_params_set_rate_near(handle, params, &srate, 0);
+		AlsaInitError::test(value, "snd_pcm_hw_params_set_rate_near");
+		value = snd_pcm_hw_params_set_period_size_near(handle, params, &frames, 0);
+		AlsaInitError::test(value, "snd_pcm_hw_params_set_period_size_near");
+		value = snd_pcm_hw_params(handle, params);
+		AlsaInitError::test(value, "snd_pcm_hw_params");
+		
+	} catch (AlsaInitError const & error) {
+		printf("%s failed: %s\n", error.msg.c_str(), snd_strerror(error.code));
+		fflush(stdout);
+		return false;
+	}
+	
+	data.clear();
+	data.resize(BUFFER_SIZE * num_channels);
+	
+	return true;
+}
+
+void AlsaOutputEngine::setParm(std::string parm, std::string value) {
+	if (parm == "dev") {
+		dev = value;
+	} else if (parm == "frames") {
+		frames = std::stoi(value);
+	} else if (parm == "srate") {
+		srate = std::stoi(value);
+	}
+}
+
+bool AlsaOutputEngine::start() {
+	return true;
+}
+
+void AlsaOutputEngine::stop() {
+}
+
+void AlsaOutputEngine::pre(size_t nsamples) {
+}
+
+void AlsaOutputEngine::run(int ch, sample_t* samples, size_t nsamples) {
+	// Write channel data in interleaved buffer
+	for (auto i = 0u; i < nsamples; ++i) {
+		data[i * num_channels + ch] = samples[i];
+	}
+}
+
+void AlsaOutputEngine::post(size_t nsamples) {
+	// Write the interleaved buffer to the soundcard
+	snd_pcm_writei(handle, data.data(), nsamples);
+}
+
+size_t AlsaOutputEngine::samplerate() {
+	return srate;
+}