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/* -*- 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() {
// note: cannot release `params` (seg fault but why?)
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(¶ms);
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;
}
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