ebiten/audio/internal/readerdriver/driver_unix.go

211 lines
4.9 KiB
Go
Raw Normal View History

// Copyright 2021 The Ebiten Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//go:build !android && !darwin && !js && !windows
// +build !android,!darwin,!js,!windows
package readerdriver
// #cgo pkg-config: alsa
//
// #include <alsa/asoundlib.h>
import "C"
import (
"fmt"
"sync"
"time"
"unsafe"
)
func IsAvailable() bool {
return true
}
type context struct {
sampleRate int
channelNum int
bitDepthInBytes int
suspended bool
handle *C.snd_pcm_t
supportsPause bool
cond *sync.Cond
players *players
}
var theContext *context
func alsaError(err C.int) error {
return fmt.Errorf("readerdriver: ALSA error: %s", C.GoString(C.snd_strerror(err)))
}
func NewContext(sampleRate, channelNum, bitDepthInBytes int) (Context, chan struct{}, error) {
ready := make(chan struct{})
close(ready)
c := &context{
sampleRate: sampleRate,
channelNum: channelNum,
bitDepthInBytes: bitDepthInBytes,
cond: sync.NewCond(&sync.Mutex{}),
players: newPlayers(),
}
theContext = c
// Open a default ALSA audio device for blocking stream playback
cname := C.CString("default")
defer C.free(unsafe.Pointer(cname))
if err := C.snd_pcm_open(&c.handle, cname, C.SND_PCM_STREAM_PLAYBACK, 0); err < 0 {
return nil, nil, alsaError(err)
}
periodSize := C.snd_pcm_uframes_t(1024)
bufferSize := periodSize * 2
if err := c.alsaPcmHwParams(sampleRate, channelNum, &bufferSize, &periodSize); err != nil {
return nil, nil, err
}
go func() {
buf32 := make([]float32, int(periodSize)*c.channelNum)
for {
if err := c.readAndWrite(buf32); err != nil {
panic(err)
}
}
}()
return c, ready, nil
}
func (c *context) alsaPcmHwParams(sampleRate, channelNum int, bufferSize, periodSize *C.snd_pcm_uframes_t) error {
var params *C.snd_pcm_hw_params_t
C.snd_pcm_hw_params_malloc(&params)
defer C.free(unsafe.Pointer(params))
if err := C.snd_pcm_hw_params_any(c.handle, params); err < 0 {
return alsaError(err)
}
if err := C.snd_pcm_hw_params_set_access(c.handle, params, C.SND_PCM_ACCESS_RW_INTERLEAVED); err < 0 {
return alsaError(err)
}
if err := C.snd_pcm_hw_params_set_format(c.handle, params, C.SND_PCM_FORMAT_FLOAT_LE); err < 0 {
return alsaError(err)
}
if err := C.snd_pcm_hw_params_set_channels(c.handle, params, C.unsigned(channelNum)); err < 0 {
return alsaError(err)
}
if err := C.snd_pcm_hw_params_set_rate_resample(c.handle, params, 1); err < 0 {
return alsaError(err)
}
sr := C.unsigned(sampleRate)
if err := C.snd_pcm_hw_params_set_rate_near(c.handle, params, &sr, nil); err < 0 {
return alsaError(err)
}
if err := C.snd_pcm_hw_params_set_buffer_size_near(c.handle, params, bufferSize); err < 0 {
return alsaError(err)
}
if err := C.snd_pcm_hw_params_set_period_size_near(c.handle, params, periodSize, nil); err < 0 {
return alsaError(err)
}
if err := C.snd_pcm_hw_params(c.handle, params); err < 0 {
return alsaError(err)
}
c.supportsPause = C.snd_pcm_hw_params_can_pause(params) == 1
return nil
}
func (c *context) readAndWrite(buf32 []float32) error {
c.cond.L.Lock()
defer c.cond.L.Unlock()
for c.suspended {
c.cond.Wait()
}
for i := range buf32 {
buf32[i] = 0
}
c.players.read(buf32)
for len(buf32) > 0 {
n := C.snd_pcm_writei(c.handle, unsafe.Pointer(&buf32[0]), C.snd_pcm_uframes_t(len(buf32)/c.channelNum))
if n == -C.EPIPE {
// Underrun or overrun occurred.
if err := C.snd_pcm_prepare(c.handle); err < 0 {
return alsaError(err)
}
continue
}
if n < 0 {
return alsaError(C.int(n))
}
buf32 = buf32[int(n)*c.channelNum:]
}
return nil
}
func (c *context) Suspend() error {
c.cond.L.Lock()
defer c.cond.L.Unlock()
c.suspended = true
if c.supportsPause {
if err := C.snd_pcm_pause(c.handle, 1); err < 0 {
return alsaError(err)
}
return nil
}
if err := C.snd_pcm_drop(c.handle); err < 0 {
return alsaError(err)
}
return nil
}
func (c *context) Resume() error {
c.cond.L.Lock()
defer c.cond.L.Unlock()
defer func() {
c.suspended = false
c.cond.Signal()
}()
if c.supportsPause {
if err := C.snd_pcm_pause(c.handle, 0); err < 0 {
return alsaError(err)
}
return nil
}
try:
if err := C.snd_pcm_resume(c.handle); err < 0 {
if err == -C.EAGAIN {
time.Sleep(100 * time.Millisecond)
goto try
}
if err == -C.ENOSYS {
if err := C.snd_pcm_prepare(c.handle); err < 0 {
return alsaError(err)
}
return nil
}
return alsaError(err)
}
return nil
}