86 lines
1.7 KiB
Go
86 lines
1.7 KiB
Go
package main
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// typedef unsigned char Uint8;
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// void SineWave(void *userdata, Uint8 *stream, int len);
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import "C"
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import (
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"log"
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"math"
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"os"
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"os/signal"
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"reflect"
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"syscall"
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"unsafe"
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"github.com/veandco/go-sdl2/sdl"
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)
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const (
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DefaultFrequency = 16000
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DefaultFormat = sdl.AUDIO_S16
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DefaultChannels = 2
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DefaultSamples = 512
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toneHz = 440
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dPhase = 2 * math.Pi * toneHz / DefaultSamples
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)
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//export SineWave
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func SineWave(userdata unsafe.Pointer, stream *C.Uint8, length C.int) {
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n := int(length) / 2
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hdr := reflect.SliceHeader{Data: uintptr(unsafe.Pointer(stream)), Len: n, Cap: n}
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buf := *(*[]C.ushort)(unsafe.Pointer(&hdr))
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var phase float64
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for i := 0; i < n; i++ {
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phase += dPhase
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sample := C.ushort((math.Sin(phase) + 0.999999) * 32768)
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buf[i] = sample
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}
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}
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func main() {
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var dev sdl.AudioDeviceID
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var err error
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// Initialize SDL2
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if err := sdl.Init(sdl.INIT_AUDIO); err != nil {
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log.Println(err)
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return
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}
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defer sdl.Quit()
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// Specify the configuration for our default playback device
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spec := sdl.AudioSpec{
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Freq: DefaultFrequency,
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Format: DefaultFormat,
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Channels: DefaultChannels,
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Samples: DefaultSamples,
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Callback: sdl.AudioCallback(C.SineWave),
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}
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// Open default playback device
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if dev, err = sdl.OpenAudioDevice("", false, &spec, nil, 0); err != nil {
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log.Println(err)
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return
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}
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defer sdl.CloseAudioDevice(dev)
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// Start playback audio
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sdl.PauseAudioDevice(dev, false)
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// Listen to OS signals
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c := make(chan os.Signal, 1)
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signal.Notify(c, os.Interrupt, syscall.SIGTERM)
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// Run infinite loop until we receive SIGINT or SIGTERM!
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running := true
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for running {
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select {
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case sig := <-c:
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log.Printf("Received signal %v. Exiting.\n", sig)
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running = false
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}
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}
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}
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