Initial

main.go

@@ -0,0 +1,122 @@
+package main
+
+import (
+	"bytes"
+	"encoding/binary"
+	"fmt"
+	"math"
+
+	"github.com/yobert/alsa"
+)
+
+func main() {
+
+	cards, err := alsa.OpenCards()
+	if err != nil {
+		fmt.Println(err)
+		return
+	}
+	defer alsa.CloseCards(cards)
+
+	for _, card := range cards {
+		fmt.Println(card)
+
+		if err := beep_card(card); err != nil {
+			fmt.Println(err)
+			return
+		}
+	}
+}
+
+func beep_card(card *alsa.Card) error {
+	devices, err := card.Devices()
+	if err != nil {
+		return err
+	}
+	for _, device := range devices {
+		if device.Type != alsa.PCM || !device.Play {
+			continue
+		}
+		fmt.Println("───", device)
+
+		if err := beep_device(device); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+func beep_device(device *alsa.Device) error {
+	var err error
+
+	if err = device.Open(); err != nil {
+		return err
+	}
+	defer device.Close()
+
+	channels, err := device.NegotiateChannels(1, 2)
+	if err != nil {
+		return err
+	}
+
+	rate, err := device.NegotiateRate(44100)
+	if err != nil {
+		return err
+	}
+
+	format, err := device.NegotiateFormat(alsa.S16_LE, alsa.S32_LE)
+	if err != nil {
+		return err
+	}
+
+	buffer_size, err := device.NegotiateBufferSize(1024, 8192, 16384)
+	if err != nil {
+		return err
+	}
+
+	if err = device.Prepare(); err != nil {
+		return err
+	}
+
+	buf := bytes.NewBuffer(nil)
+	t := 0.0
+
+	fmt.Printf("Negotiated parameters: %d channels, %d hz, %v, %d frame buffer\n",
+		channels, rate, format, buffer_size)
+
+	for {
+		buf.Reset()
+
+		for i := 0; i < buffer_size; i++ {
+			v := math.Sin(t * 2 * math.Pi * 200) // A4
+			v *= 0.01                             // make a little quieter
+
+			switch format {
+			case alsa.S16_LE:
+				sample := int16(v * ((1 << 16) - 1))
+
+				for c := 0; c < channels; c++ {
+					binary.Write(buf, binary.LittleEndian, sample)
+				}
+
+			case alsa.S32_LE:
+				sample := int32(v * ((1 << 32) - 1))
+
+				for c := 0; c < channels; c++ {
+					binary.Write(buf, binary.LittleEndian, sample)
+				}
+
+			default:
+				return fmt.Errorf("Unhandled sample format: %v", format)
+			}
+
+			t += 1.0 / float64(rate)
+		}
+
+		if err := device.Write(buf.Bytes(), buffer_size); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}