94 lines
2.1 KiB
Go
94 lines
2.1 KiB
Go
package backend
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/*
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#ifndef ARREMI
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#define ARREMI
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#cgo CFLAGS: -Ialsa_wrapper
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#cgo LDFLAGS: -lasound
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#include <stdlib.h>
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#include "alsa_wrapper/alsa_wrapper.h"
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#endif
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*/
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import "C"
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import (
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"fmt"
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"unsafe"
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"github.com/tonychee7000/Arremi/consts"
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)
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// MIDIDevice implies a Writer interface.
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type MIDIDevice struct {
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Signal chan int
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}
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// NewMIDIDevice construction func
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func NewMIDIDevice() (*MIDIDevice, error) {
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var mididev = new(MIDIDevice)
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err := mididev.Init()
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return mididev, err
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}
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// Init the client and source
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func (midiDev *MIDIDevice) Init() error {
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var status int
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midiDev.Signal = make(chan int, 4096)
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cDevName := C.CString(consts.ClientName)
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defer C.free(unsafe.Pointer(cDevName))
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status = int(C.new_client(cDevName))
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if status != 0 {
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stage, errCode := resolveErrCode(status)
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switch stage {
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case 1:
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return fmt.Errorf("Error while opening sequencer. %d", errCode)
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case 2:
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return fmt.Errorf("Error while getting sequencer id. %d", errCode)
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case 3:
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return fmt.Errorf("Error while setting sequencer name. %d", errCode)
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}
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}
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cPortName := C.CString(consts.SourceName)
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defer C.free(unsafe.Pointer(cPortName))
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status = int(C.new_port(cPortName))
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if status != 0 {
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return fmt.Errorf("Error while createing sequencer port. %d", status)
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}
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return nil
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}
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func (midiDev *MIDIDevice) Write(p []byte) (int, error) {
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midiDev.Signal <- 1
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cData := (*C.char)(unsafe.Pointer(&p[0]))
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defer C.free(unsafe.Pointer(cData))
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var status = int(C.send_data(cData, C.int(len(p))))
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if status != 0 {
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stage, errCode := resolveErrCode(status)
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switch stage {
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case 1:
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return 0, fmt.Errorf("Error while creating MIDI event. %d", errCode)
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case 2:
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return 0, fmt.Errorf("Error while encoding MIDI event. %d", errCode)
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case 3:
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return 0, fmt.Errorf("Error while sending data. %d", errCode)
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}
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}
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return len(p), nil
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}
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// AllNoteOff I don't want panic!
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func (midiDev *MIDIDevice) AllNoteOff() {
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for i := 0; i < 16; i++ {
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for j := 0; j < 128; j++ {
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midiDev.Write([]byte{byte(0x90 + i), byte(j), 0})
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}
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}
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}
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func resolveErrCode(int code) (int, int) {
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return code >> 16, code & 0xffff
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}
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