sointu/tracker/gomidi/midi.go
5684185+vsariola@users.noreply.github.com 78fc6302a0 fix(tracker/gomidi): static cgo linking to avoid DLL dependencies
The linker flags -static -static-libgcc -static-libstdc++ tell mingw
to link statically; otherwise gcc_s_seh-1, stdc++-6 and winpthread-1
are needed.

Fixes #188.
2025-02-28 15:15:17 +02:00

194 lines
4.9 KiB
Go

package gomidi
// These cgo linker flags tell mingw to link gcc_s_seh-1, stdc++-6 and
// winpthread-1 statically; otherwise they are needed as DLLs
// #cgo windows LDFLAGS: -static -static-libgcc -static-libstdc++
import "C"
import (
"errors"
"fmt"
"strings"
"github.com/vsariola/sointu/tracker"
"gitlab.com/gomidi/midi/v2"
"gitlab.com/gomidi/midi/v2/drivers"
"gitlab.com/gomidi/midi/v2/drivers/rtmididrv"
)
type (
RTMIDIContext struct {
driver *rtmididrv.Driver
currentIn drivers.In
events chan timestampedMsg
eventsBuf []timestampedMsg
eventIndex int
startFrame int
startFrameSet bool
}
RTMIDIDevice struct {
context *RTMIDIContext
in drivers.In
}
timestampedMsg struct {
frame int
msg midi.Message
}
)
func (m *RTMIDIContext) InputDevices(yield func(tracker.MIDIDevice) bool) {
if m.driver == nil {
return
}
ins, err := m.driver.Ins()
if err != nil {
return
}
for i := 0; i < len(ins); i++ {
device := RTMIDIDevice{context: m, in: ins[i]}
if !yield(device) {
break
}
}
}
// Open the driver.
func NewContext() *RTMIDIContext {
m := RTMIDIContext{events: make(chan timestampedMsg, 1024)}
// there's not much we can do if this fails, so just use m.driver = nil to
// indicate no driver available
m.driver, _ = rtmididrv.New()
return &m
}
// Open an input device while closing the currently open if necessary.
func (m RTMIDIDevice) Open() error {
if m.context.currentIn == m.in {
return nil
}
if m.context.driver == nil {
return errors.New("no driver available")
}
if m.context.HasDeviceOpen() {
m.context.currentIn.Close()
}
m.context.currentIn = m.in
err := m.in.Open()
if err != nil {
m.context.currentIn = nil
return fmt.Errorf("opening MIDI input failed: %W", err)
}
_, err = midi.ListenTo(m.in, m.context.HandleMessage)
if err != nil {
m.in.Close()
m.context.currentIn = nil
}
return nil
}
func (d RTMIDIDevice) String() string {
return d.in.String()
}
func (m *RTMIDIContext) HandleMessage(msg midi.Message, timestampms int32) {
select {
case m.events <- timestampedMsg{frame: int(int64(timestampms) * 44100 / 1000), msg: msg}: // if the channel is full, just drop the message
default:
}
}
func (c *RTMIDIContext) NextEvent(frame int) (event tracker.MIDINoteEvent, ok bool) {
F:
for {
select {
case msg := <-c.events:
c.eventsBuf = append(c.eventsBuf, msg)
if !c.startFrameSet {
c.startFrame = msg.frame
c.startFrameSet = true
}
default:
break F
}
}
if c.eventIndex > 0 { // an event was consumed, check how badly we need to adjust the timing
delta := frame + c.startFrame - c.eventsBuf[c.eventIndex-1].frame
// delta should never be a negative number, because the renderer does
// not consume an event until current frame is past the frame of the
// event. However, if it's been a while since we consumed event, delta
// may by *positive* i.e. we consume the event too late. So adjust the
// internal clock in that case.
c.startFrame -= delta / 5 // adjust the start frame towards the consumed event
}
for c.eventIndex < len(c.eventsBuf) {
var channel uint8
var velocity uint8
var key uint8
m := c.eventsBuf[c.eventIndex]
f := m.frame - c.startFrame
c.eventIndex++
if m.msg.GetNoteOn(&channel, &key, &velocity) {
return tracker.MIDINoteEvent{Frame: f, On: true, Channel: int(channel), Note: key}, true
} else if m.msg.GetNoteOff(&channel, &key, &velocity) {
return tracker.MIDINoteEvent{Frame: f, On: false, Channel: int(channel), Note: key}, true
}
}
c.eventIndex = len(c.eventsBuf) + 1
return tracker.MIDINoteEvent{}, false
}
func (c *RTMIDIContext) FinishBlock(frame int) {
c.startFrame += frame
if c.eventIndex > 0 {
copy(c.eventsBuf, c.eventsBuf[c.eventIndex-1:])
c.eventsBuf = c.eventsBuf[:len(c.eventsBuf)-c.eventIndex+1]
if len(c.eventsBuf) > 0 {
// Events were not consumed this round; adjust the start frame
// towards the future events. What this does is that it tries to
// render the events at the same time as they were received here
// delta will be always a negative number
delta := c.startFrame - c.eventsBuf[0].frame
c.startFrame -= delta / 5
}
}
c.eventIndex = 0
}
func (c *RTMIDIContext) BPM() (bpm float64, ok bool) {
return 0, false
}
func (c *RTMIDIContext) Close() {
if c.driver == nil {
return
}
if c.currentIn != nil && c.currentIn.IsOpen() {
c.currentIn.Close()
}
c.driver.Close()
}
func (c *RTMIDIContext) HasDeviceOpen() bool {
return c.currentIn != nil && c.currentIn.IsOpen()
}
func (c *RTMIDIContext) TryToOpenBy(namePrefix string, takeFirst bool) {
if namePrefix == "" && !takeFirst {
return
}
for input := range c.InputDevices {
if takeFirst || strings.HasPrefix(input.String(), namePrefix) {
input.Open()
return
}
}
if takeFirst {
fmt.Errorf("Could not find any MIDI Input.\n")
} else {
fmt.Errorf("Could not find any default MIDI Input starting with \"%s\".\n", namePrefix)
}
}