feat: initial version of midifi software

This CL introduces the initial version of the midifi software, via
a simplified CLI interface "playsmf".

Though it is far from complete, this version can be manually invoked
with the locations of the MIDI communications port (the `-com` flag),
and MIDI file. It will playback the MIDI file with the correct time.

Software is currently tested with an integration test, that invokes the
program with a known MIDI file and compares the output of the serial
port, standard out, and standard error. Golden files can be updated by
providing the `-test.update-golden` flag.

Change-Id: I312bc721736e2edf385ece5141133ffa6bd20a72
Signed-off-by: Terin Stock <terinjokes@gmail.com>

1 files changed, 114 insertions, 0 deletions

diff --git a/cmd/playsmf/main.go b/cmd/playsmf/main.go
new file mode 100644
index 0000000..7b55ff3
--- /dev/null
+++ b/cmd/playsmf/main.go
@@ -0,0 +1,114 @@
+package main
+
+import (
+	"container/list"
+	"flag"
+	"fmt"
+	"os"
+	"time"
+
+	"gitlab.com/gomidi/midi"
+	"gitlab.com/gomidi/midi/mid"
+	"gitlab.com/gomidi/midi/midimessage"
+	"gitlab.com/gomidi/midi/smf"
+	"go.terinstock.com/midifi/pkg/ttymididrv"
+)
+
+var (
+	drv        mid.Driver
+	midiSerial string
+)
+
+func init() {
+	flag.StringVar(&midiSerial, "com", "", "The serial port of the MIDI synth")
+}
+
+func main() {
+	flag.Parse()
+	drv = ttymididrv.New(midiSerial, 38400)
+	defer drv.Close()
+
+	outs, err := drv.Outs()
+	if err != nil {
+		fmt.Printf("err: %v\n", err)
+		os.Exit(-1)
+	}
+	out := outs[0]
+
+	err = out.Open()
+	if err != nil {
+		fmt.Printf("err: %v\n", err)
+		os.Exit(-1)
+	}
+	defer out.Close()
+
+	if flag.NArg() == 0 {
+		flag.Usage()
+		os.Exit(-1)
+	}
+
+	f, err := os.Open(flag.Arg(0))
+	if err != nil {
+		fmt.Println("unable to load SMF file")
+		os.Exit(-2)
+	}
+	defer f.Close()
+
+	fmt.Printf("file: %s\n", flag.Arg(0))
+
+	mf := mid.NewReader(mid.NoLogger())
+	mf.SMFHeader = func(header smf.Header) {
+		fmt.Printf("file format: %s\n", header.Format.String())
+		fmt.Printf("number of tracks: %d\n", header.NumTracks)
+		fmt.Printf("time format: %s\n", header.TimeFormat.String())
+		fmt.Println("===========")
+	}
+	events := &list.List{}
+	mf.Msg.Each = func(pos *mid.Position, msg midi.Message) {
+		addEvent(events, Event{track: pos.Track, abs: pos.AbsoluteTicks, msg: msg})
+	}
+	mf.ReadSMF(f)
+
+	w := mid.WriteTo(out)
+
+	var lastDur time.Duration
+	for event := events.Front(); event != nil; event = event.Next() {
+		dur := *mf.TimeAt(event.Value.(Event).abs)
+		if lastDur != dur {
+			<-time.After(dur - lastDur)
+			lastDur = dur
+		}
+
+		msg := event.Value.(Event).msg
+		if midimessage.IsLive(msg) {
+			fmt.Printf("%s\n", msg.String())
+			w.Write(msg)
+		}
+	}
+}
+
+type Event struct {
+	track int16
+	abs   uint64
+	msg   midi.Message
+}
+
+func addEvent(l *list.List, evt Event) {
+	if l.Front() == nil {
+		l.PushBack(evt)
+		return
+	}
+
+	for cur := l.Front(); cur != nil; cur = cur.Next() {
+		peek := cur.Next()
+		if peek == nil {
+			l.InsertAfter(evt, cur)
+			return
+		}
+
+		if peek.Value.(Event).abs >= evt.abs {
+			l.InsertAfter(evt, cur)
+			return
+		}
+	}
+}