feat(tracker): implement basic track display

go4k/tracker/music.go

@@ -0,0 +1,29 @@
+package tracker
+
+import "fmt"
+
+const baseNote = 20
+
+var notes = []string{
+	"C-",
+	"C#",
+	"D-",
+	"D#",
+	"E-",
+	"F-",
+	"F#",
+	"G-",
+	"G#",
+	"A-",
+	"A#",
+	"B-",
+}
+
+func valueAsNote(val byte) string {
+	octave := (val - baseNote) / 12
+	oNote := (val - baseNote) % 12
+	if octave < 0 || oNote < 0 || octave > 10 {
+		return "..."
+	}
+	return fmt.Sprintf("%s%d", notes[oNote], octave)
+}