feat(tracker): add reverb presets for delay unit

The options are stereo, left and right. Similar to oscillator sample settings, if you tamper with these, it starts to show "custom". Used some of the generic features of go1.18, so had to update go.mod to require go1.18.

tracker/defaultsong.go

@@ -78,6 +78,20 @@ var defaultSong = sointu.Song{
 		}}},
 }
 
+type delayPreset struct {
+	name    string
+	stereo  int
+	varArgs []int
+}
+
+var reverbs = []delayPreset{
+	{"stereo", 1, []int{1116, 1188, 1276, 1356, 1422, 1492, 1556, 1618,
+		1140, 1212, 1300, 1380, 1446, 1516, 1580, 1642,
+	}},
+	{"left", 0, []int{1116, 1188, 1276, 1356, 1422, 1492, 1556, 1618}},
+	{"right", 0, []int{1140, 1212, 1300, 1380, 1446, 1516, 1580, 1642}},
+}
+
 func init() {
 	UnitTypeNames = make([]string, 0, len(sointu.UnitTypes))
 	for k := range sointu.UnitTypes {

tracker/model.go

@@ -11,6 +11,7 @@ import (
 
 	"github.com/vsariola/sointu"
 	"github.com/vsariola/sointu/vm"
+	"golang.org/x/exp/slices"
 	"gopkg.in/yaml.v2"
 )
 
@@ -863,6 +864,23 @@ func (m *Model) setGmDlsEntry(index int) {
 	m.notifyPatchChange()
 }
 
+func (m *Model) setReverb(index int) {
+	if index < 0 || index >= len(reverbs) {
+		return
+	}
+	entry := reverbs[index]
+	unit := &m.d.Song.Patch[m.d.InstrIndex].Units[m.d.UnitIndex]
+	if unit.Type != "delay" {
+		return
+	}
+	m.saveUndo("setReverb", 20)
+	unit.Parameters["stereo"] = entry.stereo
+	unit.Parameters["notetracking"] = 0
+	unit.VarArgs = make([]int, len(entry.varArgs))
+	copy(unit.VarArgs, entry.varArgs)
+	m.notifyPatchChange()
+}
+
 func (m *Model) SwapUnits(i, j int) {
 	units := m.Instrument().Units
 	if i < 0 || j < 0 || i >= len(units) || j >= len(units) || i == j {
@@ -1121,7 +1139,7 @@ func (m *Model) NumParams() int {
 		numSettableParams = 1
 	}
 	if unit.Type == "delay" {
-		numSettableParams += 1 + len(unit.VarArgs)
+		numSettableParams += 2 + len(unit.VarArgs)
 		if len(unit.VarArgs)%2 == 1 && unit.Parameters["stereo"] == 1 {
 			numSettableParams++
 		}
@@ -1181,13 +1199,23 @@ func (m *Model) Param(index int) (Parameter, error) {
 	}
 	if unit.Type == "delay" {
 		if index == 0 {
+			i := slices.IndexFunc(reverbs, func(p delayPreset) bool {
+				return p.stereo == unit.Parameters["stereo"] && unit.Parameters["notetracking"] == 0 && slices.Equal(p.varArgs, unit.VarArgs)
+			})
+			hint := "0 / custom"
+			if i >= 0 {
+				hint = fmt.Sprintf("%v / %v", i+1, reverbs[i].name)
+			}
+			return Parameter{Type: IntegerParameter, Min: 0, Max: len(reverbs), Name: "reverb", Hint: hint, Value: i + 1}, nil
+		}
+		if index == 1 {
 			l := len(unit.VarArgs)
 			if unit.Parameters["stereo"] == 1 {
 				l = (l + 1) / 2
 			}
 			return Parameter{Type: IntegerParameter, Min: 1, Max: 32, Name: "delaylines", Hint: strconv.Itoa(l), Value: l}, nil
 		}
-		index--
+		index -= 2
 		if index < len(unit.VarArgs) {
 			val := unit.VarArgs[index]
 			var text string
@@ -1305,6 +1333,10 @@ func (m *Model) SetParam(value int) {
 		m.setGmDlsEntry(value - 1)
 		return
 	}
+	if p.Name == "reverb" {
+		m.setReverb(value - 1)
+		return
+	}
 	unit := m.Unit()
 	if p.Name == "delaylines" {
 		m.saveUndo("SetParam", 20)
@@ -1318,7 +1350,7 @@ func (m *Model) SetParam(value int) {
 		m.Instrument().Units[m.d.UnitIndex].VarArgs = m.Instrument().Units[m.d.UnitIndex].VarArgs[:targetLines]
 	} else if p.Name == "delaytime" {
 		m.saveUndo("SetParam", 20)
-		index := m.d.ParamIndex - 7
+		index := m.d.ParamIndex - 8
 		for len(m.Instrument().Units[m.d.UnitIndex].VarArgs) <= index {
 			m.Instrument().Units[m.d.UnitIndex].VarArgs = append(m.Instrument().Units[m.d.UnitIndex].VarArgs, 1)
 		}