From 7d6daba3d25ea77dd5d7f3dc5acb3a8fcdbf24d7 Mon Sep 17 00:00:00 2001
From: "5684185+vsariola@users.noreply.github.com"
 <5684185+vsariola@users.noreply.github.com>
Date: Mon, 16 Sep 2024 19:53:22 +0300
Subject: [PATCH] fix(vm/compiler/bridge): empty patch should not crash native
 synth

Fixes #148.
---
 CHANGELOG.md                            |  4 ++++
 vm/compiler/bridge/native_synth.go      | 14 +++++++++++++
 vm/compiler/bridge/native_synth_test.go | 28 +++++++++++++++++++++++++
 3 files changed, 46 insertions(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index f559514..2248e0c 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -9,6 +9,9 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
   info is shown as a label in the tracker and can be checked with `-v` flag in
   the command line tools.
 
+### Fixed
+- Empty patch should not crash the native synth ([#148][i148])
+
 ## [0.4.1]
 ### Added
 - Clicking the parameter slider also selects that parameter ([#112][i112])
@@ -209,3 +212,4 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 [i144]: https://github.com/vsariola/sointu/issues/144
 [i145]: https://github.com/vsariola/sointu/issues/145
 [i146]: https://github.com/vsariola/sointu/issues/146
+[i148]: https://github.com/vsariola/sointu/issues/148
diff --git a/vm/compiler/bridge/native_synth.go b/vm/compiler/bridge/native_synth.go
index ac13a39..d4f75c3 100644
--- a/vm/compiler/bridge/native_synth.go
+++ b/vm/compiler/bridge/native_synth.go
@@ -38,6 +38,13 @@ func Synth(patch sointu.Patch, bpm int) (*NativeSynth, error) {
 	if len(comPatch.Operands) > 16384 { // TODO: 16384 could probably be pulled automatically from cgo
 		return nil, errors.New("bridge supports at most 16384 operands; the compiled patch has more")
 	}
+	// if the patch is empty, we still need to initialize the synth with a single opcode
+	if len(comPatch.Opcodes) == 0 {
+		s.Opcodes[0] = 0
+		s.NumVoices = 1
+		s.Polyphony = 0
+		return (*NativeSynth)(s), nil
+	}
 	for i, v := range comPatch.Opcodes {
 		s.Opcodes[i] = (C.uchar)(v)
 	}
@@ -130,6 +137,13 @@ func (bridgesynth *NativeSynth) Update(patch sointu.Patch, bpm int) error {
 	if len(comPatch.Operands) > 16384 { // TODO: 16384 could probably be pulled automatically from cgo
 		return errors.New("bridge supports at most 16384 operands; the compiled patch has more")
 	}
+	// if the patch is empty, we still need to initialize the synth with a single opcode
+	if len(comPatch.Opcodes) == 0 {
+		s.Opcodes[0] = 0
+		s.NumVoices = 1
+		s.Polyphony = 0
+		return nil
+	}
 	needsRefresh := false
 	for i, v := range comPatch.Opcodes {
 		if cmdChar := (C.uchar)(v); s.Opcodes[i] != cmdChar {
diff --git a/vm/compiler/bridge/native_synth_test.go b/vm/compiler/bridge/native_synth_test.go
index 834b447..1410bca 100644
--- a/vm/compiler/bridge/native_synth_test.go
+++ b/vm/compiler/bridge/native_synth_test.go
@@ -28,6 +28,34 @@ const su_max_samples = SAMPLES_PER_ROW * TOTAL_ROWS
 
 // const bufsize = su_max_samples * 2
 
+func TestEmptyPatch(t *testing.T) {
+	patch := sointu.Patch{}
+	tracks := []sointu.Track{{NumVoices: 0, Order: []int{0}, Patterns: []sointu.Pattern{{64, 0, 68, 0, 32, 0, 0, 0, 75, 0, 78, 0, 0, 0, 0, 0}}}}
+	song := sointu.Song{BPM: 100, RowsPerBeat: 4, Score: sointu.Score{RowsPerPattern: 16, Length: 1, Tracks: tracks}, Patch: patch}
+	// make sure that the empty patch does not crash the synth
+	sointu.Play(bridge.NativeSynther{}, song, nil)
+}
+
+func TestUpdatingEmptyPatch(t *testing.T) {
+	patch := sointu.Patch{sointu.Instrument{NumVoices: 1, Units: []sointu.Unit{
+		{Type: "envelope", Parameters: map[string]int{"stereo": 0, "attack": 64, "decay": 64, "sustain": 64, "release": 80, "gain": 128}},
+		{Type: "envelope", Parameters: map[string]int{"stereo": 0, "attack": 95, "decay": 64, "sustain": 64, "release": 80, "gain": 128}},
+		{Type: "out", Parameters: map[string]int{"stereo": 1, "gain": 128}},
+	}}}
+	tracks := []sointu.Track{{NumVoices: 0, Order: []int{0}, Patterns: []sointu.Pattern{{64, 0, 68, 0, 32, 0, 0, 0, 75, 0, 78, 0, 0, 0, 0, 0}}}}
+	song := sointu.Song{BPM: 100, RowsPerBeat: 4, Score: sointu.Score{RowsPerPattern: 16, Length: 1, Tracks: tracks}, Patch: patch}
+	synth, err := bridge.NativeSynther{}.Synth(patch, song.BPM)
+	if err != nil {
+		t.Fatalf("Synth creation failed: %v", err)
+	}
+	synth.Update(sointu.Patch{}, song.BPM)
+	buffer := make(sointu.AudioBuffer, su_max_samples)
+	err = buffer[:len(buffer)/2].Fill(synth)
+	if err != nil {
+		t.Fatalf("render gave an error: %v", err)
+	}
+}
+
 func TestOscillatSine(t *testing.T) {
 	patch := sointu.Patch{sointu.Instrument{NumVoices: 1, Units: []sointu.Unit{
 		{Type: "envelope", Parameters: map[string]int{"stereo": 0, "attack": 32, "decay": 32, "sustain": 64, "release": 64, "gain": 128}},