refactor!: rename SynthService to Synther and related types

The -er suffix is more idiomatic for single method interfaces, and
the interface is not doing much more than converting the patch to a
synth. Names were updated throughout the project to reflect this
change. In particular, the "Service" in SynthService was not telling
anything helpful.

vm/go_synth_test.go

@@ -0,0 +1,169 @@
+package vm_test
+
+import (
+	"bytes"
+	"encoding/binary"
+	"io/ioutil"
+	"log"
+	"math"
+	"os"
+	"path"
+	"path/filepath"
+	"runtime"
+	"strings"
+	"testing"
+
+	"github.com/vsariola/sointu"
+	"github.com/vsariola/sointu/vm"
+	"gopkg.in/yaml.v2"
+)
+
+const errorThreshold = 1e-2
+
+func TestAllRegressionTests(t *testing.T) {
+	_, myname, _, _ := runtime.Caller(0)
+	files, err := filepath.Glob(path.Join(path.Dir(myname), "..", "tests", "*.yml"))
+	if err != nil {
+		t.Fatalf("cannot glob files in the test directory: %v", err)
+	}
+	for _, filename := range files {
+		basename := filepath.Base(filename)
+		testname := strings.TrimSuffix(basename, path.Ext(basename))
+		t.Run(testname, func(t *testing.T) {
+			if runtime.GOOS != "windows" && strings.Contains(testname, "sample") {
+				t.Skip("Samples (gm.dls) available only on Windows")
+				return
+			}
+			asmcode, err := ioutil.ReadFile(filename)
+			if err != nil {
+				t.Fatalf("cannot read the .asm file: %v", filename)
+			}
+			var song sointu.Song
+			err = yaml.Unmarshal(asmcode, &song)
+			if err != nil {
+				t.Fatalf("could not parse the .yml file: %v", err)
+			}
+			buffer, err := sointu.Play(vm.GoSynther{}, song, false)
+			buffer = buffer[:song.Score.LengthInRows()*song.SamplesPerRow()] // extend to the nominal length always.
+			if err != nil {
+				t.Fatalf("Play failed: %v", err)
+			}
+			if os.Getenv("SOINTU_TEST_SAVE_OUTPUT") == "YES" {
+				outputpath := path.Join(path.Dir(myname), "actual_output")
+				if _, err := os.Stat(outputpath); os.IsNotExist(err) {
+					os.Mkdir(outputpath, 0755)
+				}
+				outFileName := path.Join(path.Dir(myname), "actual_output", testname+".raw")
+				outfile, err := os.OpenFile(outFileName, os.O_RDWR|os.O_CREATE|os.O_TRUNC, 0755)
+				defer outfile.Close()
+				if err != nil {
+					t.Fatalf("Creating file failed: %v", err)
+				}
+				var createdbuf bytes.Buffer
+				err = binary.Write(&createdbuf, binary.LittleEndian, buffer)
+				if err != nil {
+					t.Fatalf("error converting buffer: %v", err)
+				}
+				_, err = outfile.Write(createdbuf.Bytes())
+				if err != nil {
+					log.Fatal(err)
+				}
+			}
+			compareToRawFloat32(t, buffer, testname+".raw")
+		})
+	}
+}
+
+func TestStackUnderflow(t *testing.T) {
+	patch := sointu.Patch{sointu.Instrument{NumVoices: 1, Units: []sointu.Unit{
+		sointu.Unit{Type: "pop", Parameters: map[string]int{}},
+	}}}
+	synth, err := vm.Synth(patch, 120)
+	if err != nil {
+		t.Fatalf("bridge compile error: %v", err)
+	}
+	buffer := make(sointu.AudioBuffer, 1)
+	err = sointu.Render(synth, buffer)
+	if err == nil {
+		t.Fatalf("rendering should have failed due to stack underflow")
+	}
+}
+
+func TestStackBalancing(t *testing.T) {
+	patch := sointu.Patch{
+		sointu.Instrument{NumVoices: 1, Units: []sointu.Unit{
+			sointu.Unit{Type: "push", Parameters: map[string]int{}},
+		}}}
+	synth, err := vm.Synth(patch, 120)
+	if err != nil {
+		t.Fatalf("bridge compile error: %v", err)
+	}
+	buffer := make(sointu.AudioBuffer, 1)
+	err = sointu.Render(synth, buffer)
+	if err == nil {
+		t.Fatalf("rendering should have failed due to unbalanced stack push/pop")
+	}
+}
+
+func compareToRawFloat32(t *testing.T, buffer sointu.AudioBuffer, rawname string) {
+	_, filename, _, _ := runtime.Caller(0)
+	expectedb, err := ioutil.ReadFile(path.Join(path.Dir(filename), "..", "tests", "expected_output", rawname))
+	if err != nil {
+		t.Fatalf("cannot read expected: %v", err)
+	}
+	expected := make(sointu.AudioBuffer, len(expectedb)/8)
+	buf := bytes.NewReader(expectedb)
+	err = binary.Read(buf, binary.LittleEndian, &expected)
+	if err != nil {
+		t.Fatalf("error converting expected buffer: %v", err)
+	}
+	if len(expected) != len(buffer) {
+		t.Fatalf("buffer length mismatch, got %v, expected %v", len(buffer), len(expected))
+	}
+	firsterr := -1
+	errs := 0
+	for i, v := range expected[1 : len(expected)-1] {
+		for j, s := range v {
+			if math.IsNaN(float64(buffer[i][j])) || (math.Abs(float64(s-buffer[i][j])) > errorThreshold &&
+				math.Abs(float64(s-buffer[i+1][j])) > errorThreshold && math.Abs(float64(s-buffer[i+2][j])) > errorThreshold) {
+				errs++
+				if firsterr == -1 {
+					firsterr = i
+				}
+				if errs > 200 { // we are again quite liberal with rounding errors, as different platforms have minor differences in floating point rounding
+					t.Fatalf("more than 200 errors bigger than %v detected, first at sample position %v", errorThreshold, firsterr)
+				}
+			}
+		}
+	}
+}
+
+func compareToRawInt16(t *testing.T, buffer []int16, rawname string) {
+	_, filename, _, _ := runtime.Caller(0)
+	expectedb, err := ioutil.ReadFile(path.Join(path.Dir(filename), "..", "tests", "expected_output", rawname))
+	if err != nil {
+		t.Fatalf("cannot read expected: %v", err)
+	}
+	expected := make([]int16, len(expectedb)/2)
+	buf := bytes.NewReader(expectedb)
+	err = binary.Read(buf, binary.LittleEndian, &expected)
+	if err != nil {
+		t.Fatalf("error converting expected buffer: %v", err)
+	}
+	if len(expected) != len(buffer) {
+		t.Fatalf("buffer length mismatch, got %v, expected %v", len(buffer), len(expected))
+	}
+	for i, v := range expected {
+		if math.IsNaN(float64(buffer[i])) || v != buffer[i] {
+			t.Fatalf("error at sample position %v", i)
+		}
+	}
+}
+
+func convertToInt16Buffer(buffer []float32) []int16 {
+	int16Buffer := make([]int16, len(buffer))
+	for i, v := range buffer {
+		int16Buffer[i] = int16(math.Round(math.Min(math.Max(float64(v), -1.0), 1.0) * 32767))
+	}
+	return int16Buffer
+}