feat(vm): add dbgain unit, where gain is defined in decibels

Closes #78

CHANGELOG.md

@@ -3,6 +3,10 @@ All notable changes to this project will be documented in this file.
 
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 
+## Unreleased
+### Added
+- Dbgain unit, which allows defining the gain in decibels (-40 dB to +40dB)
+
 ## v0.3.0
 ### Added
 - Scroll bars to menus, shown when a menu is too long to fit.

patch.go

@@ -82,6 +82,9 @@ var UnitTypes = map[string]([]UnitParameter){
 	"invgain": []UnitParameter{
 		{Name: "stereo", MinValue: 0, MaxValue: 1, CanSet: true, CanModulate: false},
 		{Name: "invgain", MinValue: 0, MaxValue: 128, CanSet: true, CanModulate: true}},
+	"dbgain": []UnitParameter{
+		{Name: "stereo", MinValue: 0, MaxValue: 1, CanSet: true, CanModulate: false},
+		{Name: "decibels", MinValue: 0, MaxValue: 128, CanSet: true, CanModulate: true}},
 	"filter": []UnitParameter{
 		{Name: "stereo", MinValue: 0, MaxValue: 1, CanSet: true, CanModulate: false},
 		{Name: "frequency", MinValue: 0, MaxValue: 128, CanSet: true, CanModulate: true},
@@ -494,6 +497,11 @@ func (p Patch) ParamHintString(instrIndex, unitIndex int, param string) string {
 				return "aux3 right"
 			}
 		}
+	case "dbgain":
+		switch param {
+		case "decibels":
+			return fmt.Sprintf("%.2f dB", 40*(float32(value)/64-1))
+		}
 	case "crush":
 		switch param {
 		case "resolution":

tests/CMakeLists.txt

@@ -72,6 +72,8 @@ regression_test(test_gain LOADVAL GAIN)
 regression_test(test_gain_stereo GAIN)
 regression_test(test_invgain LOADVAL INVGAIN)
 regression_test(test_invgain_stereo INVGAIN)
+regression_test(test_dbgain LOADVAL DBGAIN)
+regression_test(test_dbgain_stereo DBGAIN)
 regression_test(test_send LOADVAL SEND)
 regression_test(test_send_stereo SEND)
 regression_test(test_send_global SEND SEND_GLOBAL)

tests/test_dbgain.yml

@@ -0,0 +1,22 @@
+bpm: 100
+rowsperbeat: 4
+score:
+    rowsperpattern: 16
+    length: 1
+    tracks:
+        - numvoices: 1
+          order: [0]
+          patterns: [[64, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0]]
+patch:
+    - numvoices: 1
+      units:
+        - type: loadval
+          parameters: {stereo: 0, value: 0}
+        - type: dbgain
+          parameters: {decibels: 32, stereo: 0}
+        - type: loadval
+          parameters: {stereo: 0, value: 128}
+        - type: dbgain
+          parameters: {decibels: 32, stereo: 0}
+        - type: out
+          parameters: {gain: 128, stereo: 1}

tests/test_dbgain_stereo.yml

@@ -0,0 +1,20 @@
+bpm: 100
+rowsperbeat: 4
+score:
+    rowsperpattern: 16
+    length: 1
+    tracks:
+        - numvoices: 1
+          order: [0]
+          patterns: [[64, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0]]
+patch:
+    - numvoices: 1
+      units:
+        - type: loadval
+          parameters: {stereo: 0, value: 0}
+        - type: loadval
+          parameters: {stereo: 0, value: 128}
+        - type: dbgain
+          parameters: {decibels: 32, stereo: 1}
+        - type: out
+          parameters: {gain: 128, stereo: 1}

tracker/presets.go

@@ -49,6 +49,7 @@ var defaultUnits = map[string]sointu.Unit{
 	"pan":        {Type: "pan", Parameters: map[string]int{"stereo": 0, "panning": 64}},
 	"gain":       {Type: "gain", Parameters: map[string]int{"stereo": 0, "gain": 64}},
 	"invgain":    {Type: "invgain", Parameters: map[string]int{"stereo": 0, "invgain": 64}},
+	"dbgain":     {Type: "dbgain", Parameters: map[string]int{"stereo": 0, "decibels": 64}},
 	"crush":      {Type: "crush", Parameters: map[string]int{"stereo": 0, "resolution": 64}},
 	"clip":       {Type: "clip", Parameters: map[string]int{"stereo": 0}},
 	"hold":       {Type: "hold", Parameters: map[string]int{"stereo": 0, "holdfreq": 64}},

vm/compiler/templates/amd64-386/effects.asm

@@ -98,6 +98,41 @@ su_op_invgain_mono:
 {{- end}}
 {{end}}
 
+{{- if .HasOp "dbgain"}}
+;-------------------------------------------------------------------------------
+;   DBGAIN opcode: apply gain on the signal, with gain given in decibels
+;-------------------------------------------------------------------------------
+;   Mono:   x   ->  x*g, where g = 2**((2*d-1)*6.643856189774724) i.e. -40dB to 40dB, d=[0..1]
+;   Stereo: l r ->  l*g r*g
+;-------------------------------------------------------------------------------
+{{.Func "su_op_dbgain" "Opcode"}}
+{{- if .Stereo "dbgain"}}
+    fld     dword [{{.Input "dbgain" "decibels"}}] ; d l r
+{{- .Prepare (.Float 0.5)}}
+    fsub    dword [{{.Use (.Float 0.5)}}]          ; d-.5
+    fadd    st0, st0                               ; 2*d-1
+{{- .Prepare (.Float 6.643856189774724)}}
+    fmul    dword [{{.Use (.Float 6.643856189774724)}}] ; (2*d-1)*6.643856189774724
+    {{.Call "su_power"}}
+{{- if .Mono "dbgain"}}
+    jnc     su_op_dbgain_mono
+{{- end}}
+    fmul    st2, st0                             ; g l r/g
+su_op_dbgain_mono:
+    fmulp   st1, st0                             ; l/g (r/)
+    ret
+{{- else}}
+    fld     dword [{{.Input "dbgain" "decibels"}}] ; d l
+{{- .Prepare (.Float 0.5)}}
+    fsub    dword [{{.Use (.Float 0.5)}}]          ; d-.5
+    fadd    st0, st0                               ; 2*d-1
+{{- .Prepare (.Float 6.643856189774724)}}
+    fmul    dword [{{.Use (.Float 6.643856189774724)}}] ; (2*d-1)*6.643856189774724
+    {{.Call "su_power"}}
+    fmulp   st1, st0
+    ret
+{{- end}}
+{{end}}
 
 {{- if .HasOp "filter"}}
 ;-------------------------------------------------------------------------------

vm/compiler/templates/wasm/effects.wat

@@ -98,6 +98,26 @@
 )
 {{end}}
 
+{{- if .HasOp "dbgain"}}
+;;-------------------------------------------------------------------------------
+;;   DBGAIN opcode: apply gain on the signal, with gain given in decibels
+;;-------------------------------------------------------------------------------
+;;   Mono:   x   ->  x*g, where g = 2**((2*d-1)*6.643856189774724) i.e. -40dB to 40dB, d=[0..1]
+;;   Stereo: l r ->  l*g r*g
+;;-------------------------------------------------------------------------------
+(func $su_op_dbgain (param $stereo i32)
+{{- if .Stereo "dbgain"}}
+    (call $stereoHelper (local.get $stereo) (i32.const {{div (.GetOp "dbgain") 2}}))
+{{- end}}
+    (call $input (i32.const {{.InputNumber "dbgain" "decibels"}}))
+    (f32.sub (f32.const 0.5))
+    (f32.mul (f32.const 13.287712379549449))
+    (call $pow2)
+    (f32.mul (call $pop))
+    (call $push)
+)
+{{end}}
+
 
 {{- if .HasOp "filter"}}
 ;;-------------------------------------------------------------------------------

vm/go_synth.go

@@ -346,6 +346,12 @@ func (s *GoSynth) Render(buffer sointu.AudioBuffer, maxtime int) (samples int, t
 					stack[l-2] /= params[0]
 				}
 				stack[l-1] /= params[0]
+			case opDbgain:
+				gain := float32(math.Pow(2, float64(params[0]*2-1)*6.643856189774724))
+				if stereo {
+					stack[l-2] *= gain
+				}
+				stack[l-1] *= gain
 			case opClip:
 				if stereo {
 					stack[l-2] = clip(stack[l-2])

vm/opcodes.go

@@ -8,30 +8,31 @@ const (
 	opClip       = 4
 	opCompressor = 5
 	opCrush      = 6
-	opDelay      = 7
+	opDbgain     = 7
-	opDistort    = 8
+	opDelay      = 8
-	opEnvelope   = 9
+	opDistort    = 9
-	opFilter     = 10
+	opEnvelope   = 10
-	opGain       = 11
+	opFilter     = 11
-	opHold       = 12
+	opGain       = 12
-	opIn         = 13
+	opHold       = 13
-	opInvgain    = 14
+	opIn         = 14
-	opLoadnote   = 15
+	opInvgain    = 15
-	opLoadval    = 16
+	opLoadnote   = 16
-	opMul        = 17
+	opLoadval    = 17
-	opMulp       = 18
+	opMul        = 18
-	opNoise      = 19
+	opMulp       = 19
-	opOscillator = 20
+	opNoise      = 20
-	opOut        = 21
+	opOscillator = 21
-	opOutaux     = 22
+	opOut        = 22
-	opPan        = 23
+	opOutaux     = 23
-	opPop        = 24
+	opPan        = 24
-	opPush       = 25
+	opPop        = 25
-	opReceive    = 26
+	opPush       = 26
-	opSend       = 27
+	opReceive    = 27
-	opSpeed      = 28
+	opSend       = 28
-	opSync       = 29
+	opSpeed      = 29
-	opXch        = 30
+	opSync       = 30
+	opXch        = 31
 )
 
-var transformCounts = [...]int{0, 0, 1, 0, 5, 1, 4, 1, 5, 2, 1, 1, 0, 1, 0, 1, 0, 0, 2, 6, 1, 2, 1, 0, 0, 0, 1, 0, 0, 0}
+var transformCounts = [...]int{0, 0, 1, 0, 5, 1, 1, 4, 1, 5, 2, 1, 1, 0, 1, 0, 1, 0, 0, 2, 6, 1, 2, 1, 0, 0, 0, 1, 0, 0, 0}