fix(templates/wasm): $WRK was modified by stereo oscillators, messing up all modulations targeting units after the unit

add also tests to make sure we don't mess it up again

templates/wasm/sources.wat

@@ -106,6 +106,10 @@
 (func $su_op_oscillator (param $stereo i32) (local $flags i32) (local $detune f32) (local $phase f32) (local $color f32) (local $amplitude f32)
 {{- if .SupportsParamValueOtherThan "oscillator" "unison" 0}}
     (local $unison i32) (local $WRK_stash i32) (local $detune_stash f32)
+{{- end}}
+{{- if .Stereo "oscillator"}}
+    (local $WRK_stereostash i32)
+    (local.set $WRK_stereostash (global.get $WRK))
 {{- end}}
     (local.set $flags (call $scanValueByte))
     (local.set $detune (call $inputSigned (i32.const {{.InputNumber "oscillator" "detune"}})))
@@ -189,7 +193,7 @@
                 (f32.const 0.08333333) ;; 1/12, add small phase shift so all oscillators don't start in phase
             )
         )
-        (global.set $WRK (i32.add (global.get $WRK) (i32.const 8))) ;; WARNING: this is a bug. WRK should be nonvolatile, but we are changing it. It does not cause immediate problems but modulations will be off.
+        (global.set $WRK (i32.add (global.get $WRK) (i32.const 8)))
         (local.set $detune (f32.neg (f32.mul
             (local.get $detune) ;; each unison oscillator has a detune with flipped sign and halved amount... this creates detunes that concentrate around the fundamental
             (f32.const 0.5)
@@ -202,9 +206,12 @@
 {{- end}}
 {{- if .Stereo "oscillator"}}
     (local.set $detune (f32.neg (local.get $detune))) ;; flip the detune for secon round
-    (global.set $WRK (i32.add (global.get $WRK) (i32.const 4))) ;; WARNING: this is a bug. WRK should be nonvolatile, but we are changing it. It does not cause immediate problems but modulations will be off.
+    (global.set $WRK (i32.add (global.get $WRK) (i32.const 4))) 
     (br_if $stereoLoop (i32.eqz (local.tee $stereo (i32.eqz (local.get $stereo)))))
     end
+    (global.set $WRK (local.get $WRK_stereostash))
+    ;; TODO: all this "save WRK to local variable, modify it and then restore it" could be better thought out
+    ;; however, it is now done like this as a quick bug fix to the issue of stereo oscillators touching WRK and not restoring it
 {{- end}}
 )
 

tests/CMakeLists.txt

@@ -115,7 +115,8 @@ regression_test(test_oscillat_detunemod "VCO_SINE;ENVELOPE;FOP_MULP;FOP_PUSH;SEN
 regression_test(test_oscillat_phasemod "VCO_SINE;ENVELOPE;FOP_MULP;FOP_PUSH;SEND")
 regression_test(test_oscillat_colormod "VCO_SINE;ENVELOPE;FOP_MULP;FOP_PUSH;SEND")
 regression_test(test_oscillat_shapemod "VCO_SINE;ENVELOPE;FOP_MULP;FOP_PUSH;SEND")
-regression_test(test_oscillat_gainmod "VCO_SINE;ENVELOPE;FOP_MULP;FOP_PUSH;SEND")
+regression_test(test_oscillat_gainmod OSCGAINMOD "VCO_SINE;ENVELOPE;FOP_MULP;FOP_PUSH;SEND")
+regression_test(test_oscillat_gainmod_stereo "" OSCGAINMOD)
 
 regression_test(test_distort ENVELOPE)
 regression_test(test_distort_mod "VCO_SINE;ENVELOPE;SEND")

tests/test_oscillat_gainmod_stereo.yml

@@ -0,0 +1,43 @@
+bpm: 100
+rowsperbeat: 4
+score:
+    rowsperpattern: 16
+    length: 1
+    tracks:
+        - numvoices: 1
+          order: [0]
+          patterns: [[80, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0]]
+patch:
+    - numvoices: 1
+      units:
+        - type: envelope
+          parameters: {attack: 80, decay: 80, gain: 128, release: 80, stereo: 0, sustain: 64}
+        - type: oscillator
+          parameters: {color: 128, detune: 64, gain: 32, lfo: 0, phase: 0, shape: 64, stereo: 0, transpose: 64, type: 0, unison: 0}
+          id: 1
+        - type: oscillator
+          parameters: {color: 128, detune: 62, gain: 32, lfo: 0, phase: 0, shape: 64, stereo: 1, transpose: 64, type: 0, unison: 0}
+          id: 2
+        - type: addp
+          parameters: {stereo: 0}
+        - type: addp
+          parameters: {stereo: 0}
+        - type: oscillator
+          parameters: {color: 128, detune: 60, gain: 32, lfo: 0, phase: 0, shape: 64, stereo: 0, transpose: 64, type: 0, unison: 0}
+          id: 3
+        - type: addp
+          parameters: {stereo: 0}
+        - type: mulp
+          parameters: {stereo: 0}
+        - type: push
+          parameters: {stereo: 0}
+        - type: oscillator
+          parameters: {color: 128, detune: 64, gain: 128, lfo: 1, phase: 64, shape: 64, stereo: 0, transpose: 70, type: 0, unison: 0}
+        - type: send
+          parameters: {amount: 68, port: 5, sendpop: 0, stereo: 0, target: 1}
+        - type: send
+          parameters: {amount: 68, port: 5, sendpop: 0, stereo: 0, target: 2}
+        - type: send
+          parameters: {amount: 68, port: 5, sendpop: 1, stereo: 0, target: 3}
+        - type: out
+          parameters: {gain: 128, stereo: 1}