JonET · JonET · Apr 15, 2026 · Apr 15, 2026 · Apr 15, 2026
diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
@@ -145,6 +145,14 @@ jobs:
         working-directory: cpp
         run: cmake --build build --config Release --target MonkSynth
 
+      - name: Build and run DSP unit tests
+        if: runner.os == 'Linux'
+        working-directory: cpp
+        run: |
+          cmake -B build-tests -DMONKSYNTH_BUILD_TESTS=ON
+          cmake --build build-tests --config Release
+          ctest --test-dir build-tests --output-on-failure
+
       - name: Build AudioUnit
         if: runner.os == 'macOS'
         working-directory: cpp

diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -4,6 +4,15 @@ All notable changes to MonkSynth will be documented in this file.
 
 ## [Unreleased]
 
+### Added
+- `Pitch Bend` parameter (±12 semitones, automatable) that actually bends the pitch of held notes, independent of the existing `Vowel` parameter
+- Right-click → **Pitch Bend** submenu with `Classic (Vowel)` and `Pitch` options; toggle controls where the hardware MIDI pitch wheel lands. Classic is the default and preserves Delay Lama compatibility. The host is notified via `restartComponent(kMidiCCAssignmentChanged)` so the switch takes effect without reloading the plugin.
+- Minimal DSP unit test suite (`cpp/tests/test_voice.c`, `test_synth.c`, `test_delay.c`) covering ADSR envelope boundaries, note stack LIFO, unison detune math, pitch-bend propagation, and delay-line feedback stability. Opt-in via `-DMONKSYNTH_BUILD_TESTS=ON`; runs on the Linux CI job before packaging.
+
+### Changed
+- DSP sources refactored into a `monk_dsp` static library so the plugin and the unit tests can link against the same objects without duplicating the source list.
+- Removed dead `monk_synth_pitch_bend` DSP function that was never called and just redirected to `set_vowel`.
+
 ## [0.2.0-beta.7] - 2026-04-14
 
 ### Added

diff --git a/README.md b/README.md
@@ -17,7 +17,8 @@ A monophonic vocal synthesizer that sounds like a monk chanting. Built using for
 - FOF synthesis engine producing realistic vocal formants
 - XY pad for real-time pitch and vowel control
 - Built-in stereo delay effect
-- MIDI support: note on/off, pitch bend (vowel), CC1 (vibrato), CC5 (glide), CC7 (volume), CC12 (delay), CC13 (voice)
+- MIDI support: note on/off, pitch wheel, CC1 (vibrato), CC5 (glide), CC7 (volume), CC12 (delay), CC13 (voice)
+- Automatable **Pitch Bend** parameter (±12 semitones). The hardware pitch wheel is routable to either Vowel (Classic / Delay Lama compat, the default) or Pitch via right-click → Pitch Bend
 - ADSR envelope with configurable attack, decay, sustain, release
 - Unison mode with up to 10 detuned voices and voice spread
 - Theme system with right-click context menu for custom skins
@@ -51,26 +52,25 @@ cmake -B build -G Xcode -DSMTG_AUDIOUNIT_SDK_PATH=/path/to/AudioUnitSDK
 cmake --build build --config Release --target MonkSynth-au
 ```
 
+### DSP unit tests
+
+The pure-C DSP layer (`dsp/`) has a small unit test suite exercising ADSR envelope boundaries, the note stack, unison detune math, pitch-bend propagation, and delay-line feedback stability. Tests are opt-in so they don't affect normal plugin builds:
+
+```bash
+cd cpp
+cmake -B build-tests -DMONKSYNTH_BUILD_TESTS=ON
+cmake --build build-tests --config Release
+ctest --test-dir build-tests --output-on-failure
+```
+
+CI runs the test suite on the Linux job before packaging each release, so any DSP regression blocks the build.
+
 ## Installation
 
 - **macOS:** Run the `.pkg` installer — installs both VST3 and AU plugins
 - **Windows:** Run the `.exe` installer — installs the VST3 plugin
 - **Linux:** Extract and copy `MonkSynth.vst3` to `~/.vst3/`
 
-## Repository Layout
-
-```
-dsp/
-  voice.c, voice.h     FOF synthesis engine (formants, overlap-add grains)
-  delay.c, delay.h     Stereo delay with feedback
-  synth.c, synth.h     Public API: note stack, MIDI routing, gain staging
-cpp/
-  src/                  VST3 plugin shell (processor, controller, GUI)
-  resources/            VSTGUI editor description and placeholder assets
-  CMakeLists.txt        Build system (fetches VST3 SDK via FetchContent)
-presets/                VST3 factory preset files
-```
-
 ## Themes
 
 MonkSynth ships without a built-in skin. On first launch, it shows a setup screen where you can import the classic look from the original Delay Lama DLL (available as freeware from [audionerdz.nl](http://www.audionerdz.nl/download.htm)).

diff --git a/cpp/CMakeLists.txt b/cpp/CMakeLists.txt
@@ -69,9 +69,21 @@ configure_file(
     "${CMAKE_CURRENT_BINARY_DIR}/generated/version.h"
 )
 
-# --- DSP engine (plain C) ---
+# --- DSP engine (plain C, standalone static library) ---
+# Built as its own target so the VST3 plugin and the unit-test executables can
+# both link against the same objects without duplicating the source list.
 set(DSP_DIR "${CMAKE_CURRENT_SOURCE_DIR}/../dsp")
 
+add_library(monk_dsp STATIC
+    ${DSP_DIR}/voice.c
+    ${DSP_DIR}/delay.c
+    ${DSP_DIR}/synth.c
+)
+target_include_directories(monk_dsp PUBLIC "${DSP_DIR}")
+if(UNIX)
+    target_link_libraries(monk_dsp PRIVATE m)
+endif()
+
 # --- VST3 Plugin ---
 smtg_add_vst3plugin(MonkSynth
     src/plugin_cids.h
@@ -102,13 +114,10 @@ smtg_add_vst3plugin(MonkSynth
     src/strings_ja.h
     src/strings_ko.h
     src/stb_impl.c
-    ${DSP_DIR}/voice.c
-    ${DSP_DIR}/delay.c
-    ${DSP_DIR}/synth.c
 )
 
-target_include_directories(MonkSynth PRIVATE "${DSP_DIR}" "${CMAKE_CURRENT_BINARY_DIR}/generated")
-target_link_libraries(MonkSynth PRIVATE sdk vstgui_support)
+target_include_directories(MonkSynth PRIVATE "${CMAKE_CURRENT_BINARY_DIR}/generated")
+target_link_libraries(MonkSynth PRIVATE sdk vstgui_support monk_dsp)
 
 smtg_target_add_plugin_resources(MonkSynth
     RESOURCES
@@ -149,6 +158,17 @@ if(UNIX)
     target_link_libraries(MonkSynth PRIVATE m)
 endif()
 
+# --- DSP unit tests (opt-in) ---
+option(MONKSYNTH_BUILD_TESTS "Build DSP unit tests" OFF)
+if(MONKSYNTH_BUILD_TESTS)
+    enable_testing()
+    foreach(t test_voice test_synth test_delay)
+        add_executable(${t} tests/${t}.c)
+        target_link_libraries(${t} PRIVATE monk_dsp)
+        add_test(NAME ${t} COMMAND ${t})
+    endforeach()
+endif()
+
 # Hide all symbols except VST3 entry points when statically linking on Linux.
 # This prevents bundled cairo/pango/glib symbols from conflicting with
 # other plugins or the host DAW.

diff --git a/cpp/src/controller.cpp b/cpp/src/controller.cpp
@@ -360,6 +360,46 @@ COptionMenu *Controller::createContextMenu(const CPoint & /*pos*/, VST3Editor *e
     }
     menu->addEntry(langMenu, i18n::str(i18n::StringId::MenuLanguage));
 
+    // ---- Pitch Bend routing submenu ----
+    auto *pbMenu = new COptionMenu();
+    const bool pbRoutingIsPitch = getParamNormalized(kPitchBendRouting) >= 0.5;
+
+    struct PbOption {
+        i18n::StringId labelId;
+        bool isPitch;
+    };
+    const PbOption pbOpts[] = {
+        {i18n::StringId::MenuPitchBendClassic, false},
+        {i18n::StringId::MenuPitchBendPitch, true},
+    };
+
+    for (const auto &opt : pbOpts) {
+        CCommandMenuItem::Desc desc(i18n::str(opt.labelId));
+        if (pbRoutingIsPitch == opt.isPitch)
+            desc.flags |= CMenuItem::kChecked;
+        auto *pbItem = new CCommandMenuItem(std::move(desc));
+        bool target = opt.isPitch;
+        pbItem->setActions([this, target](CCommandMenuItem *) {
+            // Push the value through beginEdit/performEdit/endEdit so the
+            // host records the change and forwards it to the processor;
+            // setParamNormalized separately updates our own state and fires
+            // the restartComponent(kMidiCCAssignmentChanged) notification.
+            ParamValue v = target ? 1.0 : 0.0;
+            beginEdit(kPitchBendRouting);
+            performEdit(kPitchBendRouting, v);
+            endEdit(kPitchBendRouting);
+            setParamNormalized(kPitchBendRouting, v);
+        });
+        pbMenu->addEntry(pbItem);
+    }
+    // Surface the active mode in the parent menu label so users see the
+    // current state without opening the submenu. The kChecked flag on the
+    // submenu items alone is not reliably rendered by all hosts.
+    std::string pbLabel = std::string(i18n::str(i18n::StringId::MenuPitchBend)) + ": " +
+                          i18n::str(pbRoutingIsPitch ? i18n::StringId::MenuPitchBendPitch
+                                                     : i18n::StringId::MenuPitchBendClassic);
+    menu->addEntry(pbMenu, UTF8String(pbLabel));
+
     // No "Reset to Default" — there's no built-in theme. Users switch
     // between imported themes or re-import from the DLL.
 
@@ -377,7 +417,17 @@ tresult PLUGIN_API Controller::getMidiControllerAssignment(int32 busIndex, int16
         return kResultFalse;
 
     switch (midiControllerNumber) {
-        case ControllerNumbers::kPitchBend: id = kVowel; return kResultTrue;
+        case ControllerNumbers::kPitchBend:
+            // Dynamic routing: the kPitchBendRouting hidden parameter
+            // decides whether the hardware pitch wheel drives Vowel (Classic
+            // / Delay Lama compat) or PitchBend (standard synth). When the
+            // user flips the toggle, setParamNormalized below notifies the
+            // host via restartComponent(kMidiCCAssignmentChanged) so this
+            // function is re-queried.
+            id = (getParamNormalized(kPitchBendRouting) >= 0.5)
+                 ? kPitchBend
+                 : kVowel;
+            return kResultTrue;
         case ControllerNumbers::kCtrlModWheel: id = kVibrato; return kResultTrue;
         case ControllerNumbers::kCtrlPortaTime: id = kPortTime; return kResultTrue;
         case ControllerNumbers::kCtrlVolume: id = kLevel; return kResultTrue;
@@ -427,6 +477,12 @@ tresult PLUGIN_API Controller::setParamNormalized(ParamID tag, ParamValue value)
         } else if (tag == kXYNoteOn || tag == kNoteActive) {
             if (monkView_)
                 monkView_->setNoteActive(value > 0.5);
+        } else if (tag == kPitchBendRouting) {
+            // Tell the host to re-query IMidiMapping so the hardware pitch
+            // wheel assignment flips immediately instead of waiting for a
+            // plugin reload.
+            if (componentHandler)
+                componentHandler->restartComponent(kMidiCCAssignmentChanged);
         }
     }
     return result;
@@ -513,6 +569,16 @@ tresult PLUGIN_API Controller::initialize(FUnknown *context) {
     parameters.addParameter(STR16("XY Pitch"), STR16(""), 0, 0.5,
                             ParameterInfo::kCanAutomate, kXYPitchTarget);
 
+    parameters.addParameter(
+        new RangeParameter(STR16("Pitch Bend"), kPitchBend, STR16("st"),
+                           -12.0, 12.0, 0.0, 0, ParameterInfo::kCanAutomate));
+
+    // Hidden routing toggle: 0 = Classic (hardware pitch wheel → Vowel,
+    // Delay Lama compat), 1 = Pitch (wheel → PitchBend). Persists in VST3
+    // state so it travels with presets and DAW sessions.
+    parameters.addParameter(STR16("PB Routing"), STR16(""), 1, 0.0,
+                            ParameterInfo::kIsHidden, kPitchBendRouting);
+
     // Private parameters (not exposed to host automation)
     parameters.addParameter(STR16("XY Pitch Display"), STR16(""), 0, 0.5, ParameterInfo::kIsHidden,
                             kXYPitch);

diff --git a/cpp/src/i18n.h b/cpp/src/i18n.h
@@ -30,6 +30,9 @@ enum class StringId : int {
     MenuOpenFolder,
     MenuLanguage,
     MenuLanguageAuto,
+    MenuPitchBend,
+    MenuPitchBendClassic,
+    MenuPitchBendPitch,
     FileSelectThemeJson,
     FileSelectDll,
     FileExtJson,

diff --git a/cpp/src/plugin_cids.h b/cpp/src/plugin_cids.h
@@ -32,7 +32,9 @@ enum : Steinberg::Vst::ParamID {
     kXYNoteOn = 16,       // 1.0 = note on, 0.0 = note off
     kXYVowel = 17,        // target vowel from XY pad Y axis
     kXYPitchTarget = 18,  // target pitch from XY pad X axis
-    kNumParams = 19,
+    kPitchBend = 19,      // ±12 semitones, default 0
+    kPitchBendRouting = 20, // 0 = Classic (Vowel), 1 = Pitch — hidden
+    kNumParams = 21,
 
     // Private parameters (not exposed to host automation)
     kXYPitch = 101,       // smoothed pitch for indicator display

diff --git a/cpp/src/processor.cpp b/cpp/src/processor.cpp
@@ -60,6 +60,7 @@ tresult PLUGIN_API Processor::setActive(TBool state) {
         monk_synth_set_sustain(synth_, paramValues_[kSustain]);
         monk_synth_set_release(synth_, paramValues_[kRelease] * 3.0f);
         monk_synth_set_level(synth_, paramValues_[kLevel]);
+        monk_synth_set_pitch_bend(synth_, (paramValues_[kPitchBend] - 0.5f) * 24.0f);
     } else {
         if (synth_) {
             monk_synth_reset(synth_);
@@ -177,6 +178,14 @@ tresult PLUGIN_API Processor::process(ProcessData& data) {
                 case kXYVowel:
                     monk_synth_set_vowel(synth_, fval);
                     break;
+                case kPitchBend:
+                    // RangeParameter [-12,12]: normalized 0.5 = 0 semitones.
+                    monk_synth_set_pitch_bend(synth_, (fval - 0.5f) * 24.0f);
+                    break;
+                case kPitchBendRouting:
+                    // Stored in paramValues_ only; the controller handles
+                    // IMidiMapping re-query. No DSP side-effect from here.
+                    break;
                 default: break;
             }
         }

diff --git a/cpp/src/processor.h b/cpp/src/processor.h
@@ -31,9 +31,12 @@ class Processor : public Steinberg::Vst::AudioEffect {
 
   private:
     MonkSynthEngine *synth_ = nullptr;
-    float paramValues_[19] = {0.5f, 0.5f, 0.8f, 0.5f, 0.0f, 0.5f, 0.5f, 0.0f,
+    // Order must match the ParamID enum in plugin_cids.h.
+    // PitchBend (idx 19): 0.5 = 0 semitones (RangeParameter midpoint).
+    // PitchBendRouting (idx 20): 0.0 = Classic (Vowel), preserves Delay Lama.
+    float paramValues_[21] = {0.5f, 0.5f, 0.8f, 0.5f, 0.0f, 0.5f, 0.5f, 0.0f,
                               0.0f, 1.0f, 0.0f, 0.0f, 0.0f, 0.5f, 1.0f, 0.0f,
-                              0.0f, 0.5f, 0.5f};
+                              0.0f, 0.5f, 0.5f, 0.5f, 0.0f};
     bool xyNoteActive_ = false;
     float xyPendingPitch_ = 0.5f;
     int midiNoteCount_ = 0;

diff --git a/cpp/src/strings_en.h b/cpp/src/strings_en.h
@@ -58,6 +58,12 @@ constexpr const char *kStringsEn[] = {
     "Language",
     // MenuLanguageAuto
     "Auto",
+    // MenuPitchBend
+    "Pitch Bend",
+    // MenuPitchBendClassic
+    "Classic (Vowel)",
+    // MenuPitchBendPitch
+    "Pitch",
     // FileSelectThemeJson
     "Select theme.json in Theme Folder",
     // FileSelectDll

diff --git a/cpp/src/strings_ja.h b/cpp/src/strings_ja.h
@@ -65,6 +65,12 @@ constexpr const char *kStringsJa[] = {
     "言語",
     // MenuLanguageAuto
     "自動",
+    // MenuPitchBend
+    "ピッチベンド",
+    // MenuPitchBendClassic
+    "クラシック（母音）",
+    // MenuPitchBendPitch
+    "ピッチ",
     // FileSelectThemeJson
     "テーマフォルダ内の theme.json を選択",
     // FileSelectDll

diff --git a/cpp/src/strings_ko.h b/cpp/src/strings_ko.h
@@ -65,6 +65,12 @@ constexpr const char *kStringsKo[] = {
     "언어",
     // MenuLanguageAuto
     "자동",
+    // MenuPitchBend
+    "피치 벤드",
+    // MenuPitchBendClassic
+    "클래식 (모음)",
+    // MenuPitchBendPitch
+    "피치",
     // FileSelectThemeJson
     "테마 폴더에서 theme.json 선택",
     // FileSelectDll