Add README, thread-safe engine, standalone format

CMakeLists.txt

@@ -20,9 +20,9 @@ endif()
 add_subdirectory("${JUCE_ROOT}" juce_build)
 
 if(APPLE)
-    set(SM26_FORMATS AU VST3)
+    set(SM26_FORMATS Standalone AU VST3)
 elseif(UNIX)
-    set(SM26_FORMATS VST3)
+    set(SM26_FORMATS Standalone VST3)
 else()
     set(SM26_FORMATS VST3)
 endif()
@@ -68,6 +68,8 @@ target_compile_definitions(SM-26 PRIVATE
 
 juce_generate_juce_header(SM-26)
 
+target_link_libraries (SM-26 PRIVATE juce::juce_audio_utils juce::juce_audio_devices)
+
 add_custom_target(gen_buildinfo ALL
     COMMAND "${CMAKE_CURRENT_SOURCE_DIR}/tools/gen_buildinfo.sh"
             "${CMAKE_CURRENT_SOURCE_DIR}"

Makefile

@@ -83,6 +83,10 @@ install: build
 		if [ -n "$$VST3" ]; then rm -rf "$(DEST_VST3)"; cp -R "$$VST3" "$(HOME)/.vst3/"; else echo "!! VST3 not found in build dir"; exit 1; fi; \
 	fi
 	@echo ">> SM-26 installed."
+	@echo ""
+	@echo ">> To make newly-installed AUs visible to macOS immediately, run:"
+	@echo ">>   sudo killall -HUP coreaudiod"
+	@echo ">> (or simply restart your audio host / DAW)"
 
 uninstall:
 	@if [ "$(UNAME_S)" = "Darwin" ]; then \

README.md

@@ -0,0 +1,58 @@
+# SM-26
+
+A simple subtractive synthesizer plugin built with JUCE / C++.
+
+* **VST3** + **Audio Unit** (macOS arm64), **VST3** (Linux)
+* 4 rotary knobs on the front panel whose meaning follows the selected preset
+* 52 factory presets (Bass / Lead / Pad / Keys / Pluck / FX / Stab / Arp)
+* tempo-synced delay (follows the host transport / BPM)
+* 4x80 HD44780-style pixel display with a cascaded on-screen menu
+* left/right/up/down navigation diamond + ENTER / ESC controls the menu
+* status footer with the git revision and local build time
+
+## Build
+
+Requires a C++17 compiler, CMake >= 3.22 and (on Linux) X11/ALSA dev headers.
+
+```sh
+make            # clones JUCE (once) into deps/ and builds
+make install    # installs + ad-hoc signs + un-quarantines
+make uninstall  # removes the installed plugins
+make distclean  # wipes build/
+```
+
+* macOS installs to `~/Library/Audio/Plug-Ins/` (AU + VST3).
+* Linux installs to `~/.vst3/`.
+
+If a freshly installed AU is not visible to `auval` / your DAW:
+
+```sh
+sudo killall -HUP coreaudiod
+```
+
+## Usage
+
+* Ship MIDI into the plugin; the 4 front-panel knobs drive whichever
+  parameters the current preset maps them to (e.g. cutoff/resonance/
+  envelope/delay, but many other routings exist).
+* **Nav diamond + ENTER/ESC** drive the on-screen menu:
+  * root menu -> PRESETS / OSCILLATORS / FILTER / ENVELOPE / DELAY / SYSTEM
+  * up/down = move, left/right = adjust value, ENTER = open/confirm, ESC = back
+* The LCD shows the current preset, the four knob mappings with live values,
+  host BPM and voice count. The delay can be set to a rhythmic subdivision
+  (SYNC) and locks to the host tempo.
+
+## Layout
+
+```
+Build: Makefile -> CMake -> JUCE (deps/juce)
+Source/
+  PluginProcessor.*   audio processor + DSP shell
+  SynthEngine.*       osc/filter/ADSR/delay voice engine
+  Presets.*           52 preset definitions + knob routings
+  SynthParams.*       parameter model + formatting
+  PluginEditor.*      panel, knobs, nav diamond, footer
+  LcdDisplay.*        4x80 HD44780-style display renderer
+  MenuSystem.*        cascaded menu state machine
+tools/gen_buildinfo.sh  generates git-version + build-time header
+```

Source/SynthEngine.cpp

@@ -42,6 +42,7 @@ void SynthEngine::reset()
 
 void SynthEngine::loadPreset (const Preset& p)
 {
+    juce::SpinLock::ScopedLockType lock (paramLock);
     for (int i = 0; i < kNumParams; ++i)
         params[i] = p.base[i];
     for (int i = 0; i < kNumKnobs; ++i)
@@ -63,6 +64,7 @@ void SynthEngine::setPresetIndex (int i)
 void SynthEngine::setParam (int id, float n01)
 {
     if (id < 0 || id >= kNumParams) return;
+    juce::SpinLock::ScopedLockType lock (paramLock);
     params[id] = juce::jlimit (0.0f, 1.0f, n01);
 }
 
@@ -79,6 +81,8 @@ SynthEngine::KnobView SynthEngine::knobView (int knob) const
     k.name  = knobNames[knob];
     k.param = knobParams[knob];
     k.value01 = getParam (k.param);
+    k.lo = knobLows[knob];
+    k.hi = knobHighs[knob];
     return k;
 }
 
@@ -192,6 +196,14 @@ void SynthEngine::process (AudioBuffer<float>& buffer, MidiBuffer& midi,
     wasPlaying = transportPlaying;
     lastBpmValue = (bpm > 10.0 && bpm < 300.0) ? bpm : 120.0;
 
+    std::array<float, kNumParams> snap;
+    {
+        juce::SpinLock::ScopedLockType lock (paramLock);
+        for (int i = 0; i < kNumParams; ++i)
+            snap[(size_t) i] = params[i];
+    }
+    const float* const params = snap.data();
+
     const float cutN01  = params[PCUTOFF];
     const float resN01  = params[PRES];
     const float fenvN01 = params[PFENV];