Addressing #46

Author: aure

Sources/CSoundpipeAudioKit/Generators/PhaseLockedVocoderDSP.mm

@@ -24,7 +24,7 @@
     ParameterRamper pitchRatioRamp;
 
 public:
-    PhaseLockedVocoderDSP() {
+    PhaseLockedVocoderDSP() : SoundpipeDSPBase(/*inputBusCount*/0) {
         parameters[PhaseLockedVocoderParameterPosition] = &positionRamp;
         parameters[PhaseLockedVocoderParameterAmplitude] = &amplitudeRamp;
         parameters[PhaseLockedVocoderParameterPitchRatio] = &pitchRatioRamp;

Tests/CSoundpipeAudioKitTests/GeneratorInputBusTests.mm

@@ -0,0 +1,59 @@
+#import <XCTest/XCTest.h>
+#import <CSoundpipeAudioKit.h>
+#import <DSPBase.h>
+
+/// Regression tests for https://github.com/AudioKit/SoundpipeAudioKit/issues/46
+///
+/// Generators have no audio input bus. If a generator DSP inherits the
+/// SoundpipeDSPBase default of `inputBusCount=1`, its bypass path in
+/// `DSPBase::processOrBypass` neither zeroes the output (non-empty
+/// inputBufferLists skips that branch) nor can it safely copy input
+/// (there is no connected input), and with `canProcessInPlace=false`
+/// it dereferences an uninitialized buffer and crashes.
+///
+/// Every generator in this package must therefore be constructed with
+/// `inputBusCount=0`.
+@interface GeneratorInputBusTests : XCTestCase
+@end
+
+@implementation GeneratorInputBusTests
+
+static OSType fourCC(const char *s) {
+    return (OSType)((uint8_t)s[0] << 24 | (uint8_t)s[1] << 16 | (uint8_t)s[2] << 8 | (uint8_t)s[3]);
+}
+
+- (void)assertGeneratorCode:(const char *)code {
+    DSPRef dsp = akCreateDSP(fourCC(code));
+    XCTAssertTrue(dsp != NULL, @"Failed to create DSP '%s'", code);
+    XCTAssertEqual(inputBusCountDSP(dsp), 0UL,
+                   @"Generator '%s' must have inputBusCount=0", code);
+    deleteDSP(dsp);
+}
+
+- (void)testPhaseLockedVocoderIsGenerator {
+    [self assertGeneratorCode:"minc"];
+}
+
+- (void)testAllGeneratorsHaveNoInputBus {
+    // Codes from AK_REGISTER_DSP in Sources/CSoundpipeAudioKit/Generators/*.mm
+    const char *codes[] = {
+        "bron", // BrownianNoise
+        "csto", // DynamicOscillator
+        "fosc", // FMOscillator
+        "mbar", // MetalBar
+        "morf", // MorphingOscillator
+        "oscl", // Oscillator
+        "pdho", // PhaseDistortionOscillator
+        "minc", // PhaseLockedVocoder
+        "pink", // PinkNoise
+        "pluk", // PluckedString
+        "pwmo", // PWMOscillator
+        "vocw", // VocalTract
+        "wnoz", // WhiteNoise
+    };
+    for (const char *code : codes) {
+        [self assertGeneratorCode:code];
+    }
+}
+
+@end