lichen-community-systemsgh-63: Also adds two pole output for Bob.

libsignaletic/include/libsignaletic.h

@@ -1634,6 +1634,28 @@ struct sig_dsp_Filter_Inputs {
 };
 
 
+struct sig_dsp_FourPoleFilter_Outputs {
+    /**
+     * @brief The four pole 24 dB output from the filter.
+     */
+    float_array_ptr main;
+
+    /**
+     * @brief A two pole 12 dB output from the second stage of the filter.
+     */
+    float_array_ptr twoPole;
+};
+
+void sig_dsp_FourPoleFilter_Outputs_newAudioBlocks(
+    struct sig_Allocator* allocator,
+    struct sig_AudioSettings* audioSettings,
+    struct sig_dsp_FourPoleFilter_Outputs* outputs);
+
+void sig_dsp_FourPoleFilter_Outputs_destroyAudioBlocks(
+    struct sig_Allocator* allocator,
+    struct sig_dsp_FourPoleFilter_Outputs* outputs);
+
+
 /**
  * @brief Miller Pucket's 24dB Moog-style ladder low pass filter.
  * Imitates a Moog resonant filter by Runge-Kutte numerical integration
@@ -1664,7 +1686,7 @@ struct sig_dsp_BobLPF {
     struct sig_dsp_Signal signal;
     struct sig_dsp_Filter_Inputs inputs;
     // TODO: Add outputs for the other filter poles.
-    struct sig_dsp_Signal_SingleMonoOutput outputs;
+    struct sig_dsp_FourPoleFilter_Outputs outputs;
 
     float state[4];
     float deriv1[4];
@@ -1690,32 +1712,21 @@ void sig_dsp_BobLPF_destroy(struct sig_Allocator* allocator,
     struct sig_dsp_BobLPF* self);
 
 
+
 struct sig_dsp_LadderLPF_Parameters {
     /**
      * @brief The passband gain of the filter (best between 0.0-0.5),
-     * helps to offset the drop in low frequencies when resonance is high.
+     * higher values will amplify the lower frequencies when resonance is high.
      */
     float passbandGain;
 
     /**
-     * @brief Gain prior to the filter, allowing for greater saturation levels.
+     * @brief Input gain applied prior to the filter,
+     * allowing for greater saturation levels (best between 0.0-4.0)
      */
     float overdrive;
 };
 
-struct sig_dsp_LadderLPF_Outputs {
-    float_array_ptr main;
-    float_array_ptr twoPole;
-};
-
-void sig_dsp_LadderLPF_Outputs_newAudioBlocks(
-    struct sig_Allocator* allocator,
-    struct sig_AudioSettings* audioSettings,
-    struct sig_dsp_LadderLPF_Outputs* outputs);
-
-void sig_dsp_LadderLPF_Outputs_destroyAudioBlocks(
-    struct sig_Allocator* allocator,
-    struct sig_dsp_LadderLPF_Outputs* outputs);
 /**
  * @brief Valimaki and Huovilainen's Moog-style Ladder Filter
  * Ported from Infrasonic Audio LLC's adaptation of
@@ -1732,7 +1743,7 @@ struct sig_dsp_LadderLPF {
     struct sig_dsp_Filter_Inputs inputs;
     struct sig_dsp_LadderLPF_Parameters parameters;
     // TODO: Add outputs for the other filter poles.
-    struct sig_dsp_LadderLPF_Outputs outputs;
+    struct sig_dsp_FourPoleFilter_Outputs outputs;
 
     uint8_t interpolation;
     float interpolationRecip;

libsignaletic/src/libsignaletic.c

@@ -2213,12 +2213,28 @@ void sig_dsp_TwoOpFM_destroy(struct sig_Allocator* allocator,
 
 
 
+void sig_dsp_FourPoleFilter_Outputs_newAudioBlocks(
+    struct sig_Allocator* allocator,
+    struct sig_AudioSettings* audioSettings,
+    struct sig_dsp_FourPoleFilter_Outputs* outputs) {
+    outputs->main = sig_AudioBlock_newSilent(allocator, audioSettings);
+    outputs->twoPole = sig_AudioBlock_newSilent(allocator, audioSettings);
+}
+
+void sig_dsp_FourPoleFilter_Outputs_destroyAudioBlocks(
+    struct sig_Allocator* allocator,
+    struct sig_dsp_FourPoleFilter_Outputs* outputs) {
+    sig_AudioBlock_destroy(allocator, outputs->main);
+    sig_AudioBlock_destroy(allocator, outputs->twoPole);
+}
+
+
 struct sig_dsp_BobLPF* sig_dsp_BobLPF_new(struct sig_Allocator* allocator,
     struct sig_SignalContext* context) {
     struct sig_dsp_BobLPF* self = sig_MALLOC(allocator,
         struct sig_dsp_BobLPF);
     sig_dsp_BobLPF_init(self, context);
-    sig_dsp_Signal_SingleMonoOutput_newAudioBlocks(allocator,
+    sig_dsp_FourPoleFilter_Outputs_newAudioBlocks(allocator,
         context->audioSettings, &self->outputs);
 
     return self;
@@ -2327,6 +2343,7 @@ void sig_dsp_BobLPF_generate(void* signal) {
 
     for (size_t i = 0; i < self->signal.audioSettings->blockSize; i++) {
         float input = FLOAT_ARRAY(self->inputs.source)[i];
+        // TODO: Should we account for oversampling here?
         float cutoff = sig_TWOPI * FLOAT_ARRAY(self->inputs.frequency)[i];
         float resonance = FLOAT_ARRAY(self->inputs.resonance)[i];
         resonance = resonance < 0.0f ? 0.0f : resonance;
@@ -2336,38 +2353,24 @@ void sig_dsp_BobLPF_generate(void* signal) {
         }
 
         FLOAT_ARRAY(self->outputs.main)[i] = self->state[3];
+        FLOAT_ARRAY(self->outputs.twoPole)[i] = self->state[1];
     }
 }
 
 void sig_dsp_BobLPF_destroy(struct sig_Allocator* allocator,
     struct sig_dsp_BobLPF* self) {
-    sig_dsp_Signal_SingleMonoOutput_destroyAudioBlocks(allocator,
+    sig_dsp_FourPoleFilter_Outputs_destroyAudioBlocks(allocator,
         &self->outputs);
     sig_dsp_Signal_destroy(allocator, self);
 }
 
 
-void sig_dsp_LadderLPF_Outputs_newAudioBlocks(
-    struct sig_Allocator* allocator,
-    struct sig_AudioSettings* audioSettings,
-    struct sig_dsp_LadderLPF_Outputs* outputs) {
-    outputs->main = sig_AudioBlock_newSilent(allocator, audioSettings);
-    outputs->twoPole = sig_AudioBlock_newSilent(allocator, audioSettings);
-}
-
-void sig_dsp_LadderLPF_Outputs_destroyAudioBlocks(
-    struct sig_Allocator* allocator,
-    struct sig_dsp_LadderLPF_Outputs* outputs) {
-    sig_AudioBlock_destroy(allocator, outputs->main);
-    sig_AudioBlock_destroy(allocator, outputs->twoPole);
-}
-
 struct sig_dsp_LadderLPF* sig_dsp_LadderLPF_new(
     struct sig_Allocator* allocator, struct sig_SignalContext* context) {
     struct sig_dsp_LadderLPF* self = sig_MALLOC(allocator,
         struct sig_dsp_LadderLPF);
     sig_dsp_LadderLPF_init(self, context);
-    sig_dsp_LadderLPF_Outputs_newAudioBlocks(allocator,
+    sig_dsp_FourPoleFilter_Outputs_newAudioBlocks(allocator,
         context->audioSettings, &self->outputs);
 
     return self;
@@ -2470,7 +2473,7 @@ void sig_dsp_LadderLPF_generate(void* signal) {
 
 void sig_dsp_LadderLPF_destroy(struct sig_Allocator* allocator,
     struct sig_dsp_LadderLPF* self) {
-    sig_dsp_LadderLPF_Outputs_destroyAudioBlocks(allocator,
+    sig_dsp_FourPoleFilter_Outputs_destroyAudioBlocks(allocator,
         &self->outputs);
     sig_dsp_Signal_destroy(allocator, self);
 }