Adding AudioFilterFIR_F32

AudioFilterFIR_F32.h

@@ -0,0 +1,92 @@
+/*
+ * AudioFilterFIR_F32
+ * 
+ * Created: Chip Audette (OpenAudio) Feb 2017
+ *    - Building from AudioFilterFIR from Teensy Audio Library (AudioFilterFIR credited to Pete (El Supremo))
+ * 
+ */
+
+#ifndef _filter_fir_f32
+#define _filter_fir_f32
+
+#include "Arduino.h"
+#include "AudioStream_F32.h"
+#include "arm_math.h"
+
+// Indicates that the code should just pass through the audio
+// without any filtering (as opposed to doing nothing at all)
+#define FIR_F32_PASSTHRU ((const float32_t *) 1)
+
+#define FIR_MAX_COEFFS 200
+
+class AudioFilterFIR_F32 : public AudioStream_F32
+{
+public:
+  AudioFilterFIR_F32(void): AudioStream_F32(1,inputQueueArray), coeff_p(FIR_F32_PASSTHRU) {
+  }
+  void begin(const float32_t *cp, int n_coeffs) {
+    coeff_p = cp;
+    // Initialize FIR instance (ARM DSP Math Library)
+    if (coeff_p && (coeff_p != FIR_F32_PASSTHRU) && n_coeffs <= FIR_MAX_COEFFS) {
+      arm_fir_init_f32(&fir_inst, n_coeffs, (float32_t *)coeff_p,  &StateF32[0], AUDIO_BLOCK_SAMPLES);
+      //if (arm_fir_init_f32(&fir_inst, n_coeffs, (float32_t *)coeff_p,  &StateF32[0], AUDIO_BLOCK_SAMPLES) != ARM_MATH_SUCCESS) {
+        // n_coeffs must be an even number, 4 or larger
+        //coeff_p = NULL;
+      //}
+    }
+  }
+  void end(void) {
+    coeff_p = NULL;
+  }
+  virtual void update(void);
+
+  void setBlockDC(void) {
+    //helper function that sets this up for a first-order HP filter at 20Hz
+    
+  }
+private:
+  audio_block_f32_t *inputQueueArray[1];
+
+  // pointer to current coefficients or NULL or FIR_PASSTHRU
+  const float32_t *coeff_p;
+
+  // ARM DSP Math library filter instance
+  arm_fir_instance_f32 fir_inst;
+  float32_t StateF32[AUDIO_BLOCK_SAMPLES + FIR_MAX_COEFFS];
+};
+
+
+void AudioFilterFIR_F32::update(void)
+{
+  audio_block_f32_t *block, *b_new;
+
+  block = AudioStream_F32::receiveReadOnly_f32();
+  if (!block) return;
+
+  // If there's no coefficient table, give up.  
+  if (coeff_p == NULL) {
+    AudioStream_F32::release(block);
+    return;
+  }
+
+  // do passthru
+  if (coeff_p == FIR_F32_PASSTHRU) {
+    // Just passthrough
+    AudioStream_F32::transmit(block);
+    AudioStream_F32::release(block);
+    return;
+  }
+
+  // get a block for the FIR output
+  b_new = AudioStream_F32::allocate_f32();
+  if (b_new) {
+    arm_fir_f32(&fir_inst, (float32_t *)block->data, (float32_t *)b_new->data, block->length);
+    AudioStream_F32::transmit(b_new); // send the FIR output
+    AudioStream_F32::release(b_new);
+  }
+  AudioStream_F32::release(block);
+}
+
+#endif
+
+