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