Du kan inte välja fler än 25 ämnen Ämnen måste starta med en bokstav eller siffra, kan innehålla bindestreck ('-') och vara max 35 tecken långa.

filter_fir.h 2.3KB

12345678910111213141516171819202122232425262728293031323334353637383940414243444546474849505152535455565758596061626364656667
  1. /* Audio Library for Teensy 3.X
  2. * Copyright (c) 2014, Pete (El Supremo)
  3. *
  4. * Permission is hereby granted, free of charge, to any person obtaining a copy
  5. * of this software and associated documentation files (the "Software"), to deal
  6. * in the Software without restriction, including without limitation the rights
  7. * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  8. * copies of the Software, and to permit persons to whom the Software is
  9. * furnished to do so, subject to the following conditions:
  10. *
  11. * The above copyright notice and this permission notice shall be included in
  12. * all copies or substantial portions of the Software.
  13. *
  14. * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  15. * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  16. * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  17. * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  18. * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  19. * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  20. * THE SOFTWARE.
  21. */
  22. #ifndef filter_fir_h_
  23. #define filter_fir_h_
  24. #include "Arduino.h"
  25. #include "AudioStream.h"
  26. #include "arm_math.h"
  27. // Indicates that the code should just pass through the audio
  28. // without any filtering (as opposed to doing nothing at all)
  29. #define FIR_PASSTHRU ((const short *) 1)
  30. #define FIR_MAX_COEFFS 200
  31. class AudioFilterFIR : public AudioStream
  32. {
  33. public:
  34. AudioFilterFIR(void): AudioStream(1,inputQueueArray), coeff_p(NULL) {
  35. }
  36. void begin(const short *cp, int n_coeffs) {
  37. coeff_p = cp;
  38. // Initialize FIR instance (ARM DSP Math Library)
  39. if (coeff_p && (coeff_p != FIR_PASSTHRU) && n_coeffs <= FIR_MAX_COEFFS) {
  40. if (arm_fir_init_q15(&fir_inst, n_coeffs, (q15_t *)coeff_p,
  41. &StateQ15[0], AUDIO_BLOCK_SAMPLES) != ARM_MATH_SUCCESS) {
  42. // n_coeffs must be an even number, 4 or larger
  43. coeff_p = NULL;
  44. }
  45. }
  46. }
  47. void end(void) {
  48. coeff_p = NULL;
  49. }
  50. virtual void update(void);
  51. private:
  52. audio_block_t *inputQueueArray[1];
  53. // pointer to current coefficients or NULL or FIR_PASSTHRU
  54. const short *coeff_p;
  55. // ARM DSP Math library filter instance
  56. arm_fir_instance_q15 fir_inst;
  57. q15_t StateQ15[AUDIO_BLOCK_SAMPLES + FIR_MAX_COEFFS];
  58. };
  59. #endif