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  1. /* Audio Library for Teensy 3.X
  2. * Copyright (c) 2016, Paul Stoffregen, paul@pjrc.com
  3. *
  4. * Development of this audio library was funded by PJRC.COM, LLC by sales of
  5. * Teensy and Audio Adaptor boards. Please support PJRC's efforts to develop
  6. * open source software by purchasing Teensy or other PJRC products.
  7. *
  8. * Permission is hereby granted, free of charge, to any person obtaining a copy
  9. * of this software and associated documentation files (the "Software"), to deal
  10. * in the Software without restriction, including without limitation the rights
  11. * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  12. * copies of the Software, and to permit persons to whom the Software is
  13. * furnished to do so, subject to the following conditions:
  14. *
  15. * The above copyright notice, development funding notice, and this permission
  16. * notice shall be included in all copies or substantial portions of the Software.
  17. *
  18. * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  19. * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  20. * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  21. * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  22. * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  23. * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  24. * THE SOFTWARE.
  25. */
  26. #ifndef synth_karplusstrong_h_
  27. #define synth_karplusstrong_h_
  28. #include "Arduino.h"
  29. #include "AudioStream.h"
  30. #include "utility/dspinst.h"
  31. class AudioSynthKarplusStrong : public AudioStream
  32. {
  33. public:
  34. AudioSynthKarplusStrong() : AudioStream(0, NULL) {
  35. state = 0;
  36. }
  37. void noteOn(float frequency, float velocity) {
  38. if (velocity > 1.0f) {
  39. velocity = 0.0f;
  40. } else if (velocity <= 0.0f) {
  41. noteOff(1.0f);
  42. return;
  43. }
  44. magnitude = velocity * 65535.0f;
  45. int len = (AUDIO_SAMPLE_RATE_EXACT / frequency) + 0.5f;
  46. if (len > 536) len = 536;
  47. bufferLen = len;
  48. bufferIndex = 0;
  49. state = 1;
  50. }
  51. void noteOff(float velocity) {
  52. state = 0;
  53. }
  54. virtual void update(void);
  55. private:
  56. uint8_t state; // 0=steady output, 1=begin on next update, 2=playing
  57. uint16_t bufferLen;
  58. uint16_t bufferIndex;
  59. int32_t magnitude; // current output
  60. static uint32_t seed; // must start at 1
  61. int16_t buffer[536]; // TODO: dynamically use audio memory blocks
  62. };
  63. #endif