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  1. /* Audio Library for Teensy 3.X
  2. * Copyright (c) 2014, 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. #include <Arduino.h>
  27. #include "synth_whitenoise.h"
  28. // Park-Miller-Carta Pseudo-Random Number Generator
  29. // http://www.firstpr.com.au/dsp/rand31/
  30. void AudioSynthNoiseWhite::update(void)
  31. {
  32. audio_block_t *block;
  33. uint32_t *p, *end;
  34. int32_t n1, n2, gain;
  35. uint32_t lo, hi, val1, val2;
  36. gain = level;
  37. if (gain == 0) return;
  38. block = allocate();
  39. if (!block) return;
  40. p = (uint32_t *)(block->data);
  41. end = p + AUDIO_BLOCK_SAMPLES/2;
  42. lo = seed;
  43. do {
  44. #if defined(__ARM_ARCH_7EM__)
  45. hi = multiply_16bx16t(16807, lo); // 16807 * (lo >> 16)
  46. lo = 16807 * (lo & 0xFFFF);
  47. lo += (hi & 0x7FFF) << 16;
  48. lo += hi >> 15;
  49. lo = (lo & 0x7FFFFFFF) + (lo >> 31);
  50. n1 = signed_multiply_32x16b(gain, lo);
  51. hi = multiply_16bx16t(16807, lo); // 16807 * (lo >> 16)
  52. lo = 16807 * (lo & 0xFFFF);
  53. lo += (hi & 0x7FFF) << 16;
  54. lo += hi >> 15;
  55. lo = (lo & 0x7FFFFFFF) + (lo >> 31);
  56. n2 = signed_multiply_32x16b(gain, lo);
  57. val1 = pack_16b_16b(n2, n1);
  58. hi = multiply_16bx16t(16807, lo); // 16807 * (lo >> 16)
  59. lo = 16807 * (lo & 0xFFFF);
  60. lo += (hi & 0x7FFF) << 16;
  61. lo += hi >> 15;
  62. lo = (lo & 0x7FFFFFFF) + (lo >> 31);
  63. n1 = signed_multiply_32x16b(gain, lo);
  64. hi = multiply_16bx16t(16807, lo); // 16807 * (lo >> 16)
  65. lo = 16807 * (lo & 0xFFFF);
  66. lo += (hi & 0x7FFF) << 16;
  67. lo += hi >> 15;
  68. lo = (lo & 0x7FFFFFFF) + (lo >> 31);
  69. n2 = signed_multiply_32x16b(gain, lo);
  70. val2 = pack_16b_16b(n2, n1);
  71. *p++ = val1;
  72. *p++ = val2;
  73. #elif defined(KINETISL)
  74. hi = 16807 * (lo >> 16);
  75. lo = 16807 * (lo & 0xFFFF);
  76. lo += (hi & 0x7FFF) << 16;
  77. lo += hi >> 15;
  78. lo = (lo & 0x7FFFFFFF) + (lo >> 31);
  79. n1 = signed_multiply_32x16b(gain, lo);
  80. hi = 16807 * (lo >> 16);
  81. lo = 16807 * (lo & 0xFFFF);
  82. lo += (hi & 0x7FFF) << 16;
  83. lo += hi >> 15;
  84. lo = (lo & 0x7FFFFFFF) + (lo >> 31);
  85. n2 = signed_multiply_32x16b(gain, lo);
  86. val1 = pack_16b_16b(n2, n1);
  87. *p++ = val1;
  88. #endif
  89. } while (p < end);
  90. seed = lo;
  91. transmit(block);
  92. release(block);
  93. }
  94. uint16_t AudioSynthNoiseWhite::instance_count = 0;