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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 "synth_waveform.h"
  27. #include "arm_math.h"
  28. #include "utility/dspinst.h"
  29. /******************************************************************/
  30. // PAH 140415 - change sin to use Paul's interpolation which is much
  31. // faster than arm's sin function
  32. // PAH 140316 - fix calculation of sample (amplitude error)
  33. // PAH 140314 - change t_hi from int to float
  34. boolean AudioSynthWaveform::begin(float t_amp,float t_hi,short type)
  35. {
  36. tone_type = type;
  37. amplitude(t_amp);
  38. tone_freq = t_hi > 0.0;
  39. if(t_hi <= 0.0)return false;
  40. if(t_hi >= AUDIO_SAMPLE_RATE_EXACT/2)return false;
  41. tone_phase = 0;
  42. frequency(t_hi);
  43. if(0) {
  44. Serial.print("AudioSynthWaveform.begin(tone_amp = ");
  45. Serial.print(t_amp);
  46. Serial.print(", tone_hi = ");
  47. Serial.print(t_hi);
  48. Serial.print(", tone_incr = ");
  49. Serial.print(tone_incr,HEX);
  50. // Serial.print(", tone_hi = ");
  51. // Serial.print(t_hi);
  52. Serial.println(")");
  53. }
  54. return(true);
  55. }
  56. void AudioSynthWaveform::update(void)
  57. {
  58. audio_block_t *block;
  59. short *bp;
  60. int32_t val1, val2, val3;
  61. uint32_t index, scale;
  62. // temporaries for TRIANGLE
  63. uint32_t mag;
  64. short tmp_amp;
  65. if(tone_freq == 0)return;
  66. block = allocate();
  67. if(block) {
  68. bp = block->data;
  69. switch(tone_type) {
  70. case TONE_TYPE_SINE:
  71. for(int i = 0;i < AUDIO_BLOCK_SAMPLES;i++) {
  72. // Calculate interpolated sin
  73. index = tone_phase >> 23;
  74. val1 = AudioWaveformSine[index];
  75. val2 = AudioWaveformSine[index+1];
  76. scale = (tone_phase >> 7) & 0xFFFF;
  77. val2 *= scale;
  78. val1 *= 0xFFFF - scale;
  79. val3 = (val1 + val2) >> 16;
  80. *bp++ = (short)((val3 * tone_amp) >> 15);
  81. // phase and incr are both unsigned 32-bit fractions
  82. tone_phase += tone_incr;
  83. // If tone_phase has overflowed, truncate the top bit
  84. if(tone_phase & 0x80000000)tone_phase &= 0x7fffffff;
  85. }
  86. break;
  87. case TONE_TYPE_SQUARE:
  88. for(int i = 0;i < AUDIO_BLOCK_SAMPLES;i++) {
  89. if(tone_phase & 0x40000000)*bp++ = -tone_amp;
  90. else *bp++ = tone_amp;
  91. // phase and incr are both unsigned 32-bit fractions
  92. tone_phase += tone_incr;
  93. }
  94. break;
  95. case TONE_TYPE_SAWTOOTH:
  96. for(int i = 0;i < AUDIO_BLOCK_SAMPLES;i++) {
  97. *bp++ = ((short)(tone_phase>>15)*tone_amp) >> 15;
  98. // phase and incr are both unsigned 32-bit fractions
  99. tone_phase += tone_incr;
  100. }
  101. break;
  102. case TONE_TYPE_TRIANGLE:
  103. for(int i = 0;i < AUDIO_BLOCK_SAMPLES;i++) {
  104. if(tone_phase & 0x80000000) {
  105. // negative half-cycle
  106. tmp_amp = -tone_amp;
  107. }
  108. else {
  109. // positive half-cycle
  110. tmp_amp = tone_amp;
  111. }
  112. mag = tone_phase << 2;
  113. // Determine which quadrant
  114. if(tone_phase & 0x40000000) {
  115. // negate the magnitude
  116. mag = ~mag + 1;
  117. }
  118. *bp++ = ((short)(mag>>17)*tmp_amp) >> 15;
  119. tone_phase += 2*tone_incr;
  120. }
  121. break;
  122. }
  123. // send the samples to the left channel
  124. transmit(block,0);
  125. release(block);
  126. }
  127. }