grains.c

/**
 * @file grains.c
 * @author Alex Hiam - <alex@graycat.io>
 * @copyright Copyright (c) 2018 - Gray Cat Labs, Alex Hiam <alex@graycat.io>
 * @license Released under the MIT License
 * 
 * @brief A basic C library for the Ginko Synthese Grains eurorack module.
 * Grains: https://www.ginkosynthese.com/product/grains/
 * 
 * Modified from Auduino code by Peter Knight and Ginkosynthese.
 */

#include "grains.h"

#include <avr/io.h>
#include <avr/interrupt.h>
#include <avr/pgmspace.h>
#include <Arduino.h>
#include <stdint.h>

void audioOn() {
  // Set up PWM to 31.25kHz, phase accurate
  TCCR2A = _BV(COM2A1) | _BV(WGM20);
  TCCR2B = _BV(CS20);
  TIMSK2 = _BV(TOIE2);
}


uint16_t sampleAveraged(uint8_t input, avg_t *avg) {
  // Sample it:
  uint16_t value = analogRead(input);

  // Compute moving average:
  avg->sum -= avg->window[avg->i];
  avg->sum += value;
  
  avg->window[avg->i] = value;
  avg->i++;
  avg->i %= SAMPLE_AVG_LEN;

  return avg->sum / SAMPLE_AVG_LEN;
}

uint8_t getClock() {
  static avg_t cv_avg;
  return sampleAveraged(CV_IN, &cv_avg) > 32;
}

uint8_t getTrigger(edge_t edge) {
  static uint8_t last_clock_state = 0;
  uint8_t clock_state, trigger;

  // Get triggers and rate values
  clock_state = getClock();

  trigger = edge == EDGE_RISING ? clock_state > last_clock_state : last_clock_state > clock_state;
  last_clock_state = clock_state;
  return trigger;
}

// From original Grains fw:
const uint16_t freqTable[] PROGMEM = {
69,69,69,69,70,70,70,70,70,71,71,71,71,72,72,72,72,73,73,73,73,
74,74,74,74,75,75,75,75,76,76,76,76,77,77,77,77,78,78,78,78,79,
79,79,79,80,80,80,81,81,81,81,82,82,82,82,83,83,83,84,84,84,84,
85,85,85,86,86,86,86,87,87,87,88,88,88,88,89,89,89,90,90,90,91,
91,91,91,92,92,92,93,93,93,94,94,94,95,95,95,96,96,96,97,97,97,
97,98,98,98,99,99,99,100,100,100,101,101,101,102,102,102,103,103,104,104,104,
105,105,105,106,106,106,107,107,107,108,108,109,109,109,110,110,110,111,111,111,112,
112,113,113,113,114,114,114,115,115,116,116,116,117,117,118,118,118,119,119,120,120,
120,121,121,122,122,122,123,123,124,124,124,125,125,126,126,127,127,127,128,128,129,
129,130,130,130,131,131,132,132,133,133,134,134,134,135,135,136,136,137,137,138,138,
139,139,139,140,140,141,141,142,142,143,143,144,144,145,145,146,146,147,147,148,148,
149,149,150,150,151,151,152,152,153,153,154,154,155,155,156,156,157,157,158,158,159,
159,160,161,161,162,162,163,163,164,164,165,165,166,167,167,168,168,169,169,170,171,
171,172,172,173,173,174,175,175,176,176,177,178,178,179,179,180,181,181,182,182,183,
184,184,185,185,186,187,187,188,189,189,190,190,191,192,192,193,194,194,195,196,196,
197,198,198,199,200,200,201,202,202,203,204,204,205,206,206,207,208,208,209,210,211,
211,212,213,213,214,215,216,216,217,218,218,219,220,221,221,222,223,224,224,225,226,
227,227,228,229,230,231,231,232,233,234,234,235,236,237,238,238,239,240,241,242,242,
243,244,245,246,246,247,248,249,250,251,251,252,253,254,255,256,257,257,258,259,260,
261,262,263,264,264,265,266,267,268,269,270,271,272,273,273,274,275,276,277,278,279,
280,281,282,283,284,285,286,287,288,288,289,290,291,292,293,294,295,296,297,298,299,
300,301,302,303,304,305,306,307,308,310,311,312,313,314,315,316,317,318,319,320,321,
322,323,324,325,327,328,329,330,331,332,333,334,335,337,338,339,340,341,342,343,345,
346,347,348,349,350,352,353,354,355,356,357,359,360,361,362,363,365,366,367,368,370,
371,372,373,375,376,377,378,380,381,382,383,385,386,387,389,390,391,393,394,395,397,
398,399,401,402,403,405,406,407,409,410,411,413,414,416,417,418,420,421,423,424,425,
427,428,430,431,433,434,436,437,438,440,441,443,444,446,447,449,450,452,453,455,456,
458,460,461,463,464,466,467,469,470,472,474,475,477,478,480,482,483,485,486,488,490,
491,493,495,496,498,500,501,503,505,506,508,510,511,513,515,517,518,520,522,524,525,
527,529,531,532,534,536,538,540,541,543,545,547,549,551,552,554,556,558,560,562,564,
566,567,569,571,573,575,577,579,581,583,585,587,589,591,593,595,597,599,601,603,605,
607,609,611,613,615,617,619,621,623,625,627,630,632,634,636,638,640,642,644,647,649,
651,653,655,658,660,662,664,666,669,671,673,675,678,680,682,685,687,689,691,694,696,
698,701,703,705,708,710,713,715,717,720,722,725,727,729,732,734,737,739,742,744,747,
749,752,754,757,759,762,764,767,770,772,775,777,780,783,785,788,791,793,796,799,801,
804,807,809,812,815,817,820,823,826,828,831,834,837,840,842,845,848,851,854,857,860,
862,865,868,871,874,877,880,883,886,889,892,895,898,901,904,907,910,913,916,919,922,
925,928,932,935,938,941,944,947,950,954,957,960,963,966,970,973,976,979,983,986,989,
993,996,999,1003,1006,1009,1013,1016,1020,1023,1027,1030,1033,1037,1040,1044,1047,1051,1054,1058,1061,
1065,1069,1072,1076,1079,1083,1087,1090,1094,1098,1101,1105,1109,1112,1116,1120,1124,1127,1131,1135,1139,
1143,1146,1150,1154,1158,1162,1166,1170,1174,1178,1182,1186,1189,1193,1197,1201,1206,1210,1214,1218,1222,
1226,1230,1234,1238,1242,1247,1251,1255,1259,1263,1268,1272,1276,1280,1285,1289,1293,1298,1302,1306,1311,
1315,1320,1324,1328,1333,1337,1342,1346,1351,1355,1360,1365,1369,1374,1378,1383,1388,1392,1397,1402,1406,
1411,1416,1421,1425,1430,1435,1440,1444,1449,1454,1459,1464,1469,1474,1479,1484,1489,1494,1499,1504,1509,
1514,1519,1524,1529,1534,1539,1545,1550,1555,1560,1565,1571,1576,1581,1587,1592,1597,1603,1608,1613,1619,
1624,1630,1635,1641,1646,1652,1657,1663,1668,1674,1679,1685,1691,1696,1702,1708,1714,1719,1725,1731,1737,
1742,1748,1754,1760,1766,1772,1778,1784,1790,1796,1802,1808,1814,1820,1826,1832,1838,1845,1851,1857,1863,
1869,1876,1882,1888,1895,1901,1907,1914,1920,1927,1933,1940,1946,1953,1959,1966,1972,1979,1986,1992,1999,
2006,2012,2019,2026,2033,2040,2046,2053,2060,2067,2074,2081,2088,2095,2102,2109
};

// For converting linear pot input to exponential:
const uint16_t expTable[] PROGMEM = {
  0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
  0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
  0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
  0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,1,
  1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
  1,1,1,1,1,1,1,1,1,1,1,1,1,2,2,2,
  2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,
  3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,4,
  4,4,4,4,4,4,4,4,4,4,4,5,5,5,5,5,
  5,5,5,5,5,5,6,6,6,6,6,6,6,6,6,6,
  7,7,7,7,7,7,7,7,8,8,8,8,8,8,8,8,
  9,9,9,9,9,9,9,10,10,10,10,10,10,10,11,11,
  11,11,11,11,11,12,12,12,12,12,12,13,13,13,13,13,
  13,14,14,14,14,14,15,15,15,15,15,15,16,16,16,16,
  16,17,17,17,17,17,18,18,18,18,19,19,19,19,19,20,
  20,20,20,21,21,21,21,21,22,22,22,22,23,23,23,23,
  24,24,24,24,25,25,25,25,26,26,26,27,27,27,27,28,
  28,28,28,29,29,29,30,30,30,31,31,31,31,32,32,32,
  33,33,33,34,34,34,35,35,35,35,36,36,36,37,37,37,
  38,38,38,39,39,39,40,40,41,41,41,42,42,42,43,43,
  43,44,44,45,45,45,46,46,46,47,47,48,48,48,49,49,
  50,50,50,51,51,52,52,52,53,53,54,54,55,55,55,56,
  56,57,57,58,58,58,59,59,60,60,61,61,62,62,63,63,
  64,64,64,65,65,66,66,67,67,68,68,69,69,70,70,71,
  71,72,72,73,73,74,74,75,75,76,76,77,78,78,79,79,
  80,80,81,81,82,82,83,84,84,85,85,86,86,87,87,88,
  89,89,90,90,91,92,92,93,93,94,95,95,96,96,97,98,
  98,99,99,100,101,101,102,103,103,104,105,105,106,106,107,108,
  108,109,110,110,111,112,112,113,114,114,115,116,116,117,118,119,
  119,120,121,121,122,123,124,124,125,126,126,127,128,129,129,130,
  131,132,132,133,134,135,135,136,137,138,138,139,140,141,141,142,
  143,144,145,145,146,147,148,149,149,150,151,152,153,153,154,155,
  156,157,158,158,159,160,161,162,163,163,164,165,166,167,168,169,
  169,170,171,172,173,174,175,176,177,177,178,179,180,181,182,183,
  184,185,186,187,187,188,189,190,191,192,193,194,195,196,197,198,
  199,200,201,202,203,204,205,206,207,208,209,210,211,212,213,214,
  215,216,217,218,219,220,221,222,223,224,225,226,227,228,229,230,
  231,232,233,234,236,237,238,239,240,241,242,243,244,245,246,248,
  249,250,251,252,253,254,255,257,258,259,260,261,262,263,265,266,
  267,268,269,270,272,273,274,275,276,277,279,280,281,282,283,285,
  286,287,288,290,291,292,293,294,296,297,298,299,301,302,303,304,
  306,307,308,310,311,312,313,315,316,317,319,320,321,322,324,325,
  326,328,329,330,332,333,334,336,337,338,340,341,343,344,345,347,
  348,349,351,352,354,355,356,358,359,360,362,363,365,366,368,369,
  370,372,373,375,376,378,379,381,382,383,385,386,388,389,391,392,
  394,395,397,398,400,401,403,404,406,407,409,410,412,413,415,416,
  418,420,421,423,424,426,427,429,430,432,434,435,437,438,440,442,
  443,445,446,448,450,451,453,454,456,458,459,461,463,464,466,468,
  469,471,473,474,476,478,479,481,483,484,486,488,489,491,493,495,
  496,498,500,501,503,505,507,508,510,512,514,515,517,519,521,523,
  524,526,528,530,531,533,535,537,539,541,542,544,546,548,550,551,
  553,555,557,559,561,563,564,566,568,570,572,574,576,578,580,581,
  583,585,587,589,591,593,595,597,599,601,603,605,606,608,610,612,
  614,616,618,620,622,624,626,628,630,632,634,636,638,640,642,644,
  646,648,650,652,655,657,659,661,663,665,667,669,671,673,675,677,
  679,681,684,686,688,690,692,694,696,698,701,703,705,707,709,711,
  713,716,718,720,722,724,727,729,731,733,735,738,740,742,744,746,
  749,751,753,755,758,760,762,764,767,769,771,773,776,778,780,783,
  785,787,790,792,794,796,799,801,803,806,808,810,813,815,818,820,
  822,825,827,829,832,834,837,839,841,844,846,849,851,853,856,858,
  861,863,866,868,870,873,875,878,880,883,885,888,890,893,895,898,
  900,903,905,908,910,913,915,918,920,923,926,928,931,933,936,938,
  941,943,946,949,951,954,956,959,962,964,967,970,972,975,977,980,
  983,985,988,991,993,996,999,1001,1004,1007,1009,1012,1015,1018,1020,1023,
};


// For converting linear pot input to logarithmic:
const uint16_t logTable[] PROGMEM = {
  0,0,102,162,205,238,264,287,307,324,340,354,367,379,390,400,
  409,418,427,435,442,449,456,463,469,475,481,486,492,497,502,507,
  512,516,521,525,529,533,537,541,545,548,552,555,559,562,565,568,
  571,574,577,580,583,586,589,592,594,597,599,602,604,607,609,612,
  614,616,618,621,623,625,627,629,631,633,635,637,639,641,643,645,
  647,649,650,652,654,656,657,659,661,663,664,666,667,669,671,672,
  674,675,677,678,680,681,683,684,686,687,688,690,691,692,694,695,
  696,698,699,700,702,703,704,705,707,708,709,710,712,713,714,715,
  716,717,718,720,721,722,723,724,725,726,727,728,729,730,732,733,
  734,735,736,737,738,739,740,741,742,743,743,744,745,746,747,748,
  749,750,751,752,753,754,755,755,756,757,758,759,760,761,762,762,
  763,764,765,766,767,767,768,769,770,771,771,772,773,774,775,775,
  776,777,778,778,779,780,781,781,782,783,784,784,785,786,786,787,
  788,789,789,790,791,791,792,793,793,794,795,795,796,797,797,798,
  799,799,800,801,801,802,803,803,804,805,805,806,807,807,808,808,
  809,810,810,811,811,812,813,813,814,814,815,816,816,817,817,818,
  819,819,820,820,821,821,822,822,823,824,824,825,825,826,826,827,
  827,828,829,829,830,830,831,831,832,832,833,833,834,834,835,835,
  836,836,837,837,838,838,839,839,840,840,841,841,842,842,843,843,
  844,844,845,845,846,846,847,847,848,848,849,849,850,850,851,851,
  851,852,852,853,853,854,854,855,855,856,856,856,857,857,858,858,
  859,859,860,860,860,861,861,862,862,863,863,863,864,864,865,865,
  866,866,866,867,867,868,868,868,869,869,870,870,870,871,871,872,
  872,872,873,873,874,874,874,875,875,876,876,876,877,877,878,878,
  878,879,879,880,880,880,881,881,881,882,882,883,883,883,884,884,
  884,885,885,885,886,886,887,887,887,888,888,888,889,889,889,890,
  890,891,891,891,892,892,892,893,893,893,894,894,894,895,895,895,
  896,896,896,897,897,897,898,898,898,899,899,899,900,900,900,901,
  901,901,902,902,902,903,903,903,904,904,904,905,905,905,906,906,
  906,907,907,907,908,908,908,909,909,909,909,910,910,910,911,911,
  911,912,912,912,913,913,913,913,914,914,914,915,915,915,916,916,
  916,916,917,917,917,918,918,918,919,919,919,919,920,920,920,921,
  921,921,921,922,922,922,923,923,923,923,924,924,924,925,925,925,
  925,926,926,926,926,927,927,927,928,928,928,928,929,929,929,930,
  930,930,930,931,931,931,931,932,932,932,932,933,933,933,934,934,
  934,934,935,935,935,935,936,936,936,936,937,937,937,937,938,938,
  938,938,939,939,939,939,940,940,940,941,941,941,941,942,942,942,
  942,943,943,943,943,944,944,944,944,944,945,945,945,945,946,946,
  946,946,947,947,947,947,948,948,948,948,949,949,949,949,950,950,
  950,950,951,951,951,951,951,952,952,952,952,953,953,953,953,954,
  954,954,954,954,955,955,955,955,956,956,956,956,957,957,957,957,
  957,958,958,958,958,959,959,959,959,959,960,960,960,960,961,961,
  961,961,961,962,962,962,962,962,963,963,963,963,964,964,964,964,
  964,965,965,965,965,966,966,966,966,966,967,967,967,967,967,968,
  968,968,968,968,969,969,969,969,970,970,970,970,970,971,971,971,
  971,971,972,972,972,972,972,973,973,973,973,973,974,974,974,974,
  974,975,975,975,975,975,976,976,976,976,976,977,977,977,977,977,
  978,978,978,978,978,979,979,979,979,979,980,980,980,980,980,980,
  981,981,981,981,981,982,982,982,982,982,983,983,983,983,983,984,
  984,984,984,984,984,985,985,985,985,985,986,986,986,986,986,987,
  987,987,987,987,987,988,988,988,988,988,989,989,989,989,989,989,
  990,990,990,990,990,991,991,991,991,991,991,992,992,992,992,992,
  992,993,993,993,993,993,994,994,994,994,994,994,995,995,995,995,
  995,995,996,996,996,996,996,997,997,997,997,997,997,998,998,998,
  998,998,998,999,999,999,999,999,999,1000,1000,1000,1000,1000,1000,1001,
  1001,1001,1001,1001,1001,1002,1002,1002,1002,1002,1002,1003,1003,1003,1003,1003,
  1003,1004,1004,1004,1004,1004,1004,1005,1005,1005,1005,1005,1005,1006,1006,1006,
  1006,1006,1006,1007,1007,1007,1007,1007,1007,1007,1008,1008,1008,1008,1008,1008,
  1009,1009,1009,1009,1009,1009,1010,1010,1010,1010,1010,1010,1011,1011,1011,1011,
  1011,1011,1011,1012,1012,1012,1012,1012,1012,1013,1013,1013,1013,1013,1013,1013,
  1014,1014,1014,1014,1014,1014,1015,1015,1015,1015,1015,1015,1015,1016,1016,1016,
  1016,1016,1016,1017,1017,1017,1017,1017,1017,1017,1018,1018,1018,1018,1018,1018,
  1018,1019,1019,1019,1019,1019,1019,1019,1020,1020,1020,1020,1020,1020,1021,1021,
  1021,1021,1021,1021,1021,1022,1022,1022,1022,1022,1022,1022,1023,1023,1023,1023,
};


// 8-bit tables for 0-5V CV output:

const uint16_t semitoneTable[] PROGMEM = {
  0,0,0,4,4,4,4,9,9,9,9,9,13,13,13,13,
  17,17,17,17,17,21,21,21,21,21,26,26,26,26,30,30,
  30,30,30,34,34,34,34,38,38,38,38,38,43,43,43,43,
  47,47,47,47,47,51,51,51,51,55,55,55,55,55,60,60,
  60,60,60,64,64,64,64,68,68,68,68,68,73,73,73,73,
  77,77,77,77,77,81,81,81,81,85,85,85,85,85,90,90,
  90,90,94,94,94,94,94,98,98,98,98,98,102,102,102,102,
  107,107,107,107,107,111,111,111,111,115,115,115,115,115,119,119,
  119,119,124,124,124,124,124,128,128,128,128,132,132,132,132,132,
  137,137,137,137,141,141,141,141,141,145,145,145,145,145,149,149,
  149,149,154,154,154,154,154,158,158,158,158,162,162,162,162,162,
  166,166,166,166,171,171,171,171,171,175,175,175,175,179,179,179,
  179,179,183,183,183,183,183,188,188,188,188,192,192,192,192,192,
  196,196,196,196,201,201,201,201,201,205,205,205,205,209,209,209,
  209,209,213,213,213,213,218,218,218,218,218,222,222,222,222,222,
  226,226,226,226,230,230,230,230,230,235,235,235,235,239,239,239,
};

const uint16_t majorTable[] PROGMEM = {
  0,0,0,0,0,0,0,0,9,9,9,9,9,9,9,9,
  17,17,17,17,17,17,17,17,21,21,21,21,21,21,21,21,
  30,30,30,30,30,30,30,30,38,38,38,38,38,38,38,38,
  47,47,47,47,47,47,47,47,51,51,51,51,51,51,51,51,
  60,60,60,60,60,60,60,60,68,68,68,68,68,68,68,68,
  73,73,73,73,73,73,73,73,81,81,81,81,81,81,81,81,
  90,90,90,90,90,90,90,90,98,98,98,98,98,98,98,98,
  102,102,102,102,102,102,102,102,111,111,111,111,111,111,111,111,
  119,119,119,119,119,119,119,119,124,124,124,124,124,124,124,124,
  132,132,132,132,132,132,132,132,141,141,141,141,141,141,141,141,
  149,149,149,149,149,149,149,149,154,154,154,154,154,154,154,154,
  162,162,162,162,162,162,162,162,171,171,171,171,171,171,171,171,
  175,175,175,175,175,175,175,175,183,183,183,183,183,183,183,183,
  192,192,192,192,192,192,192,192,201,201,201,201,201,201,201,201,
  205,205,205,205,205,205,205,205,213,213,213,213,213,213,213,213,
  222,222,222,222,222,222,222,222,226,226,226,226,226,226,226,235,
};

const uint16_t minorTable[] PROGMEM = {
  0,0,0,0,0,0,0,0,9,9,9,9,9,9,9,9,
  13,13,13,13,13,13,13,13,21,21,21,21,21,21,21,30,
  30,30,30,30,30,30,30,34,34,34,34,34,34,34,34,43,
  43,43,43,43,43,43,43,51,51,51,51,51,51,51,60,60,
  60,60,60,60,60,60,64,64,64,64,64,64,64,64,73,73,
  73,73,73,73,73,81,81,81,81,81,81,81,81,85,85,85,
  85,85,85,85,85,94,94,94,94,94,94,94,94,102,102,102,
  102,102,102,102,111,111,111,111,111,111,111,111,115,115,115,115,
  115,115,115,115,124,124,124,124,124,124,124,124,132,132,132,132,
  132,132,132,137,137,137,137,137,137,137,137,145,145,145,145,145,
  145,145,145,154,154,154,154,154,154,154,162,162,162,162,162,162,
  162,162,166,166,166,166,166,166,166,166,175,175,175,175,175,175,
  175,175,183,183,183,183,183,183,183,188,188,188,188,188,188,188,
  188,196,196,196,196,196,196,196,196,205,205,205,205,205,205,205,
  205,213,213,213,213,213,213,213,218,218,218,218,218,218,218,218,
  226,226,226,226,226,226,226,226,235,235,235,235,235,235,235,239,
};

const uint16_t mixolydianTable[] PROGMEM = {
  0,0,0,0,0,0,0,0,9,9,9,9,9,9,9,9,
  17,17,17,17,17,17,17,17,21,21,21,21,21,21,21,21,
  30,30,30,30,30,30,30,30,38,38,38,38,38,38,38,38,
  43,43,43,43,43,43,43,43,51,51,51,51,51,51,51,51,
  60,60,60,60,60,60,60,60,68,68,68,68,68,68,68,68,
  73,73,73,73,73,73,73,73,81,81,81,81,81,81,81,81,
  90,90,90,90,90,90,90,90,94,94,94,94,94,94,94,94,
  102,102,102,102,102,102,102,102,111,111,111,111,111,111,111,111,
  119,119,119,119,119,119,119,119,124,124,124,124,124,124,124,124,
  132,132,132,132,132,132,132,132,141,141,141,141,141,141,141,141,
  145,145,145,145,145,145,145,145,154,154,154,154,154,154,154,154,
  162,162,162,162,162,162,162,162,171,171,171,171,171,171,171,171,
  175,175,175,175,175,175,175,175,183,183,183,183,183,183,183,183,
  192,192,192,192,192,192,192,192,196,196,196,196,196,196,196,196,
  205,205,205,205,205,205,205,205,213,213,213,213,213,213,213,213,
  222,222,222,222,222,222,222,222,226,226,226,226,226,226,226,235,
};