examples/audio-test/audio-test.cpp

#include <string>
#include <cstring>
#include <memory>
#include <cstdlib>

#include "audio-test.hpp"

using namespace blit;

// gadgetoid's amazing masterpiece!
int16_t notes[3][384] = {
  { // melody notes
    147, 0, 0, 0, 0, 0, 0, 0, 175, 0, 196, 0, 220, 0, 262, 0, 247, 0, 0, 0, 0, 0, 0, 0, -1, 0, 0, 0, 0, 0, 0, 0, 175, 0, 0, 0, 0, 0, 0, 0, 175, 0, 196, 0, 220, 0, 262, 0, 330, 0, 0, 0, 0, 0, 0, 0, -1, 0, 0, 0, 0, 0, 0, 0, 349, 0, 0, 0, 0, 0, 0, 0, 349, 0, 330, 0, 294, 0, 220, 0, 262, 0, 0, 0, 0, 0, 0, 0, -1, 0, 0, 0, 0, 0, 0, 0, 247, 0, 0, 0, 0, 0, 0, 0, 247, 0, 220, 0, 196, 0, 147, 0, 175, 0, 0, 0, 0, 0, 0, 0, -1, 0, 0, 0, 0, 0, 0, 0,
    147, 0, 0, 0, 0, 0, 0, 0, 175, 0, 196, 0, 220, 0, 262, 0, 247, 0, 0, 0, 0, 0, 0, 0, -1, 0, 0, 0, 0, 0, 0, 0, 175, 0, 0, 0, 0, 0, 0, 0, 175, 0, 196, 0, 220, 0, 262, 0, 330, 0, 0, 0, 0, 0, 0, 0, -1, 0, 0, 0, 0, 0, 0, 0, 349, 0, 0, 0, 0, 0, 0, 0, 349, 0, 330, 0, 294, 0, 220, 0, 262, 0, 0, 0, 0, 0, 0, 0, -1, 0, 0, 0, 0, 0, 0, 0, 247, 0, 0, 0, 0, 0, 0, 0, 247, 0, 220, 0, 196, 0, 147, 0, 175, 0, 0, 0, 0, 0, 0, 0, -1, 0, 0, 0, 0, 0, 0, 0,
    147, 0, 0, 0, 0, 0, 0, 0, 175, 0, 196, 0, 220, 0, 262, 0, 247, 0, 0, 0, 0, 0, 0, 0, -1, 0, 0, 0, 0, 0, 0, 0, 175, 0, 0, 0, 0, 0, 0, 0, 175, 0, 196, 0, 220, 0, 262, 0, 330, 0, 0, 0, 0, 0, 0, 0, -1, 0, 0, 0, 0, 0, 0, 0, 349, 0, 0, 0, 0, 0, 0, 0, 349, 0, 330, 0, 294, 0, 220, 0, 262, 0, 0, 0, 0, 0, 0, 0, -1, 0, 0, 0, 0, 0, 0, 0, 247, 0, 0, 0, 0, 0, 0, 0, 247, 0, 262, 0, 294, 0, 392, 0, 440, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
  },  
  { // rhythm notes
    294, 0, 440, 0, 587, 0, 440, 0, 294, 0, 440, 0, 587, 0, 440, 0, 294, 0, 440, 0, 587, 0, 440, 0, 294, 0, 440, 0, 587, 0, 440, 0, 294, 0, 440, 0, 587, 0, 440, 0, 294, 0, 440, 0, 587, 0, 440, 0, 392, 0, 523, 0, 659, 0, 523, 0, 392, 0, 523, 0, 659, 0, 523, 0, 698, 0, 587, 0, 440, 0, 587, 0, 698, 0, 587, 0, 440, 0, 587, 0, 523, 0, 440, 0, 330, 0, 440, 0, 523, 0, 440, 0, 330, 0, 440, 0, 349, 0, 294, 0, 220, 0, 294, 0, 349, 0, 294, 0, 220, 0, 294, 0, 262, 0, 247, 0, 220, 0, 175, 0, 165, 0, 147, 0, 131, 0, 98, 0,
    294, 0, 440, 0, 587, 0, 440, 0, 294, 0, 440, 0, 587, 0, 440, 0, 294, 0, 440, 0, 587, 0, 440, 0, 294, 0, 440, 0, 587, 0, 440, 0, 294, 0, 440, 0, 587, 0, 440, 0, 294, 0, 440, 0, 587, 0, 440, 0, 392, 0, 523, 0, 659, 0, 523, 0, 392, 0, 523, 0, 659, 0, 523, 0, 698, 0, 587, 0, 440, 0, 587, 0, 698, 0, 587, 0, 440, 0, 587, 0, 523, 0, 440, 0, 330, 0, 440, 0, 523, 0, 440, 0, 330, 0, 440, 0, 349, 0, 294, 0, 220, 0, 294, 0, 349, 0, 294, 0, 220, 0, 294, 0, 262, 0, 247, 0, 220, 0, 175, 0, 165, 0, 147, 0, 131, 0, 98, 0,
    294, 0, 440, 0, 587, 0, 440, 0, 294, 0, 440, 0, 587, 0, 440, 0, 294, 0, 440, 0, 587, 0, 440, 0, 294, 0, 440, 0, 587, 0, 440, 0, 294, 0, 440, 0, 587, 0, 440, 0, 294, 0, 440, 0, 587, 0, 440, 0, 392, 0, 523, 0, 659, 0, 523, 0, 392, 0, 523, 0, 659, 0, 523, 0, 698, 0, 587, 0, 440, 0, 587, 0, 698, 0, 587, 0, 440, 0, 587, 0, 523, 0, 440, 0, 330, 0, 440, 0, 523, 0, 440, 0, 330, 0, 440, 0, 349, 0, 294, 0, 220, 0, 294, 0, 349, 0, 294, 0, 220, 0, 294, 0, 262, 0, 247, 0, 220, 0, 175, 0, 165, 0, 147, 0, 131, 0, 98, 0,
  },  
  { // drum beats
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 587, 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, 587, 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, 587, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 587, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 587, 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, 587, 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, 587, 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, 587, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 587, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 587, 0, 0, 0, 0, 0, 0, 0,
    110, 0, 110, 0, 1047, 1175, 1175, 1175, 587, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 587, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 262, 0, 0, 1175, 587, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 587, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 587, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 587, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 262, 0, 0, 0, 587, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 587, 0, 0, 0, 0, 0, 0, 0,
  }
};

/* setup */
void init() {
  // configure voices

  // melody track
  channels[0].waveforms   = Waveform::TRIANGLE | Waveform::SQUARE;
  channels[0].attack_ms   = 16;
  channels[0].decay_ms    = 168;
  channels[0].sustain     = 0xafff;
  channels[0].release_ms  = 168;

  // rhythm track
  channels[1].waveforms   = Waveform::SQUARE;
  channels[1].attack_ms   = 38;
  channels[1].decay_ms    = 300;
  channels[1].sustain     = 0;
  channels[1].release_ms  = 0;

  // drum track
  channels[2].waveforms   = Waveform::NOISE;
  channels[2].attack_ms   = 10;
  channels[2].decay_ms    = 750;
  channels[2].sustain     = 0;
  channels[2].release_ms  = 100;

  // set global volume
  // volume = 2048;
  
  screen.pen = Pen(0, 0, 0, 255);
  screen.clear();  
}

uint16_t beat = 0;

void render(uint32_t time_ms) {
  screen.pen = Pen(20, 30, 40, 100);
  screen.clear();
  
  // yeah, this is ugly... let's find a way to get a real
  // waveform out of the audio functionality
  for(int i = 0; i < 160; i++) {
    uint8_t no = (i + beat) % 384;
    uint8_t n1 = notes[0][no] >> 4;
    uint8_t n2 = notes[1][no] >> 4;
    uint8_t n3 = notes[2][no] >> 4;

    screen.pen = Pen(255, 0, 0, 100);
    screen.line(Point(i, 120), Point(i, 120 - n1));
    screen.pen = Pen(0, 255, 0, 100);
    screen.line(Point(i, 120), Point(i, 120 - n2));
    screen.pen = Pen(0, 0, 255, 100);
    screen.line(Point(i, 120), Point(i, 120 - n3));
  }

  screen.watermark();  
} 

void update(uint32_t time_ms) {
  static uint16_t tick = 0;
  static uint16_t prev_beat = 1;
  beat = (tick / 5) % 384; // 100ms per beat
  tick++;

  if (beat == prev_beat) return;
  prev_beat = beat;

  for(uint8_t i = 0; i < 3; i++) {
    if(notes[i][beat] > 0) {
      channels[i].frequency = notes[i][beat];
      channels[i].trigger_attack();
    } else if (notes[i][beat] == -1) {
      channels[i].trigger_release();
    }
  }
}