broken-neees/lib/apu/TriangleOscillator.js

A really broken NEEES emulator that introduces glitches and random bugs on purpose!

"use strict";

Object.defineProperty(exports, "__esModule", {
  value: true
});
exports.default = void 0;
const APU_SAMPLE_RATE = 44100;
const TRIANGLE_SEQUENCE = [15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15];

/** A triangle wave generator. */
class TriangleOscillator {
  constructor() {
    this.frequency = 0;
    this._phase = 0; // (0~1)
  }

  /** Generates a new sample (0~15). */
  sample() {
    this._phase = (this._phase + this.frequency / APU_SAMPLE_RATE) % 1;
    const step = Math.floor(this._phase * TRIANGLE_SEQUENCE.length);
    return TRIANGLE_SEQUENCE[step];
  }
}
exports.default = TriangleOscillator;