Start porting DBOPL to Javascript
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bruce
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var DBOPL = new function() { // DBOPL namespace
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// dbopl.h
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this.WAVE_HANDLER = 10;
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this.WAVE_TABLELOG = 11;
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this.WAVE_TABLEMUL = 12;
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this.DBOPL_WAVE = this.WAVE_TABLEMUL;
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this.SynthMode = {
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sm2AM:0,
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sm2FM:1,
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sm3AM:2,
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sm3FM:3,
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sm4Start:4,
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sm3FMFM:5,
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sm3AMFM:6,
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sm3FMAM:7,
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sm3AMAM:8,
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sm6Start:9,
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sm2Percussion:10,
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sm3Percussion:11,
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};
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this.SHIFT_KSLBASE = 16;
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this.SHIFT_KEYCODE = 24;
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this.Operator = function() {
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// public:
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// enum
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this.MASK_KSR = 0x10;
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this.MASK_SUSTAIN = 0x20;
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this.MASK_VIBRATO = 0x40;
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this.MASK_TREMOLO = 0x80;
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this.State = { // typedef enum
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OFF:0,
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RELEASE:1,
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SUSTAIN:2,
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DECAY:3,
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ATTACK:4,
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};
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this.volHandler=0;
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this.waveBase=0;
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this.waveMask=0;
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this.waveStart=0;
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this.waveIndex=0; //WAVE_BITS shifted counter of the frequency index
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this.waveAdd=0; //The base frequency without vibrato
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this.waveCurrent=0; //waveAdd + vibratao
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this.chanData=0; //Frequency/octave and derived data coming from whatever channel controls this
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this.freqMul=0; //Scale channel frequency with this, TODO maybe remove?
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this.vibrato=0; //Scaled up vibrato strength
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this.sustainLevel=0; //When stopping at sustain level stop here
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this.totalLevel=0; //totalLevel is added to every generated volume
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this.currentLevel=0; //totalLevel + tremolo
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this.volume=0; //The currently active volume
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this.attackAdd=0; //Timers for the different states of the envelope
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this.decayAdd=0;
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this.releaseAdd=0;
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this.rateIndex=0; //Current position of the evenlope
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this.rateZero=0; //Bits for the different states of the envelope having no changes
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this.keyOn=0; //Bitmask of different values that can generate keyon
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//Registers, also used to check for changes
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this.reg20=0;
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this.reg40=0;
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this.reg60=0;
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this.reg80=0;
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this.regE0=0;
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//Active part of the envelope we're in
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this.state=0;
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//0xff when tremolo is enabled
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this.tremoloMask=0;
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//Strength of the vibrato
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this.vibStrength=0;
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//Keep track of the calculated KSR so we can check for changes
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this.ksr=0;
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return this;
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};
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// dbopl.cpp (private stuff)
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var ZeroArray = function(size) {
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// http://stackoverflow.com/questions/1295584/most-efficient-way-to-create-a-zero-filled-javascript-array
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return Array.apply(null, new Array(size)).map(Number.prototype.valueOf,0);
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};
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var PI = 3.14159265358979323846;
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var OPLRATE = 14318180.0 / 288.0;
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var TREMOLO_TABLE = 52;
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var WAVE_BITS = 10;
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var WAVE_SH = 32 - WAVE_BITS;
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var WAVE_MASK = (1 << WAVE_SH) - 1;
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var LFO_SH = WAVE_SH - 10;
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var LFO_MAX = 256 << LFO_SH;
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var ENV_BITS = 9;
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var ENV_MIN = 0;
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var ENV_EXTRA = ENV_BITS - 9;
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var ENV_MAX = 511 << ENV_EXTRA;
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var ENV_LIMIT = (12 * 256) >> (3 - ENV_EXTRA);
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var ENV_SILENT = function(_X_) { return _X_ >= ENV_LIMIT; }
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var RATE_SH = 24;
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var RATE_MASK = (1 << RATE_SH ) - 1;
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var MUL_SH = 16;
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var KslCreateTable = [
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64, 32, 24, 19,
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16, 12, 11, 10,
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8, 6, 5, 4,
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3, 2, 1, 0,
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];
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var M = function(_X_) {return _X_ * 2};
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var FreqCreateTable = [
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M(0.5), M(1), M(2), M(3), M(4), M(5), M(6), M(7),
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M(8), M(9), M(10), M(10), M(12), M(12), M(15), M(15),
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];
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var AttackSamplesTable = [
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69, 55, 46, 40,
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35, 29, 23, 20,
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19, 15, 11, 10,
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9
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];
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var EnvelopeIncreaseTable = [
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4, 5, 6, 7,
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8, 10, 12, 14,
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16, 20, 24, 28,
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32,
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];
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var WaveTable = ZeroArray(8 * 512);
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var WaveBaseTable = [
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0x000, 0x200, 0x200, 0x800,
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0xa00, 0xc00, 0x100, 0x400,
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];
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var WaveMaskTable = [
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1023, 1023, 511, 511,
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1023, 1023, 512, 1023,
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];
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var WaveStartTable = [
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512, 0, 0, 0,
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0, 512, 512, 256,
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];
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var MulTable = ZeroArray(384);
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var KslTable = ZeroArray(8 * 16);
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var TremoloTable = ZeroArray(TREMOLO_TABLE);
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var ChanOffsetTable = ZeroArray(32);
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var OpOffsetTable = ZeroArray(64);
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var VibratoTable = [
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1 - 0x00, 0 - 0x00, 1 - 0x00, 30 - 0x00,
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1 - 0x80, 0 - 0x80, 1 - 0x80, 30 - 0x80
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];
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// Note: the original used reference parameters to return index and shift..
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function EnvelopeSelect(val) {
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var shift, index;
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if ( val < 13 * 4 ) { //Rate 0 - 12
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shift = 12 - ( val >> 2 );
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index = val & 3;
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} else if ( val < 15 * 4 ) { //rate 13 - 14
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shift = 0;
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index = val - 12 * 4;
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} else { //rate 15 and up
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shift = 0;
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index = 12;
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}
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return [index, shift];
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}
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}; // end of DBOPL namespace
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