From c395d44728c0397ccd28dc169f1810f14b577daf Mon Sep 17 00:00:00 2001
From: bruce <bruces1@gmail.com>
Date: Sun, 20 Oct 2013 00:28:53 +0800
Subject: [PATCH] Start porting DBOPL to Javascript

---
 js/dbopl.js | 177 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 177 insertions(+)
 create mode 100644 js/dbopl.js

diff --git a/js/dbopl.js b/js/dbopl.js
new file mode 100644
index 0000000..a6ff076
--- /dev/null
+++ b/js/dbopl.js
@@ -0,0 +1,177 @@
+var DBOPL = new function() {	// DBOPL namespace
+
+// dbopl.h
+
+this.WAVE_HANDLER = 10;
+this.WAVE_TABLELOG = 11;
+this.WAVE_TABLEMUL = 12;
+this.DBOPL_WAVE = this.WAVE_TABLEMUL;
+
+this.SynthMode = {
+	sm2AM:0,
+	sm2FM:1,
+	sm3AM:2,
+	sm3FM:3,
+	sm4Start:4,
+	sm3FMFM:5,
+	sm3AMFM:6,
+	sm3FMAM:7,
+	sm3AMAM:8,
+	sm6Start:9,
+	sm2Percussion:10,
+	sm3Percussion:11,
+};
+
+this.SHIFT_KSLBASE = 16;
+this.SHIFT_KEYCODE = 24;
+
+this.Operator = function() {
+	// public:
+
+	// enum
+	this.MASK_KSR = 0x10;
+	this.MASK_SUSTAIN = 0x20;
+	this.MASK_VIBRATO = 0x40;
+	this.MASK_TREMOLO = 0x80;
+	this.State = {	// typedef enum
+		OFF:0,
+		RELEASE:1,
+		SUSTAIN:2,
+		DECAY:3,
+		ATTACK:4,
+	};
+	this.volHandler=0;
+	this.waveBase=0;
+	this.waveMask=0;
+	this.waveStart=0;
+
+	this.waveIndex=0;			//WAVE_BITS shifted counter of the frequency index
+	this.waveAdd=0;				//The base frequency without vibrato
+	this.waveCurrent=0;			//waveAdd + vibratao
+
+	this.chanData=0;			//Frequency/octave and derived data coming from whatever channel controls this
+	this.freqMul=0;				//Scale channel frequency with this, TODO maybe remove?
+	this.vibrato=0;				//Scaled up vibrato strength
+	this.sustainLevel=0;		//When stopping at sustain level stop here
+	this.totalLevel=0;			//totalLevel is added to every generated volume
+	this.currentLevel=0;		//totalLevel + tremolo
+	this.volume=0;				//The currently active volume
+	
+	this.attackAdd=0;			//Timers for the different states of the envelope
+	this.decayAdd=0;
+	this.releaseAdd=0;
+	this.rateIndex=0;			//Current position of the evenlope
+
+	this.rateZero=0;				//Bits for the different states of the envelope having no changes
+	this.keyOn=0;				//Bitmask of different values that can generate keyon
+	//Registers, also used to check for changes
+	this.reg20=0;
+	this.reg40=0;
+	this.reg60=0;
+	this.reg80=0;
+	this.regE0=0;
+	//Active part of the envelope we're in
+	this.state=0;
+	//0xff when tremolo is enabled
+	this.tremoloMask=0;
+	//Strength of the vibrato
+	this.vibStrength=0;
+	//Keep track of the calculated KSR so we can check for changes
+	this.ksr=0;
+
+	return this;
+};
+
+// dbopl.cpp (private stuff)
+var ZeroArray = function(size) {
+	// http://stackoverflow.com/questions/1295584/most-efficient-way-to-create-a-zero-filled-javascript-array
+	return Array.apply(null, new Array(size)).map(Number.prototype.valueOf,0);
+};
+
+var PI = 3.14159265358979323846;
+var OPLRATE = 14318180.0 / 288.0;
+var TREMOLO_TABLE = 52;
+var WAVE_BITS = 10;
+var WAVE_SH = 32 - WAVE_BITS;
+var WAVE_MASK = (1 << WAVE_SH) - 1;
+var LFO_SH = WAVE_SH - 10;
+var LFO_MAX = 256 << LFO_SH;
+var ENV_BITS = 9;
+var ENV_MIN	= 0;
+var ENV_EXTRA = ENV_BITS - 9;
+var ENV_MAX = 511 << ENV_EXTRA;
+var ENV_LIMIT = (12 * 256) >> (3 - ENV_EXTRA);
+var ENV_SILENT = function(_X_) { return _X_ >= ENV_LIMIT; }
+var RATE_SH = 24;
+var RATE_MASK = (1 << RATE_SH ) - 1;
+var MUL_SH = 16;
+
+var KslCreateTable = [
+	64, 32, 24, 19, 
+	16, 12, 11, 10, 
+	 8,  6,  5,  4,
+	 3,  2,  1,  0,
+];
+var M = function(_X_) {return _X_ * 2};
+var FreqCreateTable = [
+	M(0.5), M(1), M(2), M(3), M(4), M(5), M(6), M(7),
+	M(8), M(9), M(10), M(10), M(12), M(12), M(15), M(15),
+];
+
+var AttackSamplesTable = [
+	69, 55, 46, 40,
+	35, 29, 23, 20,
+	19, 15, 11, 10,
+	9
+];
+var EnvelopeIncreaseTable = [
+	4,  5,  6,  7,
+	8, 10, 12, 14,
+	16, 20, 24, 28,
+	32, 
+];
+
+var WaveTable = ZeroArray(8 * 512);
+
+var WaveBaseTable = [
+	0x000, 0x200, 0x200, 0x800,
+	0xa00, 0xc00, 0x100, 0x400,
+];
+
+var WaveMaskTable = [
+	1023, 1023, 511, 511,
+	1023, 1023, 512, 1023,
+];
+
+var WaveStartTable = [
+	512, 0, 0, 0,
+	0, 512, 512, 256,
+];
+
+var MulTable = ZeroArray(384);
+var KslTable = ZeroArray(8 * 16);
+var TremoloTable = ZeroArray(TREMOLO_TABLE);
+var ChanOffsetTable = ZeroArray(32);
+var OpOffsetTable = ZeroArray(64);
+var VibratoTable = [
+	1 - 0x00, 0 - 0x00, 1 - 0x00, 30 - 0x00, 
+	1 - 0x80, 0 - 0x80, 1 - 0x80, 30 - 0x80 
+];
+
+// Note: the original used reference parameters to return index and shift..
+function EnvelopeSelect(val) {
+	var shift, index;
+	if ( val < 13 * 4 ) {				//Rate 0 - 12
+		shift = 12 - ( val >> 2 );
+		index = val & 3;
+	} else if ( val < 15 * 4 ) {		//rate 13 - 14
+		shift = 0;
+		index = val - 12 * 4;
+	} else {							//rate 15 and up
+		shift = 0;
+		index = 12;
+	}
+	return [index, shift];
+}
+
+}; // end of DBOPL namespace