Initial commit
This commit is contained in:
Thomas FORGIONE
commit
ed16e84800
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@ -0,0 +1,29 @@
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const o1 = require('./o1.js');
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let value = Math.PI;
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let value2 = Math.exp(1);
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let buffer = o1.encodeArray([
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new o1.Float32(value),
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new o1.Float16(value2)
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]);
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let buffView = new DataView(buffer);
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let buff1 = new ArrayBuffer(3);
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let view1 = new DataView(buff1);
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view1.setUint8(0, buffView.getUint8(0));
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view1.setUint8(1, buffView.getUint8(1));
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view1.setUint8(2, buffView.getUint8(2));
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let buff2 = new ArrayBuffer(1);
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let view2 = new DataView(buff2);
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view2.setUint8(0, buffView.getUint8(3));
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let buff3 = new ArrayBuffer(2);
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let view3 = new DataView(buff3);
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view3.setUint8(0, buffView.getUint8(4));
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view3.setUint8(1, buffView.getUint8(5));
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let elt = o1.decodeArray([buff1, buff2, buff3], [o1.Float32, o1.Float16]);
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console.log(elt[0], elt[1]);
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@ -0,0 +1,316 @@
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o1 = (function() {
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// Float8
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const exponentSize = 5;
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const mantissaSize = 10;
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const bias = Math.pow(2, exponentSize - 1) - 1;
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// http://stackoverflow.com/questions/5678432/decompressing-half-precision-floats-in-javascript#8796597
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function decodeFloat16 (binary) {
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var exponent = (binary & 0x7C00) >> 10;
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fraction = binary & 0x03FF;
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return (binary >> 15 ? -1 : 1) * (
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exponent ?
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(
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exponent === 0x1F ?
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fraction ? NaN : Infinity :
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Math.pow(2, exponent - 15) * (1 + fraction / 0x400)
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) :
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6.103515625e-5 * (fraction / 0x400)
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);
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};
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function encodeFloat16(floating) {
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let abs = Math.floor(Math.abs(floating));
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let frac = Math.abs(floating) - abs;
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let fraction = [];
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let sign = Math.sign(floating) < 0;
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// Compute the integral
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let integral = new Number(abs).toString(2).split('').map((a) => a == 1);
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if (integral.length === 1 && integral[0] === false)
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integral = [];
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// Compute the fraction
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while (fraction.length < 16) {
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frac *= 2;
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fraction.push(frac >= 1);
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if (frac >= 1) {
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frac--;
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}
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if (frac == 0) {
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break;
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}
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}
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// Compute the exponent
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let exponent = 0;
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while (integral.length > 1) {
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fraction = [integral.pop(), ...fraction];
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exponent++;
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}
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while (integral.length < 1 || !integral[integral.length-1] && fraction.length > 0) {
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integral = [...integral, fraction.shift()];
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exponent--;
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}
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exponent += bias; // Math.pow(2, 5 - 1) - 1, the bias
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// To array of bools
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exponent = new Number(exponent).toString(2).split('').map((a) => a == 1);
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// Pad the exponent with zeros
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while (exponent.length < exponentSize) {
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exponent = [false, ...exponent];
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}
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// Pad the fraction with zeros
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while (fraction.length < mantissaSize) {
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fraction.push(false);
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}
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fraction = fraction.slice(0, mantissaSize);
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let result = [sign, ...exponent, ...fraction];
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return parseInt(result.reduce((a,b) => a + (b ? '1' : '0'), ''), 2);
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}
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let o1 = {};
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o1.encodeFloat16 = encodeFloat16;
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o1.decodeFloat16 = decodeFloat16;
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o1.IncompleteBufferError = class extends Error {};
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function newCall(Cls) {
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return new (Function.prototype.bind.apply(Cls, arguments));
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}
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o1.BinaryElement = class {
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constructor(value) {
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this.value = value;
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}
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loadFromBytes(buffers, offset) {
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if (buffers instanceof ArrayBuffer) {
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buffers = [buffers];
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} else if (! buffers instanceof Array) {
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throw new TypeError("Expecting buffer or array of buffers");
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}
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// Find correct buffer
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let currentBufferIndex = 0;
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while (offset >= buffers[currentBufferIndex].byteLength) {
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offset -= buffers[currentBufferIndex].byteLength;
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currentBufferIndex++;
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if (buffers[currentBufferIndex] === undefined)
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throw new o1.IncompleteBufferError();
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}
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let buffer = buffers[currentBufferIndex];
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let view = new DataView(buffer, offset);
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let bytes = new ArrayBuffer(this.size());
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let bytesView = new DataView(bytes);
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let offsetBetweenBuffers = 0;
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for (let byteIndex = 0; byteIndex < this.size(); byteIndex++) {
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if (byteIndex - offsetBetweenBuffers >= view.byteLength) {
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// Change view
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currentBufferIndex++;
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let newBuffer = buffers[currentBufferIndex];
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if (newBuffer === undefined) {
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throw new o1.IncompleteBufferError();
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}
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view = new DataView(newBuffer);
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offsetBetweenBuffers = byteIndex;
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}
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bytesView.setUint8(byteIndex, view.getUint8(byteIndex - offsetBetweenBuffers));
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}
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this.readFromView(bytesView);
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}
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}
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o1.Uint8 = class extends o1.BinaryElement {
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constructor(value) {
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super(value);
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}
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size() {
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return 1;
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}
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writeToView(view, offset = 0) {
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view.setUint8(offset, this.value);
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}
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readFromView(view, offset) {
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return this.value = view.getUint8(offset);
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}
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}
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o1.Uint32 = class extends o1.BinaryElement {
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constructor(value) {
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super(value);
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}
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size() {
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return 4;
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}
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writeToView(view, offset = 0) {
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view.setUint32(offset, this.value);
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}
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readFromView(view, offset) {
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return this.value = view.getUint32(offset);
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}
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}
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o1.Float16 = class extends o1.BinaryElement {
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constructor(value) {
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super(value);
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}
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size() {
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return 2;
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}
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writeToView(view, offset = 0) {
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view.setUint16(offset, encodeFloat16(this.value));
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}
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readFromView(view, offset) {
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let uint16 = view.getUint16(offset);
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this.value = decodeFloat16(uint16);
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}
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}
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o1.Float32 = class extends o1.BinaryElement {
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constructor(value) {
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super(value);
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}
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size() {
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return 4;
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}
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writeToView(view, offset = 0) {
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view.setFloat32(offset, this.value);
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}
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readFromView(view, offset) {
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return this.value = view.getFloat32(offset);
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}
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}
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o1.BufferWriter = class {
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constructor(size) {
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this.buffer = new ArrayBuffer(size);
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this.offset = 0;
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}
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write(element) {
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element.writeToView(new DataView(this.buffer, this.offset));
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this.offset += element.size();
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}
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}
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o1.BufferReader = class {
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constructor(buffers) {
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if (buffers instanceof ArrayBuffer) {
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this.buffers = [buffers];
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} else if (buffers instanceof Array) {
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this.buffers = buffers;
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} else {
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throw new TypeError("Expexting buffer or array of buffers");
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}
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this.offset = 0;
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this.array = [];
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}
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decodeElement(type) {
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let elt = newCall(type);
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elt.loadFromBytes(this.buffers, this.offset);
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this.offset += elt.size();
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this.array.push(elt);
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return elt;
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}
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}
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o1.decodeElement = function(buffer, offset, type) {
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let elt = newCall(type);
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elt.loadFromBytes(buffer, offset);
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return elt;
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}
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o1.encodeArray = function(array) {
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let size = array.map((a) => a.size()).reduce((a,b) => a+b, 0);
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let writer = new o1.BufferWriter(size);
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for (let elt of array) {
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writer.write(elt);
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}
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return writer.buffer;
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}
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o1.decodeArray = function(buffer, types) {
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let reader = new o1.BufferReader(buffer);
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for (let i = 0; i < types.length; i++) {
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reader.decodeElement(types[i]);
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}
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return reader.array;
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}
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return o1;
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})();
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if (typeof module !== 'undefined' && module.exports) {
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module.exports = o1;
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}
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@ -0,0 +1,16 @@
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{
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"name": "node-o1",
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"version": "1.0.0",
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"description": "A small library for writing binary files",
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"main": "o1.js",
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"repository": {
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"type": "git",
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"url": "https://gogs.tforgione.fr/tforgione-phd/node-o1"
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},
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"keywords": [
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"node",
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"binary"
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],
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"author": "Thomas Forgione",
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"license": "MIT"
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}
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