165 lines
4.3 KiB
JavaScript
165 lines
4.3 KiB
JavaScript
'use strict';
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function ArrayBufferSer (type, data, options) {
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if (type === undefined) {
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throw 'ArrayBufferSer should be created with a type';
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}
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this.options = options || {};
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this._initFunctions();
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this.headerSize = 8;
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this.data = data;
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this.type = type = Math.min(type, ArrayBufferSer.BUFFER);
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var size = this._sizeFor(this.headerSize, data);
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this.buffer = new Buffer(this.headerSize + size);
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this.buffer.writeUInt32BE(type, 0); // this could be one byte but for byte padding is better to be 4 bytes
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this.buffer.writeUInt32BE(size, 4);
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this.offset = this.headerSize;
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var w = this.writeFn[type];
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var i;
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if (!this.options.delta) {
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for (i = 0; i < data.length; ++i) {
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this[w](data[i]);
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}
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} else {
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this[w](data[0]);
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for (i = 1; i < data.length; ++i) {
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this[w](data[i] - data[i - 1]);
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}
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}
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}
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//
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// constants
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//
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ArrayBufferSer.INT8 = 1;
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ArrayBufferSer.UINT8 = 2;
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ArrayBufferSer.UINT8_CLAMP = 3;
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ArrayBufferSer.INT16 = 4;
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ArrayBufferSer.UINT16 = 5;
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ArrayBufferSer.INT32 = 6;
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ArrayBufferSer.UINT32 = 7;
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ArrayBufferSer.FLOAT32 = 8;
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// ArrayBufferSer.FLOAT64 = 9; not supported
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ArrayBufferSer.STRING = 10;
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ArrayBufferSer.BUFFER = 11;
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ArrayBufferSer.MAX_PADDING = ArrayBufferSer.INT32;
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ArrayBufferSer.typeNames = {
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int8: ArrayBufferSer.INT8,
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uint8: ArrayBufferSer.UINT8,
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uintclamp: ArrayBufferSer.UINT8_CLAMP,
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int16: ArrayBufferSer.INT16,
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uint16: ArrayBufferSer.UINT16,
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int32: ArrayBufferSer.INT32,
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uint32: ArrayBufferSer.UINT32,
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float32: ArrayBufferSer.FLOAT32,
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string: ArrayBufferSer.STRING,
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buffer: ArrayBufferSer.BUFFER
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};
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ArrayBufferSer.prototype = {
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// 0 not used
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sizes: [NaN, 1, 1, 1, 2, 2, 4, 4, 4, 8],
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_paddingFor: function (off, type) {
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var s = this.sizes[type];
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if (s) {
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var r = off % s;
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return r === 0 ? 0 : s - r;
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}
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return 0;
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},
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_sizeFor: function (offset, t) {
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var self = this;
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var s = this.sizes[this.type];
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if (s) {
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return s * t.length;
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}
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s = 0;
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if (this.type === ArrayBufferSer.STRING) {
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// calculate size with padding
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t.forEach(function (arr) {
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var pad = self._paddingFor(offset, ArrayBufferSer.MAX_PADDING);
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s += pad;
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offset += pad;
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var len = (self.headerSize + arr.length * 2);
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s += len;
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offset += len;
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});
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} else {
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t.forEach(function (arr) {
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var pad = self._paddingFor(offset, ArrayBufferSer.MAX_PADDING);
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s += pad;
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offset += pad;
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s += arr.getSize();
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offset += arr.getSize();
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});
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}
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return s;
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},
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getDataSize: function () {
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return this._sizeFor(0, this.data);
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},
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getSize: function () {
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return this.headerSize + this._sizeFor(this.headerSize, this.data);
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},
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writeFn: [
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'',
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'writeInt8',
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'writeUInt8',
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'writeUInt8Clamp',
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'writeInt16LE',
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'writeUInt16LE',
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'writeUInt32LE',
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'writeUInt32LE',
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'writeFloatLE',
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'writeDoubleLE',
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'writeString',
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'writteBuffer'
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],
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_initFunctions: function () {
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var self = this;
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this.writeFn.forEach(function (fn) {
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if (self[fn] === undefined) {
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self[fn] = function (d) {
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self.buffer[fn](d, self.offset);
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self.offset += self.sizes[self.type];
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};
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}
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});
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},
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writeUInt8Clamp: function (c) {
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this.buffer.writeUInt8(Math.min(255, c), this.offset);
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this.offset += 1;
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},
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writeString: function (s) {
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var arr = [];
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for (var i = 0, len = s.length; i < len; ++i) {
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arr.push(s.charCodeAt(i));
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}
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var str = new ArrayBufferSer(ArrayBufferSer.UINT16, arr);
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this.writteBuffer(str);
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},
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writteBuffer: function (b) {
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this.offset += this._paddingFor(this.offset, ArrayBufferSer.MAX_PADDING);
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// copy header
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b.buffer.copy(this.buffer, this.offset);
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this.offset += b.buffer.length;
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}
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};
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module.exports = ArrayBufferSer;
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