91 lines
2.1 KiB
JavaScript
91 lines
2.1 KiB
JavaScript
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var BufferReader = function BufferReader(buf, pos) {
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if (!(this instanceof BufferReader))
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return new BufferReader(buf);
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this.buf = buf;
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this.pos = pos || 0;
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};
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BufferReader.prototype.eof = function eof() {
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return this.pos >= this.buf.length;
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};
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BufferReader.prototype.read = function() {
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var buf = this.buf.slice(this.pos);
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this.pos = this.buf.length;
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return buf;
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};
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BufferReader.prototype.readUInt8 = function() {
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var val = this.buf.readUInt8(this.pos);
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this.pos = this.pos + 1;
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return val;
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};
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BufferReader.prototype.readUInt16BE = function() {
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var val = this.buf.readUInt16BE(this.pos);
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this.pos = this.pos + 2;
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return val;
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};
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BufferReader.prototype.readUInt16LE = function() {
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var val = this.buf.readUInt16LE(this.pos);
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this.pos = this.pos + 2;
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return val;
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};
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BufferReader.prototype.readUInt32BE = function() {
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var val = this.buf.readUInt32BE(this.pos);
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this.pos = this.pos + 4;
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return val;
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};
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BufferReader.prototype.readUInt32LE = function() {
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var val = this.buf.readUInt32LE(this.pos);
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this.pos = this.pos + 4;
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return val;
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};
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//TODO: What if n is so large that it loses precision?
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BufferReader.prototype.readUInt64BE = function() {
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var val = 0;
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for (var i = 0; i < 8; i++) {
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val += Math.pow(256, i) * this.buf[this.pos + 8 - 1 - i];
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}
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this.pos = this.pos + 8;
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return val;
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};
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//TODO: What if n is so large that it loses precision?
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BufferReader.prototype.readUInt64LE = function() {
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var val = 0;
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for (var i = 0; i < 8; i++) {
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val += Math.pow(256, i) * this.buf[this.pos + i];
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}
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this.pos = this.pos + 8;
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return val;
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};
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BufferReader.prototype.readVarInt = function() {
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var first = this.readUInt8();
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switch (first) {
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case 0xFD:
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return this.readUInt16LE();
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case 0xFE:
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return this.readUInt32LE();
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case 0xFF:
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return this.readUInt64LE();
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default:
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return first;
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}
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};
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BufferReader.prototype.reverse = function() {
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var buf = new Buffer(this.buf.length);
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for (var i = 0; i < buf.length; i++)
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buf[i] = this.buf[this.buf.length - 1 - i]
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this.buf = buf;
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return this;
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};
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module.exports = BufferReader;
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