148 lines
3.5 KiB
JavaScript
148 lines
3.5 KiB
JavaScript
const Iconv = require('iconv-lite'),
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Long = require('long');
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function readUInt64BE(buffer,offset) {
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const high = buffer.readUInt32BE(offset);
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const low = buffer.readUInt32BE(offset+4);
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return new Long(low,high,true);
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}
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function readUInt64LE(buffer,offset) {
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const low = buffer.readUInt32LE(offset);
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const high = buffer.readUInt32LE(offset+4);
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return new Long(low,high,true);
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}
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class Reader {
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constructor(query,buffer) {
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this.query = query;
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this.buffer = buffer;
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this.i = 0;
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}
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offset() {
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return this.i;
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}
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skip(i) {
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this.i += i;
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}
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string(...args) {
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let options = {};
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if(args.length === 0) {
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options = {};
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} else if(args.length === 1) {
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if(typeof args[0] === 'string') options = { delimiter: args[0] };
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else if(typeof args[0] === 'number') options = { length: args[0] };
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else options = args[0];
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}
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options.encoding = options.encoding || this.query.encoding;
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if(options.encoding === 'latin1') options.encoding = 'win1252';
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const start = this.i+0;
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let end = start;
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if(!('length' in options)) {
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// terminated by the delimiter
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let delim = options.delimiter || this.query.delimiter;
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if(typeof delim === 'string') delim = delim.charCodeAt(0);
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while(true) {
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if(end >= this.buffer.length) {
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end = this.buffer.length;
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break;
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}
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if(this.buffer.readUInt8(end) === delim) break;
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end++;
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}
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this.i = end+1;
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} else {
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end = start+options.length;
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if(end >= this.buffer.length) {
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end = this.buffer.length;
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}
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this.i = end;
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}
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let out = this.buffer.slice(start, end);
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const enc = options.encoding;
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if(enc === 'utf8' || enc === 'ucs2' || enc === 'binary') {
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out = out.toString(enc);
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} else {
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out = Iconv.decode(out,enc);
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}
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return out;
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}
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int(bytes) {
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let r = 0;
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if(this.remaining() >= bytes) {
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if(this.query.byteorder === 'be') {
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if(bytes === 1) r = this.buffer.readInt8(this.i);
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else if(bytes === 2) r = this.buffer.readInt16BE(this.i);
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else if(bytes === 4) r = this.buffer.readInt32BE(this.i);
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} else {
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if(bytes === 1) r = this.buffer.readInt8(this.i);
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else if(bytes === 2) r = this.buffer.readInt16LE(this.i);
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else if(bytes === 4) r = this.buffer.readInt32LE(this.i);
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}
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}
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this.i += bytes;
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return r;
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}
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/** @returns {number} */
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uint(bytes) {
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let r = 0;
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if(this.remaining() >= bytes) {
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if(this.query.byteorder === 'be') {
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if(bytes === 1) r = this.buffer.readUInt8(this.i);
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else if(bytes === 2) r = this.buffer.readUInt16BE(this.i);
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else if(bytes === 4) r = this.buffer.readUInt32BE(this.i);
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else if(bytes === 8) r = readUInt64BE(this.buffer,this.i).toString();
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} else {
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if(bytes === 1) r = this.buffer.readUInt8(this.i);
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else if(bytes === 2) r = this.buffer.readUInt16LE(this.i);
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else if(bytes === 4) r = this.buffer.readUInt32LE(this.i);
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else if(bytes === 8) r = readUInt64LE(this.buffer,this.i).toString();
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}
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}
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this.i += bytes;
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return r;
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}
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float() {
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let r = 0;
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if(this.remaining() >= 4) {
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if(this.query.byteorder === 'be') r = this.buffer.readFloatBE(this.i);
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else r = this.buffer.readFloatLE(this.i);
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}
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this.i += 4;
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return r;
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}
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part(bytes) {
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let r;
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if(this.remaining() >= bytes) {
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r = this.buffer.slice(this.i,this.i+bytes);
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} else {
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r = Buffer.from([]);
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}
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this.i += bytes;
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return r;
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}
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remaining() {
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return this.buffer.length-this.i;
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}
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rest() {
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return this.buffer.slice(this.i);
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}
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done() {
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return this.i >= this.buffer.length;
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}
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}
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module.exports = Reader;
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