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level2volumescan.js
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level2volumescan.js
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const { logger } = require('./logger');
const fs = require('fs');
const moment = require('moment-timezone');
const Bzip2 = require('seek-bzip');
class Level2VolumeScan {
raf;
#position = 0;
constructor(path) {
// fs.writeFileSync('/Users/alexneises/KTWX20200504_075325_V06_decoded', Level2VolumeScan.#decodeFile(path));
// this.raf = Level2VolumeScan.#decodeFile(path);
this.raf = fs.readFileSync('/Users/alexneises/KTWX20200504_075325_V06_decoded');
// HEADER BLOCK
const tape = this.#readString(9); // tape
const extension = this.#readString(3); // extension
const daysSinceEpoch = this.#readWord(); // days since unix epoch
const millisSinceMidnight = this.#readWord(); // milliseconds since midnight
const site = this.#readString(4); // site identifier
console.log('tape', tape);
console.log('extension', extension);
console.log(Level2VolumeScan.#formatDate(daysSinceEpoch, millisSinceMidnight));
console.log('site', site);
// METADATA BLOCK
// Message 15 - 77 segments (187264 bytes)
this.#position += 325888 + 28;
console.log('site', this.#readString(4));
const millis = this.#readInteger(4);
const julian = this.#readInteger(2);
console.log(Level2VolumeScan.#formatDate(julian, millis));
console.log('azimuthNumber', this.#readInteger(2));
console.log('azimuthAngle', this.#readReal(4));
console.log('compressionIndicator', this.#readCode(1));
this.#position++;
console.log('radialLength', this.#readInteger(2));
console.log('azimuthSpacing', this.#readCode(1));
console.log('radialStatus', this.#readCode(1));
console.log('elevationNumber', this.#readInteger(1));
console.log('cutSectorNumber', this.#readInteger(1));
console.log('elevationAngle', this.#readReal(4));
console.log('radialSpotBlankingStatus', this.#readCode(1));
console.log('azimuthIndexingMode', this.#readScaledInteger(1, 0.01));
console.log('dataBlockCount', this.#readInteger(2));
const prevPos = this.#position;
// console.log('dataBlockPointer', this.#readInteger(4));
this.#position += this.#readInteger(4);
console.log(this.#readString(1));
// console.log('dataBlockPointer', this.#readInteger(4));
// console.log('dataBlockPointer', this.#readInteger(4));
// console.log('dataBlockPointer', this.#readInteger(4));
// console.log('dataBlockPointer', this.#readInteger(4));
// console.log('dataBlockPointer', this.#readInteger(4));
// console.log('dataBlockPointer', this.#readInteger(4));
// console.log('dataBlockPointer', this.#readInteger(4));
// console.log('dataBlockPointer', this.#readInteger(4));
// this.#position++;
// console.log(this.raf.toString('binary', this.#position, this.#position + 1));
// this.#position++;
// console.log(this.raf.toString('hex', this.#position, this.#position + 1));
// console.log('idSeq', this.#readHalfWord());
// console.log('meta15date', this.#readHalfWord());
// console.log('meta15time', this.#readWord());
// console.log('meta15elev', this.#readHalfWord());
}
#readCode = (size) => {
if (size !== 1 && size !== 2) {
logger.error(new Error('size invalid'));
process.exit(1);
}
const buffer = new ArrayBuffer(size);
const bytes = new Uint8Array(buffer);
for (let i = 0; i < size; i++) {
bytes[i] = this.#readByte();
}
const view = new DataView(buffer);
return size === 1 ? view.getInt8(0) : view.getInt16(0, false);
}
#readInteger = (size) => {
if (size !== 1 && size !== 2 && size !== 4) {
logger.error(new Error('size invalid'));
process.exit(1);
}
const buffer = new ArrayBuffer(size);
const bytes = new Uint8Array(buffer);
for (let i = 0; i < size; i++) {
bytes[i] = this.#readByte();
}
const view = new DataView(buffer);
switch (size) {
case 1:
return view.getUint8(0);
case 2:
return view.getUint16(0, false);
default:
return view.getUint32(0, false);
}
}
#readScaledInteger = (size, precision) => {
if (size !== 1 && size !== 2 && size !== 4) {
logger.error(new Error('size invalid'));
process.exit(1);
}
const buffer = new ArrayBuffer(size);
const bytes = new Uint8Array(buffer);
for (let i = 0; i < size; i++) {
bytes[i] = this.#readByte();
}
const view = new DataView(buffer);
switch (size) {
case 1:
return view.getUint8(0) * precision;
case 2:
return view.getUint16(0, false) * precision;
default:
return view.getUint32(0, false) * precision;
}
}
#readReal = (size) => {
if (size !== 4 && size !== 8) {
logger.error(new Error('size invalid'));
process.exit(1);
}
const buffer = new ArrayBuffer(size);
const bytes = new Uint8Array(buffer);
for (let i = 0; i < size; i++) {
bytes[i] = this.#readByte();
}
const view = new DataView(buffer);
return size === 4 ? view.getFloat32(0, false) : view.getFloat64(0, false);
}
static #decodeFile = (input) => {
const decoder = fs.readFileSync(input);
let decoderPos = 0;
const bufferArray = [];
let totalLength = 0;
const headerSize = 24;
const headerBuf = Buffer.from(decoder.buffer, decoderPos, headerSize);
bufferArray.push(headerBuf);
totalLength += headerBuf.length;
decoderPos += 24;
let processor = true;
while (processor) {
const compressionSize = decoder.readInt32BE(decoderPos);
decoderPos += 4;
const buf = Buffer.from(decoder.buffer, decoderPos, compressionSize);
try {
const decoded = Bzip2.decode(buf);
bufferArray.push(decoded);
totalLength += decoded.length;
decoderPos += compressionSize;
} catch (e) {
const footerBuf = Buffer.from(decoder.buffer, decoderPos, decoder.length - decoderPos);
bufferArray.push(footerBuf);
totalLength += footerBuf.length;
processor = false;
}
}
const buff = Buffer.concat(bufferArray, totalLength);
return buff;
}
static #formatDate = (days, millis, fmt = null) => {
return new moment.tz('1969-12-31 23:59:59', 'GMT')
.add(days, 'days')
.startOf('day')
.add(millis, 'milliseconds')
.tz('America/Chicago')
.format(fmt ? fmt : 'YYYY-MM-DD HH:mm:ss zz');
}
#readByte = () => {
const pos = this.#position;
this.#position += 1;
try {
return this.raf[pos];
} catch (e) {
logger.error(e);
process.exit(1);
}
}
#readString = (size) => {
const pos = this.#position;
this.#position += size;
try {
return this.raf.toString('utf8', pos, pos + size);
} catch (e) {
logger.error(e);
}
}
}
exports.Level2VolumeScan = Level2VolumeScan;