74 lines
2.7 KiB
JavaScript
74 lines
2.7 KiB
JavaScript
'use strict';
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const assert = require('assert');
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/* Agnav Tracking binary protocol
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trk_pos_type = Record {40 bytes}
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{Header}
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trk_Header1 : byte {0xFB}
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trk_Header2 : byte {0xFB}
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trk_DataID : byte {0xF7}
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trk_ACID : LongInt; {4 bytes signed Integer}
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trk_Time : LongInt // Number of seconds since 1970, 1, 1 to current UTC time
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trk_Lat : float; {4 byte floating point}
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trk_Lon : float; {4 byte floating point}
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trk_Alt : integer; {GPS alt, m, 2 byte signed integer}
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trk_SprayStat: byte; {0: off, 1: on, unsigned char}
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trk_Speed : word; {dm/s, speed * 10 2 bytes signed integer}
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trk_Heading : integer; { 0 - 359}
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trk_Temp : byte; {C deg, offset by 100, unsigned char}
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trk_Humid : byte; {0 - 100%, unsigned char}
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trk_AppRate : integer {Application rate L/Ha * 10}
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trk_Wspd : integer; {Windspeed * 10 dm/s}
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trk_Whdg : integer; {Wind heading, 0-359}
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trk_Res : byte; {reserved = 0, unsigned char}
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trk_Chksum : word; {Sum of all bytes start from FB}
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trk_End : word; {end of record, 0x0D 0x0A}
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End;
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** NOTES:
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byte : 1-byte unsigned integer
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word : 2-byte unsigned int
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integer : 2-byte signed int
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LongInt : 4-byte signed int
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float : 4-byte floating number
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*/
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class RAPParser {
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/**
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* Parse AgNav Tracking binary response package
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* @param {*} agnPkg The package data in Buffer. Structure: <Cmd><Data>, Cmd = 0xF7
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* @returns a GPS data object
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*/
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parse(agnPkg) {
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assert.ok(Buffer.isBuffer(agnPkg), 'agnPkg argument must be an instance of Buffer'); // prettier-ignore
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assert.ok(agnPkg.length == 38, 'agnPkg must have 40 bytes'); // prettier-ignore
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let record, offset;
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record = {};
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offset = 5; // Skip the first Cmd byte (F7) + 4 bytes Aircraft Id
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record.gdt = new Date(agnPkg.readInt32LE(offset) * 1000); offset += 4;
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record.lat = agnPkg.readFloatLE(offset); offset += 4;
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record.lon = agnPkg.readFloatLE(offset); offset += 4;
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record.alt = agnPkg.readInt16LE(offset); offset += 2;
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record.inputs = agnPkg.readUInt8(offset); offset += 1;
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record.speed = agnPkg.readInt16LE(offset); offset += 2;
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if (record.speed > 0)
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record.speed = record.speed * 0.36; // dm/s to km/h
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record.head = agnPkg.readInt16LE(offset); offset += 2;
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record.temp = agnPkg.readUInt8(offset) - 100; offset += 1;
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record.humid = agnPkg.readUInt8(offset); offset += 1;
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record.appRate = agnPkg.readInt16LE(offset) * 1e-1; offset += 2;
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record.windSpd = agnPkg.readInt16LE(offset); offset += 2;
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record.windHdg = agnPkg.readInt16LE(offset); offset += 2;
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agnPkg = null;
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return record;
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}
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}
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module.exports = RAPParser; |