Add decoders for Hydronav, LABOv3 navigation headers

lib/www/server/lib/headers/error.js

@@ -0,0 +1,10 @@
+ 
+class NavHeaderError extends Error {
+	constructor (message, payload) {
+		super (message);
+		this.name = "NavHeaderError";
+		this.payload = payload;
+	}
+}
+
+module.exports = NavHeaderError;

lib/www/server/lib/headers/hydronav.js

@@ -0,0 +1,225 @@
+
+const NavHeaderError = require('./error');
+
+/**
+ * Detect if a Hydronav header is present in `buffer`.
+ */
+function detect (buffer) {
+	const s = buffer.indexOf("@@@UHEAD");
+	return s != -1 ? s : false;
+};
+
+function parse (buffer) {
+	const s = buffer.indexOf("@@@UHEAD");
+
+	if (s == -1) {
+		return; // undefined
+	}
+
+	const parser = [
+		// @@@UHEAD marker
+		(buf, ctx) => {
+			if (buf.subarray(s, s+8).toString('ascii') != "@@@UHEAD") {
+				console.log(s, buf.subarray(s, s+8).toString('ascii'));
+				throw new NavHeaderError("Expected @@@UHEAD marker not found at position "+s, buf);
+			}
+		},
+
+		// Timestamp. We also need to pick the date from further down the message
+		(buf, ctx) => {
+			const t = buf.subarray(s+8, s+8+15).toString('ascii');
+			const d = buf.subarray(s+105, s+105+10).toString('ascii');
+			ctx.tstamp = new Date(d.replace(/(.{2})\/(.{2})\/(.{4})/, "$3-$2-$1") + t.replace(/(.{8}).(.*)/, "T$1.$2Z"));
+			if (isNaN(ctx.tstamp)) {
+				throw new NavHeaderError(`Invalid timestamp from '${d}' + '${t}'`, buf);
+			}
+		},
+
+		// GPS clock, whatever that means
+		(buf, ctx) => {
+			ctx.gpsClock = Number(String.fromCharCode(buf[s+24]));
+		},
+
+		// Vessel name
+		(buf, ctx) => {
+			ctx.vesselName = buf.subarray(s+26, s+26+8).toString('ascii');
+		},
+
+		// Station number (aka shotpoint)
+		// NOTE this waypoint will not be valid if mode is offline
+		(buf, ctx) => {
+			ctx.shotPoint = Number(buf.subarray(s+35, s+35+7).toString('ascii'))
+		},
+
+		// FSID
+		// TODO Find out what this is!
+		(buf, ctx) => {
+			ctx.fsid = Number(buf.subarray(s+43, s+43+10).toString('ascii'))
+		},
+
+		// Northing
+		// NOTE We have no clue which CRS
+		(buf, ctx) => {
+			ctx.northing = Number(buf.subarray(s+54, s+54+11).toString('ascii'))
+			const hemisphere = String.fromCharCode(buf[s+65]);
+			switch (hemisphere) {
+				case "N":
+				case "n":
+					break;
+				case "S":
+				case "s":
+					ctx.northing *= -1;
+					break;
+				default:
+					throw new NavHeaderError("Unexpected hemisphere marker for northings: "+hemisphere, buf);
+			}
+		},
+
+		// Easting
+		// NOTE We have no clue which CRS
+		(buf, ctx) => {
+			ctx.easting = Number(buf.subarray(s+67, s+67+11).toString('ascii'))
+			const hemisphere = String.fromCharCode(buf[s+78]);
+			switch (hemisphere) {
+				case "E":
+				case "e":
+					break;
+				case "W":
+				case "w":
+					ctx.easting *= -1;
+					break;
+				default:
+					throw new NavHeaderError("Unexpected hemisphere marker for eastings: "+hemisphere, buf);
+			}
+		},
+
+		// Speed
+		// (we convert to metres per second)
+		(buf, ctx) => {
+			ctx.speed = Number(buf.subarray(s+80, s+80+6).toString('ascii'));
+			const units = buf.subarray(s+86, s+86+2).toString('ascii');
+			switch (units.toUpperCase()) {
+				case "KT":
+					ctx.speed *= (1.852/3.6);
+					break;
+				default:
+					throw new NavHeaderError("Unexpected speed units: "+units, buf);
+			}
+		},
+
+		// Bearing
+		// (in degrees)
+		(buf, ctx) => {
+			ctx.bearing = Number(buf.subarray(s+89, s+89+6).toString('ascii'));
+			const units = buf.subarray(s+95, s+95+2).toString('ascii');
+			switch (units.toUpperCase()) {
+				case "DG":
+					break;
+				default:
+					throw new NavHeaderError("Unexpected angular units: "+units, buf);
+			}
+		},
+
+		// Water depth
+		// (in metres)
+		(buf, ctx) => {
+			ctx.waterDepth = Number(buf.subarray(s+98, s+98+5).toString('ascii'));
+			const units = String.fromCharCode(buf[s+103]);
+			switch (units.toUpperCase()) {
+				case "M":
+					break;
+				default:
+					throw new NavHeaderError("Unexpected depth units: "+units, buf);
+			}
+		},
+
+		// Date
+		// Already taken care of along with the time part
+
+		// Distance offline
+		// (meaning crossline?)
+		(buf, ctx) => {
+			ctx.crossline = Number(buf.subarray(s+116, s+116+5).toString('ascii'));
+			const units = String.fromCharCode(buf[s+121]);
+			switch (units.toUpperCase()) {
+				case "M":
+					break;
+				default:
+					throw new NavHeaderError("Unexpected crossline units: "+units, buf);
+			}
+		},
+
+		// Distance inline
+		(buf, ctx) => {
+			ctx.inline = Number(buf.subarray(s+123, s+123+8).toString('ascii'));
+			const units = String.fromCharCode(buf[s+131]);
+			switch (units.toUpperCase()) {
+				case "M":
+					break;
+				default:
+					throw new NavHeaderError("Unexpected inline units: "+units, buf);
+			}
+		},
+
+		// Line status
+		(buf, ctx) => {
+			const status = String.fromCharCode(buf[s+133]);
+			switch (status) {
+				case "0":
+					ctx.lineStatus = "offline";
+					break;
+				case "1":
+					ctx.lineStatus = "approach";
+					break;
+				case "2":
+					ctx.lineStatus = "online";
+					break;
+				case "3":
+					ctx.lineStatus = "runout";
+					break;
+				default:
+					throw new NavHeaderError("Unrecognised line status: "+status, buf);
+			}
+		},
+
+		// GPS height
+		(buf, ctx) => {
+			ctx.gpsHeight = Number(buf.subarray(s+135, s+135+5).toString('ascii'));
+			const units = String.fromCharCode(buf[s+140]);
+			switch (units.toUpperCase()) {
+				case "M":
+					break;
+				default:
+					throw new NavHeaderError("Unexpected GPS height units: "+units, buf);
+			}
+		},
+
+		// Line name
+		(buf, ctx) => {
+			ctx.lineName = buf.subarray(s+0x8e, s+0x8e+16).toString('ascii');
+		},
+
+		// End of Hydronav data
+		(buf, ctx) => {
+			if (String.fromCharCode(buf[s+0x9e]) != "*") {
+				throw new NavHeaderError("Missing end of HYDRONAV data marker '*'", buf);
+			}
+		}
+	];
+
+	const hydronav = {};
+	hydronav._type = "hydronav";
+	hydronav._received = new Date();
+	for (const fn of parser) {
+		fn(buffer, hydronav);
+	}
+
+	return hydronav;
+}
+
+
+module.exports = {
+	name: "Hydronav",
+	detect,
+	parse
+};

lib/www/server/lib/headers/index.js

@@ -0,0 +1,5 @@
+module.exports = {
+	hydronav: require('./hydronav'),
+	labo: require('./labo'),
+	smartsource: require('./smartsource')
+};

lib/www/server/lib/headers/labo.js

@@ -0,0 +1,210 @@
+
+const NavHeaderError = require('./error');
+
+/**
+ * Detect if a LABO header is present in `buffer`.
+ */
+function detect (buffer) {
+	const s = buffer.indexOf("$1");
+	return (s != -1 &&
+		buffer.subarray(s+6, s+10).toString('ascii') == "0003") ? s : false;
+};
+
+function parse (buffer) {
+
+	const s = buffer.indexOf("$1");
+
+	if (s == -1) {
+		return; // undefined
+	}
+
+	let offset = 0;
+
+	function ascii (length) {
+		const start = offset;
+		const end = offset+length;
+		offset += length;
+// 		const v = buffer.subarray(start, end).toString('ascii');
+// 		console.log("v = ", v);
+// 		return v;
+		return buffer.subarray(start, end).toString('ascii');
+	}
+
+	const parser = [
+		// LABO marker
+		(buf, ctx) => {
+			if (! /\$[12]/.test(ascii(2))) {
+				throw new NavHeaderError("Expected LABO marker not found at position "+s, buf);
+			}
+		},
+
+		// Message length
+		// NOTE isn't this fixed?
+		(buf, ctx) => {
+			ctx.messageLength = Number(ascii(4));
+		},
+
+	   // Revision
+	   (buf, ctx) => {
+		   const rev = Number(ascii(4));
+		   if (rev != 3) {
+			   throw new NavHeaderError("Unsupported LABO header version: "+rev, buf);
+		   }
+	   },
+
+	   // Line status
+	   (buf, ctx) => {
+		   const status = Number(ascii(2));
+		   switch (status) {
+			   case 1:
+				   ctx.lineStatus = "offline";
+				   break;
+			   case 2:
+				   ctx.lineStatus = "approach";
+				   break;
+			   case 3:
+				   ctx.lineStatus = "online";
+				   break;
+			   case 4:
+				   ctx.lineStatus = "runout";
+				   break;
+			   default:
+				   throw new NavHeaderError("Unrecognised line status: "+status, buf);
+		   }
+	   },
+
+	   // Timestamp
+	   // We process a number of fields in one go
+	   (buf, ctx) => {
+		   const t = ascii(6);
+		   const ms = ascii(7);
+		   const d = ascii(8);
+		   const tref = ascii(3);
+
+		   if (tref != "UTC" && tref != "GPS") {
+			   throw new NavHeaderError("Unrecognised time reference: "+tref, buf);
+		   }
+
+		   const tstr =
+			d.replace(/^(.{4})(.{2})(.{2})$/, "$1-$2-$3") + "T" +
+			t.replace(/^(.{2})(.{2})(.{2})$/, "$1:$2:$3") +
+			ms + "Z";
+
+			const tstamp = new Date(tstr);
+
+			if (isNaN(tstamp)) {
+				throw new NavHeaderError("Invalid timestamp: "+tstr, buf);
+			}
+			ctx.tstamp = tstamp;
+	   },
+
+	   // Shotpoint
+	   (buf, ctx) => {
+		   ctx.shotPoint = Number(ascii(6));
+	   },
+
+	   // Line name
+	   (buf, ctx) => {
+		   ctx.lineName = ascii(16);
+	   },
+
+	   // Master latitude
+	   (buf, ctx) => {
+		   ctx.latitudeMaster = Number(ascii(11));
+	   },
+
+	   // Master longitude
+	   (buf, ctx) => {
+		   ctx.longitudeMaster = Number(ascii(11));
+	   },
+
+	   // Master depth
+	   // in metres
+	   (buf, ctx) => {
+		   ctx.waterDepth = Number(ascii(6));
+	   },
+
+	   // Source latitude
+	   (buf, ctx) => {
+		   ctx.latitude = Number(ascii(11));
+	   },
+
+	   // Source longitude
+	   (buf, ctx) => {
+		   ctx.longitude = Number(ascii(11));
+	   },
+
+	   // Source gyro
+	   // NOTE is this the same as Hydronav bearing?
+	   (buf, ctx) => {
+		   ctx.heading = Number(ascii(5));
+	   },
+
+	   // Master CMG
+	   (buf, ctx) => {
+		   ctx.cmg = Number(ascii(5));
+	   },
+
+	   // Master speed
+	   // FIXME Probably knots?
+	   // We convert to m/s
+	   (buf, ctx) => {
+		   ctx.speed = Number(ascii(4)) * 1.852 / 3.6;
+	   },
+
+	   // Vessel ID
+	   (buf, ctx) => {
+		   ctx.vesselId = ascii(3);
+	   },
+
+	   // Master easting
+	   (buf, ctx) => {
+		   ctx.eastingMaster = Number(ascii(11));
+	   },
+
+	   // Master northing
+	   (buf, ctx) => {
+		   ctx.northingMaster = Number(ascii(11));
+	   },
+
+	   // Source delta easting
+	   // NOTE This is the vessel's easting in Triggerfish
+	   (buf, ctx) => {
+		   ctx.deltaEasting = Number(ascii(7));
+	   },
+
+	   // Source delta northing
+	   // NOTE This is the vessel's northing in Triggerfish
+	   (buf, ctx) => {
+		   ctx.deltaNorthing = Number(ascii(7));
+	   },
+
+	   // Line bearing
+	   (buf, ctx) => {
+		   ctx.lineBearing = Number(5);
+	   }
+
+	   // Julian day
+	   // NOTE We don't care about this, ignored
+
+	   // -rstdiff option
+	   // NOTE We don't even know what this is, ignored
+	];
+
+	const labo = {};
+	labo._type = "labov3";
+	labo._received = new Date();
+	for (const fn of parser) {
+		fn(buffer, labo);
+	}
+
+	return labo;
+}
+
+
+module.exports = {
+	name: "Labo v3",
+	detect,
+	parse
+};
+

lib/www/server/lib/headers/smartsource.js

@@ -0,0 +1,14 @@
+
+function detect (buffer) {
+	return false;
+}
+
+function parse (buffer) {
+	return; // undefined
+}
+ 
+module.exports = {
+	name: "SmartSource",
+	detect,
+	parse
+};