fix: not numerical variable length fields not encoding or decoding pr…

…operly (#112)
canboat · Apr 19, 2020 · b9ea3ee · b9ea3ee
1 parent 5630b72
commit b9ea3ee
Show file tree

Hide file tree

Showing 3 changed files with 15 additions and 11 deletions.
diff --git a/lib/fromPgn.js b/lib/fromPgn.js
@@ -449,7 +449,7 @@ function readField(options, runPostProcessor, pgn, field, bs) {
       bs.readBits(bs.bitsLeft, false)
       return
     }
-    value = readValue(pgn, field, bs)
+    value = readValue(options, pgn, field, bs)
   }
 
   //console.log(`${field.Name} ${value} ${field.Resolution}`)
@@ -464,7 +464,7 @@ function readField(options, runPostProcessor, pgn, field, bs) {
       if ( field.Offset ) {
         value += field.Offset
       }
-      if ( field.Resolution ) {
+      if ( field.Resolution && typeof value === 'number' ) {
         var resolution = field.Resolution
 
         value = (value * resolution)
@@ -507,13 +507,13 @@ function readField(options, runPostProcessor, pgn, field, bs) {
   return value
 }
 
-function readValue(pgn, field, bs, bitLength) {
+function readValue(options, pgn, field, bs, bitLength) {
   var value
   if ( _.isUndefined(bitLength) ) {
     bitLength = field.BitLength
   }
   if ( bitLength == 0 ) {
-    value = readVariableLengthField(pgn, field, bs)
+    return readVariableLengthField(options, pgn, field, bs)
   } else if (bitLength === 8) {
     if ( field.Signed ) {
       value = bs.readInt8()
@@ -571,7 +571,11 @@ function readValue(pgn, field, bs, bitLength) {
     }
     //console.log(`${field.Name} ${bitLength} ${value} ${bs.view.buffer[bs.byteIndex]} ${bs.index}`)
   }
-
+
+  if ( value != null && typeof value !== 'undefined' && typeof value !== 'number' ) {
+    value = Number(value)
+  }
+
   return value
 }
 
@@ -590,7 +594,7 @@ function isMax(numBits, value, signed)
   return signed ? (value & 1) == 0 : true
 }
 
-function readVariableLengthField(pgn, field, bs) {
+function readVariableLengthField(options, pgn, field, bs) {
   /* PGN 126208 contains variable field length.
    * The field length can be derived from the PGN mentioned earlier in the message,
    * plus the field number.
@@ -605,7 +609,7 @@ function readVariableLengthField(pgn, field, bs) {
 
   if ( refField ) {
     var bits = (refField.BitLength + 7) & ~7; // Round # of bits in field refField up to complete bytes: 1->8, 7->8, 8->8 etc.
-    return readValue(pgn, refField, bs, bits)
+    return readField(options, false, pgn, refField, bs, bits)
   }
 }
 

diff --git a/lib/toPgn.js b/lib/toPgn.js
@@ -172,14 +172,14 @@ function writeField(bs, pgn_number, field, data, value, bitLength) {
       }
     }
 
-    if (field.Resolution) {
+    if (field.Resolution && typeof value === 'number' ) {
       value = (value / field.Resolution).toFixed(0);
     }
 
     if ( field.Type && fieldTypeWriters[field.Type] ) {
       fieldTypeWriters[field.Type](pgn_number, field, value, bs)
     } else {
-      if ( _.isString(value) ) {
+      if ( _.isString(value) && bitLength !== 0 ) {
         value = Number(value)
       }
 

diff --git a/test/pgns/126208.js b/test/pgns/126208.js
@@ -1,4 +1,4 @@
 module.exports = [{
-  "expected": {"timestamp":"2017-04-15T14:57:58.471Z","prio":3,"src":204,"dst":172,"pgn":126208,"description":"NMEA - Request group function","fields":{"Function Code":"Request","PGN":126720,"# of Parameters":4,"list":[{"Parameter":1,"Value":1851},{"Parameter":3,"Value":4},{"Parameter":4,"Value":1372},{"Parameter":15}]}},
-  "input": "2017-04-15T14:57:58.471Z,3,126208,204,172,21,00,00,ef,01,ff,ff,ff,ff,ff,ff,04,01,3b,07,03,04,04,5c,05,0f,ff"
+  "expected": {"prio":2,"pgn":126208,"dst":67,"src":0,"timestamp":"2020-04-19T00:35:55.571Z","fields":{"Function Code":"Command","PGN":126998,"# of Parameters":1,"list":[{"Parameter":2,"Value":"YD:VOLUME 60"}]},"description":"NMEA - Command group function"},
+  "input": "2020-04-19T00:35:55.571Z,2,126208,0,67,21,01,16,f0,01,ff,01,02,0e,01,59,44,3a,56,4f,4c,55,4d,45,20,36,30"
 }]