sigfox-parser's Introduction

sigfox-parser

Sigfox data format parser

Usage

Parse a message

require('sigfox-parser')(<messagebytes>, <formatstring>);

messagebytes: The bytes of the message encoded in a hexadecimal String.

formatstring: A formatstring according to the Sigfox documentation.

Example

var parsed = require('sigfox-parser')('C01234','b1::bool:7 b2::bool:6 i1:1:uint:16');

The variable parsed now contains:

{
  b1: true,
  b2: true,
  i1: 0x1234
}

Parse the syntax

var parser = require('sigfox-parser')

var fields = parser.parseFields('lightAmbi::uint:16 temperature:2:int:8')

console.log(fields)
/**
[ { name: 'lightAmbi',
    offset: '',
    type: 'uint',
    length: '16',
    endianness: 'big-endian' },
  { name: 'temperature',
    offset: '2',
    type: 'int',
    length: '8',
    endianness: 'big-endian' } ]
**/

Formatstring

A formatstring consists of multiple fields. A field is defined by its name, its position in the message bytes, its length and its type :

the field name is an identifier including letters, digits and the '-' and '_' characters.
the byte index is the offset in the message buffer where the field is to be read from, starting at zero. If omitted, the position used is the current byte for boolean fields and the next byte for all other types. For the first field, an omitted position means zero (start of the message buffer)
Next comes the type name and parameters, which varies depending on the type :
boolean : parameter is the bit position in the target byte
char : parameter is the number of bytes to gather in a string
float : parameters are the length in bits of the value, which can be either 32 or 64 bits, and optionally the endianness for multi-bytes floats. Default is big endian. Decoding is done according to the IEEE 754 standard.
uint (unsigned integer) : parameters are the number of bits to include in the value, and optionally the endianness for multi-bytes integers. Default is big endian.
int (signed integer) : parameters are the number of bits to include in the value, and optionally the endianness for multi-bytes integers. Default is big endian.

(cfr. Sigfox documentation)

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sigfox-parser's Issues

readFloat tests

readFloat isn't being tested, we should write at least one test and aim for 100% CC.

https://coveralls.io/github/waylayio/sigfox-parser

Log the pattern that is tried in case sigfox parsing fails

We better throw an error like "Parsing sigfox message ${msg} using ${pattern} failed"

RangeError: index out of range
  File "buffer.js", line 613, in checkOffset
  File "buffer.js", line 637, in Buffer.readUIntBE
  File "/home/waylay/dashboard/node_modules/@waylay/sigfox-parser/readers/readUInt.js", line 5, in Object.readUInt
    return buffer.readUIntBE(offset, length / 8);
  File "[as uint] (/home/waylay/dashboard/node_modules/@waylay/sigfox-parser/node_modules/lodash/lodash.js", line 4606, in Object.wrapper
  File "/home/waylay/dashboard/node_modules/@waylay/sigfox-parser/index.js", line 38, in null.<anonymous>
    obj[fields[0]] = types[fields[2]](fields[1] || l, fields[3], fields[4]);
  File "/home/waylay/dashboard/node_modules/@waylay/sigfox-parser/node_modules/lodash/lodash.js", line 664, in arrayReduce
    accumulator = iteratee(accumulator, array[index], index, array);
  File "/home/waylay/dashboard/node_modules/@waylay/sigfox-parser/node_modules/lodash/lodash.js", line 8727, in Function.reduce
    return func(collection, getIteratee(iteratee, 4), accumulator, initAccum, baseEach);
  File "/home/waylay/dashboard/node_modules/@waylay/sigfox-parser/index.js", line 31, in parseMessage
    return _.reduce(format.split(' '), (obj, value) => {
  File "/home/waylay/dashboard/controllers/api/webhook/sigfox.js", line 18, in module.exports.Resource.find.then.devices