Fails to detect units if format spec combined with units spec

[davidworkman9]

By the looks of things Eagle (sometimes?) exports the units on the same line as the coordinate system line. Example:

%FSLAX43Y43*MOMM*%

In this case, the gerber parser does not pick up the units.

[mcous]

That's frustrating. According to the Gerber spec...

There can be only one extended code command between each pair of ‘%’ delimiters

...so this is invalid output from Eagle. Do you have any idea which version(s) of Eagle are doing this and/or how prevalent this is?

[davidworkman9]

I saw that too, definitely frustrating.

Looking at the file again I think I was wrong about it being from Eagle:

G04 File Origin:  Cadence Allegro 17.2-S049*

[thetroy]

Same issue, slightly different version of Cadence Allegro.

G04 File Origin:  Cadence Allegro 17.2-S032*
...
%FSLAX25Y25*MOMM*%

Spec is clear, this is wrong. I don't have info on which versions of Cadence Allegro do this.

To address, I believe the best fix would be to add code to the RE_FORMAT case in parse() detect the extra command. A design tool detecting test could also be added to the RE_COMMENT case. I can make the change but i'd like to confirm this approach make sense to you wonderful people first.

Thanks for making, and continuing to maintaining this parser!

[thetroy]

Would have had to store the detected design tool in the parser and doing so would expand the scope of my hack/patch. I opted to just detect the suffix. Need some design guidance if I'm going to refine + PR this.

// PATCH START -- PART 1 of 4
//
// Special Case: Cadence Allegro
// The gerber spec says
//   "There can be only one extended code command between each pair of ‘%’ delimiters"
// Cadence Allegro violates this rule by including the units after the format command
//
// Sample:
//   G04 File Origin:  Cadence Allegro 17.2-S032*
//   ...
//   %FSLAX25Y25*MOMM*%
//   ...
//
var RE_CADENCE_ALLEGRO_UNITS_IN_FORMAT = /\*MO(IN|MM)$/
// PATCH END

// PATCH START -- PART 2 of 4
var parseUnits = function(parser, unitsMatch) {
  var units = unitsMatch === 'IN' ? 'in' : 'mm'
  return parser._push(commands.set('units', units))
}
// PATCH END -- PART 2 of 4

...

  if (RE_UNITS.test(block)) {
    var unitsMatch = block.match(RE_UNITS)[1]
    // PATCH START -- PART 3 of 4
    return parseUnits(parser, unitsMatch);
    // PATCH END -- PART 3 of 4
  }
...
  if (RE_FORMAT.test(block)) {
...
    if (RE_CADENCE_ALLEGRO_UNITS_IN_FORMAT.test(block)) {
      var unitsMatch = block.match(RE_CADENCE_ALLEGRO_UNITS_IN_FORMAT)[1]
      console.log('matched hack', unitsMatch);
      return parseUnits(parser, unitsMatch);
    }
...
  }