Mail Archives: geda-user/2014/08/12/18:57:25
On Aug 12, 2014, at 3:20 PM, Cirilo Bernardo wrote:
>
>
>
>
> ----- Original Message -----
>> From: Dave Curtis <davecurtis AT sonic DOT net>
>> To: geda-user AT delorie DOT com
>> Cc:
>> Sent: Wednesday, August 13, 2014 7:26 AM
>> Subject: Re: [geda-user] rs-274x nits
>>
>> On 08/12/2014 01:49 PM, Cirilo Bernardo wrote:
>>> ----- Original Message -----
>>>
>>>> From: Dave Curtis <davecurtis AT sonic DOT net>
>>>> To: geda-user AT delorie DOT com
>>>> Cc:
>>>> Sent: Wednesday, August 13, 2014 3:51 AM
>>>> Subject: [geda-user] rs-274x nits
>>>>
>>>> I'm trying to interpret the gerber format specification document
>>>> authored by Ucamco.
>>>>
>>>> 1. On page 35 it says:
>>>> The line separators CR and LF have no effect; they can be ignored when
>>>> processing the file. It
>>>> is recommended to use line separators to improve human readability.
>>>>
>>>> 2. On page 36 it says:
>>>> It is recommended to add line separators between data blocks for
>>>> readability. Do not
>>>> put a line separator within a data block, except after a comma
>> separator
>>>> in long data blocks.
>>>> The line separators have no effect on the image.
>>>>
>>>>
>>>> 3. on page 40, talking about closing parameter blocks it says:
>>>> The ‘%’ must immediately follow the ‘*’ of the last data block without
>>>> intervening line separators.
>>>> This is an exception to the general rule that a data block can be
>>>> followed by a line separator.
>>>>
>>>> #3 is clear enough.
>>>>
>>>> #1 and #2 seem to be in conflict. A strict reading of #1 would say
>> that
>>>> CR and LF should simply be expunged, and that CR/LF could even split
>>>> G-coded, numbers, etc., like this:
>>>> G
>>>> 03
>>>> X
>>>> 123
>>>> *
>>>> Which seems odd, but is a result of strict reading of #1. But is in
>>>> conflict with the advice of #2.
>>>>
>>>> It's easy enough to comply with the advice of #2 while writing.
>> But if
>>>> reading RS-274X, should CR/LF's that split lexical units be
>> ignored?
>>>> Although I realize that even if legal, I doubt if anyone writes gerber
>>>> that way.
>>>>
>>>> -dave
>>>>
>>>
>>> There is no conflict at all:
>>>
>>> 1. The CR/LF are optional; you do not need them but they are recommended
>>> to make the file look better to humans.
>>>
>>> 2. If you use CR/LF to make a data block look prettier, you can only use
>>> CR/LF after a comma.
>>
>> NO! That directly conflicts with #1 "CR and LF no effect." Which is
>> it?
>>
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>
> Well, as 2 of us have already said, it's both. If you look at #2 the
> specification does state that data blocks are an exception and that
> CR/LF are only allowed after a ',' within a data block. The specification
> is very clear that this is an exception, so why do you insist that it
> violates the other general rule?
>
Because if "CR and LF have no effect", then why the admonition against CR/LF against places after a comma? I suppose you could say that the operative word in placing CR/LF only after comma is *recommendation*, which would then by my reading allow CR/LF arbitrarily. Certainly it would make the file look like hash, but if the aim is a reader that accepts all correct RS-274X files, then these pedantic nits matter.
As you suggest, it is probably worth inconveniencing a few electrons by sending an e-mail to Ucamco. I'm not holding my breath about getting a reply, but I'd be happy to be wrong about that.
-dave
> - Cirilo
>
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