[M3devel] cm3: what are *.mc files

[Jay]

No guarantees on any of this imho. Nor the extension. The files are usually temporary. What are the magic bytes for .c? What is the purpose here? We could add 4 ignored bytes or even a guid but it'd be a waste.

 - Jay

On Jun 12, 2015, at 7:51 AM, Elmar Stellnberger <estellnb at elstel.org> wrote:

> 
> Thanks a lot Rodney and Jay;
> that will certainly help my implementation.
> 
> So far all *.mc files found on my machine have the
> following signature:
> 16_FD,00,01,{00}
> 
> except a few text - .mc from PM3 which start
> alltogether with "begin_unit". 
> 
> Rodney, do you believe that I can rely on the 4th byte
> to be zero as generated by the Modula-3 middle end. -
> or would anyone be ready to uphold such a guarantee
> for the future?
> 
> Anyone here who has applied "od" on an .mc generated
> by a very recent compiler? - do they start with
> 16_FD,10,01,?00?
> 
> Most binary file types would guarantee a header of at
> least 4 Byte and it should be more straight forward and
> secure to check 32bit instead of 24bit if possible.
> 
> Any suggestions?
> 
> 
> Am 10.06.15 um 02:21 schrieb Rodney M. Bates:
>> 
>> 
>> On 06/09/2015 03:02 PM, Elmar Stellnberger wrote: 
>>> What are *.mc - files? 
>>> They appear in TARGET - directories; 
>>> most of them are just called _m3main.mc but some of them have other names. 
>>> 
>>> I ask because I am writing a program which should recognize and clear object files. 
>>> It does not seem to be sufficient to check for uppercase directories which are located together with an src directory. 
>>> 
>>> Usually files of a specific type start with a 32bit magic; 
>>> however the mc files all have different starting sequences. 
>>> 
>>> Is there still a straight forward way to recognize an .mc file just by its binary content?
>> 
>> They will start with either 16_FD 16_00 16_01, produced by older versions of cm3, 
>>                          or 16_FD 16_10 16_01, produced by a very recent head compiler. 
>> Ignore the 4th byte.
> 
> 
> Am 09.06.15 um 22:14 schrieb Jay K:
>> ps:
>> 
>>   foo.m3 => foo.mc => cm3cg => foo.ms => as => foo.mo 
>>   foo.i3 => foo.ic => cm3cg => foo.is => as => foo.io 
>> 
>>  again, see cm3 -keep, err better yet, cm3 -keep -verbose
>>  You can see it running cm3cg and as and rm.
>> 
>> 
>>  - Jay
> 
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