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Index > Compiler Internals > Undocumented(?) preprocessor features

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gmg1812



Joined: 15 Aug 2014
Posts: 13
Location: Northern New York
gmg1812
There can be more than one symbol in a macro definition ending with [...] and initial values are permitted.
Code:
macro m [a=1,b] { db a,b }
 m ,2,3,4    

generates
Code:
  db 1,2
  db 3,4    

That is, the macro call parameters are handled in pairs with the first ref to "a" having an initial value. This is caused by the definition/call parameter matching process which restarts the definition parameter scan (within the []) until there are no more unprocessed macro call parameters. In this case, obviously the macro call must have an even number of parameters, and at least two.

Text (tokens) appearing after the "}" ending a macro/struc/rept/match/irp/irpv/irps block are considered to be on a new line. For example:
Code:
 rept 5 a {db a} mov eax,1    


I don't believe either action is documented.
Post 14 Sep 2015, 16:30
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l_inc



Joined: 23 Oct 2009
Posts: 881
l_inc
gmg1812
Do you really read the documentation? Everything you named is documented very well. There are undocumented features, but you didn't hit one yet.

As for the set of features you enumerated at the beginning, it's unclear what exactly you mean: grouping of arguments with square brackets, repetitive processing of the groups and default values are all documented in 2.3.3 Macroinstructions. You don't expect people to copy-paste here the whole section, do you? Processing of tokens after a closing brace is there as well:
2.3.3 Macroinstructions wrote:
there is one more feature which helps in such cases. Namely it is possible to put any directive, instruction or macroinstruction just after the } character that ends the macroinstruction and it will be processed in the same way as if it was put in the next line.


Quote:
In this case, obviously the macro call must have an even number of parameters, and at least two

It's not obvious and not true. A macro invocation can have any number of arguments unless there are mandatory arguments indicated by an asterisk. Well... And the number of the arguments cannot exceed the number of formal parameters for macros with no grouping. This is obvious indeed.

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Post 14 Sep 2015, 23:43
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