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Index > Macroinstructions > Is it safe to change bit operators with C/MASM syntax?

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alorent



Joined: 05 Dec 2005
Posts: 201
alorent
Hello guys,

Is it safe (I mean, it won't introduce later issues) to create my own macros like:

Code:

!=   EQU  <>
!    EQU  ~
==   EQU  = 
&&   EQU  &
||   EQU  |
...
...

    


Well, I'm not sure if the above definitions are OK as it might cause double-replacing for "!=" when "!" is another macro.

Please, advice.

Thanks!!!
Post 10 Feb 2010, 11:19
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baldr



Joined: 19 Mar 2008
Posts: 1651
baldr
alorent,

ASCII punctuation is almost used up in FASM. AFAIK only !?@^_ can be used in constant names safely (single and double quotes can be used too, only not as a first character). Thus most of your equs won't compile.

For example, "!= equ <>" is the definition of numeric constant named "!" with [invalid numeric expression] value of "equ<>".
Post 10 Feb 2010, 12:51
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alorent



Joined: 05 Dec 2005
Posts: 201
alorent
Hi baldr,

Thanks for the explanation.

Isn't it possible to do it in another flavour? that is, without using EQUs.

Thanks!
Post 10 Feb 2010, 13:36
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baldr



Joined: 19 Mar 2008
Posts: 1651
baldr
alorent,

I highly doubt it. From my analysis of PREPROCE.INC:

Tokenizer disallows the following ASCII codes in symbols:
Code:
db 9,0Ah,0Dh,1Ah,20h,'+-/*=<>()[]{}:,|&~#`;\'    
Along with NUL these codes delimit symbols.
Single and double quotes handled separately.
Thus we have:
!$%.?@^_ and alphanumeric, plus control characters not mentioned above and 80…FF — first-class name characters;
' and " — can be used if not first character.

As you can see, there is not a much left to choose from.
Post 10 Feb 2010, 16:41
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revolution
When all else fails, read the source


Joined: 24 Aug 2004
Posts: 17714
Location: In your JS exploiting you and your system
revolution
Have you tried using 'fix'?
Post 10 Feb 2010, 17:12
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baldr



Joined: 19 Mar 2008
Posts: 1651
baldr
revolution,

fix won't help.
Tokenized != fix <> is symbol("!")=symbol("fix")<>
(by symbol("name") I denote structure that holds symbol name).

symbol("fix") should be second token of line to be recognized by preprocessor (and in our case second token is =).
Post 10 Feb 2010, 17:47
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Borsuc



Joined: 29 Dec 2005
Posts: 2466
Location: Bucharest, Romania
Borsuc
baldr wrote:
For example, "!= equ <>" is the definition of numeric constant named "!" with [invalid numeric expression] value of "equ<>".
equs are symbolic constants not numeric constants (numeric constants are defined with '=', like 'a = 5'). It is perfectly possible for it to hold '<>', however the problem here comes from the name. The equal sign is a reserved symbol, so it won't work.

But for example this:
Code:
neq equ <>    
is perfectly ok

_________________
Previously known as The_Grey_Beast
Post 10 Feb 2010, 18:04
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baldr



Joined: 19 Mar 2008
Posts: 1651
baldr
Borsuc,

I know what equ directive does, but FASM doesn't recognize "!= equ <>" as that directive. This line compiles as definition of numeric constant (and fails because "equ<>" does not compute).

OTOH, "! equ ~" defines symbolic constant "!" with value of "~" just fine.
Post 10 Feb 2010, 19:03
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Borsuc



Joined: 29 Dec 2005
Posts: 2466
Location: Bucharest, Romania
Borsuc
oh you're right, I didn't think about that. Clever Wink
Post 10 Feb 2010, 22:15
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