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Index > Compiler Internals > TCHAR as label

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ouadji



Joined: 24 Dec 2008
Posts: 1081
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ouadji
Code:
include 'win32a.inc'

TCHAR:

mov eax,[TCHAR] ;(A) ok, does compile

jmp TCHAR       ;(B) does not compile (invalid operand)
    
(A) does compile, but (B) does not compile ... I am surprised.
I can understand that the compiler does not allow both cases ...
but one and not the other, I don't understand.
Can anyone tell me why? Thank you in advance.


yes, I know that "TCHAR" is a macro.
It is precisely for this reason I am surprised that "A" does compile and not "B".


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Post 15 Nov 2011, 23:46
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revolution
When all else fails, read the source


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revolution
ouadji wrote:
yes, I know that "TCHAR" is a macro.
Therein lies the problem. TCHAR is not a macro, it is a structure.
Post 16 Nov 2011, 00:17
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ouadji



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ouadji
Code:
struc TCHAR [val] { common match any, val \{ . db val \}
                           match , val \{ . db ? \} }
    
Indeed revolution, "TCHAR" is a structure
sorry for this mistake.


that said, I think a "struc" is a "macro"

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Post 16 Nov 2011, 00:22
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revolution
When all else fails, read the source


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revolution
A structure is a different from a macro in that it requires a leading label, whereas a macro cannot have a leading label.
Code:
macro ABC {do something}
struc ABC {do something else}
;
       ABC ;macro instantiation
label1 ABC ;structure instantiation
;
jmp TCHAR ;TCHAR structure with "jmp" as the label    


Last edited by revolution on 16 Nov 2011, 01:03; edited 1 time in total
Post 16 Nov 2011, 00:52
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revolution
When all else fails, read the source


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revolution
BTW: Why you no look at the error messages? Mad
Code:
jmp TCHAR       ;(B) does not compile (invalid operand)
C:\Documents and Settings\We are the Borg\Our Documents\include/win32a.inc [12] TCHAR [1]:
                           match , val \{ . db ? \} }
C:\Documents and Settings\We are the Borg\Our Documents\include/win32a.inc [12] match [0]:
                           match , val \{ . db ? \} }
error: invalid operand.    
Post 16 Nov 2011, 00:56
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typedef



Joined: 25 Jul 2010
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typedef
Code:
jmp TCHAR
    

is the same as
Code:
jmp DWORD
    


LAUGH OUT LOUD x 2
Post 16 Nov 2011, 01:29
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ouadji



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ouadji

of course i look at the error messages.
What I didn't understand was that "A" does compile and "B" does not.
Now I understand why. Thank you revolution


typedef:
not "jmp dword", but "jmp byte" (a dword and a byte are two different things, do you know that ?) Wink


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Post 16 Nov 2011, 09:10
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revolution
When all else fails, read the source


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revolution
BTW: In case you are wondering how to do what you wanted:
Code:
jmp short TCHAR    
Although I would not really encourage using things like TCHAR as label names. It all gets very confusing when you do that.
Post 16 Nov 2011, 09:42
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ouadji



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ouadji
Quote:
Although I would not really encourage using things like TCHAR as label names.
It all gets very confusing when you do that.
Of course, it was just a theoretical reflection.
(in the context of wink improvement)


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Post 16 Nov 2011, 10:23
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typedef



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typedef
ouadji wrote:


typedef:
not "jmp dword", but "jmp byte" (a dword and a byte are two different things, do you know that ?) Wink



Ok, here's a better one maybe you have hard time with comparisons, or you just make quantitative judgements.

Code:
JMP [DATA_TYPE]
    


Clearly, "DATA_TYPE" is a compiler reserved keyword.

STILL, LAUGH OUT LOUD
Post 16 Nov 2011, 19:18
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revolution
When all else fails, read the source


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revolution
typedef wrote:
Clearly, "DATA_TYPE" is a compiler reserved keyword.
TCHAR is not a compiler reserved keyword. It is defined in win32a.inc as a structure. If you decide not to include win32a.inc then you are free to use TCHAR as you please for other things.
Post 16 Nov 2011, 19:28
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typedef



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typedef
revolution wrote:
typedef wrote:
Clearly, "DATA_TYPE" is a compiler reserved keyword.
TCHAR is not a compiler reserved keyword. It is defined in win32a.inc as a structure. If you decide not to include win32a.inc then you are free to use TCHAR as you please for other things.


But if you include win32a.inc, it becomes reserved doesn't it ?

LOL
Post 16 Nov 2011, 20:32
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revolution
When all else fails, read the source


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revolution
typedef wrote:
But if you include win32a.inc, it becomes reserved doesn't it ?
No. You can always make a label the same name as a macro or struc. Also you can use restruc to clear the structure at any time.
Post 16 Nov 2011, 21:14
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ouadji



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ouadji

if "TCHAR" is a compiler reserved word, "tchar" should be one too.
However, it's not the case.

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Post 16 Nov 2011, 21:51
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Tomasz Grysztar
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Tomasz Grysztar
TCHAR is not a reserved word. It gets defined in some Win32 macroinstructions, but since preprocessor in fasm is case-sensitive, you get "TCHAR" expanded as macro/struc, while "tchar" is not recognized as a macro (but you may as well define another macro called "tchar" which will get expanded in "tchar" places).
Post 20 Nov 2011, 01:04
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