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Index > Macroinstructions > how to use macro in structure initialization?

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zhak



Joined: 12 Apr 2005
Posts: 490
Location: Belarus
zhak
Hi guys.

Lets say I have a macro which pads fixed string with spaces:
Code:
macro padded_str len, text {
    local length
    length = $
    db text
    length = $-length
    db len-length dup (0x20)
}
    


and I have a structure, which holds this string:
Code:
struct my_struct
    string rb 32
ends
    


when I try to initialize the structure in source,
Code:
s my_struct padded_str 32, sz_some_text
    

it fails with 'invalid macro arguments' error

how to do it right? thanks
Post 09 May 2013, 15:18
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revolution
When all else fails, read the source


Joined: 24 Aug 2004
Posts: 17667
Location: In your JS exploiting you and your system
revolution
Macros and strucs are the same thing except for the label usage:
Code:
struc padded_str len, text {
    local length
    length = $
    db text
    length = $-length
    db len-length dup (0x20)
}

s padded_str 32, sz_some_text    
Post 09 May 2013, 23:24
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baldr



Joined: 19 Mar 2008
Posts: 1651
baldr
Because struc requires label to precede its invocation, it could be shortened to
Code:
struc padded_str len*, pad=' ', [text*] {
common
  . db text
    db .+len-$ dup pad
}

s padded_str 32,, sz_some_text    
sz_some_text looks somewhat strange, even if it is symbolic constant (I mean sz prefix, WRT 0x20 padding). Wink
Post 11 May 2013, 19:01
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zhak



Joined: 12 Apr 2005
Posts: 490
Location: Belarus
zhak
I use this prefix (sz) to address null-terminated strings. like some sort of an acronym to String,Zero. But in this example, with padding, looks strange, I agree Smile
Post 12 May 2013, 00:41
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