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Index > Compiler Internals > Optimisation directive

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CandyMan



Joined: 04 Sep 2009
Posts: 314
Location: film "CandyMan" directed through Bernard Rose OR Candy Shop
CandyMan
Tomasz, maybe add to fasm optimisation directive that allows to generate jumps into first 64KB of the code.
For example:
use32
"jmp/jcc destination" <- will be converted automatically to -> "jmp/jcc WORD destination" when it is possible
In unreal version of fasm it saves about 3KB space.
By analogy with addressing:
"mov al,[source]" <- will be converted automatically to -> "mov al,[WORD source]" when it is possible

Thanks.
Post 16 Nov 2011, 22:36
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revolution
When all else fails, read the source


Joined: 24 Aug 2004
Posts: 17450
Location: In your JS exploiting you and your system
revolution
You can do this sort of thing with macros:
Code:
macro jmp dest {
      local .x
    virtual
             jmp near dest
               load .x dword from $-4
      end virtual
 if .x >= 0xffffff80 | .x <= 0x0000007f
                jmp short dest
      else if dest and not 0xffff = 0
             jmp word dest
       else
                jmp dest
    end if
}
use32

org 0
jmp 0
jmp 128
jmp 150
jmp 0xffff
jmp 0x1000f

org 0x10000
jmp 0
jmp 128
jmp 150
jmp 0xffff
jmp 0x1000f    
Post 16 Nov 2011, 23:17
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CandyMan



Joined: 04 Sep 2009
Posts: 314
Location: film "CandyMan" directed through Bernard Rose OR Candy Shop
CandyMan
This macro is in conflict with far jmp
Post 17 Nov 2011, 15:26
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revolution
When all else fails, read the source


Joined: 24 Aug 2004
Posts: 17450
Location: In your JS exploiting you and your system
revolution
The macro is just an example. You can extend to whatever your needs require.
Post 17 Nov 2011, 15:33
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