flat assembler
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Index > Compiler Internals > Smallest "code cannot be generated" example

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MCD



Joined: 21 Aug 2004
Posts: 604
Location: Germany
MCD
This thread should not contain some new information, it shall only (try to)
explain something related to the assembler.

The following code cannot be generated.
Code:
if ~SomeLabel
 db 0
end if

SomeLabel:
    

The assembler would hang if there were no passes_limit :<, and that's exactly
why Flat Assembler needs it!

This causes also problems in many other sciences.
(For example, an electronical amplifier with negative feedback will
oscillate, the good old "don't hold your mic to close to the speaker"
phenomen. It also occurs in the logistic growth model etc...)

Explanation for beginners: This is a classical negative feedback problem.
Fasm tries to resolve the address of SomeLabel, but this address also depends
on if SomeLabel has already been defined, but it won't succed since the
define byte instruction changes the address of SomeLabel.

_________________
MCD - the inevitable return of the Mad Computer Doggy

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Post 17 Jan 2005, 21:46
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beppe85



Joined: 23 Oct 2004
Posts: 181
beppe85
Maybe this is the defined's meaning of life.

Code:
if ~ defined SomeLabel
 db 0
end if

SomeLabel:    
Post 18 Jan 2005, 10:13
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