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NNTP-Posting-Date: Sat, 27 Oct 2012 09:59:48 -0500
From: Chris Hinsley <chris.hinsley@gmail.com>
Newsgroups: comp.lang.forth
Date: Sat, 27 Oct 2012 15:59:48 +0100
Message-ID: <2012102715594849117-chrishinsley@gmailcom>
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Subject: well formed flag ?
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Xref: csiph.com comp.lang.forth:16763

Folks, I'm doing some tweaking to my hobby Forth compiler and just been 
doing some inlineing work.

I'm not very happy about the size of the x86 code for comparision words 
(I know I could reduce the code size if I had a full optimizing code 
generator, but I don't yet…) this is my code for "<"

	defword ">", 0, WORD_GT, WORD_INLINE_COMMA
	POPDSP eax
	cmp eax, ebx
	setg bl
	movzx ebx, bl
	neg ebx
	ret
	defword_end

I followed the 'well formed flag' comments in Ms Rathers book for this, 
but the IF and TRUE, FALSE words only talk about 0 for false or not 
zero for true. Is it definately the case that Forth needs -1 to come 
from the comparason words ?

Are you allowed to write code that _needs_ the -1 from the ">" ? ie if 
it produce just a 1, would that be incorrect ?

Chris