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NNTP-Posting-Date: Sat, 27 Oct 2012 10:03:10 -0500
From: Chris Hinsley <chris.hinsley@gmail.com>
Newsgroups: comp.lang.forth
Date: Sat, 27 Oct 2012 16:03:10 +0100
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On 2012-10-27 14:59:48 +0000, Chris Hinsley said:

> 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

I might also add that my 0BRANCH word is:

	defword "0BRANCH", 0, WORD_ZBRANCH, WORD_INLINE_COMMA
	mov eax, ebx
	POPDSP ebx
	test eax, eax
	jz strict near i_jmp
	ret
	defword_end

Regards

Chris