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From: zbigniew2011@gmail.com (LIT)
Newsgroups: comp.lang.forth
Subject: Re: Stack vs stackless operation
Date: Tue, 25 Feb 2025 07:04:26 +0000
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>> : +> ( addr1 addr2 addr3 -- )
>>  rot @ rot @ + swap ! ;
>>
>> Of course the above is just an illustration; I mean coding
>> such word directly in ML. It should be significantly
>> faster than going through stack usual way.
>
> A set of three addresses on the stack is messy even before
> one does anything with them.

Yep, but I meant the case of, for example:

var1 @ var2 @ + var3 !

The above isn't messy at all.

So IMHO by using such OOS (out-of-stack) operation - coded
directly in ML - we can replace the above by:

var1 var2 var3 +>

Or we can create increment-by-one operation (and its
counterpart):

var1 ++
var1 --

Or "multiply/divide by two a number of times":

var1 2 lshift ( multiply by 4 )

etc.

In case of slower ITC non-optimizing Forths - like
fig-Forth, as the most obvious example - the "boost"
may be noticeable.
I'll check that.

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