Path: utzoo!yunexus!ists!jarvis.csri.toronto.edu!mailrus!ames!amelia!eos!jbm
From: jbm@eos.UUCP (Jeffrey Mulligan)
Newsgroups: comp.lang.forth
Subject: Re: Forth Implementation (long)
Keywords: Forth implementation
Message-ID: <5599@eos.UUCP>
Date: 17 Nov 89 22:58:58 GMT
Article-I.D.: eos.5599
References: <5172@sdcc6.ucsd.edu>
Organization: NASA Ames Research Center, California
Lines: 34

ir230@sdcc6.ucsd.edu (john wavrik) writes:

Interesting posting...  but I found the following bits a little
inconsistent:

>Please note that the problem is to add the data type "long" in such a way that 
>it has the same status as built-in types. Treating a "long" as an array or a 
>"struct" and defining functions like long_add would not do!

later:

>Let's look at the task of defining a double-precision addition in Forth. Here 
>is the definition in F-83 due to Henry Laxen:
> 
>\ 32 bit Arithmetic Operations                    11OCT83HHL
>    CODE D+  (S d1 d2 -- dsum )                                     
>      AX POP   DX POP   BX POP   CX POP   CX DX ADD   BX AX ADC     
>      2PUSH END-CODE                                                

Isn't having a special word "D+" for adding doubles (instead of using "+")
equivalent in a sense to having a special function long_add?

You made a point in the C example of pointing out that the compiler
has to be able to add double precision to single precision integers;
Does this require yet another forth word, or do you have to do it
as a series of two operations, a type conversion followed by D+ ??



-- 

	Jeff Mulligan (jbm@aurora.arc.nasa.gov)
	NASA/Ames Research Ctr., Mail Stop 239-3, Moffet Field CA, 94035
	(415) 694-3745