Path: utzoo!utgpu!jarvis.csri.toronto.edu!clyde.concordia.ca!uunet!willett!ForthNet
From: ForthNet@willett.UUCP (ForthNet articles from GEnie)
Newsgroups: comp.lang.forth
Subject: Vocabularies
Message-ID: <629.UUL1.3#5129@willett.UUCP>
Date: 8 Mar 90 01:02:34 GMT
Organization: Latest link in the ForthNet chain.  (Pgh, PA)
Lines: 63

Category 3,  Topic 18
Message 3         Wed Mar 07, 1990
R.BERKEY [Robert]            at 01:07 PST
 
 
 Re: Interpretable numeral constants

Dennis Ruffer writes, 900306:

 > Re: PETE KOZIAR

 > > Here's today's trivial speed-up.  Three of the most-used
 > > constants are certainly -1, 0 and 1.  F83 defined them as CODE
 > > words, but F-PC does not.

 >  A warning is in order here.  polyFORTH defined 0 and 1 as constants
 > for years.  Recently, however, we implemented a way to revector the
 > number conversion and interpetation process.  Under this system, it
 > is occasionally neccessary for 0 and 1 to pass through the number
 > conversion process.  Then, defining numbers as constants can get you
 > into a lot of trouble. ...

I've had problems with interpretable numeral constants, too, using F-PC.  In
response, I've created a NUMERALS vocabulary that is searched by the number
compiler, during colon compilation.  Once or twice I've tried to ' (tic) a
numeral constant and forgotten for a moment that they weren't in the usual
search order, but that's the only problem I can recall having.

Most of work was going through the F-PC source code and changing the relevant
literals to base-insensitive syntax, i.e., 10 to #10 or $0A .  Then the
reverse occurred when 3.5 came out and I used file compares to find out what
was new, and each of those changes showed up as differences.

Here are the words now in the NUMERALS vocabulary:

>browser numerals these words

         --[ NUMERALS  ]--
 2,             1,             0,             #100           #60
 #10            1K             $200           $100           $0FF
 $80            $7F            $40            $30            $20
 $1F            $18            $10            $0F            $0A
 9              8              7              6              5
 4              3              2              1              0
 -1             -2

Here's a note from the file, CONSTANTS, which includes '0' and '~' along with
17 other ascii-value constants:
 \ 890902 Constants save $90 segments, i.e.,
 \ #2300 bytes, in the creation of FORTH.EXE

I asked Tom Zimmer about constants, and he asserted that in-line constants are
faster on an 8088.  I think it was Mark Smiley he cited as someone who had
encountered a problem with interpreting numerals defined as constants.

As for speed, I'm using an 80286, and use the push immediate opcode to define
constants.  This along with identifying 2CONSTANTs adds several tests to the
decompiler, as code fields are not as easy to interpret, but it all seems to
have worked out.

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