Path: csiph.com!usenet.pasdenom.info!aioe.org!.POSTED!not-for-mail
From: "Rod Pemberton" <dont_use_email@xnohavenotit.cnm>
Newsgroups: comp.lang.forth
Subject: Re: suggestions for word names?
Date: Fri, 14 Feb 2014 20:44:22 -0500
Organization: Aioe.org NNTP Server
Lines: 44
Message-ID: <op.xbau38lc5zc71u@localhost>
References: <ldlthk$bga$1@speranza.aioe.org>
NNTP-Posting-Host: CNsg4fVcCsvs3UaOgZtQCw.user.speranza.aioe.org
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii; format=flowed; delsp=yes
Content-Transfer-Encoding: 7bit
X-Complaints-To: abuse@aioe.org
User-Agent: Opera Mail/12.16 (Linux)
X-Notice: Filtered by postfilter v. 0.8.2
Xref: csiph.com comp.lang.forth:28444

On Fri, 14 Feb 2014 15:15:48 -0500, Marcos Cruz  
<null_email_so_use_my_contact_page@programandala.net> wrote:

>
> I'm using the following two pieces of code in several words of mine:
>
>   2>r dup dup 2r>  ( x1 x2 x3 -- x1 x1 x1 x2 x3 )
>
>   >r dup dup r>  ( x1 x2 -- x1 x1 x1 x2 )
>
> Each of them is used in two or three words (customized versions of 'of',
> e.g.  'within-of', 'greater-of', etc.), and the list is expected to
> grow, so they are good candidates for factoring.
>
> Does anybody know any words (common usage or provided by any Forth
> system or library), that do the same than those code pieces?
>

I don't know what they'd be called, but you might be able
to improve that code slightly.

For the fist sequence "2>r dup dup 2r>", the 2>r
and 2r> are likely to be very expensive operations
timewise.  That sequence is also equivalent to this:

   >r nup nup r>

Even though nup isn't likely to be very efficient either,
eliminating 2>r and 2r> is likely to speed things up.

The second sequence ">r dup dup r>" is:

   nup nup

It's not likely that "nup nup" outperforms
">r dup dup r>" for your Forth, but it might.
This depends on how efficiently nup is implemented
as compared to how efficiently >r and r> are and how
much call overhead per Forth word there is.

   nup ( x1 x2 -- x1 x1 x2 )


Rod Pemberton