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Groups > comp.lang.forth > #39262

Re: unexpected +LOOP behavior

From Bernd Paysan <bernd.paysan@gmx.de>
Newsgroups comp.lang.forth
Subject Re: unexpected +LOOP behavior
Date 2015-05-25 02:21 +0200
Organization A noiseless patient Spider
Message-ID <mjtpra$6ji$1@dont-email.me> (permalink)
References <80773739-ddd7-4a06-9200-9d7145d0f492@googlegroups.com> <763a0671-2f81-4a26-aa7b-99aa856cfdcb@googlegroups.com> <5561b9b6$0$2868$e4fe514c@news2.news.xs4all.nl> <mjsnid$99v$2@dont-email.me> <55623fa0$0$2821$e4fe514c@news2.news.xs4all.nl>

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Hans Bezemer wrote:

> But why are some Forth programmers so keen on their “all bits set”
> flag? Well, you can do neat things with it.
> 
> : >CHAR DUP 9 > 7 AND + ASCII 0 + ;
> 
> This will convert a digit to its ASCII representation. True, it
> is a clever piece of programming, but in our opinion it is bad
> style. Why? Because you are using a flag as a bitmask, which is a
> completely different datatype. Although there is no such thing as
> “data typing” in Forth, this way of programming makes it
> difficult to understand and maintain a program, which the
> ANS-Forth standard acknowledges:

Honestly, this is only a problem if you don't know that idiom.  A lot of 
people don't know that you can use masks and logical operations, so they 
will find that operation strange.

I recall Andy Glew (who's one of the architects of the P6/Pentium II 
microarchitecture) telling a story that he proposed all-bit-set flags for 
MMX.  That's a SIMD instruction set, and creating several masks makes a lot 
of sense in that context.  His proposal was shelfed, because his boss did 
not understand the idiom of bit mask operations.  Andy was quite disappoined 
by that.

Later, in SSE, the proposal was revived, and we now have such bit mask flags 
in SSE.

Therefore, I would reiterate what I told Hugh some times: If you don't know 
something, it's *not* the fault of the person who uses and knows that thing.  
It's entirely your fault, and if you want to be a wise person, you'd rather 
learn it that complain.

IMHO the whole datatype based thinking about cells in Forth is ill-advised.  
First, and foremost, a cell is a bit pattern, and if you add and subtract 
it, it's a mod 2^n ring.  You can use that to some degrees as integer, but 
it's not an integer.  It's a cell.

-- 
Bernd Paysan
"If you want it done right, you have to do it yourself"
net2o ID: kQusJzA;7*?t=uy@X}1GWr!+0qqp_Cn176t4(dQ*
http://bernd-paysan.de/

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unexpected +LOOP behavior chitselb <chitselb@gmail.com> - 2015-05-23 19:27 -0700
  Re: unexpected +LOOP behavior hughaguilar96@gmail.com - 2015-05-23 20:27 -0700
    Re: unexpected +LOOP behavior Hans Bezemer <the.beez.speaks@gmail.com> - 2015-05-24 13:44 +0200
      Re: unexpected +LOOP behavior rickman <gnuarm@gmail.com> - 2015-05-24 10:36 -0400
        Re: unexpected +LOOP behavior Hans Bezemer <the.beez.speaks@gmail.com> - 2015-05-24 23:16 +0200
          Re: unexpected +LOOP behavior hughaguilar96@gmail.com - 2015-05-24 15:57 -0700
          Re: unexpected +LOOP behavior Bernd Paysan <bernd.paysan@gmx.de> - 2015-05-25 02:21 +0200
            Re: unexpected +LOOP behavior "Elizabeth D. Rather" <erather@forth.com> - 2015-05-24 15:21 -1000
              Re: unexpected +LOOP behavior hughaguilar96@gmail.com - 2015-05-24 19:49 -0700
            Re: unexpected +LOOP behavior hughaguilar96@gmail.com - 2015-05-24 18:22 -0700
            Re: unexpected +LOOP behavior "WJ" <w_a_x_man@yahoo.com> - 2015-05-26 17:20 +0000
              Re: unexpected +LOOP behavior rickman <gnuarm@gmail.com> - 2015-05-26 14:15 -0400
                Re: unexpected +LOOP behavior "Elizabeth D. Rather" <erather@forth.com> - 2015-05-26 08:37 -1000
                Re: unexpected +LOOP behavior rickman <gnuarm@gmail.com> - 2015-05-26 15:09 -0400
                Re: unexpected +LOOP behavior "Elizabeth D. Rather" <erather@forth.com> - 2015-05-26 09:19 -1000
                Re: unexpected +LOOP behavior rickman <gnuarm@gmail.com> - 2015-05-26 17:08 -0400
                Re: unexpected +LOOP behavior chitselb <chitselb@gmail.com> - 2015-05-26 15:42 -0700
                Re: unexpected +LOOP behavior rickman <gnuarm@gmail.com> - 2015-05-26 19:30 -0400
                Re: unexpected +LOOP behavior chitselb <chitselb@gmail.com> - 2015-05-26 17:45 -0700
                Re: unexpected +LOOP behavior rickman <gnuarm@gmail.com> - 2015-05-26 21:33 -0400
                Re: unexpected +LOOP behavior Coos Haak <chforth@hccnet.nl> - 2015-05-27 14:08 +0200
                Re: unexpected +LOOP behavior chitselb <chitselb@gmail.com> - 2015-05-27 06:32 -0700
                Re: unexpected +LOOP behavior Coos Haak <chforth@hccnet.nl> - 2015-05-27 16:15 +0200
                Re: unexpected +LOOP behavior "Elizabeth D. Rather" <erather@forth.com> - 2015-05-26 14:32 -1000
                Re: unexpected +LOOP behavior anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-05-27 08:30 +0000
                Re: unexpected +LOOP behavior rickman <gnuarm@gmail.com> - 2015-05-27 17:15 -0400
                Re: unexpected +LOOP behavior hughaguilar96@gmail.com - 2015-05-29 21:05 -0700
          Re: unexpected +LOOP behavior rickman <gnuarm@gmail.com> - 2015-05-25 01:41 -0400
            Re: unexpected +LOOP behavior Raimond Dragomir <raimond.dragomir@gmail.com> - 2015-05-24 23:26 -0700
              Re: unexpected +LOOP behavior anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-05-25 14:33 +0000
              Re: unexpected +LOOP behavior rickman <gnuarm@gmail.com> - 2015-05-25 10:56 -0400
                Re: unexpected +LOOP behavior Raimond Dragomir <raimond.dragomir@gmail.com> - 2015-05-25 11:28 -0700
                Re: unexpected +LOOP behavior rickman <gnuarm@gmail.com> - 2015-05-25 14:33 -0400
                Re: unexpected +LOOP behavior hughaguilar96@gmail.com - 2015-05-25 12:57 -0700
                Re: unexpected +LOOP behavior humptydumpty <ouatubi@gmail.com> - 2015-05-25 23:01 -0700
          Re: unexpected +LOOP behavior anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-05-25 14:21 +0000
          Re: unexpected +LOOP behavior albert@spenarnc.xs4all.nl (Albert van der Horst) - 2015-05-26 23:59 +0000
          Re: unexpected +LOOP behavior anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-05-27 09:15 +0000
            Re: unexpected +LOOP behavior anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-05-27 10:06 +0000
            Re: unexpected +LOOP behavior rickman <gnuarm@gmail.com> - 2015-05-27 12:03 -0400
              Re: unexpected +LOOP behavior anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-05-27 16:23 +0000
                Re: unexpected +LOOP behavior rickman <gnuarm@gmail.com> - 2015-05-27 12:39 -0400
            Re: unexpected +LOOP behavior Hans Bezemer <the.beez.speaks@gmail.com> - 2015-05-27 22:14 +0200
              Re: unexpected +LOOP behavior rickman <gnuarm@gmail.com> - 2015-05-27 17:13 -0400
                Re: unexpected +LOOP behavior Hans Bezemer <the.beez.speaks@gmail.com> - 2015-05-27 23:36 +0200
                Re: unexpected +LOOP behavior rickman <gnuarm@gmail.com> - 2015-05-27 18:06 -0400
                Re: unexpected +LOOP behavior Hans Bezemer <the.beez.speaks@gmail.com> - 2015-05-29 10:35 +0200
                Re: unexpected +LOOP behavior "Alex McDonald" <blog@rivadpm.com> - 2015-05-29 12:16 +0100
                Re: unexpected +LOOP behavior rickman <gnuarm@gmail.com> - 2015-05-29 09:42 -0400
                Re: unexpected +LOOP behavior Hans Bezemer <the.beez.speaks@gmail.com> - 2015-05-29 16:16 +0200
                Re: unexpected +LOOP behavior "Alex McDonald" <blog@rivadpm.com> - 2015-05-29 15:24 +0100
              Re: unexpected +LOOP behavior "Rod Pemberton" <fork@lllljunkqwer.cpm> - 2015-05-27 17:32 -0400
                Re: unexpected +LOOP behavior Coos Haak <chforth@hccnet.nl> - 2015-05-27 23:59 +0200
                Re: unexpected +LOOP behavior rickman <gnuarm@gmail.com> - 2015-05-27 19:31 -0400
                Re: unexpected +LOOP behavior Raimond Dragomir <raimond.dragomir@gmail.com> - 2015-05-27 23:11 -0700
              Re: unexpected +LOOP behavior "Alex McDonald" <blog@rivadpm.com> - 2015-05-28 12:21 +0100
                Re: unexpected +LOOP behavior "Alex McDonald" <blog@rivadpm.com> - 2015-05-28 12:24 +0100
                Re: unexpected +LOOP behavior Hans Bezemer <the.beez.speaks@gmail.com> - 2015-05-29 10:53 +0200
                Re: unexpected +LOOP behavior "Alex McDonald" <blog@rivadpm.com> - 2015-05-29 12:19 +0100
              Re: unexpected +LOOP behavior anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-05-29 13:51 +0000
                Re: unexpected +LOOP behavior Hans Bezemer <the.beez.speaks@gmail.com> - 2015-05-29 17:48 +0200
            Re: unexpected +LOOP behavior Bernd Paysan <bernd.paysan@gmx.de> - 2015-05-29 02:08 +0200
              Re: unexpected +LOOP behavior anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-05-29 08:25 +0000
                Re: unexpected +LOOP behavior "Alex McDonald" <blog@rivadpm.com> - 2015-05-29 12:40 +0100
                Re: unexpected +LOOP behavior anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-05-29 13:16 +0000
                Re: unexpected +LOOP behavior albert@spenarnc.xs4all.nl (Albert van der Horst) - 2015-05-29 18:43 +0000
                Re: unexpected +LOOP behavior "Alex McDonald" <blog@rivadpm.com> - 2015-05-29 20:08 +0100
                x86 tricks Lars Brinkhoff <lars.spam@nocrew.org> - 2015-06-05 09:42 +0200
                Re: x86 tricks albert@spenarnc.xs4all.nl (Albert van der Horst) - 2015-06-05 09:32 +0000
                Re: x86 tricks anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-06-05 09:40 +0000
                Re: x86 tricks albert@spenarnc.xs4all.nl (Albert van der Horst) - 2015-06-05 11:17 +0000
                Re: x86 tricks anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-06-05 15:49 +0000
                Re: x86 tricks "Alex McDonald" <blog@rivadpm.com> - 2015-06-05 17:45 +0100
                Re: x86 tricks anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-06-05 16:53 +0000
                Re: x86 tricks rickman <gnuarm@gmail.com> - 2015-06-07 13:20 -0400
                Re: x86 tricks anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-06-08 07:18 +0000
                Re: x86 tricks Bernd Paysan <bernd.paysan@gmx.de> - 2015-06-08 17:18 +0200
                Re: x86 tricks Tessa Bonting <tessa.bonting@gmail.com> - 2015-06-08 08:42 -0700
                Re: x86 tricks albert@spenarnc.xs4all.nl (Albert van der Horst) - 2015-06-06 09:47 +0000
                Re: x86 tricks anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-06-07 15:05 +0000
                Re: x86 tricks "Alex McDonald" <blog@rivadpm.com> - 2015-06-07 17:49 +0100
                Re: x86 tricks "Alex McDonald" <blog@rivadpm.com> - 2015-06-05 13:19 +0100
      Re: unexpected +LOOP behavior Mark Wills <markwills1970@gmail.com> - 2015-05-25 01:38 -0700
  Re: unexpected +LOOP behavior Michael Barry <barrym95838@yahoo.com> - 2015-05-23 21:33 -0700
    Re: unexpected +LOOP behavior hughaguilar96@gmail.com - 2015-05-23 22:10 -0700
      Re: unexpected +LOOP behavior chitselb <chitselb@gmail.com> - 2015-05-23 22:20 -0700
        Re: unexpected +LOOP behavior hughaguilar96@gmail.com - 2015-05-25 21:13 -0700
          Re: unexpected +LOOP behavior "Rod Pemberton" <fork@lllljunkqwer.cpm> - 2015-05-27 17:34 -0400
            Re: unexpected +LOOP behavior chitselb <chitselb@gmail.com> - 2015-05-27 22:04 -0700
              Re: unexpected +LOOP behavior rickman <gnuarm@gmail.com> - 2015-05-28 01:27 -0400
                Re: unexpected +LOOP behavior "Rod Pemberton" <fork@lllljunkqwer.cpm> - 2015-05-28 03:20 -0400
                Re: unexpected +LOOP behavior rickman <gnuarm@gmail.com> - 2015-05-28 04:13 -0400
                Re: unexpected +LOOP behavior "Rod Pemberton" <fork@lllljunkqwer.cpm> - 2015-05-29 04:23 -0400
                Re: unexpected +LOOP behavior rickman <gnuarm@gmail.com> - 2015-05-29 11:28 -0400
                Re: unexpected +LOOP behavior "Rod Pemberton" <fork@lllljunkqwer.cpm> - 2015-05-29 18:32 -0400
                Re: unexpected +LOOP behavior rickman <gnuarm@gmail.com> - 2015-05-29 18:53 -0400
      Re: unexpected +LOOP behavior Michael Barry <barrym95838@yahoo.com> - 2015-05-23 22:26 -0700
        Re: unexpected +LOOP behavior "Elizabeth D. Rather" <erather@forth.com> - 2015-05-23 21:37 -1000
          Re: unexpected +LOOP behavior hughaguilar96@gmail.com - 2015-05-24 10:24 -0700
            Re: unexpected +LOOP behavior "Rod Pemberton" <fork@lllljunkqwer.cpm> - 2015-05-24 20:40 -0400
            Re: unexpected +LOOP behavior Hans Bezemer <the.beez.speaks@gmail.com> - 2015-05-25 14:08 +0200
              Re: unexpected +LOOP behavior "Rod Pemberton" <fork@lllljunkqwer.cpm> - 2015-05-25 17:27 -0400
                Re: unexpected +LOOP behavior "Elizabeth D. Rather" <erather@forth.com> - 2015-05-25 14:47 -1000
                Re: unexpected +LOOP behavior "Rod Pemberton" <fork@lllljunkqwer.cpm> - 2015-05-27 17:33 -0400
            Re: unexpected +LOOP behavior Michael Barry <barrym95838@yahoo.com> - 2015-05-25 12:53 -0700
              Re: unexpected +LOOP behavior hughaguilar96@gmail.com - 2015-05-25 13:05 -0700
              Re: unexpected +LOOP behavior "Elizabeth D. Rather" <erather@forth.com> - 2015-05-25 14:49 -1000
                Re: unexpected +LOOP behavior Michael Barry <barrym95838@yahoo.com> - 2015-05-25 18:03 -0700
                Re: unexpected +LOOP behavior "Elizabeth D. Rather" <erather@forth.com> - 2015-05-25 16:44 -1000
                Re: unexpected +LOOP behavior humptydumpty <ouatubi@gmail.com> - 2015-05-25 22:56 -0700
                Re: unexpected +LOOP behavior anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-05-26 08:05 +0000
        Re: unexpected +LOOP behavior rickman <gnuarm@gmail.com> - 2015-05-24 10:43 -0400
          Re: unexpected +LOOP behavior Michael Barry <barrym95838@yahoo.com> - 2015-05-24 08:29 -0700
            Re: unexpected +LOOP behavior anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-05-24 15:44 +0000
              Re: unexpected +LOOP behavior Michael Barry <barrym95838@yahoo.com> - 2015-05-27 00:57 -0700
              Re: unexpected +LOOP behavior chitselb <chitselb@gmail.com> - 2015-06-05 13:11 -0700
                Re: unexpected +LOOP behavior "Elizabeth D. Rather" <erather@forth.com> - 2015-06-05 12:24 -1000
                Re: unexpected +LOOP behavior JennyB <jennybrien@googlemail.com> - 2015-06-06 13:29 -0700
                Re: unexpected +LOOP behavior anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-06-07 14:56 +0000
                Re: unexpected +LOOP behavior "Elizabeth D. Rather" <erather@forth.com> - 2015-06-07 10:38 -1000
                Re: unexpected +LOOP behavior anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-06-08 08:08 +0000
        Re: unexpected +LOOP behavior hughaguilar96@gmail.com - 2015-05-24 10:01 -0700
      Re: unexpected +LOOP behavior rickman <gnuarm@gmail.com> - 2015-05-24 10:40 -0400
        Re: unexpected +LOOP behavior hughaguilar96@gmail.com - 2015-05-24 11:29 -0700
          Re: unexpected +LOOP behavior "Alex McDonald" <blog@rivadpm.com> - 2015-05-25 09:51 -0700
            Re: unexpected +LOOP behavior hughaguilar96@gmail.com - 2015-05-25 10:44 -0700
              Re: unexpected +LOOP behavior "Alex McDonald" <blog@rivadpm.com> - 2015-05-25 12:34 -0700
                Re: unexpected +LOOP behavior hughaguilar96@gmail.com - 2015-05-25 12:59 -0700
  unexpected +LOOP behavior Mark Wills <markwills1970@gmail.com> - 2015-05-24 01:39 -0700
    Re: unexpected +LOOP behavior Coos Haak <chforth@hccnet.nl> - 2015-05-24 14:46 +0200
      Re: unexpected +LOOP behavior Mark Wills <markwills1970@gmail.com> - 2015-05-25 01:17 -0700
    Re: unexpected +LOOP behavior "Rod Pemberton" <fork@lllljunkqwer.cpm> - 2015-05-24 20:48 -0400
      Re: unexpected +LOOP behavior hughaguilar96@gmail.com - 2015-05-24 18:15 -0700
      Re: unexpected +LOOP behavior anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-05-25 12:35 +0000
        Re: unexpected +LOOP behavior "Rod Pemberton" <fork@lllljunkqwer.cpm> - 2015-05-25 17:27 -0400
          Re: unexpected +LOOP behavior rickman <gnuarm@gmail.com> - 2015-05-25 18:16 -0400
            Re: unexpected +LOOP behavior chitselb <chitselb@gmail.com> - 2015-05-25 16:17 -0700
              Re: unexpected +LOOP behavior chitselb <chitselb@gmail.com> - 2015-05-25 17:16 -0700
                Re: unexpected +LOOP behavior Michael Barry <barrym95838@yahoo.com> - 2015-05-25 17:50 -0700
                Re: unexpected +LOOP behavior chitselb <chitselb@gmail.com> - 2015-05-25 18:47 -0700
              Re: unexpected +LOOP behavior Michael Barry <barrym95838@yahoo.com> - 2015-05-25 20:01 -0700
                Re: unexpected +LOOP behavior chitselb <chitselb@gmail.com> - 2015-05-25 20:29 -0700
                Re: unexpected +LOOP behavior chitselb <chitselb@gmail.com> - 2015-05-25 20:32 -0700
              Re: unexpected +LOOP behavior anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-05-26 08:03 +0000
                Re: unexpected +LOOP behavior Mark Wills <markwills1970@gmail.com> - 2015-05-26 01:10 -0700
                Re: unexpected +LOOP behavior Michael Barry <barrym95838@yahoo.com> - 2015-05-26 22:31 -0700
                Re: unexpected +LOOP behavior Michael Barry <barrym95838@yahoo.com> - 2015-05-26 20:07 -0700
                Re: unexpected +LOOP behavior chitselb <chitselb@gmail.com> - 2015-05-26 20:20 -0700
                Re: unexpected +LOOP behavior Michael Barry <barrym95838@yahoo.com> - 2015-05-26 22:00 -0700
                Re: unexpected +LOOP behavior chitselb <chitselb@gmail.com> - 2015-05-27 02:41 -0700
  Re: unexpected +LOOP behavior anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-05-24 14:06 +0000

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