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Groups > comp.lang.forth > #39358

Re: unexpected +LOOP behavior

From rickman <gnuarm@gmail.com>
Newsgroups comp.lang.forth
Subject Re: unexpected +LOOP behavior
Date 2015-05-27 12:03 -0400
Organization A noiseless patient Spider
Message-ID <mk4pr1$dem$1@dont-email.me> (permalink)
References (1 earlier) <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> <2015May27.111505@mips.complang.tuwien.ac.at>

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On 5/27/2015 5:15 AM, Anton Ertl wrote:
> Hans Bezemer <the.beez.speaks@gmail.com> writes:
>> 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.
>
> This is Forth, and in Forth it's the same data type.  And a
> straight-line piece of code is preferable to a piece of code for the
> same task that contains an IF (as someone posted elsewhere): You can
> test the straight-line code against stack errors with just one test
> case (if it does not contain variable-stack-effect words like ?DUP).
>
> What is not so great in this piece of code is the unexplained "7".
> One can fix this with
>
> : >char ( u -- c )
>    dup 9 > 'A' '0' 10 + - and + '0' + ;
>
> Or, for Forth systems that don't do constant folding in the compiler:
>
> : >char ( u -- c )
>    dup 9 > [ 'A' '0' 10 + - ] literal and + '0' + ;
>
> It may be easier to comprehend the purpose of the > ... AND + when
> rearranged as follows:
>
> : >char ( u -- c )
>    '0' + dup '9' > [ 'A' '0' 10 + - ] literal and + ;
>
> For cases where AND alone is not sufficient, Gforth contains the
> following word in the development version:
>
> select ( u1 u2 f -- u )	   gforth
> ""select @i{u1} if @i{f} is true, @i{u2} if false.""
>
> With that you can write >CHAR as follows:
>
> : >char ( u -- c )
>    dup '0' [ 'A' 10 - ] literal rot 9 > select + ;

How about...

\ Convert n to ASCII char - constant 7 spans gap between ASCII 9 and A
: >CHAR ( n -- char ) DUP 9 > 7 AND + ASCII 0 + ;

BTW, I haven't seen the character notation 'A' before.  Is that done in 
number?  I take it this is not part of the ANS standard?

-- 

Rick

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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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