Re: revisiting a prgramming problem

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From	"Alex McDonald" <blog@rivadpm.com>
Newsgroups	comp.lang.forth
Subject	Re: revisiting a prgramming problem
Date	Thu, 23 Oct 2014 20:02:05 +0100
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on 23/10/2014 19:21:12, "Alex McDonald" wrote:
> on 23/10/2014 15:46:13,  wrote:
>> In article <7xoat37r0s.fsf@ruckus.brouhaha.com>,
>> Paul Rubin  <no.email@nospam.invalid> wrote:
>>>Gerry Jackson <spam@qlikz.org> writes:
>>>>> MAX of course wraps a conditional
>>>> 'Of course'? In practice you are almost certainly correct but MAX (and
>>>> MIN) can be implemented in ANS Forth without an IF...
>>>> : max 2dup < 1+ pick nip nip ;
>>>
>>>How do you think < works?
>>
>> Typical code for 32 bits Pentium (from yourforth):
>>
>> header  _less_,   _less_+5*cw, 0, 0, lastlink, "<"
>> pop     edx
>> pop     ebx
>> xor     eax,eax
>> cmp     ebx,edx
>> setl    al       ; Set bit to "less"
>> neg     eax
>> push    eax
>> next
>>
>> Groetjes Albert
> 
> This requires only 2 registers & 5 instructions. It may be faster.
> 
> pop     ebx
> or      eax, -1
> cmp     [esp], ebx
> mov     [esp], 0
> cmovl   [esp], eax

Sorry, due to a cut/paste/modify of code where the target operand of the
CMOVL was cached in a register, the above is wrong. CMOVxx can't take a
target memory operand. It should be

                pop     ebx
                or      eax, -1
                xor     ecx, ecx
                cmp     [esp], ebx
                cmovl   ecx, eax
                mov     [esp], ecx

which is a much less interesting 3 registers and 6 instructions.

Thread

revisiting a prgramming problem gavino_himself <visploveslisp@gmail.com> - 2014-10-14 15:55 -0700
  Re: revisiting a prgramming problem hughaguilar96@yahoo.com - 2014-10-14 18:52 -0700
    Re: revisiting a prgramming problem Hans Bezemer <the.beez.speaks@gmail.com> - 2014-10-21 17:58 +0200
      Re: revisiting a prgramming problem Paul Rubin <no.email@nospam.invalid> - 2014-10-21 09:09 -0700
        Re: revisiting a prgramming problem Hans Bezemer <the.beez.speaks@gmail.com> - 2014-10-21 22:18 +0200
          Re: revisiting a prgramming problem rickman <gnuarm@gmail.com> - 2014-10-23 15:44 -0400
            Re: revisiting a prgramming problem "Rod Pemberton" <buzzoff@nonamewhichexists.cmm> - 2014-10-23 17:01 -0400
            Re: revisiting a prgramming problem the_gavino_himself <visphatesjava@gmail.com> - 2014-11-08 21:33 -0800
              Re: revisiting a prgramming problem rickman <gnuarm@gmail.com> - 2014-11-29 20:40 -0500
                Re: revisiting a prgramming problem the_gavino_himself <visphatesjava@gmail.com> - 2014-12-01 22:43 -0800
                Re: revisiting a prgramming problem rickman <gnuarm@gmail.com> - 2014-12-02 02:47 -0500
                Re: revisiting a prgramming problem Paul E Bennett <Paul_E.Bennett@topmail.co.uk> - 2014-12-02 11:53 +0000
                Re: revisiting a prgramming problem the_gavino_himself <visphatesjava@gmail.com> - 2014-12-02 05:23 -0800
                Re: revisiting a prgramming problem rickman <gnuarm@gmail.com> - 2014-12-02 09:01 -0500
        Re: revisiting a prgramming problem Hans Bezemer <the.beez.speaks@gmail.com> - 2014-10-21 22:25 +0200
          Re: revisiting a prgramming problem Paul Rubin <no.email@nospam.invalid> - 2014-10-21 16:10 -0700
            Re: revisiting a prgramming problem the_gavino_himself <visphatesjava@gmail.com> - 2014-11-08 21:41 -0800
        Re: revisiting a prgramming problem Hans Bezemer <the.beez.speaks@gmail.com> - 2014-10-21 22:30 +0200
          Re: revisiting a prgramming problem the_gavino_himself <visphatesjava@gmail.com> - 2014-12-01 22:45 -0800
        Re: revisiting a prgramming problem Hans Bezemer <the.beez.speaks@gmail.com> - 2014-10-21 23:04 +0200
      Re: revisiting a prgramming problem Mark Wills <markwills1970@gmail.com> - 2014-10-21 10:17 -0700
        Re: revisiting a prgramming problem "Rod Pemberton" <buzzoff@nonamewhichexists.cmm> - 2014-10-22 02:13 -0400
          Re: revisiting a prgramming problem Paul Rubin <no.email@nospam.invalid> - 2014-10-21 23:26 -0700
            Re: revisiting a prgramming problem "Alex McDonald" <blog@rivadpm.com> - 2014-10-22 16:18 +0100
              Re: revisiting a prgramming problem mhx@iae.nl (Marcel Hendrix) - 2014-10-22 21:27 +0200
                Re: revisiting a prgramming problem albert@spenarnc.xs4all.nl (Albert van der Horst) - 2014-10-24 10:30 +0000
                Optimal comparisons for m maximums from n items  (was Re: revisiting a prgramming problem) "Alex McDonald" <blog@rivadpm.com> - 2014-10-24 16:29 +0100
                Re: Optimal comparisons for m maximums from n items  (was Re: revisiting a prgramming problem) albert@spenarnc.xs4all.nl (Albert van der Horst) - 2014-10-25 08:27 +0000
                Re: Optimal comparisons for m maximums from n items (was Re: revisiting a prgramming problem) "Alex McDonald" <blog@rivadpm.com> - 2014-10-25 18:54 +0100
                Re: revisiting a prgramming problem mhx@iae.nl (Marcel Hendrix) - 2014-10-25 13:28 +0200
                Re: revisiting a prgramming problem mhx@iae.nl (Marcel Hendrix) - 2014-10-25 14:28 +0200
                Re: revisiting a prgramming problem mhx@iae.nl (Marcel Hendrix) - 2014-10-25 15:17 +0200
            Re: revisiting a prgramming problem Gerry Jackson <spam@qlikz.org> - 2014-10-22 21:57 +0100
              Re: revisiting a prgramming problem Paul Rubin <no.email@nospam.invalid> - 2014-10-22 14:06 -0700
                Re: revisiting a prgramming problem Bernd Paysan <bernd.paysan@gmx.de> - 2014-10-23 00:03 +0200
                Re: revisiting a prgramming problem albert@spenarnc.xs4all.nl (Albert van der Horst) - 2014-10-23 14:46 +0000
                Re: revisiting a prgramming problem Paul Rubin <no.email@nospam.invalid> - 2014-10-23 08:16 -0700
                Re: revisiting a prgramming problem "Alex McDonald" <blog@rivadpm.com> - 2014-10-23 19:21 +0100
                Re: revisiting a prgramming problem "Alex McDonald" <blog@rivadpm.com> - 2014-10-23 20:02 +0100
                Re: revisiting a prgramming problem albert@spenarnc.xs4all.nl (Albert van der Horst) - 2014-10-23 20:29 +0000
                Re: revisiting a prgramming problem Coos Haak <chforth@hccnet.nl> - 2014-10-23 22:23 +0200
              Re: revisiting a prgramming problem awegel@arcor.de (Alexander Wegel) - 2014-10-23 00:36 +0200
                Re: revisiting a prgramming problem Gerry Jackson <gerry@jackson9000.fsnet.co.uk> - 2014-10-24 10:44 +0100
              Re: revisiting a prgramming problem hughaguilar96@yahoo.com - 2014-10-22 17:26 -0700
                Re: revisiting a prgramming problem Michael Barry <barrym95838@yahoo.com> - 2014-10-23 00:02 -0700
          Re: revisiting a prgramming problem the_gavino_himself <visphatesjava@gmail.com> - 2014-11-08 23:10 -0800
        Re: revisiting a prgramming problem the_gavino_himself <visphatesjava@gmail.com> - 2014-11-08 21:42 -0800
  Re: revisiting a prgramming problem Roger Levy <roger.levy@gmail.com> - 2014-10-15 08:18 -0700
    Re: revisiting a prgramming problem Roger Levy <roger.levy@gmail.com> - 2014-10-15 08:18 -0700
      Re: revisiting a prgramming problem november.nihal@gmail.com - 2014-10-15 08:57 -0700
      Re: revisiting a prgramming problem Gerry Jackson <gerry@jackson9000.fsnet.co.uk> - 2014-10-15 17:10 +0100
      Re: revisiting a prgramming problem "Rod Pemberton" <buzzoff@nonamewhichexists.cmm> - 2014-10-17 21:53 -0400
    Re: revisiting a prgramming problem Roger Levy <roger.levy@gmail.com> - 2014-10-15 08:19 -0700
  Re: revisiting a prgramming problem awegel@arcor.de (Alexander Wegel) - 2014-10-22 00:30 +0200
    Re: revisiting a prgramming problem hughaguilar96@yahoo.com - 2014-10-21 16:07 -0700
      Re: revisiting a prgramming problem awegel@arcor.de (Alexander Wegel) - 2014-10-22 03:23 +0200
        Re: revisiting a prgramming problem "Rod Pemberton" <buzzoff@nonamewhichexists.cmm> - 2014-10-22 02:15 -0400
          Re: revisiting a prgramming problem awegel@arcor.de (Alexander Wegel) - 2014-10-22 12:52 +0200
        Re: revisiting a prgramming problem hughaguilar96@yahoo.com - 2014-10-22 17:19 -0700
          Re: revisiting a prgramming problem awegel@arcor.de (Alexander Wegel) - 2014-10-23 16:10 +0200
      Re: revisiting a prgramming problem "Rod Pemberton" <buzzoff@nonamewhichexists.cmm> - 2014-10-22 02:14 -0400
      Re: revisiting a prgramming problem the_gavino_himself <visphatesjava@gmail.com> - 2014-11-08 23:21 -0800
      Re: revisiting a prgramming problem "WJ" <w_a_x_man@yahoo.com> - 2014-12-06 02:34 +0000
      Re: revisiting a prgramming problem "WJ" <w_a_x_man@yahoo.com> - 2014-12-27 08:00 +0000
        Re: revisiting a prgramming problem Mark Wills <markwills1970@gmail.com> - 2014-12-27 05:15 -0800
  Re: revisiting a prgramming problem "WJ" <w_a_x_man@yahoo.com> - 2014-11-29 17:20 +0000
    Re: revisiting a prgramming problem the_gavino_himself <visphatesjava@gmail.com> - 2014-11-29 12:00 -0800
    Re: revisiting a prgramming problem "WJ" <w_a_x_man@yahoo.com> - 2014-12-02 16:15 +0000
  Re: revisiting a prgramming problem Paul Sephton <prsephton@gmail.com> - 2014-12-02 05:06 -0800
    Re: revisiting a prgramming problem Paul Sephton <prsephton@gmail.com> - 2014-12-02 05:14 -0800
    Re: revisiting a prgramming problem the_gavino_himself <visphatesjava@gmail.com> - 2014-12-02 05:24 -0800

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