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Groups > comp.lang.forth > #30533 > unrolled thread

BEGIN with multiple AGAINs?

Started byDavid J <skamolex@gmail.com>
First post2014-05-21 13:44 -0700
Last post2014-06-28 14:00 -0700
Articles 20 on this page of 88 — 20 participants

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  BEGIN with multiple AGAINs? David J <skamolex@gmail.com> - 2014-05-21 13:44 -0700
    Re: BEGIN with multiple AGAINs? rickman <gnuarm@gmail.com> - 2014-05-21 17:11 -0400
    Re: BEGIN with multiple AGAINs? mhx@iae.nl - 2014-05-21 14:31 -0700
      Re: BEGIN with multiple AGAINs? mhx@iae.nl - 2014-05-21 15:07 -0700
    Re: BEGIN with multiple AGAINs? David J <skamolex@gmail.com> - 2014-05-21 14:51 -0700
    Re: BEGIN with multiple AGAINs? albert@spenarnc.xs4all.nl (Albert van der Horst) - 2014-05-21 21:59 +0000
    Re: BEGIN with multiple AGAINs? Gerry Jackson <gerry@jackson9000.fsnet.co.uk> - 2014-05-22 00:09 +0100
    Re: BEGIN with multiple AGAINs? David J <skamolex@gmail.com> - 2014-05-21 22:31 -0700
      Re: BEGIN with multiple AGAINs? rickman <gnuarm@gmail.com> - 2014-05-22 01:58 -0400
        Re: BEGIN with multiple AGAINs? David J <skamolex@gmail.com> - 2014-05-22 08:02 -0700
          Re: BEGIN with multiple AGAINs? rickman <gnuarm@gmail.com> - 2014-05-22 11:31 -0400
            Re: BEGIN with multiple AGAINs? David J <skamolex@gmail.com> - 2014-05-22 11:03 -0700
              Re: BEGIN with multiple AGAINs? forthisit@gmail.com - 2014-05-22 11:13 -0700
                Re: BEGIN with multiple AGAINs? forthisit@gmail.com - 2014-05-22 11:15 -0700
          Re: BEGIN with multiple AGAINs? forthisit@gmail.com - 2014-05-22 08:57 -0700
    Re: BEGIN with multiple AGAINs? anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2014-05-22 13:47 +0000
    Re: BEGIN with multiple AGAINs? David J <skamolex@gmail.com> - 2014-05-22 11:27 -0700
      Re: BEGIN with multiple AGAINs? David J <skamolex@gmail.com> - 2014-05-22 11:38 -0700
      Re: BEGIN with multiple AGAINs? rickman <gnuarm@gmail.com> - 2014-05-22 14:47 -0400
        Re: BEGIN with multiple AGAINs? David J <skamolex@gmail.com> - 2014-05-22 12:22 -0700
    Re: BEGIN with multiple AGAINs? Andrew Haley <andrew29@littlepinkcloud.invalid> - 2014-05-23 02:44 -0500
      Re: BEGIN with multiple AGAINs? David J <skamolex@gmail.com> - 2014-05-23 02:06 -0700
        Re: BEGIN with multiple AGAINs? rickman <gnuarm@gmail.com> - 2014-05-23 05:47 -0400
      Re: BEGIN with multiple AGAINs? "Elizabeth D. Rather" <erather@forth.com> - 2014-05-24 13:04 -1000
        Re: BEGIN with multiple AGAINs? Andrew Haley <andrew29@littlepinkcloud.invalid> - 2014-05-25 15:06 -0500
          Re: BEGIN with multiple AGAINs? "Elizabeth D. Rather" <erather@forth.com> - 2014-05-25 16:37 -1000
            Re: BEGIN with multiple AGAINs? rickman <gnuarm@gmail.com> - 2014-05-25 23:56 -0400
            Re: BEGIN with multiple AGAINs? Andrew Haley <andrew29@littlepinkcloud.invalid> - 2014-05-26 04:02 -0500
              Re: BEGIN with multiple AGAINs? "Elizabeth D. Rather" <erather@forth.com> - 2014-05-26 07:44 -1000
    Re: BEGIN with multiple AGAINs? "Clyde W. Phillips Jr." <cwpjr02@gmail.com> - 2014-05-23 12:39 -0700
    Re: BEGIN with multiple AGAINs? "Clyde W. Phillips Jr." <cwpjr02@gmail.com> - 2014-05-23 16:49 -0700
      Re: BEGIN with multiple AGAINs? Coos Haak <chforth@hccnet.nl> - 2014-05-24 02:00 +0200
    Re: BEGIN with multiple AGAINs? "Clyde W. Phillips Jr." <cwpjr02@gmail.com> - 2014-05-23 17:00 -0700
    Re: BEGIN with multiple AGAINs? "Clyde W. Phillips Jr." <cwpjr02@gmail.com> - 2014-05-23 21:29 -0700
      Re: BEGIN with multiple AGAINs? David J <skamolex@gmail.com> - 2014-05-24 08:10 -0700
        Re: BEGIN with multiple AGAINs? "Clyde W. Phillips Jr." <cwpjr02@gmail.com> - 2014-05-24 13:55 -0700
          Re: BEGIN with multiple AGAINs? rickman <gnuarm@gmail.com> - 2014-05-24 18:41 -0400
    Re: BEGIN with multiple AGAINs? Bee <forth@calcentral.com> - 2014-05-24 17:09 -0700
      Re: BEGIN with multiple AGAINs? "Clyde W. Phillips Jr." <cwpjr02@gmail.com> - 2014-05-24 18:05 -0700
        Re: BEGIN with multiple AGAINs? "Clyde W. Phillips Jr." <cwpjr02@gmail.com> - 2014-05-24 18:09 -0700
          Re: BEGIN with multiple AGAINs? ForthFreak <forthfreak@gmail.com> - 2014-05-25 02:03 -0700
            Re: BEGIN with multiple AGAINs? rickman <gnuarm@gmail.com> - 2014-05-25 05:18 -0400
              Re: BEGIN with multiple AGAINs? ForthFreak <forthfreak@gmail.com> - 2014-05-25 03:01 -0700
                Re: BEGIN with multiple AGAINs? David J <skamolex@gmail.com> - 2014-05-25 14:10 -0700
                  Re: BEGIN with multiple AGAINs? "Clyde W. Phillips Jr." <cwpjr02@gmail.com> - 2014-05-25 15:19 -0700
    Re: BEGIN with multiple AGAINs? Bee <forth@calcentral.com> - 2014-05-25 10:13 -0700
      Re: BEGIN with multiple AGAINs? David J <skamolex@gmail.com> - 2014-05-25 15:22 -0700
        Re: BEGIN with multiple AGAINs? BruceMcF <agila61@netscape.net> - 2014-06-12 13:11 -0700
          Re: BEGIN with multiple AGAINs? David J <skamolex@gmail.com> - 2014-06-12 19:06 -0700
    Re: BEGIN with multiple AGAINs? BruceMcF <agila61@netscape.net> - 2014-06-12 12:36 -0700
      Re: BEGIN with multiple AGAINs? BruceMcF <agila61@netscape.net> - 2014-06-12 19:50 -0700
        Re: BEGIN with multiple AGAINs? rickman <gnuarm@gmail.com> - 2014-06-13 01:02 -0400
          Re: BEGIN with multiple AGAINs? "Rod Pemberton" <dont_use_email@xnothavet.cqm> - 2014-06-13 04:16 -0400
            Re: BEGIN with multiple AGAINs? rickman <gnuarm@gmail.com> - 2014-06-13 05:22 -0400
              Re: BEGIN with multiple AGAINs? "Rod Pemberton" <dont_use_email@xnothavet.cqm> - 2014-06-14 00:33 -0400
                Re: BEGIN with multiple AGAINs? rickman <gnuarm@gmail.com> - 2014-06-14 01:15 -0400
                Re: BEGIN with multiple AGAINs? bruce.mcfarling@gmail.com - 2014-06-13 23:45 -0700
                  Re: BEGIN with multiple AGAINs? bruce.mcfarling@gmail.com - 2014-06-14 00:00 -0700
            Re: BEGIN with multiple AGAINs? rickman <gnuarm@gmail.com> - 2014-06-13 05:26 -0400
              Re: BEGIN with multiple AGAINs? "Rod Pemberton" <dont_use_email@xnothavet.cqm> - 2014-06-14 00:32 -0400
            Re: BEGIN with multiple AGAINs? "Alex McDonald" <blog@rivadpm.com> - 2014-06-13 12:27 +0100
              Re: BEGIN with multiple AGAINs? "Rod Pemberton" <dont_use_email@xnothavet.cqm> - 2014-06-14 00:35 -0400
                Re: BEGIN with multiple AGAINs? rickman <gnuarm@gmail.com> - 2014-06-14 01:22 -0400
                  Re: BEGIN with multiple AGAINs? "Rod Pemberton" <dont_use_email@xnothavet.cqm> - 2014-06-15 08:23 -0400
                    Re: BEGIN with multiple AGAINs? BruceMcF <agila61@netscape.net> - 2014-06-15 11:57 -0700
                    Re: BEGIN with multiple AGAINs? "Elizabeth D. Rather" <erather@forth.com> - 2014-06-15 09:13 -1000
                Re: BEGIN with multiple AGAINs? Andrew Haley <andrew29@littlepinkcloud.invalid> - 2014-06-14 04:32 -0500
                  Re: BEGIN with multiple AGAINs? "Rod Pemberton" <dont_use_email@xnothavet.cqm> - 2014-06-15 08:23 -0400
                    Re: BEGIN with multiple AGAINs? "Alex McDonald" <blog@rivadpm.com> - 2014-06-15 19:20 +0100
                Re: BEGIN with multiple AGAINs? "Alex McDonald" <blog@rivadpm.com> - 2014-06-14 23:19 +0100
                  Re: BEGIN with multiple AGAINs? "Rod Pemberton" <dont_use_email@xnothavet.cqm> - 2014-06-15 08:36 -0400
                    Re: BEGIN with multiple AGAINs? "Alex McDonald" <blog@rivadpm.com> - 2014-06-15 19:18 +0100
                      Re: BEGIN with multiple AGAINs? "Rod Pemberton" <dont_use_email@xnothavet.cqm> - 2014-06-26 18:34 -0400
                        Re: BEGIN with multiple AGAINs? bruce.mcfarling@gmail.com - 2014-06-26 16:04 -0700
                    Re: BEGIN with multiple AGAINs? albert@spenarnc.xs4all.nl (Albert van der Horst) - 2014-06-15 19:27 +0000
                Re: BEGIN with multiple AGAINs? Mark Wills <markwills1970@gmail.com> - 2014-06-16 01:45 -0700
            Re: BEGIN with multiple AGAINs? BruceMcF <agila61@netscape.net> - 2014-06-13 09:14 -0700
              Re: BEGIN with multiple AGAINs? november.nihal@gmail.com - 2014-06-13 09:44 -0700
              Re: BEGIN with multiple AGAINs? "Rod Pemberton" <dont_use_email@xnothavet.cqm> - 2014-06-14 00:32 -0400
                Re: BEGIN with multiple AGAINs? bruce.mcfarling@gmail.com - 2014-06-13 23:25 -0700
          Re: BEGIN with multiple AGAINs? Andrew Haley <andrew29@littlepinkcloud.invalid> - 2014-06-13 03:13 -0500
          Re: BEGIN with multiple AGAINs? BruceMcF <agila61@netscape.net> - 2014-06-13 08:38 -0700
            Re: BEGIN with multiple AGAINs? rickman <gnuarm@gmail.com> - 2014-06-13 13:29 -0400
              Re: BEGIN with multiple AGAINs? BruceMcF <agila61@netscape.net> - 2014-06-13 11:49 -0700
                Re: BEGIN with multiple AGAINs? "Rod Pemberton" <dont_use_email@xnothavet.cqm> - 2014-06-14 00:41 -0400
                  Re: BEGIN with multiple AGAINs? Elizabeth D Rather <erather@forth.com> - 2014-06-13 19:08 -1000
        Re: BEGIN with multiple AGAINs? Gerry Jackson <gerry@jackson9000.fsnet.co.uk> - 2014-06-13 21:27 +0100
    Re: BEGIN with multiple AGAINs? BruceMcF <agila61@netscape.net> - 2014-06-28 14:00 -0700

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#30682

FromForthFreak <forthfreak@gmail.com>
Date2014-05-25 02:03 -0700
Message-ID<b312bcb3-4958-44a4-84e9-6c1841e98240@googlegroups.com>
In reply to#30660
Clyde's reply on 24 May seems to be the closest solution to the OP's question, however, the OP wanted to start processing the list of words from the BEGINNING again when an exit/exception condition was detected.

A small addition to Clyde's solution provides that exact behaviour:

: ?EXIT ( f -- ) IF R> DROP THEN ;

: DoMe1rst ( -- f )
        CR ." A" CR
        0 ( -- f = CONTINUE ) ;

: DoMe2nd ( -- f )
        CR ." B" CR
        1 ( -- f = STOP HERE ) ;

: DoMe3rd ( -- f )
        CR ." C" CR
         0 ( -- f = CONTINUE ) ;

: TS
        BEGIN
        DoMe1rst ?EXIT
        DoMe2nd  ?EXIT ( SHOULD PRINT A and B and not C )
        DoMe3rd        ( unless you use AGAIN )
                ( The flag is handled by until here! )
        UNTIL
; 

: FOREVER
	BEGIN
		TS
	AGAIN ;
	

(continually displays A B A B A B A B etc...)

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#30683

Fromrickman <gnuarm@gmail.com>
Date2014-05-25 05:18 -0400
Message-ID<llscge$kkt$1@dont-email.me>
In reply to#30682
On 5/25/2014 5:03 AM, ForthFreak wrote:
> Clyde's reply on 24 May seems to be the closest solution to the OP's question, however, the OP wanted to start processing the list of words from the BEGINNING again when an exit/exception condition was detected.
>
> A small addition to Clyde's solution provides that exact behaviour:
>
> : ?EXIT ( f -- ) IF R> DROP THEN ;
>
> : DoMe1rst ( -- f )
>          CR ." A" CR
>          0 ( -- f = CONTINUE ) ;
>
> : DoMe2nd ( -- f )
>          CR ." B" CR
>          1 ( -- f = STOP HERE ) ;
>
> : DoMe3rd ( -- f )
>          CR ." C" CR
>           0 ( -- f = CONTINUE ) ;
>
> : TS
>          BEGIN
>          DoMe1rst ?EXIT
>          DoMe2nd  ?EXIT ( SHOULD PRINT A and B and not C )
>          DoMe3rd        ( unless you use AGAIN )
>                  ( The flag is handled by until here! )
>          UNTIL
> ;
>
> : FOREVER
> 	BEGIN
> 		TS
> 	AGAIN ;
> 	
>
> (continually displays A B A B A B A B etc...)

Except it has unneeded code.  The BEGIN UNTIL of the TS word is not 
needed.  Just include ?EXIT or DROP after DoMe3rd and omit the loop 
inside TS.  Or was this intended to be an optimization of some sort?

-- 

Rick

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#30684

FromForthFreak <forthfreak@gmail.com>
Date2014-05-25 03:01 -0700
Message-ID<b5f8d5c5-70c2-4a9c-b72d-0ef6baed1409@googlegroups.com>
In reply to#30683
Ah, yes, of course. Thanks Rick.

Corrected/improved:

: ?EXIT ( f -- ) IF R> DROP THEN ;

: DoMe1rst ( -- f )
         CR ." A" CR
         0 ( -- f = CONTINUE ) ;

: DoMe2nd ( -- f )
         CR ." B" CR
         1 ( -- f = STOP HERE ) ;

: DoMe3rd ( -- f )
         CR ." C" CR
          0 ( -- f = CONTINUE ) ;

: TS
         DoMe1rst ?EXIT
         DoMe2nd  ?EXIT ( SHOULD PRINT A and B and not C )
         DoMe3rd  ?EXIT ( or DROP)
;

: FOREVER
        BEGIN
                TS
        AGAIN ;

(tested on my Forth 83 system. Works fine)

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#30718

FromDavid J <skamolex@gmail.com>
Date2014-05-25 14:10 -0700
Message-ID<28f870ac-ede7-4571-8172-81ec87ca98fe@googlegroups.com>
In reply to#30684
On Sunday, May 25, 2014 4:01:45 AM UTC-6, ForthFreak wrote:
> Ah, yes, of course. Thanks Rick.
> 
> 
> 
> Corrected/improved:
> 
> 
> 
> : ?EXIT ( f -- ) IF R> DROP THEN ;
> 
> 
> 
> : DoMe1rst ( -- f )
> 
>          CR ." A" CR
> 
>          0 ( -- f = CONTINUE ) ;
> 
> 
> 
> : DoMe2nd ( -- f )
> 
>          CR ." B" CR
> 
>          1 ( -- f = STOP HERE ) ;
> 
> 
> 
> : DoMe3rd ( -- f )
> 
>          CR ." C" CR
> 
>           0 ( -- f = CONTINUE ) ;
> 
> 
> 
> : TS
> 
>          DoMe1rst ?EXIT
> 
>          DoMe2nd  ?EXIT ( SHOULD PRINT A and B and not C )
> 
>          DoMe3rd  ?EXIT ( or DROP)
> 
> ;
> 
> 
> 
> : FOREVER
> 
>         BEGIN
> 
>                 TS
> 
>         AGAIN ;
> 
> 
> 
> (tested on my Forth 83 system. Works fine)

Thank you FF, Rick, Clyde, and all!  This is exactly what was/is needed.  The embedded controller is expected to loop (or repeat or whatever-term-is-appropriate-and-unambiguous) 24/7 for the next 15 years.  And ForthFreak is right...processing of the list has to return to the BEGINNING whenever one of the words in the list reports an exception.

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#30719

From"Clyde W. Phillips Jr." <cwpjr02@gmail.com>
Date2014-05-25 15:19 -0700
Message-ID<b799dcee-d4ae-4252-85eb-4fc1aa174a67@googlegroups.com>
In reply to#30718
Thanks you all!

Cheers, Clyde

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#30696

FromBee <forth@calcentral.com>
Date2014-05-25 10:13 -0700
Message-ID<5553d59a-af39-4534-8e5b-c8bb904bad32@googlegroups.com>
In reply to#30533
On 5/22/2014 1:31 AM, David J wrote:
(I'd love to use Rick's first idea,
for example, but there is no EXIT.)

What version of Forth is it?
What is the threading mechanism?
+ indirect, direct, subroutine, bit-threaded
Does it have a word spelled 'SEMI'?
What is the action of ';' ?


On Sunday, May 25, 2014 3:01:45 AM UTC-7, ForthFreak wrote:
> Ah, yes, of course. Thanks Rick.
> Corrected/improved:
> : ?EXIT ( f -- ) IF R> DROP THEN ;

Using  R> DROP  like this is implementation dependent
(it will NOT work on some implementations)
and therefor should NOT be used.

The following now tested with gForth and SwiftForth on Linux.

\ .......1.........2.........3.........4.........5.........6....

: DoMe1 ( -- f ) ." a"  0 ( -- f = continue ) ;
: DoMe2 ( -- f ) ." b"  1 ( -- f = stop here ) ;
: DoMe3 ( -- f ) ." c"  0 ( -- f = continue ) ;

create taskList ( -- a )
  ' DoMe1 ,
  ' DoMe2 ,
  ' DoMe3 ,
  ( more tasks )
here
  ' taskList , ( non-zero dummy )
here swap -    ( calculate cell size )
constant cell ( -- u )

0 [if] ( runtime version )

: taskLoop ( a -- )
  cell - dup        ( a a )
  begin
    begin cell +    ( next in task list )
      dup @ execute ( a a f )
    until drop dup  ( restart task list )
  again ;

[else] ( test version )

: taskLoop ( a -- )
  cell - dup        ( a a )
  begin
    begin cell +    ( next in task list )
      dup @ execute ( a a f )
    until drop dup  ( restart task list )
    space           ( mark restart list )
    key [char] q =  ( pace output )
  until 2drop ;

[then]

taskList taskLoop ( start task loop )

\ .......1.........2.........3.........4.........5.........6....

Bill

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#30720

FromDavid J <skamolex@gmail.com>
Date2014-05-25 15:22 -0700
Message-ID<badc15a0-cba1-4762-9701-f4e4d0a797f3@googlegroups.com>
In reply to#30696
On Sunday, May 25, 2014 11:13:41 AM UTC-6, Bee wrote:
> On 5/22/2014 1:31 AM, David J wrote:
> 
> (I'd love to use Rick's first idea,
> 
> for example, but there is no EXIT.)
> 
> 
> 
> What version of Forth is it?
> 
> What is the threading mechanism?
> 
> + indirect, direct, subroutine, bit-threaded
> 
> Does it have a word spelled 'SEMI'?
>

Bill, it's an embedded Forth that is resident in a memory-constrained microcontroller.  Therefore the selection of words to include had to be carefully considered.  As a consequence, it has no native SEMI or EXIT.  And while cross-platform compatibility is a worthy goal, this particular project is so specialized, and coupled so tightly to the hardware on which it runs, that compatibility is probably one of the less important design criteria.

As for indirect, direct, subroutine, or bit-threaded, I don't know.  I know the core words are implemented in assembly language for speed.

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#31462

FromBruceMcF <agila61@netscape.net>
Date2014-06-12 13:11 -0700
Message-ID<29abb6bc-9f8c-414e-84e1-19dea80ef6a6@googlegroups.com>
In reply to#30720
On Sunday, May 25, 2014 6:22:31 PM UTC-4, David J wrote: 
> As for indirect, direct, subroutine, or bit-threaded, I don't know.  I know the core words are implemented in assembly language for speed.

The key issue is whether it uses the R stack as the actual return stack, how the return address is stored, and whether the top of stack is the instruction pointer ~ in a common classical FORTH implementation, EXIT can be provided with:

: exit1 R> DROP ;

With returns two cells wide, its:

: exit2 2R> 2DROP ;

If the R is not the hardware return stack, your out of luck. But you can try EXIT2 with a word that is nested two deep, and if it exits two levels, you probably have a classical single-cell return value on stack.

: test-level3 ( index -- index- ) exit2 2+ ;
: test-level2 ( index -- index ) test-level3 1+ ;

: exit-test
   CR CR ." --------------------------"
   0 test-level2
   DUP 0= IF
      DROP CR ." Classic Forth R stack as return stack."
   ELSE 1 = IF
         CR ." Classic Forth R stack with return values double in size."
      ELSE
         CR ." Does not look like a classical R as return stack."
      THEN
   THEN CR CR    CR CR ." --------------------------" CR CR ;

When I run that one gforth for Windows, it tests as a classic rack. The two results that test as something else are the "Does not look like" message or crashing or aborting the Forth compiler.

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#31467

FromDavid J <skamolex@gmail.com>
Date2014-06-12 19:06 -0700
Message-ID<3f8f52a4-6e15-4b92-87ea-8736fc8a355e@googlegroups.com>
In reply to#31462
On Thursday, June 12, 2014 2:11:51 PM UTC-6, BruceMcF wrote:
> On Sunday, May 25, 2014 6:22:31 PM UTC-4, David J wrote: 
> > As for indirect, direct, subroutine, or bit-threaded, I don't know.  I know the core words are implemented in assembly language for speed.
> 
> The key issue is whether it uses the R stack as the actual return stack, how the return address is stored, and whether the top of stack is the instruction pointer ~ in a common classical FORTH implementation, EXIT can be provided with:
> 
> : exit1 R> DROP ;

This solved the problem very well in FISH Forth.  The design is finished and installed.  It's been working 24/7 without the slightest glitch.  I'm delighted with the platform, language, and everything else.  Haven't had so much fun programming in a long time. :)

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#31461

FromBruceMcF <agila61@netscape.net>
Date2014-06-12 12:36 -0700
Message-ID<59197a5d-9e3b-47b1-bf85-d883081c21e0@googlegroups.com>
In reply to#30533
On Wednesday, May 21, 2014 4:44:45 PM UTC-4, David J wrote:
> Trying to think through Forth flow.  I have a situation where I need to call a succession of words, endlessly.  Each word returns a status (on the stack, of course).  This status is evaluated and either the next word in the list is called or else execution goes back to the BEGINning of the list.
> 
> 
> 
> So, can an AGAIN be used in each IF ELSE test? Or a REPEAT?  Or is there a better way to handle this in Forth?

Could you do it with a state machine? Say its four operations, and the status returns are all TRUE for go on to the next and FALSE to start over from the beginning. Then end the state machine with a FALSE and it will go back to the beginning even if all four succeed.

CREATE op-sequence ' op-a , ' op-b , ' op-c , ' op-d , ' FALSE ,

: run-machine ( a -- ) \ address of a structure with an op-sequence
   >R BEGIN
      R@ REPEAT DUP CELL+ SWAP @ EXECUTE 0= UNTIL DROP
   AGAIN ;

op-sequence run-machine

If you have CELL-COUNT that would be:

: run-machine ( a -- ) \ address of a structure with an op-sequence
   >R BEGIN
      R@ REPEAT CELL-COUNT EXECUTE 0= UNTIL DROP
   AGAIN ;

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#31468

FromBruceMcF <agila61@netscape.net>
Date2014-06-12 19:50 -0700
Message-ID<e65928d9-46d9-464f-b67c-ace0fc8918cb@googlegroups.com>
In reply to#31461
On Thursday, June 12, 2014 3:36:06 PM UTC-4, BruceMcF wrote:
> CREATE op-sequence ' op-a , ' op-b , ' op-c , ' op-d , ' FALSE ,

> : run-machine ( a -- ) \ address of a structure with an op-sequence
>    >R BEGIN
>       R@ REPEAT DUP CELL+ SWAP @ EXECUTE 0= UNTIL DROP
>    AGAIN ;

Sadly I wasn't drinking when I wrote that ... that is, of course:

: run-machine ( a -- ) \ address of a structure with an op-sequence
   >R BEGIN
      R@ BEGIN DUP CELL+ SWAP @ EXECUTE 0= UNTIL DROP
   AGAIN ;

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#31471

Fromrickman <gnuarm@gmail.com>
Date2014-06-13 01:02 -0400
Message-ID<lne0l5$dt8$1@dont-email.me>
In reply to#31468
On 6/12/2014 10:50 PM, BruceMcF wrote:
> On Thursday, June 12, 2014 3:36:06 PM UTC-4, BruceMcF wrote:
>> CREATE op-sequence ' op-a , ' op-b , ' op-c , ' op-d , ' FALSE ,
>
>> : run-machine ( a -- ) \ address of a structure with an op-sequence
>>     >R BEGIN
>>        R@ REPEAT DUP CELL+ SWAP @ EXECUTE 0= UNTIL DROP
>>     AGAIN ;
>
> Sadly I wasn't drinking when I wrote that ... that is, of course:
>
> : run-machine ( a -- ) \ address of a structure with an op-sequence
>     >R BEGIN
>        R@ BEGIN DUP CELL+ SWAP @ EXECUTE 0= UNTIL DROP
>     AGAIN ;

: run-list ( a -- ) \ address of a structure with an op-sequence
     BEGIN DUP @ EXECUTE WHILE CELL+ AGAIN DROP ;

: run-machine ( a -- ) \ address of a structure with an op-sequence
     >R BEGIN
        R@ run-list
     AGAIN ;

I'm just exploring my inner forth.  I don't like to have nested loops 
unless there is a need.  In this case it lets you test the list word 
without going into an infinite loop that requires a reset to exit.

I also think the dup cell+ swap is a bit wordy.  I believe these two 
code sequences are equivalent.  I'm assuming 0= UNTIL or WHILE is 
evaluating the value left by the call to EXECUTE.  Does the inner loop 
exit when reaching the end of the list?  I assume the list ends with an 
XT that calls a word which simply returns a TRUE?  That seems fairly 
expedient.

I don't feel like digging into the standard at the moment.  Is the XT 
guaranteed to be one cell in all machines or is this an environmental 
dependency?

-- 

Rick

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#31474

From"Rod Pemberton" <dont_use_email@xnothavet.cqm>
Date2014-06-13 04:16 -0400
Message-ID<op.xhdvw1ao6zenlw@localhost>
In reply to#31471
On Fri, 13 Jun 2014 01:02:40 -0400, rickman <gnuarm@gmail.com> wrote:
> On 6/12/2014 10:50 PM, BruceMcF wrote:
>> On Thursday, June 12, 2014 3:36:06 PM UTC-4, BruceMcF wrote:

>>> CREATE op-sequence ' op-a , ' op-b , ' op-c , ' op-d , ' FALSE ,
>>>
>>> : run-machine ( a -- ) \ address of a structure with an op-sequence
>>>     >R BEGIN
>>>        R@ REPEAT DUP CELL+ SWAP @ EXECUTE 0= UNTIL DROP
>>>     AGAIN ;
>>
>> Sadly I wasn't drinking when I wrote that ... that is, of course:
>>
>> : run-machine ( a -- ) \ address of a structure with an op-sequence
>>     >R BEGIN
>>        R@ BEGIN DUP CELL+ SWAP @ EXECUTE 0= UNTIL DROP
>>     AGAIN ;
>
> : run-list ( a -- ) \ address of a structure with an op-sequence
>      BEGIN DUP @ EXECUTE WHILE CELL+ AGAIN DROP ;
>

Isn't it time for a RECURSE LEAVE or EXIT ?
  (untested, probably bad coding style jumping out of an IF ...)

  DUP @ IF EXECUTE CELL+ RECURSE THEN ;

> I'm assuming 0= UNTIL or WHILE is evaluating the value left by the
> call to EXECUTE.  Does the inner loop exit when reaching the end of
> the list?

No, he was drunk.  He meant to test for FALSE after @ before the EXECUTE.


Rod Pemberton

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#31478

Fromrickman <gnuarm@gmail.com>
Date2014-06-13 05:22 -0400
Message-ID<lnefs1$tgk$1@dont-email.me>
In reply to#31474
On 6/13/2014 4:16 AM, Rod Pemberton wrote:
> On Fri, 13 Jun 2014 01:02:40 -0400, rickman <gnuarm@gmail.com> wrote:
>> On 6/12/2014 10:50 PM, BruceMcF wrote:
>>> On Thursday, June 12, 2014 3:36:06 PM UTC-4, BruceMcF wrote:
>
>>>> CREATE op-sequence ' op-a , ' op-b , ' op-c , ' op-d , ' FALSE ,
>>>>
>>>> : run-machine ( a -- ) \ address of a structure with an op-sequence
>>>>     >R BEGIN
>>>>        R@ REPEAT DUP CELL+ SWAP @ EXECUTE 0= UNTIL DROP
>>>>     AGAIN ;
>>>
>>> Sadly I wasn't drinking when I wrote that ... that is, of course:
>>>
>>> : run-machine ( a -- ) \ address of a structure with an op-sequence
>>>     >R BEGIN
>>>        R@ BEGIN DUP CELL+ SWAP @ EXECUTE 0= UNTIL DROP
>>>     AGAIN ;
>>
>> : run-list ( a -- ) \ address of a structure with an op-sequence
>>      BEGIN DUP @ EXECUTE WHILE CELL+ AGAIN DROP ;
>>
>
> Isn't it time for a RECURSE LEAVE or EXIT ?
>   (untested, probably bad coding style jumping out of an IF ...)
>
>   DUP @ IF EXECUTE CELL+ RECURSE THEN ;
>
>> I'm assuming 0= UNTIL or WHILE is evaluating the value left by the
>> call to EXECUTE.  Does the inner loop exit when reaching the end of
>> the list?
>
> No, he was drunk.  He meant to test for FALSE after @ before the EXECUTE.

So you think the list is null terminated?

-- 

Rick

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#31510

From"Rod Pemberton" <dont_use_email@xnothavet.cqm>
Date2014-06-14 00:33 -0400
Message-ID<op.xhff9tpi6zenlw@localhost>
In reply to#31478
On Fri, 13 Jun 2014 05:22:22 -0400, rickman <gnuarm@gmail.com> wrote:
> On 6/13/2014 4:16 AM, Rod Pemberton wrote:

>> He meant to test for FALSE after @ before the EXECUTE.
>
> So you think the list is null terminated?
>

I assumed that was his intent, yes.  Otherwise, the design is
somewhat ... backwards, don't you think?  What if you want to
use a normal word like SWAP or DUP as part of the op-sequence?
Isn't he is checking for a return code from an EXECUTEd word?
So, how do you do that?  Are you going to do the following
just to use DUP ? ...

: DUP DUP TRUE ;


Rod Pemberton

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#31516

Fromrickman <gnuarm@gmail.com>
Date2014-06-14 01:15 -0400
Message-ID<lnglos$678$1@dont-email.me>
In reply to#31510
On 6/14/2014 12:33 AM, Rod Pemberton wrote:
> On Fri, 13 Jun 2014 05:22:22 -0400, rickman <gnuarm@gmail.com> wrote:
>> On 6/13/2014 4:16 AM, Rod Pemberton wrote:
>
>>> He meant to test for FALSE after @ before the EXECUTE.
>>
>> So you think the list is null terminated?
>>
>
> I assumed that was his intent, yes.  Otherwise, the design is
> somewhat ... backwards, don't you think?  What if you want to
> use a normal word like SWAP or DUP as part of the op-sequence?
> Isn't he is checking for a return code from an EXECUTEd word?
> So, how do you do that?  Are you going to do the following
> just to use DUP ? ...
>
> : DUP DUP TRUE ;

No, I understand the intent now.  I'm sure he would not be using DUP in 
this list.  Each word used in his list is a word he wrote to use in the 
list and so it returns a status which is used to control the loop.

If you want to argue whether he should be writing such an app, I'll 
leave you to it.  It's his app and he can define his own needs.

-- 

Rick

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#31521

Frombruce.mcfarling@gmail.com
Date2014-06-13 23:45 -0700
Message-ID<9da78510-24fc-46f8-bcf8-379885fac4d8@googlegroups.com>
In reply to#31510
On Saturday, June 14, 2014 12:33:19 AM UTC-4, Rod Pemberton wrote:
> On Fri, 13 Jun 2014 05:22:22 -0400, rickman <gnuarm At Google's Mail dcom> wrote:
 
>> On 6/13/2014 4:16 AM, Rod Pemberton wrote:
>>> He meant to test for FALSE after @ before the EXECUTE.

>> So you think the list is null terminated?

> I assumed that was his intent, yes.  Otherwise, the design is
> somewhat ... backwards, don't you think?  What if you want to
> use a normal word like SWAP or DUP as part of the
> op-sequence?

We've already covered those use cases. If you want to do it because you are drunk, stop programming until sober. If you want to do it because you are too tired to think straight, stop programming until better rested.

The OP clearly specified a scenario in which four TASKS have to be performed in an endless loop, with each returning a status flag, and each running in order unless one failed, then it restarts at the beginning.

I pointed out one way to do it is with a state machine.

The notion that one of those tasks would be "SWAP" and another "DUP" is quite La La land stuff.

As set up, the status return for do not continue is 0 and for continue is anything non-zero. If error is more varied than success (as is often the case), then that could well be flipped, with 0 as success and some non-zero error code on failure.

CREATE op-sequence ' op-a , ' op-b , ' op-c , ' op-d , ' TRUE ,

: run-sequence ( a -- ) \ addr of an op sequence structure
   BEGIN DUP @ EXECUTE 0= WHILE CELL+ UNTIL DROP ;

: run-machine ( a -- ) \ addr of an op-sequence structure
   >R BEGIN R@ run-sequence AGAIN ;

op-sequence run-machine

A second way is to spread the state machine among the operations, with each operation built on a patten of  (assuming at this point that 0=success, non-zero=error, restart):

\ op-a ( fl1 -- fl2 ) 

: op-a ( fl1 -- fl2 ) \ Only proceed if fl1=0, return 0 on success
   0= IF FALSE EXIT THEN
   \ ... continue ...

Then its:

: op-sequence ( -- return ) \ ops automatically fall through on failure
   0 op-a op-b op-c op-d ;

: run-machine ( -- ) BEGIN op-sequence drop AGAIN ;

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#31522

Frombruce.mcfarling@gmail.com
Date2014-06-14 00:00 -0700
Message-ID<5edd8f5c-4626-4c64-aee2-fccf109b9eaa@googlegroups.com>
In reply to#31521
Of course,

: run-sequence ( a -- ) \ addr of an op sequence structure
   BEGIN DUP @ EXECUTE 0= WHILE CELL+ REPEAT DROP ;

... since, as the estimable Ms. Rather correctly infers, I've got gforth installed on the basement machine and I not going to run down two stories to test this code right now.
~~~~~~~~~~~~~

Debugging of what is going on is improved if each run returns the final result (0 success allows each process to have distinct failure returns, TRUE is the return for sequence success). With a TRUE xt terminated op-sequence structure:

: run-sequence ( a -- status ) \ addr of an op sequence structure
   BEGIN
      DUP @ EXECUTE DUP >R 0= WHILE
         CELL+ RDROP
   REPEAT DROP R> ;

: run-machine ( a -- ) >R BEGIN R@ run-sequence DROP AGAIN ;

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#31479

Fromrickman <gnuarm@gmail.com>
Date2014-06-13 05:26 -0400
Message-ID<lneg4s$vs0$1@dont-email.me>
In reply to#31474
On 6/13/2014 4:16 AM, Rod Pemberton wrote:
> On Fri, 13 Jun 2014 01:02:40 -0400, rickman <gnuarm@gmail.com> wrote:
>> On 6/12/2014 10:50 PM, BruceMcF wrote:
>>> On Thursday, June 12, 2014 3:36:06 PM UTC-4, BruceMcF wrote:
>
>>>> CREATE op-sequence ' op-a , ' op-b , ' op-c , ' op-d , ' FALSE ,
>>>>
>>>> : run-machine ( a -- ) \ address of a structure with an op-sequence
>>>>     >R BEGIN
>>>>        R@ REPEAT DUP CELL+ SWAP @ EXECUTE 0= UNTIL DROP
>>>>     AGAIN ;
>>>
>>> Sadly I wasn't drinking when I wrote that ... that is, of course:
>>>
>>> : run-machine ( a -- ) \ address of a structure with an op-sequence
>>>     >R BEGIN
>>>        R@ BEGIN DUP CELL+ SWAP @ EXECUTE 0= UNTIL DROP
>>>     AGAIN ;
>>
>> : run-list ( a -- ) \ address of a structure with an op-sequence
>>      BEGIN DUP @ EXECUTE WHILE CELL+ AGAIN DROP ;
>>
>
> Isn't it time for a RECURSE LEAVE or EXIT ?
>   (untested, probably bad coding style jumping out of an IF ...)
>
>   DUP @ IF EXECUTE CELL+ RECURSE THEN ;

BTW, isn't this going to execute the pointer into the list rather than 
the address in the list, also the IF consumes the XT and the EXECUTE 
consumes the address so the first time through the routine you get a 
stack underflow.

Perhaps you meant DUP @ DUP IF ...

-- 

Rick

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#31509

From"Rod Pemberton" <dont_use_email@xnothavet.cqm>
Date2014-06-14 00:32 -0400
Message-ID<op.xhff8w2o6zenlw@localhost>
In reply to#31479
On Fri, 13 Jun 2014 05:26:55 -0400, rickman <gnuarm@gmail.com> wrote:

> BTW, isn't this going to execute the pointer into the list rather than  
> the address in the list, also the IF consumes the XT and the EXECUTE  
> consumes the address so the first time through the routine you get a  
> stack underflow.
>
> Perhaps you meant DUP @ DUP IF ...
>

Perhaps.  I said it was untested.  I was sleepy too.

RP

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