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Re: How can " dup drop " be anything other than a nop

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Bob Armstrong <bob@cosy.com> writes:
>Rod and Anton , thanks for your feedback . It's hard to find the time to attack this problem .
>
>I've been trying to strip it down to the nub . Here's where I am .:
>
>: SF+ esi@ cell- SFptr xchg ;
> | puts previous esi on the stack and save current 
>	  
>reset  1  SF+ 0 SF+ $.s 
> (4) 1 427870 0 427868 
>reset  : stst SF+ 0 SF+ ; 1 stst $.s   | 0 could be any number . gets replaced
> (4) 1 427870 4 427868 
>
>reset  1  SF+ 0 0 SF+ $.s 
> (5) 1 427870 0 0 427868 
>reset  : stst SF+ 0 0 SF+ ; 1 stst $.s 
> (5) 1 427870 0 432078 427868 
>
>| as per Anton's important point :
> see SF+ 
>0062AD8C  E8 DB BE FF FF              call esi@
>0062AD91  8D 40 FC                    lea eax,[eax-04]
>0062AD94  8D 76 FC                    lea esi,[esi-04]
>0062AD97  89 06                       mov [esi],eax
>0062AD99  B8 5C AD 62 00              mov eax,0062AD5C
>0062AD9E  E9 91 0B FF FF              jmp xchg
> see esi@ 
>00626C6C  8D 76 FC                    lea esi,[esi-04]
>00626C6F  89 F0                       mov eax,esi
>00626C71  C3                          ret

It seems that you have TOS in eax and SP in esi.  ESI@ fails to store
the previous value of the TOS into memory, so whatever was there
previously remains there.  This could be the bug you are after.

As for the font, yes, a fixed-width font is a good idea for
programming newsgroups.

- anton
-- 
M. Anton Ertl  http://www.complang.tuwien.ac.at/anton/home.html
comp.lang.forth FAQs: http://www.complang.tuwien.ac.at/forth/faq/toc.html
     New standard: http://www.forth200x.org/forth200x.html
   EuroForth 2015: http://www.rigwit.co.uk/EuroForth2015/

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How can  " dup drop " be anything other than a nop Bob Armstrong <bob@cosy.com> - 2015-09-30 19:20 -0700
  Re: How can  " dup drop " be anything other than a nop "Rod Pemberton" <boo@fasdfrewar.cdm> - 2015-10-02 01:02 -0400
    Re: How can  " dup drop " be anything other than a nop Bob Armstrong <bob@cosy.com> - 2015-10-02 17:05 -0700
      Re: How can  " dup drop " be anything other than a nop "Rod Pemberton" <boo@fasdfrewar.cdm> - 2015-10-02 22:29 -0400
      Re: How can  " dup drop " be anything other than a nop anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-10-08 06:25 +0000
        Re: How can  " dup drop " be anything other than a nop Bob Armstrong <bob@cosy.com> - 2015-10-11 23:35 -0700
          Re: How can  " dup drop " be anything other than a nop Bob Armstrong <bob@cosy.com> - 2015-10-11 23:51 -0700
          Re: How can  " dup drop " be anything other than a nop anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-10-12 09:49 +0000
            Re: How can  " dup drop " be anything other than a nop Bob Armstrong <bob@cosy.com> - 2015-10-12 16:19 -0700

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