XPost: comp.theory   
   From: NoOne@nospicedham.NoWhere.com   
      
   On 12/22/2020 4:07 AM, Bernhard Schornak wrote:   
   > olcott wrote:   
   >   
   > _H_Hat:   
   > [000005e6](01)  55                  push ebp   
   > [000005e7](02)  8bec                mov ebp,esp   
   > [000005e9](01)  51                  push ecx   
   > [000005ea](03)  8b4508              mov eax,[ebp+08]   
   > [000005ed](01)  50                  push eax   
   > [000005ee](03)  8b4d08              mov ecx,[ebp+08]   
   > [000005f1](01)  51                  push ecx   
   > [000005f2](05)  e8effdffff          call 000003e6   
   > [000005f7](03)  83c408              add esp,+08   
   > [000005fa](03)  8945fc              mov [ebp-04],eax   
   > [000005fd](04)  837dfc00            cmp dword [ebp-04],+00   
   > [00000601](02)  7404                jz 00000607   
   > [00000603](02)  ebfe                jmp 00000603   
   > [00000605](02)  eb01                jmp 00000608   
   > [00000607](01)  f4                  hlt   
   > [00000608](02)  8be5                mov esp,ebp   
   > [0000060a](01)  5d                  pop ebp   
   > [0000060b](01)  c3                  ret   
   >   
   >   
   > 0603 jumps to itself. Reduce to   
   >   
   > _H-Hat:movl  0x0C(%esp), %eax   
   >         subl  $0x08,      %esp   
   >         movl  %eax,       0x00(%esp)   
   >         movl  %eax,       0x04(%esp)   
   >         call  _WHATEVER_THAT_IS   
   >         testl %eax,       %eax   
   >         je    0f   
   >     L00:jmp   L00                      # loop   
   forever   
   >       0:hlt                            #   
   CLI/STI?   
   >         addl $0x08,       %esp   
   >         ret   
   >   
   >   
   >   
   > As long as the code at 0x03E6 is unknown, it is impossible to tell   
   > anything. _H_Hat itself does nothing ... except wasting clocks and   
   > electrical power when the returned value is not zero.   
   >   
   > The only thing I can see in your debug trace is that you would run   
   > out of stack,   
      
   That is the answer that I expected and confirms that I am correct.   
      
   I am using the x86 code that was translated from C as the machine   
   description language of a Universal Turing Machine equivalent. I wrote a   
   whole x86utm operating system for this purpose. This means that the   
   assumption is infinite memory and thus infinite stack.   
      
   > if the debugger did not stop your attempts with this   
   > error message before ESP reached your stack's bottom. Maybe a good   
   > proof the debugger works well, but nothing else... ;)   
   >   
      
   In my actual test case the debugger is a halt decider that recognizes   
   the pattern, (in my prior post) stops simulating this code and reports   
   not halting.   
      
   It turns out that all the halting problem proofs depend on the   
   assumption that such a halt decider is impossible.   
      
   Thanks for your help. The people in the other forums don't seem to have   
   a clue about the x86 language.   
      
   >   
   > Merry Winter Solstice!   
   >   
   > Bernhard Schornak   
   >   
      
      
   --   
   Copyright 2020 Pete Olcott   
      
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