[puzzle] Escape

kuroneko

Given the listed code fragment, you have 4 longs (code, no data) to execute the instructions at pick and exit. After executing exit the task is done so you can safely execute the cogstop. Further limitations:

• the red coloured instructions are read-only and can't be changed
• cnt's shadow register is read-only (add cnt, #n|reg & Co are therefore invalid)
• the blue instructions are an example, they are unknown to you for the purpose of this exercise

Once a solution is found, reduce the code space to 3 longs and do it again. If that's too easy, consider pick and exit non-relocatable.

DAT             org     0

escape          [COLOR="Red"]cogid   cnt[/COLOR]

                nop                             ' |
                [COLOR="DarkOrange"]nop[/COLOR]                             ' |
                [COLOR="DarkOrange"]nop[/COLOR]                             ' |
                [COLOR="DarkOrange"]nop[/COLOR]                             ' | your code here
                
                [COLOR="Red"]cogstop cnt[/COLOR]

pick            [COLOR="Blue"]mov     par, #42[/COLOR]

                [COLOR="Red"]cogstop cnt[/COLOR]

exit            [COLOR="Blue"]wrlong  par, par[/COLOR]

                [COLOR="Red"]cogstop cnt[/COLOR]

                fit

Andrey Demenev

DAT             org     0

escape          cogid   cnt
                mov     :i1, pick
:i1             movs    :i2, #exit
:i2             jmp     #:i1
                cogstop cnt
pick            mov     par, #42
                cogstop cnt
exit            wrlong  par, par
                cogstop cnt
                fit

OR

DAT             org     0

escape          cogid   cnt
                mov     :i1, pick
:i1             mov     :i2, exit
:i2             jmp     #:i1
                cogstop cnt
pick            mov     par, #42
                cogstop cnt
exit            wrlong  par, par
                cogstop cnt
                fit

tonyp12

DAT             org     0

escape          cogid   cnt

                mov newcode, pick
                nop
newcode         nop
                jmp #exit
                cogstop cnt

pick            mov     par, #42
                cogstop cnt
exit            wrlong  par, par
                cogstop cnt
                fit

kuroneko

• A further - third party - restriction for the 3 long case: only use one mov[dis] instruction.
• And don't forget the non-relocatable case I added to the OP.