Free42 with big stack, test version

[Sylvain Cote]

Like I said before, I think the NLBL/LBL/RTN/END is the safest way to distinguish between two programs and their stack mode usage.

This is what I would do if I was doing it:

• at program startup
  • alloc a temporary n-levels stack (running-nstk) and running-nstk = empty
  • alloc a temporary 4-levels stack (running-4stk) and running-4stk = 0
  • alloc a temporary L register (running-lreg) and running-lreg = 0
  • if interactive mode is n-levels → push interactive n-levels stack (interactive-nstk) in running-nstk, running-nstk is activated
  • if interactive mode is 4-levels → copy interactive 4-levels stack (interactive-4stk) over running-4stk, running-4stk is activated
  • running-lreg = interactive-lreg
    
• mode switch on LBL, NLBL, RTN and END
  • switch from 4-levels to 4-levels → nothing to copy, running-4stk stay active
  • switch from n-levels to n-levels → nothing to copy, running-nstk stay active
  • switch from 4-levels to n-levels → copy running-4stk to running-nstk (see note #1), running-nstk is activated
  • switch from n-levels to 4-levels → copy running-nstk to running-4stk (see note #2), running-4stk is activated
    
• at program exit
  • if interactive mode is n-levels → apply mode switch if needed, flush interactive-nstk, push running-nstk in interactive-nstk, interactive-lreg = running-lreg, free running-nstk, free running-4stk, free running-lreg
  • if interactive mode is 4-levels → apply mode switch if needed, copy running-4stk over interactive-4stk, interactive-lreg = running-lreg, free running-nstk, free running-4stk, free running-lreg
    

Note #1: copy 4stk to nstk (running & interactive)

• if nstk depth < 5 then flush nstk, push 4stk into nstk
• if nstk depth > 4 then drop 4 data from nstk, push 4stk into nstk
  

Note #2: copy nstk to 4stk (running & interactive)

• if nstk depth > 3 then copy nstk 4th lowest levels to 4stk
• if nstk depth = 3 then copy nstk 3th lowest levels to 4stk, T=Z
• if nstk depth = 2 then copy nstk 2th lowest levels to 4stk, TZ=Y
• if nstk depth = 1 then copy nstk 1st level to 4stk, TZY=X
• if nstk depth = 0 then TZYX=0