Is "repeat until not" better, worse or the same as "repeat while"

Comments

• Phil Pilgrim (PhiPi) Posts: 23,514

  2014-01-02 15:47 edited 2014-01-02 15:47

  Code space and execution time are two things you can check on your own. For code space, just hit F8 in the PropTool to see how much is required for each version. For execution time, use two readings of cnt, subtracting the earlier one from the latter one to get the duration.
  
  -Phil
• kuroneko Posts: 3,623

  2014-01-02 15:59 edited 2014-01-02 15:59

  re: execution time, it's a bit tricky with polling loops as it depends on when the lock state changes to trigger the exit path, e.g. changing shortly after the check adds another loop run before you can exit. In your case I'd stick with the while but write it like this (less space):

  repeat
    while lockset(namelock)
  
• Ariba Posts: 2,694

  2014-01-02 23:06 edited 2014-01-02 23:06

  BST can generate a listing of the resulting bytecodes.
  Here is the output a bit simplified:

  repeat until not lockset(namelock)
  
  Addr : 0018:       36     : Constant 2 $00000001
  Addr : 0019:       2A     : LockSet(Id) Push
  Addr : 001A:       FF     : Math Op NOT   
  Addr : 001B:       0B 02  : jnz 001F  +2
  Addr : 001D:       04 79  : Jmp 0018  -7   
  
  
                     repeat while lockset(namelock)
  
  Addr : 001F:       36     : Constant 2 $00000001
  Addr : 0020:       2A     : LockSet(Id) Push
  Addr : 0021:       0A 02  : jz 0025   +2
  Addr : 0023:       04 7A  : Jmp 001F  -6   
  

  I would say that the WHILE version is faster because UNTIL NOT needs one bycode more. The other bytecodes are similar.
  
  Andy