SaveIP

A command for Oblivion Script Extender

Syntax:

SaveIP [labelID]

An alias for Label. This command allows you to set up one or more named labels within a script. Using GoTo or RestoreIP causes script processing to jump to the label, allowing you to set up simple loops. By providing an optional label ID, multiple labels or nested loops can be defined.

Example:

begin onActivate
    ; declare a variable to keep track of the number of times we've gone through the loop
    long var
    set var to 0
   
    ; save the current instruction pointer
    ; this records that the beginning of the loop is right before the PrintToConsole command
    SaveIP ; could also use Label
   
    ; print the current loop count
    PrintToConsole "loop %f" var
   
    ; update the loop counter
    set var to var + 1
   
    ; we only want to go through the loop three times, so check the loop counter
    if var < 3
        ; jump back to the saved location
        RestoreIP ; could also use Goto
    endif
   
    ; if we get here, we're done with the loop
end

When activated, this script will print:

loop 0.0000
loop 1.0000
loop 2.0000

To support nested loops, the SaveIP and RestoreIP commands take an optional integer parameter specifying which 'slot' to save the instruction location in. If you don't specify a number, it defaults to 0. There are 256 slots in the internal list.

A more familiar For-loop in a normal programming language would look like this:

for (i = 0; i < 5; i++)
{
  for (j = 0; j < 3 ; j++)
  {
    //Do Something
  }
}

To create the same loop using OBSE functions:

short i
short j

Label 0 ; top of outer loop, equivalent to SaveIP 0
  set j to 0
  Label 1 ; top of inner loop
    PrintToConsole "i = %.0f, j = %.0f" i, j
    set j to ( j + 1 )
    if ( j < 3 )
      GoTo 1 ; equivalent to RestoreIP 1
    endif
  set i to ( i + 1 )
  if ( i < 5 )
    GoTo 0
  endif

Note that unless the above loop is wrapped inside a conditional statement or a block like OnActivate, it will restart the very next frame and every frame thereafter.

Notes

• Be careful to make sure your loop has an exit condition, otherwise you run the risk of creating an infinite loop, which can freeze the game and make it impossible for the player to exit.
• For the most part, scripts will run one at a time and different scripts can use the same label IDs without any problems. However, result scripts and scripts with onActivate blocks will run instantly when called via script (SetStage and ObjectRef.Activate player, 1, respectively), before the next line of code proceeds. For those two script types, make sure the IDs are unique.
  • If you use a label ID in the calling script, and then the same ID in the called script, the ID will be set to the location in the called script. If the calling script uses Goto ID, when that ID is set to another script, it will act as a Return.

See Also

• Label
• RestoreIP
• GoTo