Utility routines: SetRandomNumber

       Name: SetRandomNumber                                         [Show more]
       Type: Subroutine
   Category: Utility routines
    Summary: Set the next item in the randomNumbers list to a new random number
             and update the pointer to point to it
  Deep dive: Random numbers
    Context: See this subroutine in context in the source code
 References: This subroutine is called as follows:
             * MainLoop (Part 13 of 15) calls SetRandomNumber


.SetRandomNumber

 LDX randomNumbers      \ Fetch the pointer for the randomNumbers list

 LDA VIA+&64            \ Read the 6522 User VIA T1C-L timer 1 low-order
                        \ counter (SHEILA &64), which decrements one million
                        \ times a second and will therefore be pretty random

 STA randomNumbers+1,X  \ Set the next item in the list to the random number we
                        \ just fetched

                        \ Fall through into NextRandomNumber to move the list
                        \ pointer to point to the new number we just added