Drawing planets: PL2

       Name: PL2                                                     [Show more]
       Type: Subroutine
   Category: Drawing planets
    Summary: Remove the planet or sun from the screen
    Context: See this subroutine in context in the source code
 References: This subroutine is called as follows:
             * PLANET calls PL2
             * PROJ calls via PL2-1


 Other entry points:

   PL2-1                Contains an RTS


.PL2

 LDA TYPE               ; Shift bit 0 of the planet/sun's type into the C flag
 LSR A

 BCS P%+5               ; If the planet/sun's type has bit 0 clear, then it's
                        ; either 128 or 130, which is a planet; meanwhile, the
                        ; sun has type 129, which has bit 0 set. So if this is
                        ; the sun, skip the following instruction

 JMP WPLS2              ; This is the planet, so jump to WPLS2 to remove it from
                        ; screen, returning from the subroutine using a tail
                        ; call

 JMP WPLS               ; This is the sun, so jump to WPLS to remove it from
                        ; screen, returning from the subroutine using a tail
                        ; call