Maths (Arithmetic): VCSU1

       Name: VCSU1                                                   [Show more]
       Type: Subroutine
   Category: Maths (Arithmetic)
    Summary: Calculate vector K3(8 0) = [x y z] - coordinates of the sun or
             space station
    Context: See this subroutine in context in the source code
 References: This subroutine is called as follows:
             * DOCKIT calls VCSU1


 Calculate the following:

   K3(2 1 0) = (x_sign x_hi x_lo) - x-coordinate of the sun or space station

   K3(5 4 3) = (y_sign y_hi z_lo) - y-coordinate of the sun or space station

   K3(8 7 6) = (z_sign z_hi z_lo) - z-coordinate of the sun or space station

 where the first coordinate is from the ship data block in INWK, and the second
 coordinate is from the sun or space station's ship data block which they
 share.


.VCSU1

 LDA #LO(K%+NI%)        ; Set the low byte of V(1 0) to point to the coordinates
 STA V                  ; of the sun or space station

 LDA #HI(K%+NI%)        ; Set A to the high byte of the address of the
                        ; coordinates of the sun or space station

                        ; Fall through into VCSUB to calculate:
                        ;
                        ;   K3(2 1 0) = (x_sign x_hi x_lo) - x-coordinate of sun
                        ;               or space station
                        ;
                        ;   K3(2 1 0) = (x_sign x_hi x_lo) - x-coordinate of sun
                        ;               or space station
                        ;
                        ;   K3(8 7 6) = (z_sign z_hi z_lo) - z-coordinate of sun
                        ;               or space station