Maths (Geometry): SPS1, Removed

       Name: SPS1, Removed                                           [Show more]
       Type: Subroutine
   Category: Maths (Geometry)
    Summary: Calculate the vector to the planet, sun or station and store it in
             XX15
    Context: See this subroutine in context in the source code
 References: No direct references to this subroutine in this source file


 Arguments:

   Y                    Determines the object whose vector we are calculating:

                          * 0 = calculate the vector to the planet

                          * NI% = calculate the vector to the sun/space station

 Other entry points:

   SPS1+1               A BRK instruction


                        \ --- Mod: Code removed for Elite-A: ------------------>

\.SPS1
\
\LDX #0                 \ Copy the two high bytes of the planet's x-coordinate
\JSR SPS3               \ into K3(2 1 0), separating out the sign bit into K3+2
\
\LDX #3                 \ Copy the two high bytes of the planet's y-coordinate
\JSR SPS3               \ into K3(5 4 3), separating out the sign bit into K3+5
\
\LDX #6                 \ Copy the two high bytes of the planet's z-coordinate
\JSR SPS3               \ into K3(8 7 6), separating out the sign bit into K3+8
\
\                       \ Fall through into TAS2 to build XX15 from K3

                        \ --- End of removed code ----------------------------->