Skip to navigation

BBC Micro Elite

Maths (Geometry): SPS1

Name: SPS1 [View in context] Type: Subroutine Category: Maths (Geometry) Summary: Calculate the vector to the planet and store it in XX15
Other entry points: SPS1+1 A BRK instruction
.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 }