Universe: hyp1

       Name: hyp1                                                    [Show more]
       Type: Subroutine
   Category: Universe
    Summary: Process a jump to the system closest to (QQ9, QQ10)
    Context: See this subroutine in context in the source code
 References: This subroutine is called as follows:
             * BR1 (Part 2 of 2) calls hyp1


 Do a hyperspace jump to the system closest to galactic coordinates
 (QQ9, QQ10), and set up the current system's state to those of the new system.


 Returns:

   (QQ0, QQ1)           The galactic coordinates of the new system

   QQ2 to QQ2+6         The seeds of the new system

   EV                   Set to 0

   QQ28                 The new system's economy

   tek                  The new system's tech level

   gov                  The new system's government


 Other entry points:

   hyp1+3               Jump straight to the system at (QQ9, QQ10) without
                        first calculating which system is closest. We do this
                        if we already know that (QQ9, QQ10) points to a system


.hyp1

 JSR TT111              \ Select the system closest to galactic coordinates
                        \ (QQ9, QQ10)

 JSR jmp                \ Set the current system to the selected system

 LDX #5                 \ We now want to copy the seeds for the selected system
                        \ in QQ15 into QQ2, where we store the seeds for the
                        \ current system, so set up a counter in X for copying
                        \ 6 bytes (for three 16-bit seeds)

.TT112

 LDA QQ15,X             \ Copy the X-th byte in QQ15 to the X-th byte in QQ2, to
 STA QQ2,X              \ update the selected system to the new one. Note that
                        \ this approach has a minor bug associated with it: if
                        \ your hyperspace counter hits 0 just as you're docking,
                        \ then you will magically appear in the station in your
                        \ hyperspace destination, without having to go to the
                        \ effort of actually flying there. This bug was fixed in
                        \ later versions by saving the destination seeds in a
                        \ separate location called safehouse, and using those
                        \ instead... but that isn't the case in this version

 DEX                    \ Decrement the counter

 BPL TT112              \ Loop back to TT112 if we still have more bytes to
                        \ copy

 INX                    \ Set X = 0 (as we ended the above loop with X = &FF)

 STX EV                 \ Set EV, the extra vessels spawning counter, to 0, as
                        \ we are entering a new system with no extra vessels
                        \ spawned

 LDA QQ3                \ Set the current system's economy in QQ28 to the
 STA QQ28               \ selected system's economy from QQ3

 LDA QQ5                \ Set the current system's tech level in tek to the
 STA tek                \ selected system's economy from QQ5

 LDA QQ4                \ Set the current system's government in gov to the
 STA gov                \ selected system's government from QQ4

 RTS                    \ Return from the subroutine