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Elite on the BBC Micro

Missions: THERE (6502SP version)

Name: THERE [View in context] Type: Subroutine Category: Missions Summary: Check whether we are in the Constrictor's system in mission 1
The stolen Constrictor is the target of mission 1. We finally track it down to the Orarra system in the second galaxy, which is at galactic coordinates (144, 33). This routine checks whether we are in this system and sets the C flag accordingly. Returns: C flag Set if we are in the Constrictor system, otherwise clear
.THERE LDX GCNT \ Set X = GCNT - 1 DEX BNE THEX \ If X is non-zero (i.e. GCNT is not 1, so we are not in \ the second galaxy), then jump to THEX LDA QQ0 \ Set A = the current system's galactic x-coordinate CMP #144 \ If A <> 144 then jump to THEX BNE THEX LDA QQ1 \ Set A = the current system's galactic y-coordinate CMP #33 \ If A = 33 then set the C flag BEQ THEX+1 \ If A = 33 then jump to THEX+1, so we return from the \ subroutine with the C flag set (otherwise we clear the \ C flag with the next instruction) .THEX CLC \ Clear the C flag RTS \ Return from the subroutine