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Elite on the BBC Micro

Tactics: TACTICS (Part 5 of 7) (Cassette version)

Name: TACTICS (Part 5 of 7) [View in context] Type: Subroutine Category: Tactics Summary: Apply tactics: Consider whether to launch a missile at us Deep dive: Program flow of the tactics routine
This section considers whether to launch a missile. Specifically: * If the ship doesn't have any missiles, skip to the next part * If an E.C.M. is firing, skip to the next part * Randomly decide whether to fire a missile (or, in the case of Thargoids, release a Thargon), and if we do, we're done
.ta3 \ If we get here then the ship has less than half energy \ so there may not be enough juice for lasers, but let's \ see if we can fire a missile LDA INWK+31 \ Set A = bits 0-2 of byte #31, the number of missiles AND #%00000111 \ the ship has left BEQ TA3 \ If it doesn't have any missiles, jump to TA3 STA T \ Store the number of missiles in T JSR DORND \ Set A and X to random numbers AND #31 \ Restrict A to a random number in the range 0-31 CMP T \ If A >= T, which is quite likely, though less likely BCS TA3 \ with higher numbers of missiles, jump to TA3 LDA ECMA \ If an E.C.M. is currently active (either our's or an BNE TA3 \ opponent's), jump to TA3 DEC INWK+31 \ We're done with the checks, so it's time to fire off a \ missile, so reduce the missile count in byte #31 by 1 LDA TYPE \ If this is not a Thargoid, jump down to TA16 to launch CMP #THG \ a missile BNE TA16 LDX #TGL \ This is a Thargoid, so instead of launching a missile, LDA INWK+32 \ the mothership launches a Thargon, so call SFS1 to JMP SFS1 \ spawn a Thargon from the parent ship, and return from \ the subroutine using a tail call .TA16 JMP SFRMIS \ Jump to SFRMIS to spawn a missile as a child of the \ current ship, make a noise and print a message warning \ of incoming missiles, and return from the subroutine \ using a tail call