Tactics: TACTICS (Part 4 of 7)

       Name: TACTICS (Part 4 of 7)                                   [Show more]
       Type: Subroutine
   Category: Tactics
    Summary: Apply tactics: Check energy levels, maybe launch escape pod if low
  Deep dive: Program flow of the tactics routine
    Context: See this subroutine in context in the source code
 References: No direct references to this subroutine in this source file


 This section works out what kind of condition the ship is in. Specifically:

   * If this is a large ship that can spawn smaller ships, such as an Anaconda
     or a Dragon, then consider spawning (22% chance) a Worm

   * Rarely (2.5% chance) roll the ship by a noticeable amount

   * If the ship has at least half its energy banks full, jump to part 6 to
     consider firing the lasers

   * If the ship is not into the last 1/8th of its energy, jump to part 5 to
     consider firing a missile

   * If the ship is into the last 1/8th of its energy, and this ship type has
     an escape pod fitted, then rarely (10% chance) the ship launches an escape
     pod and is left drifting in space


 LDA TYPE               \ If this is not a missile, skip the following
 CMP #MSL               \ instruction
 BNE P%+5

 JMP TA20               \ This is a missile, so jump down to TA20 to get
                        \ straight into some aggressive manoeuvring

 CMP #14                \ If this is not a large ship that can spawn smaller
 BNE TN7                \ ships (e.g. an Anaconda or Dragon), which will be in
                        \ slot 14 in the ship files, jump down to TN7 to skip
                        \ the following

 JSR DORND              \ Set A and X to random numbers

 CMP #200               \ If A < 200 (78% chance), jump down to TN7 to skip the
 BCC TN7                \ following

 LDX #15                \ Set X to the ship in slot 15, which will be the kind
                        \ of ship that the large ship in slot 14 can spawn
                        \ (e.g. an Anaconda can spawn a Worm, while a Dragon can
                        \ spawn a Sidewinder)

 JMP TN6                \ Jump to TN6 to spawn the Worm and return from
                        \ the subroutine using a tail call

.TN7

 JSR DORND              \ Set A and X to random numbers

 CMP #250               \ If A < 250 (97.5% chance), jump down to TA7 to skip
 BCC TA7                \ the following

 JSR DORND              \ Set A and X to random numbers

 ORA #104               \ Bump A up to at least 104 and store in the roll
 STA INWK+29            \ counter, to gives the ship a noticeable roll

.TA7

 LDY #14                \ Set A = the ship's maximum energy / 2
 LDA (XX0),Y
 LSR A

 CMP INWK+35            \ If the ship's current energy in byte #35 > A, i.e. the
 BCC TA3                \ ship has at least half of its energy banks charged,
                        \ jump down to TA3

 LSR A                  \ If the ship's current energy in byte #35 > A / 4, i.e.
 LSR A                  \ the ship is not into the last 1/8th of its energy,
 CMP INWK+35            \ jump down to ta3 to consider firing a missile
 BCC ta3

 JSR DORND              \ Set A and X to random numbers

 CMP #230               \ If A < 230 (90% chance), jump down to ta3 to consider
 BCC ta3                \ firing a missile

 LDX TYPE               \ Fetch the ship blueprint's default NEWB flags from the
 LDA E%-1,X             \ table at E%, and if bit 7 is clear (i.e. this ship
 BPL ta3                \ does not have an escape pod), jump to ta3 to skip the
                        \ spawning of an escape pod

                        \ By this point, the ship has run out of both energy and
                        \ luck, so it's time to bail

 LDA #0                 \ Set the AI flag to 0 to disable AI, hostility and
 STA INWK+32            \ E.C.M., so the ship's a sitting duck

 JMP SESCP              \ Jump to SESCP to spawn an escape pod from the ship,
                        \ returning from the subroutine using a tail call