Tactics: ANGRY

       Name: ANGRY                                                   [Show more]
       Type: Subroutine
   Category: Tactics
    Summary: Make a ship hostile
    Context: See this subroutine in context in the source code
 References: This subroutine is called as follows:
             * FRMIS calls ANGRY
             * Main flight loop (Part 11 of 16) calls ANGRY


 All this routine does is set the ship's hostile flag, start it turning and
 give it a kick of acceleration - later calls to TACTICS will make the ship
 start to attack us.


 Arguments:

   A                    The type of ship we're going to irritate

   INF                  The address of the data block for the ship we're going
                        to infuriate


.ANGRY

 CMP #SST               ; If this is the space station, jump to AN2 to make the
 BEQ AN2                ; space station hostile

 LDY #36                ; Fetch the ship's NEWB flags from byte #36
 LDA (INF),Y

 AND #%00100000         ; If bit 5 of the ship's NEWB flags is clear, skip the
 BEQ P%+5               ; following instruction, otherwise bit 5 is set, meaning
                        ; this ship is an innocent bystander, and attacking it
                        ; will annoy the space station

 JSR AN2                ; Call AN2 to make the space station hostile

 LDY #32                ; Fetch the ship's byte #32 (AI flag)
 LDA (INF),Y

 BEQ HI1                ; If the AI flag is zero then this ship has no AI and
                        ; it can't get hostile, so return from the subroutine
                        ; (as HI1 contains an RTS)

 ORA #%10000000         ; Otherwise set bit 7 (AI enabled) to ensure AI is
 STA (INF),Y            ; definitely enabled

 LDY #28                ; Set the ship's byte #28 (acceleration) to 2, so it
 LDA #2                 ; speeds up
 STA (INF),Y

 ASL A                  ; Set the ship's byte #30 (pitch counter) to 4, so it
 LDY #30                ; starts diving
 STA (INF),Y

 LDA TYPE               ; If the ship's type is < #CYL (i.e. a missile, Coriolis
 CMP #CYL               ; space station, escape pod, plate, cargo canister,
 BCC AN3                ; boulder, asteroid, splinter, Shuttle or Transporter),
                        ; then jump to AN3 to skip the following

 LDY #36                ; Set bit 2 of the ship's NEWB flags in byte #36 to
 LDA (INF),Y            ; make this ship hostile
 ORA #%00000100
 STA (INF),Y

.AN3

 RTS                    ; Return from the subroutine

.AN2

 LDA K%+NI%+36          ; Set bit 2 of the NEWB flags in byte #36 of the second
 ORA #%00000100         ; ship in the ship data workspace at K%, which is
 STA K%+NI%+36          ; reserved for the sun or the space station (in this
                        ; case it's the latter), to make it hostile

 RTS                    ; Return from the subroutine