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Routines |
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Used by the routine at CheckSpecialShot.
Launches a shot, from the first free slot out of the four at ShotSlots. It faces the way the ship is facing and starts at the ship. Three kinds of shot can be launched: an ordinary one, a chasing shot if the ship has part 08 and the weapon toggle at WeaponToggle is one, and a special shot if bit 2 of the toggle is set.
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| LaunchShot | B752 | LD IX,$B37A | The shot slots. | |
| B756 | LD A,$04 | A=04. | ||
| LaunchShot_Slot | B758 | EX AF,AF' | Switch to the alternate accumulator and flags. | |
| B759 | BIT 7,(IX+$16) | Jump to LaunchShot_Check if bit 7 of offset 16 of IX is set. | ||
| B75D | JR NZ,LaunchShot_Check | |||
| B75F | LD A,(IX+$0B) | Read offset 0B of IX. | ||
| B762 | AND A | Jump to LaunchShot_Free if A is zero. | ||
| B763 | JR Z,LaunchShot_Free | |||
| LaunchShot_Check | B765 | LD A,(IX+$00) | Read offset 00 of IX. | |
| B768 | INC A | Advance A. | ||
| B769 | JR NZ,LaunchShot_Next | Jump to LaunchShot_Next if the zero flag is clear. | ||
| LaunchShot_Free | B76B | CALL FreeObjectSlot | Call FreeObjectSlot. | |
| B76E | LD A,($C8FD) | The ship's facing. | ||
| B771 | LD (IX+$00),A | Write A to offset 00 of IX. | ||
| B774 | LD (IX+$0B),$99 | Store 99 at offset 0B of IX. | ||
| B778 | CALL StartShotAtShip | Call StartShotAtShip. | ||
| B77B | LD A,($B730) | The weapon toggle. | ||
| B77E | BIT 2,A | Jump to LaunchShot_Special if bit 2 of A is set. | ||
| B780 | JP NZ,LaunchShot_Special | |||
| B783 | DEC A | Step A back. | ||
| B784 | JP Z,LaunchShot_Chasing | Jump to LaunchShot_Chasing if the zero flag is set. | ||
| LaunchShot_Ordinary | B787 | CALL MoveObject | Call MoveObject. | |
| B78A | LD (IX+$09),$00 | Store 00 at offset 09 of IX. | ||
| B78E | BIT 7,(IX+$15) | Return if bit 7 of offset 15 of IX is set. | ||
| B792 | RET NZ | |||
| B793 | JP PlayShotSound | Jump to PlayShotSound. | ||
| LaunchShot_Next | B796 | LD BC,$0018 | BC=18. | |
| B799 | ADD IX,BC | IX gains BC. | ||
| B79B | EX AF,AF' | Switch to the alternate accumulator and flags. | ||
| B79C | DEC A | Step A back. | ||
| B79D | JR NZ,LaunchShot_Slot | Jump to LaunchShot_Slot if the zero flag is clear. | ||
| B79F | RET | Return. | ||
| LaunchShot_Chasing | B7A0 | LD A,($F5F5) | The eighth part, which makes a chasing shot. | |
| B7A3 | AND A | Jump to LaunchShot_Ordinary if A is zero. | ||
| B7A4 | JP Z,LaunchShot_Ordinary | |||
| B7A7 | LD A,(IX+$07) | Read offset 07 of IX. | ||
| B7AA | CP $08 | Jump to LaunchShot_Speed if A is 08. | ||
| B7AC | JR Z,LaunchShot_Speed | |||
| B7AE | LD (IX+$07),$20 | Store 20 at offset 07 of IX. | ||
| LaunchShot_Speed | B7B2 | LD A,(IX+$09) | Read offset 09 of IX. | |
| B7B5 | SUB $03 | Subtract 03 from A. | ||
| B7B7 | LD (IX+$09),A | Write A to offset 09 of IX. | ||
| B7BA | LD (IX+$08),$00 | Store 00 at offset 08 of IX. | ||
| B7BE | LD (IX+$0A),$00 | Store 00 at offset 0A of IX. | ||
| B7C2 | CALL MoveObject | Call MoveObject. | ||
| B7C5 | LD (IX+$09),$00 | Store 00 at offset 09 of IX. | ||
| B7C9 | LD (IX+$10),$27 | Store 27 at offset 10 of IX. | ||
| B7CD | LD A,(IX+$07) | Read offset 07 of IX. | ||
| B7D0 | LD (IX+$07),$08 | Store 08 at offset 07 of IX. | ||
| B7D4 | CP $20 | Jump to LaunchShot_Set if A is 20. | ||
| B7D6 | JR Z,LaunchShot_Set | |||
| B7D8 | LD (IX+$07),$F8 | Store F8 at offset 07 of IX. | ||
| LaunchShot_Set | B7DC | LD (IX+$00),$00 | Store 00 at offset 00 of IX. | |
| B7E0 | LD (IX+$0D),$DD | Store DD at offset 0D of IX. | ||
| B7E4 | LD (IX+$15),$7F | Store 7F at offset 15 of IX. | ||
| B7E8 | LD (IX+$16),$80 | Store 80 at offset 16 of IX. | ||
| B7EC | CALL ClearShot | Call ClearShot. | ||
| B7EF | LD (IX+$17),$F0 | Store F0 at offset 17 of IX. | ||
| B7F3 | JP PlayShotSound | Jump to PlayShotSound. | ||
| LaunchShot_Special | B7F6 | LD A,$80 | A=80. | |
| B7F8 | LD (IX+$15),A | Write A to offset 15 of IX. | ||
| B7FB | LD ($B832),A | A special shot has been launched. | ||
| B7FE | LD (IX+$0D),$43 | Store 43 at offset 0D of IX. | ||
| B802 | LD A,($5C38) | The ship row. | ||
| B805 | ADD A,$09 | Add 09 to A. | ||
| B807 | LD (IX+$0C),A | Write A to offset 0C of IX. | ||
| B80A | LD A,(IX+$09) | Read offset 09 of IX. | ||
| B80D | ADD A,$09 | Add 09 to A. | ||
| B80F | LD (IX+$09),A | Write A to offset 09 of IX. | ||
| B812 | LD A,(IX+$07) | Read offset 07 of IX. | ||
| B815 | ADD A,$08 | Add 08 to A. | ||
| B817 | AND %00100000 | Keep the bits of A that are set in 20. | ||
| B819 | LD (IX+$07),A | Write A to offset 07 of IX. | ||
| B81C | LD (IX+$12),$F8 | Store F8 at offset 12 of IX. | ||
| B820 | LD (IX+$0B),$60 | Store 60 at offset 0B of IX. | ||
| B824 | JP Z,LaunchShot_Ordinary | Jump to LaunchShot_Ordinary if the zero flag is set. | ||
| B827 | LD (IX+$12),$08 | Store 08 at offset 12 of IX. | ||
| B82B | LD (IX+$0B),$90 | Store 90 at offset 0B of IX. | ||
| B82F | JP LaunchShot_Ordinary | Jump to LaunchShot_Ordinary. | ||
| B832 | NOP | Do nothing. | ||
| Prev: B731 | Up: Map | Next: B833 |