|
Routines |
| Prev: B483 | Up: Map | Next: B625 |
|
Used by the routine at UpdateSpecialShot.
The end of the routines that update a shot. Moves the shot by the vertical scroll speed, then erases the old picture of the shot with EraseRows and draws the new one with DrawRows. If the shot has ended, its slot is made free; if it was a special shot that ends the flag at B832 is cleared. Otherwise the area of the screen under it is given its attribute by SetShotAttributes.
|
||||||||
| DrawShot | B5B5 | LD A,($CCBA) | The vertical scroll speed. | |||||
| B5B8 | ADD A,(IX+$0C) | Add the byte at offset 0C of IX to A. | ||||||
| B5BB | LD (IX+$0C),A | Write the low byte of the horizontal acceleration. | ||||||
| B5BE | CALL FindObjectScreenAddress | Call FindObjectScreenAddress. | ||||||
| B5C1 | LD B,(IX+$0E) | The high byte of the vertical acceleration. | ||||||
| B5C4 | BIT 7,B | Jump to DrawShot_Draw if bit 7 of B is clear. | ||||||
| B5C6 | JR Z,DrawShot_Draw | |||||||
| B5C8 | LD B,$00 | Clear B. | ||||||
| B5CA | LD (IX+$0E),B | Write the high byte of the vertical acceleration. | ||||||
| DrawShot_Draw | B5CD | CALL EraseRows | Call EraseRows. | |||||
| B5D0 | CALL DrawRows | Call DrawRows. | ||||||
| B5D3 | CALL MoveObject | Call MoveObject. | ||||||
| B5D6 | LD A,(IX+$0E) | The high byte of the vertical acceleration. | ||||||
| B5D9 | AND A | Jump to DrawShot_Attributes if A is not zero. | ||||||
| B5DA | JR NZ,DrawShot_Attributes | |||||||
| B5DC | LD (IX+$0B),$00 | Store 00 at offset 0B of IX. | ||||||
| B5E0 | BIT 7,(IX+$15) | Return if bit 7 of offset 15 of IX is clear. | ||||||
| B5E4 | RET Z | |||||||
| B5E5 | XOR A | Clear A. | ||||||
| B5E6 | LD ($B832),A | The special shot has ended. | ||||||
| B5E9 | JP AddToStack | Jump to AddToStack. | ||||||
| DrawShot_Attributes | B5EC | BIT 7,(IX+$15) | Jump to SetShotAttributes if bit 7 of offset 15 of IX is clear. | |||||
| B5F0 | JR Z,SetShotAttributes | |||||||
| B5F2 | LD A,$43 | A=43. | ||||||
| B5F4 | LD ($AF03),A | The special shot is bright magenta. | ||||||
| B5F7 | LD L,(IX+$0B) | The high byte of the horizontal acceleration. | ||||||
| B5FA | LD H,(IX+$0C) | The low byte of the horizontal acceleration. | ||||||
| B5FD | LD A,($A1D8) | The rows of the shot. | ||||||
| B600 | LD D,A | D=A. | ||||||
| B601 | LD A,(IX+$0E) | The high byte of the vertical acceleration. | ||||||
| B604 | ADD A,A | Double A. | ||||||
| B605 | ADD A,A | Double A. | ||||||
| B606 | ADD A,A | Double A. | ||||||
| B607 | LD B,A | B=A. | ||||||
| B608 | JP SetObjectAttributes_Sum | Jump to SetObjectAttributes_Sum. | ||||||
| SetShotAttributes | B60B | LD DE,$B625 | The shot attribute area. | |||||
| B60E | LD A,(IX+$0E) | The high byte of the vertical acceleration. | ||||||
| B611 | LD (DE),A | Write A where DE points. | ||||||
| B612 | INC DE | Advance DE. | ||||||
| B613 | INC DE | Advance DE. | ||||||
| B614 | LD A,(IX+$0D) | The attribute. | ||||||
| B617 | LD (DE),A | Write A where DE points. | ||||||
| B618 | LD L,(IX+$0B) | The high byte of the horizontal acceleration. | ||||||
| B61B | LD H,(IX+$0C) | The low byte of the horizontal acceleration. | ||||||
| B61E | LD DE,$B625 | The shot attribute area. | ||||||
| B621 | CALL FillAttributes | Call FillAttributes. | ||||||
| B624 | RET | Return. | ||||||
| Prev: B483 | Up: Map | Next: B625 |