|
Routines |
| Prev: CD23 | Up: Map | Next: CD8C |
|
Used by the routine at HandleTumbleweed.
Checks the walls for each speed on its own, so that the object slides along a wall instead of stopping. For each speed it sets the heading to the direction of that speed, and checks the walls with the other speed set to zero.
|
||||||||
|
Check the walls for the horizontal speed.
|
||||||||
| CheckWallsEachWay | CD40 | LD A,($A214) | Fetch HorizontalSpeed. | |||||
| CD43 | AND A | Jump to CheckWallsEachWay_Vertical if it is zero. | ||||||
| CD44 | JR Z,CheckWallsEachWay_Vertical | |||||||
| CD46 | LD A,$40 | Use heading one. | ||||||
| CD48 | JP P,CheckWallsEachWay_SetHorizontal | Jump to CheckWallsEachWay_SetHorizontal if the speed is not negative. | ||||||
| CD4B | OR %10000000 | Use heading three. | ||||||
|
Set the heading, zero VerticalSpeed, and check the walls.
|
||||||||
| CheckWallsEachWay_SetHorizontal | CD4D | LD C,A | Keep the heading in C. | |||||
| CD4E | LD A,(IX+$06) | Fetch the heading and flags. | ||||||
| CD51 | AND %00111111 | Keep the other bits. | ||||||
| CD53 | OR C | Put in the new heading. | ||||||
| CD54 | LD (IX+$06),A | Set the heading and flags. | ||||||
| CD57 | LD A,($A215) | Fetch VerticalSpeed. | ||||||
| CD5A | PUSH AF | Stash the vertical speed on the stack. | ||||||
| CD5B | XOR A | Set VerticalSpeed to 00. | ||||||
| CD5C | LD ($A215),A | |||||||
| CD5F | CALL TestMove | Call TestMove. | ||||||
| CD62 | POP AF | Restore the vertical speed from the stack. | ||||||
| CD63 | LD ($A215),A | Set VerticalSpeed. | ||||||
|
Check the walls for the vertical speed.
|
||||||||
| CheckWallsEachWay_Vertical | CD66 | LD A,($A215) | Fetch VerticalSpeed. | |||||
| CD69 | AND A | Return if it is zero. | ||||||
| CD6A | RET Z | |||||||
| CD6B | LD A,$00 | Use heading zero. | ||||||
| CD6D | JP P,CheckWallsEachWay_SetVertical | Jump to CheckWallsEachWay_SetVertical if the speed is not negative. | ||||||
| CD70 | OR %10000000 | Use heading two. | ||||||
|
Set the heading, zero HorizontalSpeed, and check the walls.
|
||||||||
| CheckWallsEachWay_SetVertical | CD72 | LD C,A | Keep the heading in C. | |||||
| CD73 | LD A,(IX+$06) | Fetch the heading and flags. | ||||||
| CD76 | AND %00111111 | Keep the other bits. | ||||||
| CD78 | OR C | Put in the new heading. | ||||||
| CD79 | LD (IX+$06),A | Set the heading and flags. | ||||||
| CD7C | LD A,($A214) | Fetch HorizontalSpeed. | ||||||
| CD7F | PUSH AF | Stash the horizontal speed on the stack. | ||||||
| CD80 | XOR A | Set HorizontalSpeed to 00. | ||||||
| CD81 | LD ($A214),A | |||||||
| CD84 | CALL CheckWalls | Call CheckWalls. | ||||||
| CD87 | POP AF | Restore the horizontal speed from the stack. | ||||||
| CD88 | LD ($A214),A | Set HorizontalSpeed. | ||||||
| CD8B | RET | Return. | ||||||
| Prev: CD23 | Up: Map | Next: CD8C |