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Routines |
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Used by the routine at ScrollWorld.
Runs once a frame to look after the six map objects in the slots at MapObjectSlots. For each used slot it erases the old sprite, removes the object if it is flagged for removal or lets it move and draws it in its new place, sets the attributes under it, and checks whether it has been shot.
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| UpdateMapObjects | 44128 | LD A,(23612) | The scroll-in flag. | |
| 44131 | AND A | Call UpdateCrystalStack if A is zero. | ||
| 44132 | CALL Z,UpdateCrystalStack | |||
| 44135 | LD IX,43019 | The map object slots. | ||
| 44139 | LD B,6 | B=6. | ||
| UpdateMapObjects_Loop | 44141 | PUSH BC | Stash BC on the stack. | |
| 44142 | PUSH IX | Stash IX on the stack. | ||
| 44144 | LD A,(IX+0) | Read offset 0 of IX. | ||
| 44147 | CP 255 | Jump to UpdateMapObjects_Next if A is 255. | ||
| 44149 | JR Z,UpdateMapObjects_Next | |||
| 44151 | BIT 7,(IX+3) | Jump to UpdateMapObjects_Next2 if bit 7 of offset 3 of IX is set. | ||
| 44155 | JR NZ,UpdateMapObjects_Next2 | |||
| 44157 | LD A,(IX+24) | Read offset 24 of IX. | ||
| 44160 | AND %00001110 | Keep the bits of A that are set in 14. | ||
| 44162 | SRL A | Shift A right. | ||
| 44164 | LD (23580),A | The bits that fire a shot from the object. | ||
| 44167 | CALL NZ,FireShotWhenHit | Call FireShotWhenHit if the zero flag is clear. | ||
| UpdateMapObjects_Next2 | 44170 | CALL ResetSprites | Call ResetSprites. | |
| 44173 | BIT 7,(IX+16) | Call PrepareErase if bit 7 of offset 16 of IX is set. | ||
| 44177 | CALL NZ,PrepareErase | |||
| 44180 | RES 6,(IX+16) | Reset bit 6 of offset 16 of IX. | ||
| 44184 | EXX | Switch to the alternate registers. | ||
| 44185 | BIT 7,(IX+21) | Call StepObjectState if bit 7 of offset 21 of IX is set. | ||
| 44189 | CALL NZ,StepObjectState | |||
| 44192 | BIT 7,(IX+3) | Call CheckItemPickup if bit 7 of offset 3 of IX is set. | ||
| 44196 | CALL NZ,CheckItemPickup | |||
| 44199 | BIT 4,(IX+16) | Jump to UpdateMapObjects_Move if bit 4 of offset 16 of IX is clear. | ||
| 44203 | JR Z,UpdateMapObjects_Move | |||
| 44205 | LD (IX+0),255 | Store 255 at offset 0 of IX. | ||
| 44209 | LD (IX+16),0 | Store 0 at offset 16 of IX. | ||
| 44213 | JR UpdateMapObjects_Draw | Jump to UpdateMapObjects_Draw. | ||
| UpdateMapObjects_Move | 44215 | CALL PrepareDraw | Call PrepareDraw. | |
| UpdateMapObjects_Draw | 44218 | CALL DrawObject | Call DrawObject. | |
| 44221 | LD IY,(44358) | Fetch the word at CurrentObject into IY. | ||
| 44225 | BIT 7,(IY+3) | Call TrimObjectSprite if bit 7 of offset 3 of IY is clear. | ||
| 44229 | CALL Z,TrimObjectSprite | |||
| 44232 | CALL SetObjectAttributes | Call SetObjectAttributes. | ||
| 44235 | LD IX,(44358) | Fetch the word at CurrentObject into IX. | ||
| 44239 | CALL CheckObjectHitByShot | Call CheckObjectHitByShot. | ||
| UpdateMapObjects_Next | 44242 | POP IX | Bring IX back off the stack. | |
| 44244 | LD BC,26 | BC=26. | ||
| 44247 | ADD IX,BC | IX gains BC. | ||
| 44249 | POP BC | Bring BC back off the stack. | ||
| 44250 | DJNZ UpdateMapObjects_Loop | Decrease B and jump to UpdateMapObjects_Loop until none remain. | ||
| 44252 | RET | Return. | ||
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