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Routines |
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Used by the routines at MOVE_ARCS, MOVE_ACTOR, MOVE_BAT, MOVE_HOPPER, MOVE_FACE, MOVE_GHOST, MOVE_WITCH and MOVE_FACING_FLYER.
The mirror image of CHECK_HIT. Same test, same 12-pixel box, but reading $EA98 onwards -- the upper half of the player's record, where a weapon in flight lives -- so this asks whether the player has hit the monster rather than the other way round. The two are called back to back from the same place.
This pair was previously written up as two entries of an 8-byte "object table". That was wrong. $EA90 is one 16-byte record laid out exactly like a monster's, and $EA98 is its second half, not a neighbouring record; the giveaway is that ACTOR_TO_WORKSPACE is called with $EA90 and with the monster records but never with $EA98.
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| CHECK_SHOT_HIT | 8566 | LD A,($EA99) | +$09 is the weapon's room, +$08 its type, +$0B and +$0C its position. | |||||||
| 8569 | LD E,$00 | |||||||||
| 856B | CP (IX+$01) | |||||||||
| 856E | RET NZ | |||||||||
| 856F | LD A,($EA98) | |||||||||
| 8572 | AND A | |||||||||
| 8573 | RET Z | |||||||||
| 8574 | LD A,($EA9B) | |||||||||
| 8577 | SUB (IX+$03) | |||||||||
| 857A | JP P,CHECK_SHOT_HIT_0 | |||||||||
| 857D | NEG | |||||||||
| CHECK_SHOT_HIT_0 | 857F | CP $0C | ||||||||
| 8581 | RET NC | |||||||||
| 8582 | LD A,($EA9C) | |||||||||
| 8585 | SUB (IX+$04) | |||||||||
| 8588 | JP P,CHECK_SHOT_HIT_1 | |||||||||
| 858B | NEG | |||||||||
| CHECK_SHOT_HIT_1 | 858D | CP $0C | ||||||||
| 858F | RET NC | |||||||||
| 8590 | LD A,$01 | |||||||||
| 8592 | LD ($EA9A),A | |||||||||
| 8595 | LD E,$01 | |||||||||
| 8597 | RET | |||||||||
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