Routines
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64162: Check whether a falling character has hit anyone on the head
Used by the routine at 64227. Returns with the zero flag set if the falling character has struck another character, and knocks that other character over.
Input
H Character number (215-230)
64162 LD L,1 Point HL at byte 1 of the falling character's buffer
64164 LD E,(HL) E=falling character's x-coordinate
64165 DEC E Decrement this
64166 INC L L=2
64167 LD D,(HL) D=falling character's y-coordinate
64168 INC D Add 3 to this
64169 INC D
64170 INC D
64171 LD HL,55042 H=215 (first potential target character to check), L=2
The following loop compares the falling character's coordinates with those of every other character to see if there was a collision.
64174 LD A,D A=3+falling character's y-coordinate
64175 CP (HL) Does it match the potential target's y-coordinate?
64176 JR NZ,64208 Jump if not to check the next potential target
64178 DEC L L=1
64179 LD A,(HL) A=T (potential target character's x-coordinate)
64180 SUB E A=T-x+1 (where x is the falling character's x-coordinate)
64181 CP 3 Is this less than 3?
64183 JR NC,64206 Jump if not to check the next potential target
64185 LD BC,64005 Point BC at the uninterruptible subcommand routine at 64005
64188 RRCA Does T=x?
64189 JR NC,64193 Jump if not
64191 LD C,9 BC=64009
64193 DEC L L=0
64194 LD A,(HL) A=target character's animatory state
64195 AND 7 Keep only bits 0-2
64197 CP 4 Is the target character in standing/walking animation phase 1-4?
64199 JR NC,64206 Jump if not to check the next potential target
64201 LD A,H A=target character's character number
64202 CALL 63981 Attempt to place the address of the uninterruptible subcommand routine at 64005 (if T=x-1 or x+1) or 64009 (if T=x) into bytes 18 and 19 of the target character's buffer
64205 RET Z Return with the zero flag set if the attempt was successful (the target character was not already occupied by some other uninterruptible subcommand)
64206 LD L,2 Point HL at byte 2 of the target character's buffer
64208 INC H Next potential target character to check
64209 LD A,H A=next target character number
64210 CP 231 Have we checked every potential target?
64212 JR NZ,64174 Jump back if not
64214 ADD A,A Reset the zero flag (no one was struck by the falling character)
64215 RET
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