Routines
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27886: Get the x-coordinate range within which a character can see or be seen
Used by the routines at 28002 and 28029. Returns with C and B holding the lower and upper x-coordinates of the range within which the target character can see or be seen. This routine is called with H holding either (a) the character number of a teacher (to determine where kids must be in order to get lines), or (b) the character number of a kid (to determine where a teacher must be in order to give lines).
Input
H Target character's number
27886 LD L,2 Point HL at byte 2 of the character's buffer
27888 LD D,(HL) D=character's y-coordinate
27889 DEC L L=1
27890 LD E,(HL) E=character's x-coordinate
27891 LD C,0 Prepare a lower limit of 0 in case E<10
27893 LD A,E A=X (character's x-coordinate)
27894 SUB 10
27896 JR C,27899
27898 LD C,A C=max(0, X-10) (lower limit of the range)
27899 ADD A,20
27901 LD B,A B=X+10 (upper limit of the range)
27902 RET
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