Routines
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26453: Get the identifier and coordinates of the blackboard close to a character
Used by the routines at 24133, 26513, 26752, 28658 and 61696. If the character is not standing at a blackboard, the routine returns with the carry flag set. Otherwise the routine returns with the carry flag reset, B holding the blackboard identifier (the LSB of 32596, 32602, 32608, 32614 or 32620), and DE holding the coordinates of the top left-hand square of the board.
Input
H Character number (200-204, 206)
26453 LD B,3 There are three blackboards on the top floors
26455 LD DE,54071 The table at 54071 contains the x-coordinates of the left edges of the blackboards
26458 LD L,2 Byte 2 of the character's buffer holds his y-coordinate
26460 LD A,(HL) Pick this up in A
26461 DEC L L=1
26462 CP B Is the character on the top floor?
26463 JR Z,26472 Jump if so
26465 LD E,58 DE=54074
26467 DEC B B=2 (two blackboards on the middle floors)
26468 CP 10 Is the character on the middle floor?
26470 JR NZ,26484 Jump if not
26472 LD A,(DE) A=x-coordinate of the left edge of a blackboard
26473 CP (HL) Is the character to the left of this blackboard?
26474 JR NC,26484 Jump if so
26476 ADD A,4 Is the character no more than 4 (or 12, if coming from 28658) spaces to the right of the left edge of this blackboard?
26478 CP (HL)
26479 JR NC,26486 Jump if so
26481 INC E Next blackboard
26482 DJNZ 26472
26484 SCF Signal: the character is not standing at a blackboard
26485 RET
The character is standing close enough to the blackboard (to either write on it or start wiping it).
26486 EX DE,HL Now HL points to the blackboard info table
26487 LD A,(HL) A=x-coordinate of the left edge of the blackboard (from the table at 54071)
26488 INC H
26489 LD B,(HL) B=blackboard identifier (from the table at 54327)
26490 INC H
26491 LD H,(HL) H=y-coordinate of the top row of the blackboard (from the table at 54583)
26492 LD L,A Pass the x-coordinate to L
26493 AND A Clear the carry flag to indicate success
26494 EX DE,HL DE=coordinates of the top-left corner of the blackboard
26495 RET
The contents of the blackboard info tables are as follows:
x ID y Room
3 84 3 Blue Room
41 90 3 Yellow Room
161 96 3 Top-floor room in the girls' skool
32 102 9 Science Lab
161 108 9 Middle-floor room in the girls' skool
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