| Routines

28767: Check for a closed door in front of a character

Used by the routines at 25843 and 28814. Returns with the carry flag set if the character is facing a closed door, and C holding the door identifier:
ID | Door
--- | ---
1 | Left study door
2 | Right study door
4 | Science Lab storeroom door
8 | Boys' skool door
16 | Skool gate
Input
H | Character number (183-210)
28767 | LD L,0 | Pick up the character's animatory state in A
28769 | LD A,(HL)
28770 | RLCA | Set A=-1 if the character is facing left, 1 if facing right
28771 | CCF
28772 | SBC A,A
28773 | ADD A,A
28774 | INC A
28775 | INC L | Byte 1 of the character's buffer holds his x-coordinate
28776 | ADD A,(HL) | Add this to A
28777 | LD E,A | E=x-coordinate of the location directly in front of the character
28778 | INC L | L=2
28779 | LD D,(HL) | Pick up the character's y-coordinate in D
28780 | PUSH HL |
28781 | LD HL,47422 | 47422 is the address of the door location table
28784 | LD BC,1281 | B=5 (there are 5 doors), C=1 (the left study door is the first one)
28787 | LD A,E | A=x-coordinate of the location directly in front of the character
28788 | CP (HL) | Compare this with the x-coordinate of the door
28789 | INC HL |
28790 | JR NZ,28796 | Jump if the x-coordinates don't match
28792 | LD A,D | A=character's y-coordinate
28793 | CP (HL) | Compare this with the y-coordinate of the door
28794 | JR Z,28804 | Jump if they match (the character is standing at this door)
28796 | INC HL |
28797 | RLC C | Move the set bit in C one place to the left
28799 | DJNZ 28787 | Jump back to consider the remaining doors
28801 | POP HL |
28802 | XOR A | Reset the carry flag: there is no door in front of the character
28803 | RET |
The character is standing in front of a door.
28804 | LD A,(32756) | Pick up the doors flags from 32756
28807 | AND C | Check the bit corresponding to the door
28808 | POP HL |
28809 | RET NZ | Return with the carry flag reset if the door is open
28810 | SCF | Set the carry flag: the door is closed
28811 | RET |