Manic Miner: Routine at 921B

| Routines

921B: Flip a switch in a Kong Beast cavern if Willy is touching it

Used by the routine at 9135. Returns with the zero flag set if Willy flips the switch.
Input
HL | Address of the switch's location in the attribute buffer at 5C00
921B | LD A,($806C) | Pick up the LSB of the address of Willy's location in the attribute buffer at 5C00 from 806C
921E | INC A | Is it equal to or one less than the LSB of the address of the switch's location?
921F | AND $FE
9221 | CP L
9222 | RET NZ | Return (with the zero flag reset) if not
9223 | LD A,($806D) | Pick up the MSB of the address of Willy's location in the attribute buffer at 5C00 from 806D
9226 | CP H | Does it match the MSB of the address of the switch's location?
9227 | RET NZ | Return (with the zero flag reset) if not
9228 | LD A,($8065) | Pick up the sixth byte of the graphic data for the switch tile from 8065
922B | LD H,$75 | Point HL at the sixth row of pixels of the switch tile in the screen buffer at 7000
922D | CP (HL) | Has the switch already been flipped?
922E | RET NZ | Return (with the zero flag reset) if so
Willy is flipping the switch.
922F | LD (HL),$08 | Update the sixth, seventh and eighth rows of pixels of the switch tile in the screen buffer at 7000 to make it appear flipped
9231 | INC H
9232 | LD (HL),$06
9234 | INC H
9235 | LD (HL),$06
9237 | XOR A | Set the zero flag: Willy has flipped the switch
9238 | OR A | This instruction is redundant
9239 | RET |