| Routines

FC25: Add or remove the rope above the roof of no. 19

Used by the routines at 7BB6 (to add the rope) and FC00 (to remove it). Also updates the screen refresh buffer (SRB) once the rope has been added or removed.
FC25 | PUSH HL |
FC26 | PUSH DE |
FC27 | LD HL,$B91A | Flip bit 1 of the Z values in the block at B900 that correspond to the rope (reset=rope, set=no rope)
FC2A | LD A,(HL)
FC2B | XOR $02
FC2D | LD (HL),A
FC2E | INC L
FC2F | LD (HL),A
FC30 | LD E,$D0 | This is the x-coordinate of the left end of the rope
FC32 | LD BC,$0AFF | B=10 (y-coordinate of the rope), C=0xFF (11111111)
FC35 | CALL $F123 | Update the SRB for the left half of the rope
FC38 | LD E,$D8 | This is the x-coordinate of the middle of the rope
FC3A | LD BC,$0AFF | B=10 (y-coordinate of the rope), C=0xFF (11111111)
FC3D | CALL $F123 | Update the SRB for the right half of the rope
FC40 | POP DE |
FC41 | POP HL |
FC42 | RET |