| Routines

31670: Control the hook while it's flying

The address of this uninterruptible subcommand routine is placed into bytes 18 and 19 of the hook's buffer by the routine at 31713. It controls the hook until the end of its flight, at which point it places a rope above the roof of no. 19 if necessary, or else restores the hook to its original location on the top floor of no. 74.
Input
H | 229 (hook)
31670 | CALL 59848 | Update the SRB for the hook's current animatory state and location
31673 | LD L,20 | Byte 20 of the hook's buffer holds the distance remaining in the hook's flight
31675 | DEC (HL) | Decrease this by 1
31676 | JR Z,31688 | Jump if the hook's flight has ended
31678 | RLCA | Set the carry flag if the hook is flying rightwards
31679 | RRCA
31680 | DEC E | Decrement the hook's x-coordinate
31681 | JR NC,31685 | Jump if the hook is flying leftwards
31683 | INC E | Otherwise increment the hook's x-coordinate
31684 | INC E
31685 | JP NZ,59861 | Update the hook's animatory state and location and update the SRB (unless the hook has flown off the edge of the play area)
The hook's flight has ended (either naturally or by escaping the play area). Check whether it reached the roof of no. 17.
31688 | DEC L | L=19
31689 | XOR A | Remove the address of this routine from bytes 18 and 19 of the hook's buffer
31690 | LD (HL),A
31691 | LD L,3 | Clear all flags in byte 3 of the hook's buffer
31693 | LD (HL),A
31694 | DEC L | Set the hook's y-coordinate to 50 (out of sight)
31695 | LD (HL),50
31697 | LD A,D | A=hook's y-coordinate while it was flying
31698 | CP 9 | Was it greater than 9?
31700 | JR NC,31708 | Jump if so
31702 | LD A,E | A=x-coordinate of the hook at the end of its flight
31703 | CP 223 | Did the hook reach the roof of no. 17?
31705 | JP NC,64549 | Jump if so
31708 | LD HL,32028 | Reactivate the entry for the hook in the object table at 32028
31711 | DEC (HL)
31712 | RET |