Routines
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25399: Move Horace and the guards
Called from the main loop at 25129.
25399 LD A,(31841) Decrement the sprite movement timer.
25402 DEC A
25403 LD (31841),A
25406 RET NZ Return unless it's zero.
25407 LD A,(31842) Reset the sprite movement timer to the value of the game speed parameter.
25410 LD (31841),A
25413 LD A,(31865) Pick up the tunnel timer.
25416 AND A Is Horace in a tunnel at the moment?
25417 JR NZ,25535 Jump if so.
25419 LD A,(31856) Pick up Horace's animation frame.
25422 LD HL,(31851) Pick up Horace's current location.
25425 CALL 27842 Check the tiles in front of Horace.
25428 CP 0 Is there anything in front of Horace?
25430 JR Z,25515 Jump if not.
25432 CP 1 Is Horace facing a tunnel entrance?
25434 JR Z,25450 Jump if so.
25436 CP 2 Is Horace facing a maze exit or entrance?
25438 JR NZ,25529 Jump if not.
25440 LD A,(31856) Pick up Horace's animation frame.
25443 CP 1 Is Horace facing right?
25445 JP Z,27166 Jump if so (Horace is leaving the maze).
25448 JR 25529
Horace is about to enter a tunnel.
25450 LD A,90 Initialise the tunnel timer.
25452 LD (31865),A
25455 LD BC,(28623) Pick up the tunnel offset for the current maze.
25459 LD HL,(31851) Pick up Horace's location.
25462 LD A,(31856) Pick up Horace's animation frame.
25465 AND A Is Horace going up?
25466 JR Z,25472 Jump if so.
25468 SBC HL,BC Subtract the tunnel offset from Horace's location.
25470 JR 25473
25472 ADD HL,BC Add the tunnel offset to Horace's location.
25473 PUSH HL Save HL (which holds Horace's new location) temporarily.
25474 LD HL,31849 Pick up the sound on/off indicator.
25477 LD C,16 Initialise C for the loop that follows.
25479 PUSH BC Save the loop counter (unnecessarily).
25480 LD B,C Set B and E equal to 8*C. This value determines the pitch.
25481 SLA B
25483 SLA B
25485 SLA B
25487 LD E,B
25488 LD D,8 This value determines the duration.
25490 LD B,E Produce a sound (if the sound on/off indicator is on) with pitch and duration determined by E and D.
25491 LD A,31
25493 AND (HL)
25494 OUT (254),A
25496 DJNZ 25496
25498 LD A,7
25500 OUT (254),A
25502 LD B,E
25503 DJNZ 25503
25505 DEC D
25506 JR NZ,25490
25508 POP BC Restore the loop counter to C (unnecessarily).
25509 DEC C Finished yet?
25510 JR NZ,25479 Jump back if not.
25512 POP HL Restore Horace's new location to HL.
25513 JR 25524
There's nothing in front of Horace, so he can move one space forward.
25515 LD HL,(31851) Pick up Horace's current location.
25518 LD A,(31856) Pick up Horace's animation frame.
25521 CALL 27927 Get the location of the spot one space in front of Horace.
25524 LD (31853),HL Update Horace's location.
25527 JR 25535
Horace is facing a wall or the maze entrance, and so cannot move forward.
25529 LD HL,(31851) Pick up Horace's current location.
25532 LD (31853),HL Set Horace's new location.
Now it's time to move the guards.
25535 LD HL,28070 Point HL at the first of the guard countdown timers.
25538 LD B,4 There are four guards to consider.
25540 PUSH BC Save the guard counter.
25541 LD A,(HL) Set the zero flag if this guard is in play.
25542 INC HL
25543 OR (HL)
25544 INC HL Point HL at the next guard's countdown timer.
25545 PUSH HL Save the guard countdown timer pointer.
25546 JR NZ,25557 Jump if this guard is not in play at the moment.
25548 CALL 27199 Copy the guard's buffer into the temporary location (28088).
25551 CALL 25562 Move the guard.
25554 CALL 27242 Copy the guard's buffer back to the original location.
25557 POP HL Restore the guard countdown timer pointer to HL.
25558 POP BC Restore the guard counter to B.
25559 DJNZ 25540 Jump back to handle the next guard.
25561 RET
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