Routines
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36564: Move Willy (2)
Used by the routine at 36307. This routine checks the keyboard and joystick.
Input
HL Attribute buffer address of the left-hand cell below Willy's sprite (if Willy is not on a rope)
36564 LD E,255 Initialise E to 255 (all bits set); it will be used to hold keyboard and joystick readings
36566 LD A,(34262) Pick up the rope status indicator from 34262
36569 DEC A Is Willy on a rope?
36570 BIT 7,A
36572 JR Z,36602 Jump if so
36574 LD A,(34257) Pick up the airborne status indicator from 34257
36577 CP 12 Has Willy just landed after falling from too great a height?
36579 JP NC,37047 If so, kill him
36582 XOR A Reset the airborne status indicator at 34257 (Willy has landed safely)
36583 LD (34257),A
36586 LD A,(32973) Pick up the attribute byte of the conveyor tile for the current room from 32973
36589 CP (HL) Does the attribute byte of the left-hand cell below Willy's sprite match that of the conveyor tile?
36590 JR Z,36596 Jump if so
36592 INC HL Point HL at the right-hand cell below Willy's sprite
36593 CP (HL) Does the attribute byte of the right-hand cell below Willy's sprite match that of the conveyor tile?
36594 JR NZ,36602 Jump if not
36596 LD A,(32982) Pick up the direction byte of the conveyor definition from 32982 (0=left, 1=right)
36599 SUB 3 Now E=253 (bit 1 reset) if the conveyor is moving left, or 254 (bit 0 reset) if it's moving right
36601 LD E,A
36602 LD BC,57342 Read keys P-O-I-U-Y (right, left, right, left, right) into bits 0-4 of A
36605 IN A,(C)
36607 AND 31 Set bit 5 and reset bits 6 and 7
36609 OR 32
36611 AND E Reset bit 0 if the conveyor is moving right, or bit 1 if it's moving left
36612 LD E,A Save the result in E
36613 LD A,(34271) Pick up the game mode indicator (0, 1 or 2) from 34271
36616 AND 2 Now A=1 if Willy is running to the toilet, 0 otherwise
36618 RRCA
36619 XOR E Flip bit 0 of E if Willy is running to the toilet, forcing him to move right (unless he's jumped onto the bed, in which case bit 0 of E is now set, meaning that the conveyor does not move him, and the 'P' key has no effect; this is a bug)
36620 LD E,A
36621 LD BC,64510 Read keys Q-W-E-R-T (left, right, left, right, left) into bits 0-4 of A
36624 IN A,(C)
36626 AND 31 Keep only bits 0-4, shift them into bits 1-5, and set bit 0
36628 RLC A
36630 OR 1
36632 AND E Merge this keyboard reading into bits 1-5 of E
36633 LD E,A
36634 LD B,231 Read keys 1-2-3-4-5 ('5' is left) and 0-9-8-7-6 (jump, nothing, right, right, left) into bits 0-4 of A
36636 IN A,(C)
36638 RRCA Rotate the result right and set bits 0-2 and 4-7; this ignores every key except '5' and '6' (left)
36639 OR 247
36641 AND E Merge this reading of the '5' and '6' keys into bit 3 of E
36642 LD E,A
36643 LD B,239 Read keys 0-9-8-7-6 (jump, nothing, right, right, left) into bits 0-4 of A
36645 IN A,(C)
36647 OR 251 Set bits 0, 1 and 3-7; this ignores every key except '8' (right)
36649 AND E Merge this reading of the '8' key into bit 2 of E
36650 LD E,A
36651 IN A,(C) Read keys 0-9-8-7-6 (jump, nothing, right, right, left) into bits 0-4 of A
36653 RRCA Rotate the result right and set bits 0, 1 and 3-7; this ignores every key except '7' (right)
36654 OR 251
36656 AND E Merge this reading of the '7' key into bit 2 of E
36657 LD E,A
36658 LD A,(34254) Collect the Kempston joystick indicator from 34254
36661 OR A Is the joystick connected?
36662 JR Z,36674 Jump if not
36664 LD BC,31 Collect input from the joystick
36667 IN A,(C)
36669 AND 3 Keep only bits 0 (right) and 1 (left) and flip them
36671 CPL
36672 AND E Merge this reading of the joystick right and left buttons into bits 0 and 1 of E
36673 LD E,A
At this point, bits 0-5 in E indicate the direction in which Willy is being moved or trying to move. If bit 0, 2 or 4 is reset, Willy is being moved or trying to move right; if bit 1, 3 or 5 is reset, Willy is being moved or trying to move left.
36674 LD C,0 Initialise C to 0 (no movement)
36676 LD A,E Copy the movement bits into A
36677 AND 42 Keep only bits 1, 3 and 5 (the 'left' bits)
36679 CP 42 Are any of these bits reset?
36681 JR Z,36689 Jump if not
36683 LD C,4 Set bit 2 of C: Willy is moving left
36685 XOR A Reset the inactivity timer at 34272
36686 LD (34272),A
36689 LD A,E Copy the movement bits into A
36690 AND 21 Keep only bits 0, 2 and 4 (the 'right' bits)
36692 CP 21 Are any of these bits reset?
36694 JR Z,36702 Jump if not
36696 SET 3,C Set bit 3 of C: Willy is moving right
36698 XOR A Reset the inactivity timer at 34272
36699 LD (34272),A
36702 LD A,(34256) Pick up Willy's direction and movement flags from 34256
36705 ADD A,C Point HL at the entry in the left-right movement table at 33825 that corresponds to the direction Willy is facing, and the direction in which he is being moved or trying to move
36706 LD C,A
36707 LD B,0
36709 LD HL,33825
36712 ADD HL,BC
36713 LD A,(HL) Update Willy's direction and movement flags at 34256 with the entry from the left-right movement table
36714 LD (34256),A
That is left-right movement taken care of. Now check the jump keys.
36717 LD BC,32510 Read keys SHIFT-Z-X-C-V and B-N-M-SS-SPACE
36720 IN A,(C)
36722 AND 31 Are any of these keys being pressed?
36724 CP 31
36726 JR NZ,36751 Jump if so
36728 LD B,239 Read keys 6-7-8-9-0
36730 IN A,(C)
36732 BIT 0,A Is '0' being pressed?
36734 JR Z,36751 Jump if so
36736 LD A,(34254) Collect the Kempston joystick indicator from 34254
36739 OR A Is the joystick connected?
36740 JR Z,36796 Jump if not
36742 LD BC,31 Collect input from the joystick
36745 IN A,(C)
36747 BIT 4,A Is the fire button being pressed?
36749 JR Z,36796 Jump if not
A jump key or the fire button is being pressed. Time to make Willy jump.
36751 LD A,(34271) Pick up the game mode indicator from 34271
36754 BIT 1,A Is Willy running to the toilet?
36756 JR NZ,36796 Jump if so
36758 XOR A Initialise the jumping animation counter at 34261 to 0
36759 LD (34261),A
36762 LD (34272),A Reset the inactivity timer at 34272
36765 INC A Set the airborne status indicator at 34257 to 1: Willy is jumping
36766 LD (34257),A
36769 LD A,(34262) Pick up the rope status indicator from 34262
36772 DEC A Is Willy on a rope?
36773 BIT 7,A
36775 JR NZ,36796 Jump if not
36777 LD A,240 Set the rope status indicator at 34262 to 240
36779 LD (34262),A
36782 LD A,(34255) Round down Willy's y-coordinate at 34255 to the nearest multiple of 16; this might move him upwards a little, but ensures that his actual pixel y-coordinate is a multiple of 8 (making his sprite cell-aligned) before he begins the jump off the rope
36785 AND 240
36787 LD (34255),A
36790 LD HL,34256 Set bit 1 at 34256: during this jump off the rope, Willy will move in the direction he's facing
36793 SET 1,(HL)
36795 RET
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