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Routines |
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7603 | LD HL,$E601 | Point HL at byte 0x01 of Sam's buffer | ||||||
7606 | LD C,(HL) | C=Sam's x-coordinate | ||||||
7607 | INC L | L=0x02 | ||||||
7608 | LD B,(HL) | B=Sam's y-coordinate | ||||||
7609 | LD HL,$7D1C | Point HL at the object location table at 7D1C | ||||||
760C | LD A,(HL) | Collect the first byte of an entry | ||||||
760D | INC A | Have we reached the end of the table? | ||||||
760E | JR Z,$763C | Jump if so | ||||||
7610 | INC HL | Move HL to the second byte of the entry | ||||||
7611 | AND $02 | Is this entry active? | ||||||
7613 | JR NZ,$761F | Proceed to the next entry if not | ||||||
7615 | LD A,(HL) | A=x-coordinate of the object | ||||||
7616 | CP C | Is Sam's x-coordinate the same? | ||||||
7617 | JR NZ,$761F | Jump if not | ||||||
7619 | INC HL | Move HL to the third byte of the entry | ||||||
761A | LD A,(HL) | A=y-coordinate of the object | ||||||
761B | CP B | Set the zero flag if Sam's y-coordinate is the same | ||||||
761C | DEC HL | Move HL back to the second byte of the entry | ||||||
761D | JR Z,$7624 | Jump if Sam's coordinates match the object's | ||||||
761F | INC HL | Point HL at the first byte of the next entry | ||||||
7620 | INC HL | |||||||
7621 | INC HL | |||||||
7622 | JR $760C | Jump back to check the next entry | ||||||
Sam's coordinates match those of the object. Is it the hook or the budgie?
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7624 | DEC HL | Move HL back to the first byte of the entry | ||||||
7625 | BIT 6,(HL) | Is this entry for an object that can be picked up (i.e. the hook or the budgie)? | ||||||
7627 | JR Z,$763F | Jump if not | ||||||
7629 | LD A,($E600) | A=Sam's animatory state | ||||||
762C | AND $7F | Discard bit 7 (the direction bit) | ||||||
762E | CP $06 | 0x06: Is Sam bending his knees? | ||||||
7630 | JR NZ,$763E | Jump if not | ||||||
7632 | INC (HL) | Increment the first byte of the entry (thus deactivating it) | ||||||
7633 | INC HL | Point HL at the fourth byte of the entry | ||||||
7634 | INC HL | |||||||
7635 | INC HL | |||||||
7636 | LD A,(HL) | Pick up the fourth byte of the entry | ||||||
7637 | LD HL,$7FE9 | Set the appropriate bit at 7FE9 to give Sam the object | ||||||
763A | OR (HL) | |||||||
763B | LD (HL),A | |||||||
763C | JR $7683 | Jump forward to update the icon panel | ||||||
763E | DEC (HL) | Decrement the first byte of the entry | ||||||
763F | INC (HL) | Increment the first byte of the entry (thus deactivating it if it's not the hook or the budgie) | ||||||
7640 | LD A,(HL) | A=first byte of the entry | ||||||
7641 | INC HL | Point HL at the fourth byte of the entry | ||||||
7642 | INC HL | |||||||
7643 | INC HL | |||||||
7644 | PUSH HL | Save the object table entry pointer | ||||||
7645 | PUSH BC | Save Sam's coordinates | ||||||
7646 | BIT 6,A | Is this entry for an object that can be picked up (i.e. the hook or the budgie)? | ||||||
7648 | JR Z,$7654 | Jump if not | ||||||
764A | LD A,(HL) | A=fourth byte of the entry | ||||||
764B | LD HL,$7FA8 | Store the object ID at 7FA8 for now | ||||||
764E | LD (HL),A | |||||||
764F | POP BC | Restore Sam's coordinates to BC | ||||||
7650 | POP HL | Restore the object table entry pointer to HL | ||||||
7651 | INC HL | Point HL at the first byte of the next entry | ||||||
7652 | JR $760C | Jump back to check the next entry | ||||||
It's not the hook or the budgie. Does a message need to be displayed?
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7654 | BIT 5,A | Is this entry for a message that needs to be displayed? | ||||||
7656 | JR Z,$765E | Jump if not | ||||||
7658 | LD A,(HL) | A=message number | ||||||
7659 | CALL $6EC5 | Queue the message | ||||||
765C | JR $764F | Jump back to check the next entry | ||||||
It's not the hook, the budgie or a message. Is it a key?
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765E | BIT 4,A | Is this entry for a key? | ||||||
7660 | JR Z,$7671 | Jump if not | ||||||
7662 | LD A,(HL) | A=key identifier (0x08, 0x10, 0x20 or 0x40) | ||||||
7663 | LD HL,$7FEA | Set the appropriate bit at 7FEA, thus giving Sam the key | ||||||
7666 | OR (HL) | |||||||
7667 | LD (HL),A | |||||||
7668 | LD A,$64 | $100 to add to Sam's cash supply | ||||||
766A | JR $7672 | |||||||
766C | INC D | This block of code is never executed | ||||||
766D | LD D,$02 | |||||||
766F | JR $767C | |||||||
If it's not the hook, the budgie, a message or a key, it must be cash.
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7671 | LD A,(HL) | A=number of bucks | ||||||
7672 | CALL $6E92 | Add this to Sam's total | ||||||
7675 | LD HL,$1406 | Prepare the cash bonus sound effect parameters | ||||||
7678 | LD C,$90 | |||||||
767A | LD D,$01 | |||||||
767C | LD A,$02 | |||||||
767E | CALL $7565 | Make a sound effect | ||||||
7681 | JR $764F | Jump back to check the next entry | ||||||
Now we set the attribute bytes for the budgie and hook in the icon panel.
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7683 | LD HL,$7FA8 | 7FA8 holds the ID of the object Sam is standing next to (if any) | ||||||
7686 | LD A,(HL) | A=object ID | ||||||
7687 | LD (HL),$00 | Reset 7FA8 to 0 | ||||||
7689 | LD L,$E9 | HL=7FE9 (object inventory) | ||||||
768B | LD H,(HL) | H=object inventory flags | ||||||
768C | LD L,A | L=ID of the object Sam is standing next to (if any) | ||||||
768D | LD E,$B0 | 0xB0 is the LSB of 5AB0 (the attribute file address for the top-left tile of the budgie icon) | ||||||
768F | LD BC,$0602 | B=6, C=2 (2 objects: budgie and hook) | ||||||
7692 | RL L | Move an object ID bit (if any) into bit 0 of H, and an object inventory flag into the carry flag | ||||||
7694 | RL H | |||||||
7696 | LD A,$30 | 0x30=PAPER 6: INK 0 | ||||||
7698 | JR C,$76A0 | Jump if Sam already has this object | ||||||
769A | ADD A,B | A=0x38 (INK 6: PAPER 6) | ||||||
769B | BIT 0,H | Is Sam standing next to this object? | ||||||
769D | JR Z,$76A0 | Jump if not | ||||||
769F | LD A,B | A=0x06 (INK 6: PAPER 0) | ||||||
76A0 | CALL $7025 | Set the attribute bytes for the object in the icon panel | ||||||
76A3 | LD E,$B2 | 0xB2 is the LSB of 5AB2 (the attribute file address for the top-left tile of the hook icon) | ||||||
76A5 | DEC C | Have we dealt with both objects yet? | ||||||
76A6 | JR NZ,$7692 | Jump back to deal with the second object if not | ||||||
Now we display the keys Sam has found.
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76A8 | LD A,($7FEA) | Pick up the key inventory flags from 7FEA | ||||||
76AB | ADD A,A | Move bits 3-6 into bits 4-7 (thus discarding bit 7, which corresponds to the key to no. 19) | ||||||
76AC | LD BC,$0430 | B=4 (there are 4 keys), C=0x30 (INK 6: PAPER 0) | ||||||
76AF | LD HL,$5AF0 | Point HL at the attribute byte for the leftmost key in the icon panel | ||||||
This entry point is used by the routine at 7414 with HL=5AE8 (attribute byte for the leftmost first aid kit in the icon panel) and C=0x32 (INK 2: PAPER 6).
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76B2 | LD (HL),$36 | Set the attribute byte to 0x36 (INK 6: PAPER 6) by default | ||||||
76B4 | ADD A,A | Should there be a first aid kit or key displayed here? | ||||||
76B5 | JR NC,$76B8 | Jump if not | ||||||
76B7 | LD (HL),C | Otherwise reveal the first aid kit or key by setting the attribute byte to 0x32 (INK 2: PAPER 6) or 0x30 (INK 6: PAPER 0) | ||||||
76B8 | INC L | Move HL to the attribute byte for the next first aid kit or key | ||||||
76B9 | DJNZ $76B2 | Jump back until all the first aid kits or keys have been done | ||||||
76BB | RET |
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