Routines
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43608: Move Right
Used by the routines at MoveEntity and MoveRobot.
Moves an entity in direction two, which increases the X position. See MoveEntity for how the move works.
Input
B Number of steps to take
DE X position
HL Y position
Output
A 1 if the entity has been blocked
B Number of steps that are left
DE New X position
F The zero flag is reset if the entity has been blocked
MoveRight 43608 LD A,B Return if there are no steps left.
43609 AND A
43610 RET Z
43611 LD A,E Jump if the entity is at the start of a cell.
43612 AND A
43613 JR Z,MoveRight_CellStart
43615 ADD A,B Add the steps to the fraction, and jump if that goes into the next cell.
43616 JR C,MoveRight_NextCell
43618 LD E,A Store the new fraction.
MoveRight_Finish 43619 XOR A Clear the number of steps that are left, and return with the zero flag set.
43620 LD B,A
43621 RET
MoveRight_NextCell 43622 LD B,A Keep the steps that are left over.
43623 LD A,D Fetch the X cell...
43624 INC A ...and add one...
43625 AND 63 ...making sure that the cell is within the map.
43627 LD D,A
43628 XOR A Move to the start of the cell, and return with the zero flag set.
43629 LD E,A
43630 RET Return.
MoveRight_CellStart 43631 ADD A,B Add the steps to the fraction...
43632 LD E,A ...and keep it.
43633 LD (38483),DE Keep this position.
43637 PUSH DE Save the X position.
43638 LD A,D Fetch the X cell...
43639 INC A ...and add one...
43640 AND 63 ...making sure that the cell is within the map.
43642 LD D,A
43643 CALL FindMapCell Find the cell using FindMapCell.
43646 JR Z,MoveRight_Clear Jump if the cell is empty.
43648 PUSH HL Save the Y position.
43649 LD HL,(38446) Fetch the address of the cell...
43652 LD A,(HL) ...and its contents...
43653 POP HL ...and restore the Y position.
43654 AND 15 Jump if the cell has no type.
43656 JR Z,MoveRight_Clear
43658 CP 15 Jump if the cell is not type 15, which is an obstacle.
43660 JR NZ,MoveRight_Blocked
MoveRight_Clear 43662 POP DE Restore the X position...
43663 JR MoveRight_Finish ...and jump to finish the move.
MoveRight_Blocked 43665 POP DE The entity is blocked, so restore the old X position.
43666 XOR A Clear the number of steps that are left...
43667 LD B,A
43668 LD E,A ...and the fraction...
43669 INC A ...and set A to 1.
43670 RET Return.
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