Routines
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E512: Controls: Left/ Up
Used by the routine at Controls_CheckRightUp.
Did the player press diagonally left/ up?
Controls_CheckLeftUp E512 CP $0A Jump to F43E if the player didn't press left up (02+08=0A).
E514 JP NZ,$F43E
Left/ up movement checks for boundaries and the home box.
E517 LD A,($D82D) A=*DestinationCursor_X_Position.
Can the player move left?
E51A CP $05 If *DestinationCursor_X_Position is at or beyond the left-most boundary jump to MoveUp_Checks.
E51C JP M,MoveUp_Checks
Is the player about to enter the home box?
This is position 06/ 06 and also position 06/ 02:
06/ 06 (Below) 06/ 02 (Beside)
cursor-06-06 cursor-06-02
E51F CP $06 If *DestinationCursor_X_Position is not 06 (which confirms the player can't be beside the home box), jump to MoveLeftUp.
E521 JR NZ,MoveLeftUp
Else it is now confirmed that *DestinationCursor_X_Position is at position 06.
E523 LD A,($D82C) If *DestinationCursor_Y_Position is 06 (which confirms that yes, the player is diagonally below the home box) jump to Handler_CursorMovement.
E526 CP $06
E528 JP Z,Handler_CursorMovement
E52B CP $02 If *DestinationCursor_Y_Position is 02 (which confirms that yes, the player is beside the home box) jump to MoveLeft_Checks so this routine can handle the rest of the movement update.
E52D JP Z,MoveLeft_Checks
Normal left movement.
E530 LD A,($D82D) Reload *DestinationCursor_X_Position into A.
MoveLeftUp E533 SUB $04 Move 04 character blocks left.
E535 LD ($D82D),A Update *DestinationCursor_X_Position.
Update the tile ID the player has now landed on (note, this only covers the "left" movement here - the jump below covers if up should also alter the value).
E538 DEC (HL) Decrease *HL by one.
E539 JP MoveUp_Checks Jump to MoveUp_Checks.
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