Routines
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CF50: Check Wall Horizontal
Used by the routine at TestMoveRight.
Checks whether an object that is moving in the direction of heading one touches a wall in the cell containing a point. If it does, HorizontalSpeed is reduced by twice the depth and the object is marked as having hit a wall.
Input
DE The horizontal position of the point
HL The vertical position of the point
IX The address of the object
Output
F The carry flag is set if the object hit a wall
Check the walls, then push the object back if it is touching one.
CheckWallHorizontal CF50 CALL CheckWallsVerticalFirst Call CheckWallsVerticalFirst.
CF53 RET NC Return if the object is not touching a wall.
This entry point is used by the routine at CheckWallHorizontalReverse.
Reduce HorizontalSpeed by twice the depth.
CheckWallHorizontal_PushBack CF54 ADD A,A Double the depth and keep it in C.
CF55 LD C,A
CF56 LD A,($A214) Fetch HorizontalSpeed.
CF59 ADD A,C Add the depth and set HorizontalSpeed.
CF5A LD ($A214),A
CF5D JR CheckWall_Hit Jump to CheckWall_Hit.
View the equivalent code in;
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