Pushout function

[King_Cool]

Hi
Im trying to create a pixel perfect push-out function.

Example:
An Object moves from point A to point B, and at point B is stuck in an Obstacle.
Object then moves incrementally backwards untill he no longer is overlapping an obstacle ( with pixel perfect accuracy ).

Anybody got any ideas about how to do this, with perfect accuracy?
Thing is ive been trying for a long while now, ive got it got it pretty good, but there is an occasional error where the Object is shifted by a single pixel after the pushout, and i dont know where or at what point the system fails.

Im looking for:

A
Anybody having any new idea about how to do this with flawless accuracy.

B
Someone technical minded who can help me by looking at what ive got and identify the origin/ reason for the slight error.

Thanks in advance

[Phanto]

on loop "loop"
->move Object to x(Object)+1

on loop "loop"
if Object overlap Obstacle
-> move Object to x(Object)-1

[King_Cool]

Yes off cource thats easy
But a 'point' in my example above consists of an X and Y position
Objects dont just move along one of the axis alone in my case

[Phanto]

save position as two seperate values (X and Y) in Object alternable values and recall if object overlaps?