In the algorithm there is a subtraction (int - unsigned), which results (potentially overflowed)
unsigned.
Passing this to macro ABS and the assigning to int doesn't work ( unsigned is always >= 0 ).
Fix this by replacing (dangerous) ABS macro with stdlib's standard "int abs(int)"
and change the substraction to (int - int).
Signed-off-by: Jukka Laitinen <jukkax@ssrc.tii.ae>