I also noticed the following bugs :
1.
col << x; doesnt work
col = col << x; works

2.
P0 = (P0 & 0x0f8) | (col & 7);
doesnt work while :
P0 = P0 & 0x0f8;
P0 |= (col & 7);
works
the problem is I dont get error messages and i had to spend hours of debugging to find out these things.
I also noticed the more complicated and short the code is the more you get chance for errors.