# define S1(t,x) _Off=(_Off+0)&~0; x=_Off; _Off=_Off+1
# define S2(t,x) _Off=(_Off+1)&~1; x=_Off; _Off=_Off+2
# define S4(t,x) _Off=(_Off+3)&~3; x=_Off; _Off=_Off+4
# define S1(t,x) _Off=(_Off+0)&~0; x=_Off; _Off=_Off+1
# define S2(t,x) _Off=(_Off+1)&~1; x=_Off; _Off=_Off+2
# define S4(t,x) _Off=(_Off+3)&~3; x=_Off; _Off=_Off+4