#define getsextet(UV, I) (( (UV) & ( 0x7f << (6*(I)) ) >> 6*(I))

##</code><code>##

#define clrsextet(UV, I) ( (UV) & ~( 0x7f << (6*(I)) )
#define setsextet(UV, I, S) ( (UV) | ( ((S) & 0x7f) << (6*(I)) )