COLL_REVERSE
coll_flags = COLL_REVERSE;
coll_flags = COLL_REVERSE;
int mask = (coll_flag & COLL_REVERSE) ? INT_SIGN_FLIP_MASK :
int mask = (coll_flag & COLL_REVERSE) ? INT_SIGN_FLIP_MASK :
coll_flags = COLL_REVERSE;
coll_flags = COLL_REVERSE;