函数ut_bit_set_nth

/*****************************************************************//**
Sets the nth bit of a ulint.
@return    the ulint with the bit set as requested */
UNIV_INLINE
ulint
ut_bit_set_nth(
/*===========*/
    ulint    a,    /*!< in: ulint */
    ulint    n,    /*!< in: nth bit requested */
    ibool    val)    /*!< in: value for the bit to set */
{
    ut_ad(n <  * sizeof(ulint));
#if TRUE != 1
# error "TRUE != 1"
#endif
    if (val) {
         << n) | a);
    } else {
         << n) & a);
    }
}