LOWER_MASK        118 third_party/mt19937ar/mt19937ar.cc             y = (mt[kk]&UPPER_MASK)|(mt[kk+1]&LOWER_MASK);
LOWER_MASK        122 third_party/mt19937ar/mt19937ar.cc             y = (mt[kk]&UPPER_MASK)|(mt[kk+1]&LOWER_MASK);
LOWER_MASK        125 third_party/mt19937ar/mt19937ar.cc         y = (mt[N-1]&UPPER_MASK)|(mt[0]&LOWER_MASK);