code: def rowxcol(row, col):
      
      row = row.reshape(4, 4)
      col = col.reshape(4, 8)
      ret = uint2exprs(0, 8)
      for i in range(4):
          for j in range(4):
              if row[i, j]:
                  ret ^= xtime(col[i], j)
      return ret
docs: Multiply one row and one column.