void BubbleSort(int n, int data[])
{register int i,j;

 for (i = 0; i < n-1; i++)
 /* LI: The i smallest elements are in their proper places.
        data[0],...,data[n-1] is a permutation of 
        data0[0],...,data0[n-1]. If 0 <= n, then i <= n.
        If n < 0, then i = 0. */
   for (j = n-1; j > i; --j)
     /* LI: data[j] is the smallest element in 
            data[j],...,data[n-1].
            data[0],...,data[n-1] is a permutation of 
            data0[0],...,data0[n-1]. j >= i. */
     if (data[j] < data[j-1])
       swap (data+j, data+(j-1));
}