Division.cs

using System;

class Division
{
    static void Main(string[] args)
    {
        var r = new Random();
        for (int i = 0; i < 10; i++)
        {
            int a = r.Next(), b = r.Next() & 0xffff;
            Console.WriteLine("{0} / {1} = {2} ({3})", a, b, a / b, Div(a, b));
        }
    }

    static int Div(int a, int b)
    {
        if (b == 0) throw new DivideByZeroException();

        uint aa = (uint)Math.Abs(a), ab = (uint)Math.Abs(b);
        if (aa < ab) return 0;

        int sa = Math.Sign(a), sb = Math.Sign(b);
        uint ret = 0, v = 1, aa2 = aa, ab2 = ab;
        for (; aa > ab2; ab2 <<= 1, v <<= 1) ;
        for (; ; )
        {
            ab2 >>= 1;
            v >>= 1;
            if (v == 0) break;
            if (aa2 >= ab2)
            {
                ret += v;
                aa2 -= ab2;
            }
        }
        return sa == sb ? (int)ret : -(int)ret;
    }
}