// Hash function based on MD5
// This class computes MD5 hashes.
// Manually translated by Jon Howell <jonh@cs.dartmouth.edu>
// from some public domain C code (md5.c) included with the ssh-1.2.22 source.
//
// Modified by Matthew Cary for cse326 2004 winter


public class Hash326 {

	static private abstract class Fcore {
		abstract int f(int x, int y, int z);
	}
	static private Fcore F1 = new Fcore() {
		int f(int x, int y, int z) { return (z ^ (x & (y ^ z))); }};
	static private Fcore F2 = new Fcore() {
		int f(int x, int y, int z) { return (y ^ (z & (x ^ y))); }};
	static private Fcore F3 = new Fcore() {
		int f(int x, int y, int z) { return (x ^ y ^ z); }};
	static private Fcore F4 = new Fcore() {
		int f(int x, int y, int z) { return (y ^ (x | ~z)); }};

	static private int MD5STEP(Fcore f, int w, int x, int y, int z, int data, int s) {
		w += f.f(x, y, z) + data;
		w = w<<s | w>>>(32-s);
		w += x;
		return w;
	}

	static public int hash(int n, int v) {
		int buf[] = new int[4];
		int vals[] = new int[16];
		int a,b,c,d;

		// fill the hash accumulator with a seed value
		a = 0x67452301;
		b = 0xefcdab89;
		c = 0x98badcfe;
		d = 0x10325476;

		for (int i=0; i < 8; i++) {
			vals[i] = n;
			vals[8+i] = v;
		}

	    a = MD5STEP(F1, a, b, c, d, vals[0]	+ 0xd76aa478, 7);
	    d = MD5STEP(F1, d, a, b, c, vals[1]	+ 0xe8c7b756, 12);
	    c = MD5STEP(F1, c, d, a, b, vals[2]	+ 0x242070db, 17);
	    b = MD5STEP(F1, b, c, d, a, vals[3]	+ 0xc1bdceee, 22);
	    a = MD5STEP(F1, a, b, c, d, vals[4]	+ 0xf57c0faf, 7);
	    d = MD5STEP(F1, d, a, b, c, vals[5]	+ 0x4787c62a, 12);
	    c = MD5STEP(F1, c, d, a, b, vals[6]	+ 0xa8304613, 17);
	    b = MD5STEP(F1, b, c, d, a, vals[7]	+ 0xfd469501, 22);
	    a = MD5STEP(F1, a, b, c, d, vals[8]	+ 0x698098d8, 7);
	    d = MD5STEP(F1, d, a, b, c, vals[9]	+ 0x8b44f7af, 12);
	    c = MD5STEP(F1, c, d, a, b, vals[10]	+ 0xffff5bb1, 17);
	    b = MD5STEP(F1, b, c, d, a, vals[11]	+ 0x895cd7be, 22);
	    a = MD5STEP(F1, a, b, c, d, vals[12]	+ 0x6b901122, 7);
	    d = MD5STEP(F1, d, a, b, c, vals[13]	+ 0xfd987193, 12);
	    c = MD5STEP(F1, c, d, a, b, vals[14]	+ 0xa679438e, 17);
	    b = MD5STEP(F1, b, c, d, a, vals[15]	+ 0x49b40821, 22);
	
	    a = MD5STEP(F2, a, b, c, d, vals[1]	+ 0xf61e2562, 5);
	    d = MD5STEP(F2, d, a, b, c, vals[6]	+ 0xc040b340, 9);
	    c = MD5STEP(F2, c, d, a, b, vals[11]	+ 0x265e5a51, 14);
	    b = MD5STEP(F2, b, c, d, a, vals[0]	+ 0xe9b6c7aa, 20);
	    a = MD5STEP(F2, a, b, c, d, vals[5]	+ 0xd62f105d, 5);
	    d = MD5STEP(F2, d, a, b, c, vals[10]	+ 0x02441453, 9);
	    c = MD5STEP(F2, c, d, a, b, vals[15]	+ 0xd8a1e681, 14);
	    b = MD5STEP(F2, b, c, d, a, vals[4]	+ 0xe7d3fbc8, 20);
	    a = MD5STEP(F2, a, b, c, d, vals[9]	+ 0x21e1cde6, 5);
	    d = MD5STEP(F2, d, a, b, c, vals[14]	+ 0xc33707d6, 9);
	    c = MD5STEP(F2, c, d, a, b, vals[3]	+ 0xf4d50d87, 14);
	    b = MD5STEP(F2, b, c, d, a, vals[8]	+ 0x455a14ed, 20);
	    a = MD5STEP(F2, a, b, c, d, vals[13]	+ 0xa9e3e905, 5);
	    d = MD5STEP(F2, d, a, b, c, vals[2]	+ 0xfcefa3f8, 9);
	    c = MD5STEP(F2, c, d, a, b, vals[7]	+ 0x676f02d9, 14);
	    b = MD5STEP(F2, b, c, d, a, vals[12]	+ 0x8d2a4c8a, 20);
	
	    a = MD5STEP(F3, a, b, c, d, vals[5]	+ 0xfffa3942, 4);
	    d = MD5STEP(F3, d, a, b, c, vals[8]	+ 0x8771f681, 11);
	    c = MD5STEP(F3, c, d, a, b, vals[11]	+ 0x6d9d6122, 16);
	    b = MD5STEP(F3, b, c, d, a, vals[14]	+ 0xfde5380c, 23);
	    a = MD5STEP(F3, a, b, c, d, vals[1]	+ 0xa4beea44, 4);
	    d = MD5STEP(F3, d, a, b, c, vals[4]	+ 0x4bdecfa9, 11);
	    c = MD5STEP(F3, c, d, a, b, vals[7]	+ 0xf6bb4b60, 16);
	    b = MD5STEP(F3, b, c, d, a, vals[10]	+ 0xbebfbc70, 23);
	    a = MD5STEP(F3, a, b, c, d, vals[13]	+ 0x289b7ec6, 4);
	    d = MD5STEP(F3, d, a, b, c, vals[0]	+ 0xeaa127fa, 11);
	    c = MD5STEP(F3, c, d, a, b, vals[3]	+ 0xd4ef3085, 16);
	    b = MD5STEP(F3, b, c, d, a, vals[6]	+ 0x04881d05, 23);
	    a = MD5STEP(F3, a, b, c, d, vals[9]	+ 0xd9d4d039, 4);
	    d = MD5STEP(F3, d, a, b, c, vals[12]	+ 0xe6db99e5, 11);
	    c = MD5STEP(F3, c, d, a, b, vals[15]	+ 0x1fa27cf8, 16);
	    b = MD5STEP(F3, b, c, d, a, vals[2]	+ 0xc4ac5665, 23);
	
	    a = MD5STEP(F4, a, b, c, d, vals[0]	+ 0xf4292244, 6);
	    d = MD5STEP(F4, d, a, b, c, vals[7]	+ 0x432aff97, 10);
	    c = MD5STEP(F4, c, d, a, b, vals[14]	+ 0xab9423a7, 15);
	    b = MD5STEP(F4, b, c, d, a, vals[5]	+ 0xfc93a039, 21);
	    a = MD5STEP(F4, a, b, c, d, vals[12]	+ 0x655b59c3, 6);
	    d = MD5STEP(F4, d, a, b, c, vals[3]	+ 0x8f0ccc92, 10);
	    c = MD5STEP(F4, c, d, a, b, vals[10]	+ 0xffeff47d, 15);
	    b = MD5STEP(F4, b, c, d, a, vals[1]	+ 0x85845dd1, 21);
	    a = MD5STEP(F4, a, b, c, d, vals[8]	+ 0x6fa87e4f, 6);
	    d = MD5STEP(F4, d, a, b, c, vals[15]	+ 0xfe2ce6e0, 10);
	    c = MD5STEP(F4, c, d, a, b, vals[6]	+ 0xa3014314, 15);
	    b = MD5STEP(F4, b, c, d, a, vals[13]	+ 0x4e0811a1, 21);
	    a = MD5STEP(F4, a, b, c, d, vals[4]	+ 0xf7537e82, 6);
	    d = MD5STEP(F4, d, a, b, c, vals[11]	+ 0xbd3af235, 10);
	    c = MD5STEP(F4, c, d, a, b, vals[2]	+ 0x2ad7d2bb, 15);
	    b = MD5STEP(F4, b, c, d, a, vals[9]	+ 0xeb86d391, 21);
	
		// add the initial values once again to the output

	    int retval =  a + 0x67452301;
		// java doesn't have unsigned vals, so a little bit of tomfoolery.
		if (retval < 0) retval *= -1;
		return retval;
	}
}