busybox

/* vi: set sw=4 ts=4: */

/*

 * dirhash.c -- Calculate the hash of a directory entry

 *

 * Copyright (c) 2001  Daniel Phillips

 *

 * Copyright (c) 2002 Theodore Ts'o.

 *

 * %Begin-Header%

 * This file may be redistributed under the terms of the GNU Public

 * License.

 * %End-Header%

 */

​

#include <stdio.h>

#include <string.h>

​

#include "ext2_fs.h"

#include "ext2fs.h"

​

/*

 * Keyed 32-bit hash function using TEA in a Davis-Meyer function

 *   H0 = Key

 *   Hi = E Mi(Hi-1) + Hi-1

 *

 * (see Applied Cryptography, 2nd edition, p448).

 *

 * Jeremy Fitzhardinge <jeremy@zip.com.au> 1998

 *

 * This code is made available under the terms of the GPL

 */

#define DELTA 0x9E3779B9

​

static void TEA_transform(__u32 buf[4], __u32 const in[])

{

    __u32   sum = 0;

    __u32   b0 = buf[0], b1 = buf[1];

    __u32   a = in[0], b = in[1], c = in[2], d = in[3];

    int n = 16;

​

    do {

        sum += DELTA;

        b0 += ((b1 << 4)+a) ^ (b1+sum) ^ ((b1 >> 5)+b);

        b1 += ((b0 << 4)+c) ^ (b0+sum) ^ ((b0 >> 5)+d);

    } while (--n);

​

    buf[0] += b0;

    buf[1] += b1;

}

​

/* F, G and H are basic MD4 functions: selection, majority, parity */

#define F(x, y, z) ((z) ^ ((x) & ((y) ^ (z))))

#define G(x, y, z) (((x) & (y)) + (((x) ^ (y)) & (z)))

#define H(x, y, z) ((x) ^ (y) ^ (z))

​

/*

 * The generic round function.  The application is so specific that

 * we don't bother protecting all the arguments with parens, as is generally

 * good macro practice, in favor of extra legibility.

 * Rotation is separate from addition to prevent recomputation

 */

#define ROUND(f, a, b, c, d, x, s)  \

    (a += f(b, c, d) + x, a = (a << s) | (a >> (32-s)))