/*
* Copyright (C) 2007 Oracle. All rights reserved.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public
* License v2 as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public
* License along with this program; if not, write to the
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* Boston, MA 021110-1307, USA.
*/
/*
* Original copy from:
* linux/fs/ext3/hash.c
*
* Copyright (C) 2002 by Theodore Ts'o
*
* This file is released under the GPL v2.
*
* This file may be redistributed under the terms of the GNU Public
* License.
*/
#include <linux/types.h>
#include "hash.h"
#define DELTA 0x9E3779B9
static void TEA_transform(__u32 buf[2], __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;
}
static void str2hashbuf(const char *msg, int len, __u32 *buf, int num)
{
__u32 pad, val;
int i;
pad = (__u32)len | ((__u32)len << 8);
pad |= pad << 16;
val = pad;
if (len > num*4)
len = num * 4;
for (i=0; i < len; i++) {
if ((i % 4) == 0)
val = pad;
val = msg[i] + (val << 8);
if ((i % 4) == 3) {
*buf++ = val;
val = pad;
num--;
}
}
if (--num >= 0)
*buf++ = val;
while (--num >= 0)
*buf++ = pad;
}
u64 btrfs_name_hash(const char *name, int len)
{
__u32 hash;
__u32 minor_hash = 0;
const char *p;
__u32 in[8], buf[4];
u64 hash_result;
if (len == 1 && *name == '.') {
return 1;
} else if (len == 2 && name[0] == '.' && name[1] == '.') {
return 2;
}
/* Initialize the default seed for the hash checksum functions */
buf[0] = 0x67452301;
buf[1] = 0xefcdab89;
buf[2] = 0x98badcfe;
buf[3] = 0x10325476;
p = name;
while (len > 0) {
str2hashbuf(p, len, in, 4);
TEA_transform(buf, in);
len -= 16;
p += 16;
}
hash = buf[0];
minor_hash = buf[1];
hash_result = buf[0];
hash_result <<= 32;
hash_result |= buf[1];
return hash_result;
}
