https://bitbucket.org/ddevine/haiku
C++ | 257 lines | 181 code | 38 blank | 38 comment | 35 complexity | 47ef76b6d440fa15d863b176ae5fe06a MD5 | raw file
Possible License(s): Apache-2.0, LGPL-2.0, LGPL-2.1, MPL-2.0-no-copyleft-exception, MIT, ISC, BSD-3-Clause, AGPL-1.0, GPL-2.0, GPL-3.0, LGPL-3.0
``````

/*
* 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
*
* Jeremy has agreed to the contents of reiserfs/README. -Hans
* Yura's function is added (04/07/2000)
*/

// Modified by Ingo Weinhold (bonefish), Jan. 2003:
// Fixed r5_hash() and added key_offset_for_name().

//
// keyed_hash
// yura_hash
// r5_hash
//

#include "hashes.h"
#include "reiserfs.h"

#define DELTA 0x9E3779B9
#define FULLROUNDS 10		/* 32 is overkill, 16 is strong crypto */
#define PARTROUNDS 6		/* 6 gets complete mixing */

/* a, b, c, d - data; h0, h1 - accumulated hash */
#define TEACORE(rounds)							\
do {								\
uint32 sum = 0;						\
int n = rounds;						\
uint32 b0, b1;						\
\
b0 = h0;						\
b1 = h1;						\
\
do							\
{							\
sum += DELTA;					\
b0 += ((b1 << 4)+a) ^ (b1+sum) ^ ((b1 >> 5)+b);	\
b1 += ((b0 << 4)+c) ^ (b0+sum) ^ ((b0 >> 5)+d);	\
} while(--n);						\
\
h0 += b0;						\
h1 += b1;						\
} while(0)

uint32 keyed_hash(const signed char *msg, int len)
{
uint32 k[] = { 0x9464a485, 0x542e1a94, 0x3e846bff, 0xb75bcfc3};

uint32 h0 = k[0], h1 = k[1];
uint32 a, b, c, d;
int i;

//	assert(len >= 0 && len < 256);

pad = (uint32)len | ((uint32)len << 8);

while(len >= 16)
{
a = (uint32)msg[ 0]      |
(uint32)msg[ 1] << 8 |
(uint32)msg[ 2] << 16|
(uint32)msg[ 3] << 24;
b = (uint32)msg[ 4]      |
(uint32)msg[ 5] << 8 |
(uint32)msg[ 6] << 16|
(uint32)msg[ 7] << 24;
c = (uint32)msg[ 8]      |
(uint32)msg[ 9] << 8 |
(uint32)msg[10] << 16|
(uint32)msg[11] << 24;
d = (uint32)msg[12]      |
(uint32)msg[13] << 8 |
(uint32)msg[14] << 16|
(uint32)msg[15] << 24;

TEACORE(PARTROUNDS);

len -= 16;
msg += 16;
}

if (len >= 12)
{
//assert(len < 16);
if (len >= 16)
*(int *)0 = 0;

a = (uint32)msg[ 0]      |
(uint32)msg[ 1] << 8 |
(uint32)msg[ 2] << 16|
(uint32)msg[ 3] << 24;
b = (uint32)msg[ 4]      |
(uint32)msg[ 5] << 8 |
(uint32)msg[ 6] << 16|
(uint32)msg[ 7] << 24;
c = (uint32)msg[ 8]      |
(uint32)msg[ 9] << 8 |
(uint32)msg[10] << 16|
(uint32)msg[11] << 24;

for(i = 12; i < len; i++)
{
d <<= 8;
d |= msg[i];
}
}
else if (len >= 8)
{
//assert(len < 12);
if (len >= 12)
*(int *)0 = 0;
a = (uint32)msg[ 0]      |
(uint32)msg[ 1] << 8 |
(uint32)msg[ 2] << 16|
(uint32)msg[ 3] << 24;
b = (uint32)msg[ 4]      |
(uint32)msg[ 5] << 8 |
(uint32)msg[ 6] << 16|
(uint32)msg[ 7] << 24;

for(i = 8; i < len; i++)
{
c <<= 8;
c |= msg[i];
}
}
else if (len >= 4)
{
//assert(len < 8);
if (len >= 8)
*(int *)0 = 0;
a = (uint32)msg[ 0]      |
(uint32)msg[ 1] << 8 |
(uint32)msg[ 2] << 16|
(uint32)msg[ 3] << 24;

b = c = d = pad;
for(i = 4; i < len; i++)
{
b <<= 8;
b |= msg[i];
}
}
else
{
//assert(len < 4);
if (len >= 4)
*(int *)0 = 0;
a = b = c = d = pad;
for(i = 0; i < len; i++)
{
a <<= 8;
a |= msg[i];
}
}

TEACORE(FULLROUNDS);

/*	return 0;*/
return h0^h1;
}

/* What follows in this file is copyright 2000 by Hans Reiser, and the
* licensing of what follows is governed by reiserfs/README */

uint32 yura_hash (const signed char *msg, int len)
{
int j, pow;
uint32 a, c;
int i;

for (pow=1,i=1; i < len; i++) pow = pow * 10;

if (len == 1)
a = msg[0]-48;
else
a = (msg[0] - 48) * pow;

for (i=1; i < len; i++) {
c = msg[i] - 48;
for (pow=1,j=i; j < len-1; j++) pow = pow * 10;
a = a + c * pow;
}

for (; i < 40; i++) {
c = '0' - 48;
for (pow=1,j=i; j < len-1; j++) pow = pow * 10;
a = a + c * pow;
}

for (; i < 256; i++) {
c = i;
for (pow=1,j=i; j < len-1; j++) pow = pow * 10;
a = a + c * pow;
}

a = a << 7;
return a;
}

uint32 r5_hash (const signed char *msg, int len)
{
uint32 a=0;
// bonefish: len was ignored
//  while(*msg) {
while(len--) {
a += *msg << 4;
a += *msg >> 4;
a *= 11;
msg++;
}
return a;
}

// bonefish:
// from reiserfs_fs.h:
/* hash value occupies bits from 7 up to 30 */
#define GET_HASH_VALUE(offset) ((offset) & 0x7fffff80LL)
#define MAX_GENERATION_NUMBER  127

// bonefish:
// derived from name.c: get_third_component()
uint32
key_offset_for_name(hash_function_t hash, const char *name, int len)
{
uint32 res;

if (!len || (len == 1 && name[0] == '.'))
return DOT_OFFSET;
if (len == 2 && name[0] == '.' && name[1] == '.')
return DOT_DOT_OFFSET;

res = (*hash)((const signed char*)name, len);

// take bits from 7-th to 30-th including both bounds
res = GET_HASH_VALUE(res);
if (res == 0)
// needed to have no names before "." and ".." those have hash
// value == 0 and generation conters 1 and 2 accordingly
res = 128;
return res + MAX_GENERATION_NUMBER;
}

``````