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/*
* 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)
*/
//
// keyed_hash
// yura_hash
// r5_hash
//
#include <linux/kernel.h>
#include <linux/reiserfs_fs.h>
#include <asm/types.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 { \
u32 sum = 0; \
int n = rounds; \
u32 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)
u32 keyed_hash(const signed char *msg, int len)
{
u32 k[] = { 0x9464a485, 0x542e1a94, 0x3e846bff, 0xb75bcfc3 };
u32 h0 = k[0], h1 = k[1];
u32 a, b, c, d;
u32 pad;
int i;
// assert(len >= 0 && len < 256);
pad = (u32) len | ((u32) len << 8);
pad |= pad << 16;
while (len >= 16) {
a = (u32) msg[0] |
(u32) msg[1] << 8 | (u32) msg[2] << 16 | (u32) msg[3] << 24;
b = (u32) msg[4] |
(u32) msg[5] << 8 | (u32) msg[6] << 16 | (u32) msg[7] << 24;
c = (u32) msg[8] |
(u32) msg[9] << 8 |
(u32) msg[10] << 16 | (u32) msg[11] << 24;
d = (u32) msg[12] |
(u32) msg[13] << 8 |
(u32) msg[14] << 16 | (u32) msg[15] << 24;
TEACORE(PARTROUNDS);
len -= 16;
msg += 16;
}
if (len >= 12) {
a = (u32) msg[0] |
(u32) msg[1] << 8 | (u32) msg[2] << 16 | (u32) msg[3] << 24;
b = (u32) msg[4] |
(u32) msg[5] << 8 | (u32) msg[6] << 16 | (u32) msg[7] << 24;
c = (u32) msg[8] |
(u32) msg[9] << 8 |
(u32) msg[10] << 16 | (u32) msg[11] << 24;
d = pad;
for (i = 12; i < len; i++) {
d <<= 8;
d |= msg[i];
}
} else if (len >= 8) {
a = (u32) msg[0] |
(u32) msg[1] << 8 | (u32) msg[2] << 16 | (u32) msg[3] << 24;
b = (u32) msg[4] |
(u32) msg[5] << 8 | (u32) msg[6] << 16 | (u32) msg[7] << 24;
c = d = pad;
for (i = 8; i < len; i++) {
c <<= 8;
c |= msg[i];
}
} else if (len >= 4) {
a = (u32) msg[0] |
(u32) msg[1] << 8 | (u32) msg[2] << 16 | (u32) msg[3] << 24;
b = c = d = pad;
for (i = 4; i < len; i++) {
b <<= 8;
b |= msg[i];
}
} else {
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 */
u32 yura_hash(const signed char *msg, int len)
{
int j, pow;
u32 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;
}
u32 r5_hash(const signed char *msg, int len)
{
u32 a = 0;
while (*msg) {
a += *msg << 4;
a += *msg >> 4;
a *= 11;
msg++;
}
return a;
}
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