```
/*
* 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)
*/

#include <linux/kernel.h>
#include "reiserfs.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;
int i;

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

pad = (u32) len | ((u32) len << 8);

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;

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;

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;
}```