1
2/*
3 * Keyed 32-bit hash function using TEA in a Davis-Meyer function
4 *   H0 = Key
5 *   Hi = E Mi(Hi-1) + Hi-1
6 *
7 * (see Applied Cryptography, 2nd edition, p448).
8 *
9 * Jeremy Fitzhardinge <jeremy@zip.com.au> 1998
10 *
11 * Jeremy has agreed to the contents of reiserfs/README. -Hans
12 * Yura's function is added (04/07/2000)
13 */
14
15#include <linux/kernel.h>
16#include "reiserfs.h"
17#include <asm/types.h>
18
19#define DELTA 0x9E3779B9
20#define FULLROUNDS 10		/* 32 is overkill, 16 is strong crypto */
21#define PARTROUNDS 6		/* 6 gets complete mixing */
22
23/* a, b, c, d - data; h0, h1 - accumulated hash */
24#define TEACORE(rounds)							\
25	do {								\
26		u32 sum = 0;						\
27		int n = rounds;						\
28		u32 b0, b1;						\
29									\
30		b0 = h0;						\
31		b1 = h1;						\
32									\
33		do							\
34		{							\
35			sum += DELTA;					\
36			b0 += ((b1 << 4)+a) ^ (b1+sum) ^ ((b1 >> 5)+b);	\
37			b1 += ((b0 << 4)+c) ^ (b0+sum) ^ ((b0 >> 5)+d);	\
38		} while(--n);						\
39									\
40		h0 += b0;						\
41		h1 += b1;						\
42	} while(0)
43
44u32 keyed_hash(const signed char *msg, int len)
45{
46	u32 k[] = { 0x9464a485, 0x542e1a94, 0x3e846bff, 0xb75bcfc3 };
47
48	u32 h0 = k[0], h1 = k[1];
49	u32 a, b, c, d;
50	u32 pad;
51	int i;
52
53	/*      assert(len >= 0 && len < 256); */
54
55	pad = (u32) len | ((u32) len << 8);
56	pad |= pad << 16;
57
58	while (len >= 16) {
59		a = (u32) msg[0] |
60		    (u32) msg[1] << 8 | (u32) msg[2] << 16 | (u32) msg[3] << 24;
61		b = (u32) msg[4] |
62		    (u32) msg[5] << 8 | (u32) msg[6] << 16 | (u32) msg[7] << 24;
63		c = (u32) msg[8] |
64		    (u32) msg[9] << 8 |
65		    (u32) msg[10] << 16 | (u32) msg[11] << 24;
66		d = (u32) msg[12] |
67		    (u32) msg[13] << 8 |
68		    (u32) msg[14] << 16 | (u32) msg[15] << 24;
69
70		TEACORE(PARTROUNDS);
71
72		len -= 16;
73		msg += 16;
74	}
75
76	if (len >= 12) {
77		a = (u32) msg[0] |
78		    (u32) msg[1] << 8 | (u32) msg[2] << 16 | (u32) msg[3] << 24;
79		b = (u32) msg[4] |
80		    (u32) msg[5] << 8 | (u32) msg[6] << 16 | (u32) msg[7] << 24;
81		c = (u32) msg[8] |
82		    (u32) msg[9] << 8 |
83		    (u32) msg[10] << 16 | (u32) msg[11] << 24;
84
85		d = pad;
86		for (i = 12; i < len; i++) {
87			d <<= 8;
88			d |= msg[i];
89		}
90	} else if (len >= 8) {
91		a = (u32) msg[0] |
92		    (u32) msg[1] << 8 | (u32) msg[2] << 16 | (u32) msg[3] << 24;
93		b = (u32) msg[4] |
94		    (u32) msg[5] << 8 | (u32) msg[6] << 16 | (u32) msg[7] << 24;
95
96		c = d = pad;
97		for (i = 8; i < len; i++) {
98			c <<= 8;
99			c |= msg[i];
100		}
101	} else if (len >= 4) {
102		a = (u32) msg[0] |
103		    (u32) msg[1] << 8 | (u32) msg[2] << 16 | (u32) msg[3] << 24;
104
105		b = c = d = pad;
106		for (i = 4; i < len; i++) {
107			b <<= 8;
108			b |= msg[i];
109		}
110	} else {
111		a = b = c = d = pad;
112		for (i = 0; i < len; i++) {
113			a <<= 8;
114			a |= msg[i];
115		}
116	}
117
118	TEACORE(FULLROUNDS);
119
120/*	return 0;*/
121	return h0 ^ h1;
122}
123
124/*
125 * What follows in this file is copyright 2000 by Hans Reiser, and the
126 * licensing of what follows is governed by reiserfs/README
127 */
128u32 yura_hash(const signed char *msg, int len)
129{
130	int j, pow;
131	u32 a, c;
132	int i;
133
134	for (pow = 1, i = 1; i < len; i++)
135		pow = pow * 10;
136
137	if (len == 1)
138		a = msg[0] - 48;
139	else
140		a = (msg[0] - 48) * pow;
141
142	for (i = 1; i < len; i++) {
143		c = msg[i] - 48;
144		for (pow = 1, j = i; j < len - 1; j++)
145			pow = pow * 10;
146		a = a + c * pow;
147	}
148
149	for (; i < 40; i++) {
150		c = '0' - 48;
151		for (pow = 1, j = i; j < len - 1; j++)
152			pow = pow * 10;
153		a = a + c * pow;
154	}
155
156	for (; i < 256; i++) {
157		c = i;
158		for (pow = 1, j = i; j < len - 1; j++)
159			pow = pow * 10;
160		a = a + c * pow;
161	}
162
163	a = a << 7;
164	return a;
165}
166
167u32 r5_hash(const signed char *msg, int len)
168{
169	u32 a = 0;
170	while (*msg) {
171		a += *msg << 4;
172		a += *msg >> 4;
173		a *= 11;
174		msg++;
175	}
176	return a;
177}
178