kernel-ark/fs/reiserfs/hashes.c
Jeff Mahoney 098297b27d reiserfs: cleanup, reformat comments to normal kernel style
This patch reformats comments in the reiserfs code to fit in 80 columns and
to follow the style rules.

There is no functional change but it helps make my eyes bleed less.

Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: Jan Kara <jack@suse.cz>
2014-05-06 22:52:19 +02:00

178 lines
3.5 KiB
C

/*
* 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;
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;
}