Release 4.10 fs/reiserfs/hashes.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;
}

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674
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3
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/*
 * 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;
}

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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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50
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100.00%

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linus torvalds
994
99.10%
2
28.57%
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3
0.30%
1
14.29%
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jeff mahoney
3
0.30%
2
28.57%
adrian bunk
adrian bunk
2
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Total
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7
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Directory: fs/reiserfs

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