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-rw-r--r--fs/reiserfs/hashes.c177
1 files changed, 177 insertions, 0 deletions
diff --git a/fs/reiserfs/hashes.c b/fs/reiserfs/hashes.c
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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)
+ */
+
+#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;
+}