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/*
Copyright (c) 2008 Z RESEARCH, Inc. <http://www.zresearch.com>
This file is part of GlusterFS.
GlusterFS is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published
by the Free Software Foundation; either version 3 of the License,
or (at your option) any later version.
GlusterFS is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see
<http://www.gnu.org/licenses/>.
*/
#include <stdint.h>
#include <stdio.h>
#include <string.h>
#define DELTA 0x9E3779B9
#define FULLROUNDS 10 /* 32 is overkill, 16 is strong crypto */
#define PARTROUNDS 6 /* 6 gets complete mixing */
static int
tearound (int rounds, uint32_t *array, uint32_t *h0, uint32_t *h1)
{
uint32_t sum = 0;
int n = 0;
uint32_t b0 = 0;
uint32_t b1 = 0;
b0 = *h0;
b1 = *h1;
n = rounds;
do {
sum += DELTA;
b0 += ((b1 << 4) + array[0])
^ (b1 + sum)
^ ((b1 >> 5) + array[1]);
b1 += ((b0 << 4) + array[2])
^ (b0 + sum)
^ ((b0 >> 5) + array[3]);
} while (--n);
*h0 += b0;
*h1 += b1;
return 0;
}
uint32_t
__pad (int len)
{
uint32_t pad = 0;
pad = (uint32_t) len | ((uint32_t) len << 8);
pad |= pad << 16;
return pad;
}
uint32_t
dht_hashfn_tea (const char *msg, int len)
{
uint32_t h0 = 0x9464a485;
uint32_t h1 = 0x542e1a94;
uint32_t array[4];
uint32_t pad = 0;
int i = 0;
int j = 0;
int full_quads = 0;
int full_words = 0;
int full_bytes = 0;
uint32_t *intmsg = NULL;
int word = 0;
intmsg = (uint32_t *) msg;
pad = __pad (len);
full_bytes = len;
full_words = len / 4;
full_quads = len / 16;
for (i = 0; i < full_quads; i++) {
for (j = 0; j < 4; j++) {
word = *intmsg;
array[j] = word;
intmsg++;
full_words--;
full_bytes -= 4;
}
tearound (PARTROUNDS, &array[0], &h0, &h1);
}
if ((len % 16) == 0) {
goto done;
}
for (j = 0; j < 4; j++) {
if (full_words) {
word = *intmsg;
array[j] = word;
intmsg++;
full_words--;
full_bytes -= 4;
} else {
array[j] = pad;
while (full_bytes) {
array[j] <<= 8;
array[j] |= msg[len - full_bytes];
full_bytes--;
}
}
}
tearound (FULLROUNDS, &array[0], &h0, &h1);
done:
return h0 ^ h1;
}
#if 0
int
main (int argc, char *argv[])
{
int i = 0;
int hashval = 0;
for (i = 1; i < argc; i++) {
hashval = tea (argv[i], strlen (argv[i]));
printf ("%s: %x\n", argv[i], hashval);
}
}
#endif
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