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/*
This file is part of GNUnet.
(C) 2001, 2002, 2003, 2004, 2006 Christian Grothoff (and other contributing authors)
GNUnet 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 2, or (at your
option) any later version.
GNUnet 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 GNUnet; see the file COPYING. If not, write to the
Free Software Foundation, Inc., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA.
For the actual CRC code:
Copyright abandoned; this code is in the public domain.
Provided to GNUnet by peter@horizon.com
*/
/**
* @file monkey/bug_crypto_crc.c
* @brief implementation of CRC32 (this code has been copied from GNUnet util source directory, and modified to be Seaspider friendly)
* @author Christian Grothoff, Safey A.Halim
*/
#include <assert.h>
#include <stdlib.h>
#include <stdio.h>
#include <stdint.h>
#define Z_NULL 0
#define POLYNOMIAL (unsigned long)0xedb88320
static unsigned long crc_table[256];
/*
* This routine writes each crc_table entry exactly once,
* with the ccorrect final value. Thus, it is safe to call
* even on a table that someone else is using concurrently.
*/
static void
crc_init ()
{
static int once;
unsigned int i, j;
unsigned long h = 1;
if (once)
return;
once = 1;
crc_table[0] = 0;
for (i = 128; i; i >>= 1)
{
h = (h >> 1) ^ ((h & 1) ? POLYNOMIAL : 0);
/* h is now crc_table[i] */
for (j = 0; j < 256; j += 2 * i)
crc_table[i + j] = crc_table[j] ^ h;
}
}
/*
* This computes the standard preset and inverted CRC, as used
* by most networking standards. Start by passing in an initial
* chaining value of 0, and then pass in the return value from the
* previous crc32() call. The final return value is the CRC.
* Note that this is a little-endian CRC, which is best used with
* data transmitted lsbit-first, and it should, itself, be appended
* to data in little-endian byte and bit order to preserve the
* property of detecting all burst errors of length 32 bits or less.
*/
static unsigned long
crc_go (unsigned long crc, const char *buf, size_t len)
{
crc_init ();
assert (crc_table[255] != 0);
crc ^= 0xffffffff;
while (len--)
crc = (crc >> 8) ^ crc_table[(crc ^ *buf++) & 0xff];
return crc ^ 0xffffffff;
}
/**
* Compute the CRC32 checksum for the first len bytes of the buffer.
*
* @param buf the data over which we're taking the CRC
* @param len the length of the buffer
* @return the resulting CRC32 checksum
*/
int32_t
crc32_n (const void *buf, size_t len)
{
unsigned long crc;
crc = crc_go (0L, Z_NULL, 0);
crc = crc_go (crc, (char *) buf, len);
return crc;
}
int main ()
{
char buf[1024];
int i;
for (i = 0; i < 1024; i++)
{
buf[i] = (char) i;
}
for (i = 0; i < 1024; i++)
{
printf("%d\n", crc32_n (&buf[i], 1024 - i));
}
return 0;
}
/* end of bug_crypto_crc.c */
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