crypto_crc.c File Reference

implementation of CRC16 and CRC32 More...

#include "platform.h"
#include "gnunet_util_lib.h"

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Macros
#define	LOG(kind, ...)   GNUNET_log_from (kind, "util-crypto-crc", __VA_ARGS__)
#define	Z_NULL   0
#define	POLYNOMIAL   (GNUNET_uLong) 0xedb88320

Functions
static void	crc_init ()
static GNUNET_uLong	gn_crc32 (GNUNET_uLong crc, const char *buf, size_t len)
int32_t	GNUNET_CRYPTO_crc32_n (const void *buf, size_t len)
	Compute the CRC32 checksum for the first len bytes of the buffer. More...
uint32_t	GNUNET_CRYPTO_crc16_step (uint32_t sum, const void *buf, size_t len)
	Perform an incremental step in a CRC16 (for TCP/IP) calculation. More...
uint16_t	GNUNET_CRYPTO_crc16_finish (uint32_t sum)
	Convert results from GNUNET_CRYPTO_crc16_step to final crc16. More...
uint16_t	GNUNET_CRYPTO_crc16_n (const void *buf, size_t len)
	Calculate the checksum of a buffer in one step. More...
uint8_t	GNUNET_CRYPTO_crc8_n (const void *buf, size_t len)
	Calculate the checksum of a buffer in one step. More...

Variables
static GNUNET_uLong	crc_table [256]

Detailed Description

implementation of CRC16 and CRC32

Author

Christian Grothoff

Definition in file crypto_crc.c.

Macro Definition Documentation

LOG

#define LOG	(		kind,
			...
	)		GNUNET_log_from (kind, "util-crypto-crc", __VA_ARGS__)

Definition at line 34 of file crypto_crc.c.

Z_NULL

#define Z_NULL   0

Definition at line 45 of file crypto_crc.c.

POLYNOMIAL

#define POLYNOMIAL   (GNUNET_uLong) 0xedb88320

Definition at line 48 of file crypto_crc.c.

Function Documentation

crc_init()

static void crc_init ( )

static

Definition at line 57 of file crypto_crc.c.

{
  static int once;
  GNUNET_uLong h = 1;
 
  if (once)
    return;
  once = 1;
  crc_table[0] = 0;
  for (unsigned int i = 128; i; i >>= 1)
  {
    h = (h >> 1) ^ ((h & 1) ? POLYNOMIAL : 0);
    /* h is now crc_table[i] */
    for (unsigned int j = 0; j < 256; j += 2 * i)
      crc_table[i + j] = crc_table[j] ^ h;
  }
}

References crc_table, h, once, and POLYNOMIAL.

Referenced by gn_crc32().

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gn_crc32()

static GNUNET_uLong gn_crc32 ( GNUNET_uLong  crc, const char *  buf, size_t  len  )

static

Definition at line 87 of file crypto_crc.c.

{
  crc_init ();
  GNUNET_assert (crc_table[255] != 0);
  crc ^= 0xffffffff;
  while (len--)
    crc = (crc >> 8) ^ crc_table[(crc ^ *buf++) & 0xff];
  return crc ^ 0xffffffff;
}

References crc_init(), crc_table, and GNUNET_assert.

Referenced by GNUNET_CRYPTO_crc32_n().

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Variable Documentation

crc_table

GNUNET_uLong crc_table[256]

static

Definition at line 49 of file crypto_crc.c.

Referenced by crc_init(), and gn_crc32().