Subversion Repositories 1g_ethernet_dpi

//////////////////////////////////////////////////////////////////////////////////

#include <stdlib.h>

#include <stdio.h>

//////////////////////////////////////////////////////////////////////////////////

// AUTODIN II, Ethernet, & FDDI

#define CRC32_POLY 0x04c11db7

// Generating polynomial:

typedef unsigned int uint32_t;

typedef unsigned char u8_t;

const uint32_t ethernet_polynomial_le = 0xedb88320U;

//////////////////////////////////////////////////////////////////////////////////

long crc_ether(char *buf, int len) { // Ethernet FCS, 32bit

    int length; u8_t *data; int foxes;

    length = len;

    data = buf;

    foxes = 1;

    unsigned int crc = (foxes) ? 0xffffffff: 0;  /* Initial value. */

    while(--length >= 0)

      {

        unsigned char current_octet = *data++;

        int bit;

        // printf("%02X, %08X,  inv %08X\n", current_octet, crc, ~crc);

        for (bit = 8; --bit >= 0; current_octet >>= 1) {

          if ((crc ^ current_octet) & 1) {

            crc >>= 1;

            crc ^= ethernet_polynomial_le;

          } else

            crc >>= 1;

        }

      }

    return ~crc;

}

/*

The CRC algorithm implementation by C language is as follows: This algorithm is often used as the Ethernet FCS(Frame Check Sequence).

#define CRCPOLY2 0xEDB88320UL  // left-right reversal

static unsigned long crc2(int n, unsigned char c[])

{

        int i, j;

        unsigned long r;

        r = 0xFFFFFFFFUL;

        for (i = 0; i < n; i++) {

                r ^= c[i];

                for (j = 0; j < CHAR_BIT; j++)

                        if (r & 1) r = (r >> 1) ^ CRCPOLY2;

                        else       r >>= 1;

        }

        return r ^ 0xFFFFFFFFUL;

}

*/

//////////////////////////////////////////////////////////////////////////////////