itpp::CRC_Code Class Reference
[Forward Error Correcting Codes]

Cyclic Redundancy Check Codes. More...

#include <crc.h>

List of all members.

Public Member Functions
	CRC_Code ()
	Default Constructor.
	CRC_Code (const std::string &code)
	Set CRC code to one of the standardpolynomials using the string value.
void	set_generator (const bvec &poly)
	Set an arbitary polynomial in bvec form. Start with highest order terms.
void	set_code (const std::string &code)
	Set CRC code to one of the standardpolynomials using the string value.
void	parity (const bvec &in_bits, bvec &out) const
	Calulate the parity bits.
bool	check_parity (const bvec &coded_bits) const
	Return true if parity checks OK otherwise flase.
void	encode (const bvec &in_bits, bvec &out) const
	Calculate and add parity to the in_bits.
bvec	encode (const bvec &in_bits) const
	Returns the in_bits vector with parity added.
bool	decode (const bvec &coded_bits, bvec &out) const
	Return true if parity checks OK otherwise flase. Also returns the message part in out.
bool	decode (bvec &bits) const
	Return true if parity checks OK otherwise flase. Also returns the message part in bits.

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Detailed Description

Cyclic Redundancy Check Codes.

This class will add the CRC bits after each input word. With b(i) denoting the i-th input bit and p(i) the i-th parity check bit, the order of the outbut bits will be:

 [b(1), b(2), ..., b(k), p(1), p(2), ..., p(n-k)] 

When the WCDMA CRC polynomials are used, this class will reverse the order of the parity check bits in order to comply to the WCDMA standard. Thus for the polynomials WCDMA-8, WCDMA-12, WCDMA-16, and WCDMA-24 the output will be:

 [b(1), b(2), ..., b(k), p(n-k), ..., p(2), p(1)] 

Usage:

  CRC_Code crc(string("CRC-4"));
  bvec bits = randb(10), coded_bits, decoded_bits;
  bool error;

  coded_bits = crc.encode(bits);
  error = crc.decode(rec_bits, decoded_bits);

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Constructor & Destructor Documentation

itpp::CRC_Code::CRC_Code

(

const std::string &

code

)

[inline]

Set CRC code to one of the standardpolynomials using the string value.

Parameters:

code

Possible values: CRC-4, CRC-7, CRC-8, CRC-12, CRC-24, CRC-32, CCITT-4, CCITT-5, CCITT-6, CCITT-16, CCITT-32, WCDMA-8, WCDMA-12, WCDMA-16, WCDMA-24, ATM-8, ANSI-16, SDLC-16

References set_code().

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The documentation for this class was generated from the following files:

• crc.h
• crc.cpp