CRC Class Reference

Static class for computing CRCs. More...

#include <CRC.h>

Collaboration diagram for CRC:

Classes
struct	Parameters
	CRC parameters. More...
struct	Table
	CRC lookup table. After construction, the CRC parameters are fixed. More...

Static Public Member Functions
template<typename CRCType , crcpp_uint16 CRCWidth>
static CRCType	Calculate (const void *data, crcpp_size size, const Parameters< CRCType, CRCWidth > &parameters)
	Computes a CRC. More...
template<typename CRCType , crcpp_uint16 CRCWidth>
static CRCType	Calculate (const void *data, crcpp_size size, const Parameters< CRCType, CRCWidth > &parameters, CRCType crc)
	Appends additional data to a previous CRC calculation. More...
template<typename CRCType , crcpp_uint16 CRCWidth>
static CRCType	Calculate (const void *data, crcpp_size size, const Table< CRCType, CRCWidth > &lookupTable)
	Computes a CRC via a lookup table. More...
template<typename CRCType , crcpp_uint16 CRCWidth>
static CRCType	Calculate (const void *data, crcpp_size size, const Table< CRCType, CRCWidth > &lookupTable, CRCType crc)
	Appends additional data to a previous CRC calculation using a lookup table. More...
static const Parameters< crcpp_uint8, 8 > &	CRC_8 ()
	Returns a set of parameters for CRC-8 SMBus. More...
static const Parameters< crcpp_uint16, 16 > &	CRC_16_ARC ()
	Returns a set of parameters for CRC-16 ARC (aka CRC-16 IBM, CRC-16 LHA). More...
static const Parameters< crcpp_uint16, 16 > &	CRC_16_BUYPASS ()
	Returns a set of parameters for CRC-16 BUYPASS (aka CRC-16 VERIFONE, CRC-16 UMTS). More...
static const Parameters< crcpp_uint16, 16 > &	CRC_16_CCITTFALSE ()
	Returns a set of parameters for CRC-16 CCITT FALSE. More...
static const Parameters< crcpp_uint16, 16 > &	CRC_16_GENIBUS ()
	Returns a set of parameters for CRC-16 GENIBUS (aka CRC-16 EPC, CRC-16 I-CODE, CRC-16 DARC). More...
static const Parameters< crcpp_uint16, 16 > &	CRC_16_KERMIT ()
	Returns a set of parameters for CRC-16 KERMIT (aka CRC-16 CCITT, CRC-16 CCITT-TRUE). More...
static const Parameters< crcpp_uint16, 16 > &	CRC_16_X25 ()
	Returns a set of parameters for CRC-16 X-25 (aka CRC-16 IBM-SDLC, CRC-16 ISO-HDLC, CRC-16 B). More...
static const Parameters< crcpp_uint16, 16 > &	CRC_16_XMODEM ()
	Returns a set of parameters for CRC-16 XMODEM (aka CRC-16 ZMODEM, CRC-16 ACORN, CRC-16 LTE). More...
static const Parameters< crcpp_uint32, 32 > &	CRC_32 ()
	Returns a set of parameters for CRC-32 (aka CRC-32 ADCCP, CRC-32 PKZip). More...
static const Parameters< crcpp_uint32, 32 > &	CRC_32_BZIP2 ()
	Returns a set of parameters for CRC-32 BZIP2 (aka CRC-32 AAL5, CRC-32 DECT-B, CRC-32 B-CRC). More...
static const Parameters< crcpp_uint32, 32 > &	CRC_32_MPEG2 ()
	Returns a set of parameters for CRC-32 MPEG-2. More...
static const Parameters< crcpp_uint32, 32 > &	CRC_32_POSIX ()
	Returns a set of parameters for CRC-32 POSIX. More...

Private Member Functions
	CRC ()
	CRC (const CRC &other)
CRC &	operator= (const CRC &other)

Static Private Member Functions
template<typename IntegerType >
static IntegerType	Reflect (IntegerType value, crcpp_uint16 numBits)
	Reflects (i.e. reverses the bits within) an integer value. More...
template<typename CRCType , crcpp_uint16 CRCWidth>
static CRCType	Finalize (CRCType remainder, CRCType finalXOR, bool reflectOutput)
	Computes the final reflection and XOR of a CRC remainder. More...
template<typename CRCType , crcpp_uint16 CRCWidth>
static CRCType	UndoFinalize (CRCType remainder, CRCType finalXOR, bool reflectOutput)
	Undoes the process of computing the final reflection and XOR of a CRC remainder. More...
template<typename CRCType , crcpp_uint16 CRCWidth>
static CRCType	CalculateRemainder (const void *data, crcpp_size size, const Parameters< CRCType, CRCWidth > &parameters, CRCType remainder)
	Computes a CRC remainder. More...
template<typename CRCType , crcpp_uint16 CRCWidth>
static CRCType	CalculateRemainder (const void *data, crcpp_size size, const Table< CRCType, CRCWidth > &lookupTable, CRCType remainder)
	Computes a CRC remainder using lookup table. More...

Detailed Description

Static class for computing CRCs.

Note

This class supports computation of full and multi-part CRCs, using a bit-by-bit algorithm or a byte-by-byte lookup table. The CRCs are calculated using as many optimizations as is reasonable. If compiling with C++11, the constexpr keyword is used liberally so that many calculations are performed at compile-time instead of at runtime.

Definition at line 144 of file CRC.h.

Constructor & Destructor Documentation

CRC::CRC ( )

private

CRC::CRC ( const CRC &  other )

private

Member Function Documentation

template<typename CRCType , crcpp_uint16 CRCWidth>

CRCType CRC::Calculate ( const void *  data, crcpp_size  size, const Parameters< CRCType, CRCWidth > &  parameters  )

inlinestatic

Computes a CRC.

Parameters

[in]	data	Data over which CRC will be computed
[in]	size	Size of the data
[in]	parameters	CRC parameters

Template Parameters

CRCType	Integer type for storing the CRC result
CRCWidth	Number of bits in the CRC

Returns

CRC

Definition at line 436 of file CRC.h.

References CalculateRemainder(), CRC::Parameters< CRCType, CRCWidth >::finalXOR, CRC::Parameters< CRCType, CRCWidth >::initialValue, CRC::Parameters< CRCType, CRCWidth >::reflectInput, and CRC::Parameters< CRCType, CRCWidth >::reflectOutput.

Referenced by crypt_crc32().

Here is the caller graph for this function:

template<typename CRCType , crcpp_uint16 CRCWidth>

CRCType CRC::Calculate ( const void *  data, crcpp_size  size, const Parameters< CRCType, CRCWidth > &  parameters, CRCType  crc  )

inlinestatic

Appends additional data to a previous CRC calculation.

Note

This function can be used to compute multi-part CRCs.

Parameters

[in]	data	Data over which CRC will be computed
[in]	size	Size of the data
[in]	parameters	CRC parameters
[in]	crc	CRC from a previous calculation

Template Parameters

CRCType	Integer type for storing the CRC result
CRCWidth	Number of bits in the CRC

Returns

CRC

Definition at line 456 of file CRC.h.

References CalculateRemainder(), CRC::Parameters< CRCType, CRCWidth >::finalXOR, CRC::Parameters< CRCType, CRCWidth >::reflectInput, and CRC::Parameters< CRCType, CRCWidth >::reflectOutput.

template<typename CRCType , crcpp_uint16 CRCWidth>

CRCType CRC::Calculate ( const void *  data, crcpp_size  size, const Table< CRCType, CRCWidth > &  lookupTable  )

inlinestatic

Computes a CRC via a lookup table.

Parameters

[in]	data	Data over which CRC will be computed
[in]	size	Size of the data
[in]	lookupTable	CRC lookup table

Template Parameters

CRCType	Integer type for storing the CRC result
CRCWidth	Number of bits in the CRC

Returns

CRC

Definition at line 477 of file CRC.h.

References CalculateRemainder(), CRC::Parameters< CRCType, CRCWidth >::finalXOR, CRC::Table< CRCType, CRCWidth >::GetParameters(), CRC::Parameters< CRCType, CRCWidth >::initialValue, CRC::Table< CRCType, CRCWidth >::parameters, CRC::Parameters< CRCType, CRCWidth >::reflectInput, and CRC::Parameters< CRCType, CRCWidth >::reflectOutput.

template<typename CRCType , crcpp_uint16 CRCWidth>

CRCType CRC::Calculate ( const void *  data, crcpp_size  size, const Table< CRCType, CRCWidth > &  lookupTable, CRCType  crc  )

inlinestatic

Appends additional data to a previous CRC calculation using a lookup table.

Note

This function can be used to compute multi-part CRCs.

Parameters

[in]	data	Data over which CRC will be computed
[in]	size	Size of the data
[in]	lookupTable	CRC lookup table
[in]	crc	CRC from a previous calculation

Template Parameters

CRCType	Integer type for storing the CRC result
CRCWidth	Number of bits in the CRC

Returns

CRC

Definition at line 500 of file CRC.h.

References CalculateRemainder(), CRC::Parameters< CRCType, CRCWidth >::finalXOR, CRC::Table< CRCType, CRCWidth >::GetParameters(), CRC::Table< CRCType, CRCWidth >::parameters, CRC::Parameters< CRCType, CRCWidth >::reflectInput, and CRC::Parameters< CRCType, CRCWidth >::reflectOutput.

template<typename CRCType , crcpp_uint16 CRCWidth>

CRCType CRC::CalculateRemainder ( const void *  data, crcpp_size  size, const Parameters< CRCType, CRCWidth > &  parameters, CRCType  remainder  )

inlinestaticprivate

Computes a CRC remainder.

Parameters

[in]	data	Data over which the remainder will be computed
[in]	size	Size of the data
[in]	parameters	CRC parameters
[in]	remainder	Running CRC remainder. Can be an initial value or the result of a previous CRC remainder calculation.

Template Parameters

CRCType	Integer type for storing the CRC result
CRCWidth	Number of bits in the CRC

Returns

CRC remainder

Definition at line 603 of file CRC.h.

References crcpp_constexpr, crcpp_size, i, CRC::Parameters< CRCType, CRCWidth >::polynomial, Reflect(), and CRC::Parameters< CRCType, CRCWidth >::reflectInput.

Referenced by Calculate().

Here is the caller graph for this function:

template<typename CRCType , crcpp_uint16 CRCWidth>

CRCType CRC::CalculateRemainder ( const void *  data, crcpp_size  size, const Table< CRCType, CRCWidth > &  lookupTable, CRCType  remainder  )

inlinestaticprivate

Computes a CRC remainder using lookup table.

Parameters

[in]	data	Data over which the remainder will be computed
[in]	size	Size of the data
[in]	lookupTable	CRC lookup table
[in]	remainder	Running CRC remainder. Can be an initial value or the result of a previous CRC remainder calculation.

Template Parameters

CRCType	Integer type for storing the CRC result
CRCWidth	Number of bits in the CRC

Returns

CRC remainder

Definition at line 720 of file CRC.h.

References crcpp_constexpr, CRC::Table< CRCType, CRCWidth >::GetParameters(), and CRC::Table< CRCType, CRCWidth >::parameters.

const CRC::Parameters< crcpp_uint16, 16 > & CRC::CRC_16_ARC ( )

inlinestatic

Returns a set of parameters for CRC-16 ARC (aka CRC-16 IBM, CRC-16 LHA).

Note

The parameters are static and are delayed-constructed to reduce memory footprint.

CRC-16 ARC has the following parameters and check value:

• polynomial = 0x8005
• initial value = 0x0000
• final XOR = 0x0000
• reflect input = true
• reflect output = true
• check value = 0xBB3D

Returns

CRC-16 ARC parameters

Definition at line 1164 of file CRC.h.

References CRC::Table< CRCType, CRCWidth >::parameters.

const CRC::Parameters< crcpp_uint16, 16 > & CRC::CRC_16_BUYPASS ( )

inlinestatic

Returns a set of parameters for CRC-16 BUYPASS (aka CRC-16 VERIFONE, CRC-16 UMTS).

Note

The parameters are static and are delayed-constructed to reduce memory footprint.

CRC-16 BUYPASS has the following parameters and check value:

• polynomial = 0x8005
• initial value = 0x0000
• final XOR = 0x0000
• reflect input = false
• reflect output = false
• check value = 0xFEE8

Returns

CRC-16 BUYPASS parameters

Definition at line 1182 of file CRC.h.

References CRC::Table< CRCType, CRCWidth >::parameters.

const CRC::Parameters< crcpp_uint16, 16 > & CRC::CRC_16_CCITTFALSE ( )

inlinestatic

Returns a set of parameters for CRC-16 CCITT FALSE.

Note

The parameters are static and are delayed-constructed to reduce memory footprint.

CRC-16 CCITT FALSE has the following parameters and check value:

• polynomial = 0x1021
• initial value = 0xFFFF
• final XOR = 0x0000
• reflect input = false
• reflect output = false
• check value = 0x29B1

Returns

CRC-16 CCITT FALSE parameters

Definition at line 1200 of file CRC.h.

References CRC::Table< CRCType, CRCWidth >::parameters.

const CRC::Parameters< crcpp_uint16, 16 > & CRC::CRC_16_GENIBUS ( )

inlinestatic

Returns a set of parameters for CRC-16 GENIBUS (aka CRC-16 EPC, CRC-16 I-CODE, CRC-16 DARC).

Note

The parameters are static and are delayed-constructed to reduce memory footprint.

CRC-16 GENIBUS has the following parameters and check value:

• polynomial = 0x1021
• initial value = 0xFFFF
• final XOR = 0xFFFF
• reflect input = false
• reflect output = false
• check value = 0xD64E

Returns

CRC-16 GENIBUS parameters

Definition at line 1310 of file CRC.h.

References CRC::Table< CRCType, CRCWidth >::parameters.

const CRC::Parameters< crcpp_uint16, 16 > & CRC::CRC_16_KERMIT ( )

inlinestatic

Returns a set of parameters for CRC-16 KERMIT (aka CRC-16 CCITT, CRC-16 CCITT-TRUE).

Note

The parameters are static and are delayed-constructed to reduce memory footprint.

CRC-16 KERMIT has the following parameters and check value:

• polynomial = 0x1021
• initial value = 0x0000
• final XOR = 0x0000
• reflect input = true
• reflect output = true
• check value = 0x2189

Returns

CRC-16 KERMIT parameters

Definition at line 1328 of file CRC.h.

References CRC::Table< CRCType, CRCWidth >::parameters.

const CRC::Parameters< crcpp_uint16, 16 > & CRC::CRC_16_X25 ( )

inlinestatic

Returns a set of parameters for CRC-16 X-25 (aka CRC-16 IBM-SDLC, CRC-16 ISO-HDLC, CRC-16 B).

Note

The parameters are static and are delayed-constructed to reduce memory footprint.

CRC-16 X-25 has the following parameters and check value:

• polynomial = 0x1021
• initial value = 0xFFFF
• final XOR = 0xFFFF
• reflect input = true
• reflect output = true
• check value = 0x906E

Returns

CRC-16 X-25 parameters

Definition at line 1421 of file CRC.h.

References CRC::Table< CRCType, CRCWidth >::parameters.

const CRC::Parameters< crcpp_uint16, 16 > & CRC::CRC_16_XMODEM ( )

inlinestatic

Returns a set of parameters for CRC-16 XMODEM (aka CRC-16 ZMODEM, CRC-16 ACORN, CRC-16 LTE).

Note

The parameters are static and are delayed-constructed to reduce memory footprint.

CRC-16 XMODEM has the following parameters and check value:

• polynomial = 0x1021
• initial value = 0x0000
• final XOR = 0x0000
• reflect input = false
• reflect output = false
• check value = 0x31C3

Returns

CRC-16 XMODEM parameters

Definition at line 1439 of file CRC.h.

References CRC::Table< CRCType, CRCWidth >::parameters.

const CRC::Parameters< crcpp_uint32, 32 > & CRC::CRC_32 ( )

inlinestatic

Returns a set of parameters for CRC-32 (aka CRC-32 ADCCP, CRC-32 PKZip).

Note

The parameters are static and are delayed-constructed to reduce memory footprint.

CRC-32 has the following parameters and check value:

• polynomial = 0x04C11DB7
• initial value = 0xFFFFFFFF
• final XOR = 0xFFFFFFFF
• reflect input = true
• reflect output = true
• check value = 0xCBF43926

Returns

CRC-32 parameters

Definition at line 1567 of file CRC.h.

References CRC::Table< CRCType, CRCWidth >::parameters.

Referenced by crypt_crc32().

Here is the caller graph for this function:

const CRC::Parameters< crcpp_uint32, 32 > & CRC::CRC_32_BZIP2 ( )

inlinestatic

Returns a set of parameters for CRC-32 BZIP2 (aka CRC-32 AAL5, CRC-32 DECT-B, CRC-32 B-CRC).

Note

The parameters are static and are delayed-constructed to reduce memory footprint.

CRC-32 BZIP2 has the following parameters and check value:

• polynomial = 0x04C11DB7
• initial value = 0xFFFFFFFF
• final XOR = 0xFFFFFFFF
• reflect input = false
• reflect output = false
• check value = 0xFC891918

Returns

CRC-32 BZIP2 parameters

Definition at line 1585 of file CRC.h.

References CRC::Table< CRCType, CRCWidth >::parameters.

const CRC::Parameters< crcpp_uint32, 32 > & CRC::CRC_32_MPEG2 ( )

inlinestatic

Returns a set of parameters for CRC-32 MPEG-2.

Note

The parameters are static and are delayed-constructed to reduce memory footprint.

CRC-32 MPEG-2 has the following parameters and check value:

• polynomial = 0x04C11DB7
• initial value = 0xFFFFFFFF
• final XOR = 0x00000000
• reflect input = false
• reflect output = false
• check value = 0x0376E6E7

Returns

CRC-32 MPEG-2 parameters

Definition at line 1623 of file CRC.h.

References CRC::Table< CRCType, CRCWidth >::parameters.

const CRC::Parameters< crcpp_uint32, 32 > & CRC::CRC_32_POSIX ( )

inlinestatic

Returns a set of parameters for CRC-32 POSIX.

Note

The parameters are static and are delayed-constructed to reduce memory footprint.

CRC-32 POSIX has the following parameters and check value:

• polynomial = 0x04C11DB7
• initial value = 0x00000000
• final XOR = 0xFFFFFFFF
• reflect input = false
• reflect output = false
• check value = 0x765E7680

Returns

CRC-32 POSIX parameters

Definition at line 1641 of file CRC.h.

References CRC::Table< CRCType, CRCWidth >::parameters.

const CRC::Parameters< crcpp_uint8, 8 > & CRC::CRC_8 ( )

inlinestatic

Returns a set of parameters for CRC-8 SMBus.

Note

The parameters are static and are delayed-constructed to reduce memory footprint.

CRC-8 SMBus has the following parameters and check value:

• polynomial = 0x07
• initial value = 0x00
• final XOR = 0x00
• reflect input = false
• reflect output = false
• check value = 0xF4

Returns

CRC-8 SMBus parameters

Definition at line 928 of file CRC.h.

References CRC::Table< CRCType, CRCWidth >::parameters.

template<typename CRCType , crcpp_uint16 CRCWidth>

CRCType CRC::Finalize ( CRCType  remainder, CRCType  finalXOR, bool  reflectOutput  )

inlinestaticprivate

Computes the final reflection and XOR of a CRC remainder.

Parameters

[in]	remainder	CRC remainder to reflect and XOR
[in]	finalXOR	Final value to XOR with the remainder
[in]	reflectOutput	true to reflect each byte of the remainder before the XOR

Template Parameters

CRCType	Integer type for storing the CRC result
CRCWidth	Number of bits in the CRC

Returns

Final CRC

Definition at line 544 of file CRC.h.

References crcpp_constexpr, and Reflect().

CRC& CRC::operator= ( const CRC &  other )

private

template<typename IntegerType >

IntegerType CRC::Reflect ( IntegerType  value, crcpp_uint16  numBits  )

inlinestaticprivate

Reflects (i.e. reverses the bits within) an integer value.

Parameters

[in]	value	Value to reflect
[in]	numBits	Number of bits in the integer which will be reflected

Template Parameters

IntegerType

Integer type of the value being reflected

Returns

Reflected value

Definition at line 521 of file CRC.h.

References crcpp_uint16, and i.

Referenced by CalculateRemainder(), Finalize(), and UndoFinalize().

Here is the caller graph for this function:

template<typename CRCType , crcpp_uint16 CRCWidth>

CRCType CRC::UndoFinalize ( CRCType  crc, CRCType  finalXOR, bool  reflectOutput  )

inlinestaticprivate

Undoes the process of computing the final reflection and XOR of a CRC remainder.

Note

This function allows for computation of multi-part CRCs

Calling UndoFinalize() followed by Finalize() (or vice versa) will always return the original remainder value:

CRCType x = ...;
CRCType y = Finalize(x, finalXOR, reflectOutput);
CRCType z = UndoFinalize(y, finalXOR, reflectOutput);
assert(x == z);

Parameters

[in]	crc	Reflected and XORed CRC
[in]	finalXOR	Final value XORed with the remainder
[in]	reflectOutput	true if the remainder is to be reflected

Template Parameters

CRCType	Integer type for storing the CRC result
CRCWidth	Number of bits in the CRC

Returns

Un-finalized CRC remainder

Definition at line 576 of file CRC.h.

References crcpp_constexpr, and Reflect().

---

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

• src/base/CRC.h