CRC core framework using Rocksoft^tm Model characteristics. More...

#include </mnt/devel/pabigot-cxx/include/pabigot/crc.hpp>

Inheritance diagram for pabigot::crc::details::base_crc< W, Rin >:

Public Types
using	uint_traits = typename support_traits::uint_traits

using	fast_type = typename support_traits::fast_type
	A fast native unsigned integral type capable of holding width-bit CRC values. More...

using	least_type = typename support_traits::least_type
	A small native unsigned integral type capable of holding width-bit CRC values. More...

Static Public Member Functions
static constexpr fast_type	reflect (const fast_type &v)
	Delegate to support_traits::reflect.

static constexpr uint8_t *	store (fast_type crc, uint8_t *bp)
	Store a finalized CRC into a buffer in a way that enables crc::residue(). More...

Static Public Attributes
static constexpr unsigned int	width = W
	The width of the CRC in bits.

static constexpr unsigned int	size = (7 + width) / 8
	The width of the CRC in bytes.

static constexpr fast_type	mask = support_traits::mask
	The mask that discards bits of a fast_type that would be outside the width limit.

static constexpr bool	refin = Rin
	`true` iff the input message bit stream is reflected. More...

Protected Types
using	support_traits = details::uint_support< width >
	Traits class providing native integral types and parameter-independent values supporting width-bit operations.

Static Protected Member Functions
static constexpr least_type	lookup_for_byte (const fast_type &poly, std::uint_fast8_t byte)
	Calculate a single lookup table entry using the given polynomial. More...

static constexpr fast_type	crc_apply (const fast_type &poly, const fast_type &crc, fast_type msg, unsigned int n)
	Apply message bits into a CRC. More...

Detailed Description

template<unsigned int W, bool Rin = false>
class pabigot::crc::details::base_crc< W, Rin >

CRC core framework using Rocksoft^tm Model characteristics.

This class supports the basic operations that are common when parameterized by polynomial and output processing.

Template Parameters

W	initializes width.
Rin	initializes refin.

Member Typedef Documentation

◆ fast_type

template<unsigned int W, bool Rin = false>

using pabigot::crc::details::base_crc< W, Rin >::fast_type = typename support_traits::fast_type

A fast native unsigned integral type capable of holding width-bit CRC values.

Warning: This value may have more octets or bits than are required to store the CRC.

◆ least_type

template<unsigned int W, bool Rin = false>

using pabigot::crc::details::base_crc< W, Rin >::least_type = typename support_traits::least_type

A small native unsigned integral type capable of holding width-bit CRC values.

Warning: This value may have more octets or bits than are required to store the CRC.

Member Function Documentation

◆ crc_apply()

template<unsigned int W, bool Rin = false>

static constexpr fast_type pabigot::crc::details::base_crc< W, Rin >::crc_apply	(	const fast_type &	poly,
		const fast_type &	crc,
		fast_type	msg,
		unsigned int	n
	)

inlinestaticconstexprprotected

Apply message bits into a CRC.

Parameters

poly	the normal-form polynomial for the CRC.
crc	the remainder polynomial for the previously encountered message bits.
msg	bits of message, already reflected.
n	the number of bits in `msg` that carry message bits.

Returns: the CRC after incorporating msg using poly.

◆ lookup_for_byte()

template<unsigned int W, bool Rin = false>

static constexpr least_type pabigot::crc::details::base_crc< W, Rin >::lookup_for_byte	(	const fast_type &	poly,
		std::uint_fast8_t	byte
	)

inlinestaticconstexprprotected

Calculate a single lookup table entry using the given polynomial.

Parameters

index	the table index for which the precomputed CRC adjustment is desired.
poly	the polynomial for which the table is being generated.

Returns: the effective CRC adjustment using poly when the next 8 bits to shift out of the CRC are index.

◆ store()

template<unsigned int W, bool Rin = false>

static constexpr uint8_t* pabigot::crc::details::base_crc< W, Rin >::store	(	fast_type	crc,
		uint8_t *	bp
	)

inlinestaticconstexpr

Store a finalized CRC into a buffer in a way that enables crc::residue().

Warning: If the CRC width is not a multiple of 8 the stored value will not be correct, as this namespace provides no API to operate on messages that are not an integral number of octets.

Parameters

crc	the finalized CRC of a message.
bp	pointer to space of size bytes immediately following the message, into which the CRC can be stored.

Returns: pointer into the region identified by bp immediately following the stored CRC.

Field Documentation

◆ refin

template<unsigned int W, bool Rin = false>

constexpr bool pabigot::crc::details::base_crc< W, Rin >::refin = Rin

staticconstexpr

true iff the input message bit stream is reflected.

The CRC is a linear shift register; it is necessary to know which bit in a byte should be fed in first:

When refin is false the most significant bit of the byte is consumed first. This is the "big-endian" configuration.
When refin is true the least significant bit of the byte is consumed first. This is the "little-endian" configuration.

This parameter also affects crc::store() in that CRCs with width greater than 8 must use the byte order that matches the bit order when catenated to the end of a message to ensure that the aggregate CRC matches the crc::residual().

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

/mnt/devel/pabigot-cxx/include/pabigot/crc.hpp

Public Types

Static Public Member Functions

Static Public Attributes

Protected Types

Static Protected Member Functions

Detailed Description

template<unsigned int W, bool Rin = false> class pabigot::crc::details::base_crc< W, Rin >

Member Typedef Documentation

◆ fast_type

◆ least_type

Member Function Documentation

◆ crc_apply()

◆ lookup_for_byte()

◆ store()

Field Documentation

◆ refin

template<unsigned int W, bool Rin = false>
class pabigot::crc::details::base_crc< W, Rin >