pabigot::crc::details::uint_support< B > Struct Template Reference

Type and policy traits providing support for operations on B-bit values. More...

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

Public Types
using	uint_traits = details::uint_traits< uint_category< B >()>
	Characteristics of the unsigned integer support required for a width-bit value.
using	fast_type = typename uint_traits::fast_type
	The type used to hold values while they're being operated on. More...
using	least_type = typename uint_traits::least_type
	The type used to hold values while they're being stored. More...

Static Public Member Functions
static constexpr fast_type	reflect (const fast_type &v, unsigned int n=width)
	Reflect a value around its center. More...
static constexpr fast_type	crc_apply (const fast_type &poly, const fast_type &crc, const fast_type &msg, const unsigned int n)
	Apply message bits into the CRC. More...

Static Public Attributes
static constexpr unsigned int	width = B
	The number of bits for which this class is targeted. More...
static constexpr unsigned int	fast_width = std::numeric_limits<fast_type>::digits
	The number of bits used in fast_type, should that be useful.
static constexpr unsigned int	least_width = std::numeric_limits<least_type>::digits
	The number of bits used in least_type, should that be useful.
static constexpr fast_type	mask {uint_traits::mask_for_bits(width)}
	A mask value that will discard bits at and above bit number width in a value.
static constexpr fast_type	msbit {static_cast<fast_type>(1) << (width - 1)}
	Mask isolating the most significant bit in a value.
static constexpr fast_type	lsbit {static_cast<fast_type>(1)}
	Mask isolating the least significant bit in a value.

Detailed Description

template<unsigned int B>
struct pabigot::crc::details::uint_support< B >

Type and policy traits providing support for operations on B-bit values.

Template Parameters

B	the number of bits as a positive value not exceeding 64.

Member Typedef Documentation

fast_type

template<unsigned int B>

using pabigot::crc::details::uint_support< B >::fast_type = typename uint_traits::fast_type

The type used to hold values while they're being operated on.

This is the fastest unsigned type capable of holding at least width bits.

least_type

template<unsigned int B>

using pabigot::crc::details::uint_support< B >::least_type = typename uint_traits::least_type

The type used to hold values while they're being stored.

This is the smallest type capable of holding at least width bits.

Member Function Documentation

crc_apply()

template<unsigned int B>

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

inlinestaticconstexpr

Apply message bits into the 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 and shifted so the first bit is in bit n-1 and the last bit is in bit 0.
n	the number of bits in msg that carry message bits. This must not exceed width.

Returns

the CRC after incorporating msg using poly.

reflect()

template<unsigned int B>

static constexpr fast_type pabigot::crc::details::uint_support< B >::reflect ( const fast_type &  v, unsigned int  n = width  )

inlinestaticconstexpr

Reflect a value around its center.

Parameters

v	the value to be reflected
n	the number of bits of in that are valid. Bit n-1 of in is reflected into bit 0 of the returned value; similarly bit 0 of in shows up in bit n-1 of the returned value. Defaults to width, but 8 and other values may be required when reflecting input chunks.

Field Documentation

width

template<unsigned int B>

constexpr unsigned int pabigot::crc::details::uint_support< B >::width = B

staticconstexpr

The number of bits for which this class is targeted.

This is a lower bound on the number of bits supported by fast_type and least_type, and influences the values of msbit, lsbit, mask, and the default upper bit position used in reflect().

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

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