#include "comms/field/Bitfield.h"

Detailed Description

template<typename TFieldBase, typename TMembers, typename... TOptions>
class comms::field::Bitfield< TFieldBase, TMembers, TOptions >

Sometimes one or several bytes can be logically split into two or more independent values, which are packed together to save some space. For example, one enum type that has only 4 possible values, i.e only two bits are needed to encode such value. It would be a waste to allocate full byte for it. Instead, it is packed with some other, say unsigned counter that requires up to 6 bits to encode its valid range of values. The following code defines such field:

enum class MyEnumType : std::uint8_t
{
    Value1,
    Value2,
    Value3,
    Value4
};
 
using MyFieldBase = comms::Field<comms::option::def::BigEndian>;
using MyField =
    comms::field::Bitfield<
        MyFieldBase,
        std::tuple<
            comms::field::EnumValue<
                MyFieldBase,
                MyEnumType,
                comms::option::def::FixedBitLength<2>
            >,
            comms::field::IntValue<
                MyFieldBase,
                std::uint8_t,
                comms::option::def::FixedBitLength<6>
            >
        >
    >;

Note, that bitfield members fields specify their length in bits using comms::option::def::FixedBitLength option. Also note, that all bitfield member's lengths in bits combined create a round number of bytes, i.e all the bits must sum up to 8, 16, 24, 32, ... bits.

Refer to Bitfield Fields for tutorial and usage examples.

Template Parameters

TFieldBase	Base class for this field, expected to be a variant of comms::Field.
TMembers	All member fields bundled together in std::tuple.
TOptions	Zero or more options that modify/refine default behaviour of the field. Supported options are: comms::option::def::HasCustomRead comms::option::def::HasCustomRefresh comms::option::def::EmptySerialization comms::option::def::VersionStorage comms::option::def::FieldType comms::option::def::HasVersionDependentMembers

Precondition: TMember is a variant of std::tuple, that contains other fields.; Every field member specifies its length in bits using comms::option::def::FixedBitLength option.

See also: COMMS_FIELD_MEMBERS_NAMES(); COMMS_FIELD_MEMBERS_ACCESS(); COMMS_FIELD_MEMBERS_ACCESS_NOTEMPLATE(); COMMS_FIELD_ALIAS()

Inheritance diagram for comms::field::Bitfield< TFieldBase, TMembers, TOptions >:

Public Types
using	CommsTag = typename BaseImpl::CommsTag
	Tag indicating type of the field.

using	Endian = typename BaseImpl::Endian
	Endian used for serialisation.

using	FieldBase = TFieldBase
	Base class provided in the first template parameter.

using	FieldType = typename ParsedOptions::FieldType
	Type of actual extending field specified via comms::option::def::FieldType. More...

using	ParsedOptions = details::OptionsParser< TOptions... >
	All the options provided to this class bundled into struct.

using	ValueType = typename BaseImpl::ValueType
	Value type. More...

using	VersionType = typename BaseImpl::VersionType
	Version type.

Public Member Functions
	Bitfield ()=default
	Default constructor. More...

	Bitfield (const ValueType &val)
	Constructor. More...

	Bitfield (ValueType &&val)
	Constructor. More...

bool	canWrite () const
	Check of whether the field has a consistent value for writing.

const ValueType &	getValue () const
	Get value. More...

VersionType	getVersion () const
	Get version of the field. More...

constexpr std::size_t	length () const
	Get length required to serialise the current field value. More...

template<typename TIter >
ErrorStatus	read (TIter &iter, std::size_t size)
	Read field value from input data sequence. More...

template<typename TIter >
void	readNoStatus (TIter &iter)
	Read field value from input data sequence without error check and status report. More...

bool	refresh ()
	Refresh the field's contents. More...

template<typename U >
void	setValue (U &&val)
	Set value. More...

bool	setVersion (VersionType version)
	Default implementation of version update. More...

bool	valid () const
	Check validity of the field value.

ValueType &	value ()
	Get access to the stored tuple of fields. More...

const ValueType &	value () const
	Get access to the stored tuple of fields. More...

template<typename TIter >
ErrorStatus	write (TIter &iter, std::size_t size) const
	Write current field value to output data sequence. More...

template<typename TIter >
void	writeNoStatus (TIter &iter) const
	Write current field value to output data sequence without error check and status report. More...

Static Public Member Functions
static constexpr bool	canWrite ()
	Default check of whether the field has a consistent value for writing. More...

static constexpr bool	hasEmptySerialization ()
	Compile time inquiry of whether comms::option::def::EmptySerialization option has been used.

static constexpr bool	hasFailOnInvalid ()
	Compile time inquiry of whether comms::option::def::FailOnInvalid option has been used.

static constexpr bool	hasFieldType ()
	Compile time inquiry of whether comms::option::def::FieldType option has been used.

static constexpr bool	hasIgnoreInvalid ()
	Compile time inquiry of whether comms::option::def::IgnoreInvalid option has been used.

static constexpr bool	hasNonDefaultRefresh ()
	Compile time check if this class has non-default refresh functionality.

static constexpr bool	hasReadNoStatus ()
	Compile time check of whether the field has proper readNoStatus() member function.

static constexpr bool	hasVarLength ()
	Default check of whether the field has variable length definition via comms::option::def::VarLength option. More...

static constexpr bool	hasWriteNoStatus ()
	Compile time check of whether the field has proper writeNoStatus() member function.

static constexpr bool	isVersionDependent ()
	Compile time check if this class is version dependent.

static constexpr std::size_t	maxLength ()
	Get maximal length that is required to serialise field of this type. More...

template<std::size_t TIdx>
static constexpr std::size_t	memberBitLength ()
	Retrieve number of bits specified member field consumes. More...

static constexpr std::size_t	minLength ()
	Get minimal length that is required to serialise field of this type. More...

static constexpr bool	valid ()
	Default validity check. More...

Static Protected Member Functions
template<typename T , typename TIter >
static T	readData (TIter &iter)
	Read data from input buffer. More...

template<typename T , std::size_t TSize, typename TIter >
static T	readData (TIter &iter)
	Read partial data from input buffer. More...

template<typename T , typename TIter >
static void	writeData (T value, TIter &iter)
	Write data into the output buffer. More...

template<std::size_t TSize, typename T , typename TIter >
static void	writeData (T value, TIter &iter)
	Write partial data into the output buffer. More...

Related Functions
(Note that these are not member functions.)
template<typename T >
constexpr bool	isBitfield ()
	Compile time check function of whether a provided type is any variant of comms::field::Bitfield. More...

template<typename TFieldBase , typename TMembers , typename... TOptions>
bool	operator!= (const Bitfield< TFieldBase, TMembers, TOptions... > &field1, const Bitfield< TFieldBase, TMembers, TOptions... > &field2) noexcept
	Non-equality comparison operator. More...

template<typename TFieldBase , typename TMembers , typename... TOptions>
bool	operator< (const Bitfield< TFieldBase, TMembers, TOptions... > &field1, const Bitfield< TFieldBase, TMembers, TOptions... > &field2) noexcept
	Equivalence comparison operator. More...

template<typename TFieldBase , typename TMembers , typename... TOptions>
bool	operator== (const Bitfield< TFieldBase, TMembers, TOptions... > &field1, const Bitfield< TFieldBase, TMembers, TOptions... > &field2) noexcept
	Equality comparison operator. More...

template<typename TFieldBase , typename TMembers , typename... TOptions>
Bitfield< TFieldBase, TMembers, TOptions... > &	toFieldBase (Bitfield< TFieldBase, TMembers, TOptions... > &field)
	Upcast type of the field definition to its parent comms::field::Bitfield type in order to have access to its internal types.

template<typename TFieldBase , typename TMembers , typename... TOptions>
const Bitfield< TFieldBase, TMembers, TOptions... > &	toFieldBase (const Bitfield< TFieldBase, TMembers, TOptions... > &field)
	Upcast type of the field definition to its parent comms::field::Bitfield type in order to have access to its internal types.

Member Typedef Documentation

◆ FieldType

template<typename TFieldBase , typename TMembers , typename... TOptions>

using comms::field::Bitfield< TFieldBase, TMembers, TOptions >::FieldType = typename ParsedOptions::FieldType

Type of actual extending field specified via comms::option::def::FieldType.

void if comms::option::def::FieldType hasn't been applied.

◆ ValueType

template<typename TFieldBase , typename TMembers , typename... TOptions>

using comms::field::Bitfield< TFieldBase, TMembers, TOptions >::ValueType = typename BaseImpl::ValueType

Value type.

Same as TMemebers template argument, i.e. it is std::tuple of all the member fields.

Constructor & Destructor Documentation

◆ Bitfield() [1/3]

template<typename TFieldBase , typename TMembers , typename... TOptions>

comms::field::Bitfield< TFieldBase, TMembers, TOptions >::Bitfield ( )

default

Default constructor.

All field members are initialised using their default constructors.

◆ Bitfield() [2/3]

template<typename TFieldBase , typename TMembers , typename... TOptions>

comms::field::Bitfield< TFieldBase, TMembers, TOptions >::Bitfield ( const ValueType & val )

explicit

Constructor.

Parameters

[in] val Value of the field to initialise it with.

◆ Bitfield() [3/3]

template<typename TFieldBase , typename TMembers , typename... TOptions>

comms::field::Bitfield< TFieldBase, TMembers, TOptions >::Bitfield ( ValueType && val )

explicit

Constructor.

Parameters

[in] val Value of the field to initialise it with.

Member Function Documentation

◆ canWrite()

template<typename... TOptions>

static constexpr bool comms::Field< TOptions >::canWrite ( )

staticconstexprinherited

Default check of whether the field has a consistent value for writing.

Returns: Always true.

◆ getValue()

template<typename TFieldBase , typename TMembers , typename... TOptions>

const ValueType& comms::field::Bitfield< TFieldBase, TMembers, TOptions >::getValue ( ) const

Get value.

Implemented by calling value(), but can be overriden in the derived class

◆ getVersion()

template<typename TFieldBase , typename TMembers , typename... TOptions>

VersionType comms::field::Bitfield< TFieldBase, TMembers, TOptions >::getVersion ( ) const

Get version of the field.

Exists only if comms::option::def::VersionStorage option has been provided.

◆ hasVarLength()

template<typename... TOptions>

static constexpr bool comms::Field< TOptions >::hasVarLength ( )

staticconstexprinherited

Default check of whether the field has variable length definition via comms::option::def::VarLength option.

Returns: Always false.

◆ length()

template<typename TFieldBase , typename TMembers , typename... TOptions>

constexpr std::size_t comms::field::Bitfield< TFieldBase, TMembers, TOptions >::length ( ) const

constexpr

Get length required to serialise the current field value.

Returns: Number of bytes it will take to serialise the field value.

◆ maxLength()

template<typename TFieldBase , typename TMembers , typename... TOptions>

static constexpr std::size_t comms::field::Bitfield< TFieldBase, TMembers, TOptions >::maxLength ( )

staticconstexpr

Get maximal length that is required to serialise field of this type.

Returns: Maximal number of bytes required serialise the field value.

◆ memberBitLength()

template<typename TFieldBase , typename TMembers , typename... TOptions>

template<std::size_t TIdx>

static constexpr std::size_t comms::field::Bitfield< TFieldBase, TMembers, TOptions >::memberBitLength ( )

staticconstexpr

Retrieve number of bits specified member field consumes.

Template Parameters

TIdx	Index of the member field.

Returns: Number of bits, specified with comms::option::def::FixedBitLength option used with the requested member.

◆ minLength()

template<typename TFieldBase , typename TMembers , typename... TOptions>

static constexpr std::size_t comms::field::Bitfield< TFieldBase, TMembers, TOptions >::minLength ( )

staticconstexpr

Get minimal length that is required to serialise field of this type.

Returns: Minimal number of bytes required serialise the field value.

◆ read()

template<typename TFieldBase , typename TMembers , typename... TOptions>

template<typename TIter >

ErrorStatus comms::field::Bitfield< TFieldBase, TMembers, TOptions >::read	(	TIter &	iter,
		std::size_t	size
	)

Read field value from input data sequence.

Parameters

[in,out]	iter	Iterator to read the data.
[in]	size	Number of bytes available for reading.

Returns: Status of read operation.

Postcondition: Iterator is advanced.

◆ readData() [1/2]

template<typename... TOptions>

template<typename T , typename TIter >

static T comms::Field< TOptions >::readData ( TIter & iter )

staticprotectedinherited

Read data from input buffer.

Use this function to read data from the intput buffer maintained by the caller. The endianness of the data will be as specified in options of the class.

Template Parameters

T	Return type
TIter	Type of input iterator

Parameters

[in,out] iter Input iterator.

Returns: The integral type value.

Precondition: TSize <= sizeof(T); The iterator must be valid and can be successfully dereferenced and incremented at least sizeof(T) times.

Postcondition: The iterator is advanced.

Note: Thread safety: Safe for distinct stream buffers, unsafe otherwise.

◆ readData() [2/2]

template<typename... TOptions>

template<typename T , std::size_t TSize, typename TIter >

static T comms::Field< TOptions >::readData ( TIter & iter )

staticprotectedinherited

Read partial data from input buffer.

Use this function to read data from the intput buffer maintained by the caller. The endianness of the data will be as specified in options of the class.

Template Parameters

T	Return type
TSize	number of bytes to read
TIter	Type of input iterator

Parameters

[in,out] iter Input iterator.

Returns: The integral type value.

Precondition: TSize <= sizeof(T); The iterator must be valid and can be successfully dereferenced and incremented at least TSize times.

Postcondition: The internal pointer of the stream buffer is advanced.

Note: Thread safety: Safe for distinct stream buffers, unsafe otherwise.

◆ readNoStatus()

template<typename TFieldBase , typename TMembers , typename... TOptions>

template<typename TIter >

void comms::field::Bitfield< TFieldBase, TMembers, TOptions >::readNoStatus ( TIter & iter )

Read field value from input data sequence without error check and status report.

Similar to read(), but doesn't perform any correctness checks and doesn't report any failures.

Parameters

[in,out] iter Iterator to read the data.

Postcondition: Iterator is advanced.

◆ refresh()

template<typename TFieldBase , typename TMembers , typename... TOptions>

bool comms::field::Bitfield< TFieldBase, TMembers, TOptions >::refresh ( )

Refresh the field's contents.

Calls refresh() member function on every member field, will return true if any of the calls returns true.

◆ setValue()

template<typename TFieldBase , typename TMembers , typename... TOptions>

template<typename U >

void comms::field::Bitfield< TFieldBase, TMembers, TOptions >::setValue ( U && val )

Set value.

Implemented as re-assigning to value(), but can be overriden in the derived class.

◆ setVersion()

template<typename TFieldBase , typename TMembers , typename... TOptions>

bool comms::field::Bitfield< TFieldBase, TMembers, TOptions >::setVersion ( VersionType version )

Default implementation of version update.

Returns: true in case the field contents have changed, false otherwise

◆ valid()

template<typename... TOptions>

static constexpr bool comms::Field< TOptions >::valid ( )

staticconstexprinherited

Default validity check.

Always returns true, can be overriden by the derived class

Returns: Always true

◆ value() [1/2]

template<typename TFieldBase , typename TMembers , typename... TOptions>

ValueType& comms::field::Bitfield< TFieldBase, TMembers, TOptions >::value ( )

Get access to the stored tuple of fields.

Returns: Reference to the underlying stored value.

◆ value() [2/2]

template<typename TFieldBase , typename TMembers , typename... TOptions>

const ValueType& comms::field::Bitfield< TFieldBase, TMembers, TOptions >::value ( ) const

Get access to the stored tuple of fields.

Returns: Const reference to the underlying stored value.

◆ write()

template<typename TFieldBase , typename TMembers , typename... TOptions>

template<typename TIter >

ErrorStatus comms::field::Bitfield< TFieldBase, TMembers, TOptions >::write	(	TIter &	iter,
		std::size_t	size
	)		const

Write current field value to output data sequence.

Parameters

[in,out]	iter	Iterator to write the data.
[in]	size	Maximal number of bytes that can be written.

Returns: Status of write operation.

Postcondition: Iterator is advanced.

◆ writeData() [1/2]

template<typename... TOptions>

template<typename T , typename TIter >

static void comms::Field< TOptions >::writeData	(	T	value,
		TIter &	iter
	)

staticprotectedinherited

Write data into the output buffer.

Use this function to write data to the the buffer maintained by the caller. The endianness of the data will be as specified in the options provided to the class.

Template Parameters

T	Type of the value to write. Must be integral.
Type	of output iterator

Parameters

[in]	value	Integral type value to be written.
[in,out]	iter	Output iterator.

Precondition: The iterator must be valid and can be successfully dereferenced and incremented at least sizeof(T) times.

Postcondition: The iterator is advanced.

Note: Thread safety: Safe for distinct buffers, unsafe otherwise.

◆ writeData() [2/2]

template<typename... TOptions>

template<std::size_t TSize, typename T , typename TIter >

static void comms::Field< TOptions >::writeData	(	T	value,
		TIter &	iter
	)

staticprotectedinherited

Write partial data into the output buffer.

Use this function to write partial data to the buffer maintained by the caller. The endianness of the data will be as specified the class options.

Template Parameters

TSize	Length of the value in bytes known in compile time.
T	Type of the value to write. Must be integral.
TIter	Type of output iterator

Parameters

[in]	value	Integral type value to be written.
[in,out]	iter	Output iterator.

Precondition: TSize <= sizeof(T); The iterator must be valid and can be successfully dereferenced and incremented at least TSize times.

Postcondition: The iterator is advanced.

Note: Thread safety: Safe for distinct buffers, unsafe otherwise.

◆ writeNoStatus()

template<typename TFieldBase , typename TMembers , typename... TOptions>

template<typename TIter >

void comms::field::Bitfield< TFieldBase, TMembers, TOptions >::writeNoStatus ( TIter & iter ) const

Write current field value to output data sequence without error check and status report.

Similar to write(), but doesn't perform any correctness checks and doesn't report any failures.

Parameters

[in,out] iter Iterator to write the data.

Postcondition: Iterator is advanced.

Friends And Related Function Documentation

◆ isBitfield()

template<typename T >

constexpr bool isBitfield ( )

Template Parameters

T Any type.

Returns: true in case provided type is any variant of Bitfield

◆ operator!=()

template<typename TFieldBase , typename TMembers , typename... TOptions>

bool operator!=	(	const Bitfield< TFieldBase, TMembers, TOptions... > &	field1,
		const Bitfield< TFieldBase, TMembers, TOptions... > &	field2
	)

Parameters

[in]	field1	First field.
[in]	field2	Second field.

Returns: true in case fields are NOT equal, false otherwise.

◆ operator<()

template<typename TFieldBase , typename TMembers , typename... TOptions>

bool operator<	(	const Bitfield< TFieldBase, TMembers, TOptions... > &	field1,
		const Bitfield< TFieldBase, TMembers, TOptions... > &	field2
	)

Parameters

[in]	field1	First field.
[in]	field2	Second field.

Returns: true in case value of the first field is lower than than the value of the second.

◆ operator==()

template<typename TFieldBase , typename TMembers , typename... TOptions>

bool operator==	(	const Bitfield< TFieldBase, TMembers, TOptions... > &	field1,
		const Bitfield< TFieldBase, TMembers, TOptions... > &	field2
	)

Parameters

[in]	field1	First field.
[in]	field2	Second field.

Returns: true in case fields are equal, false otherwise.

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

include/comms/field/Bitfield.h

Detailed Description

template<typename TFieldBase, typename TMembers, typename... TOptions> class comms::field::Bitfield< TFieldBase, TMembers, TOptions >

Public Types

Public Member Functions

Static Public Member Functions

Static Protected Member Functions

Related Functions

Member Typedef Documentation

◆ FieldType

◆ ValueType

Constructor & Destructor Documentation

◆ Bitfield() [1/3]

◆ Bitfield() [2/3]

◆ Bitfield() [3/3]

Member Function Documentation

◆ canWrite()

◆ getValue()

◆ getVersion()

◆ hasVarLength()

◆ length()

◆ maxLength()

◆ memberBitLength()

◆ minLength()

◆ read()

◆ readData() [1/2]

◆ readData() [2/2]

◆ readNoStatus()

◆ refresh()

◆ setValue()

◆ setVersion()

◆ valid()

◆ value() [1/2]

◆ value() [2/2]

◆ write()

◆ writeData() [1/2]

◆ writeData() [2/2]

◆ writeNoStatus()

Friends And Related Function Documentation

◆ isBitfield()

◆ operator!=()

◆ operator<()

◆ operator==()

template<typename TFieldBase, typename TMembers, typename... TOptions>
class comms::field::Bitfield< TFieldBase, TMembers, TOptions >