Description:

template<typename TIntegral>
class alib::bitbuffer::ac_v1::ArrayCompressor::Array< TIntegral >

Helper-class that allows access the array data. The design goal for introducing this class (instead of providing array references in the interface methods) is to allow a minimum of flexibility in respect to the data provision, while not using callback functions (or virtual methods) to access each single array element.

The approach implemented here, allows the array value to be a single attribute residing in an array of structs. For this, besides a base pointer to the first value and the length of the array, the distance between two values within the array of structs (or classes) has to be given.

By nature, to do this, basic pointer manipulation is needed, which imposes the need using char* values internally, which are cast back to the source type with setters/getters.
Consequently, templated constructors are given, which accept array types to restrict such pointer conversion within the type.

Note: In the case an application uses a more complex data scheme for storing array data to be compressed, which are not accessible with this simple mechanism, such data has to be written into temporary arrays before compression.

Besides this, this accessor type, provides a transparent inline conversion of signed integer values to its unsigned counterparts by performing "zig zag encoding".

Template Parameters

TIntegral The integral array type.

Definition at line 69 of file ac.inl.

Public Type Index:
using	TUI = typename std::make_unsigned<TIntegral>::type
	The unsigned version of template type `TIntegral`.

Public Field Index:
TUI	max
	Maximum value (when zig-zag encoded)

TUI	maxDec
	Maximum decrease between two adjacent values.

TUI	maxInc
	Maximum increase between two adjacent values.

TUI	min
	Maximum value (when zig-zag encoded)

TUI	minDec
	Minimum decrease between two adjacent values.

TUI	minInc
	Minimum increase between two adjacent values.

Public Method Index:
	Array (const TIntegral &firstValue, const TIntegral &secondValue, size_t length)

	Array (const TIntegral *arrayStart, size_t length)

void	calcMinMax ()

TUI	get (size_t idx) const

size_t	length () const

void	set (size_t idx, TUI value)

Private Field Index:
size_t	distance
	The distance in memory between two array values.

char *	firstVal
	Pointer to the first array value.

size_t	len
	The length of the array.

Type Definition Details:

◆ TUI

template<typename TIntegral>

using alib::bitbuffer::ac_v1::ArrayCompressor::Array< TIntegral >::TUI = typename std::make_unsigned<TIntegral>::type

The unsigned version of template type TIntegral.

Definition at line 73 of file ac.inl.

Field Details:

◆ distance

template<typename TIntegral>

size_t alib::bitbuffer::ac_v1::ArrayCompressor::Array< TIntegral >::distance

private

The distance in memory between two array values.

Definition at line 77 of file ac.inl.

◆ firstVal

template<typename TIntegral>

char* alib::bitbuffer::ac_v1::ArrayCompressor::Array< TIntegral >::firstVal

private

Pointer to the first array value.

Definition at line 76 of file ac.inl.

◆ len

template<typename TIntegral>

size_t alib::bitbuffer::ac_v1::ArrayCompressor::Array< TIntegral >::len

private

The length of the array.

Definition at line 78 of file ac.inl.

◆ max

template<typename TIntegral>

TUI alib::bitbuffer::ac_v1::ArrayCompressor::Array< TIntegral >::max

Maximum value (when zig-zag encoded)

Definition at line 82 of file ac.inl.

◆ maxDec

template<typename TIntegral>

TUI alib::bitbuffer::ac_v1::ArrayCompressor::Array< TIntegral >::maxDec

Maximum decrease between two adjacent values.

Definition at line 84 of file ac.inl.

◆ maxInc

template<typename TIntegral>

TUI alib::bitbuffer::ac_v1::ArrayCompressor::Array< TIntegral >::maxInc

Maximum increase between two adjacent values.

Definition at line 83 of file ac.inl.

◆ min

template<typename TIntegral>

TUI alib::bitbuffer::ac_v1::ArrayCompressor::Array< TIntegral >::min

Maximum value (when zig-zag encoded)

Definition at line 81 of file ac.inl.

◆ minDec

template<typename TIntegral>

TUI alib::bitbuffer::ac_v1::ArrayCompressor::Array< TIntegral >::minDec

Minimum decrease between two adjacent values.

Definition at line 86 of file ac.inl.

◆ minInc

template<typename TIntegral>

TUI alib::bitbuffer::ac_v1::ArrayCompressor::Array< TIntegral >::minInc

Minimum increase between two adjacent values.

Definition at line 85 of file ac.inl.

Constructor(s) / Destructor Details:

◆ Array() [1/2]

template<typename TIntegral>

alib::bitbuffer::ac_v1::ArrayCompressor::Array< TIntegral >::Array	(	const TIntegral *	arrayStart,
		size_t	length )

inline

This constructor may (and must only) be used when the data is stored in simple arrays, hence when the data is not nested in an array of structs.

Parameters

arrayStart	Pointer to the first value of the array.
length	The length of the array

Definition at line 96 of file ac.inl.

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◆ Array() [2/2]

template<typename TIntegral>

alib::bitbuffer::ac_v1::ArrayCompressor::Array< TIntegral >::Array	(	const TIntegral &	firstValue,
		const TIntegral &	secondValue,
		size_t	length )

inline

This constructor takes the first and the second array value as pointers. The second is used to "assume" (!) the distance in memory between each value.

Attention: If the assumption of such basic memory layout is wrong, array values have to be copied to a temporary memory that satisfies this rule.

Parameters

firstValue	Pointer to the first value of the array.
secondValue	Pointer to the second value of the array
length	The length of the array

Definition at line 116 of file ac.inl.

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Method Details:

◆ calcMinMax()

template<typename TIntegral>

void alib::bitbuffer::ac_v1::ArrayCompressor::Array< TIntegral >::calcMinMax ( )

inline

Loops over the data and stores minimum and maximum values as well as minimum and maximum value distances.

Definition at line 186 of file ac.inl.

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◆ get()

template<typename TIntegral>

TUI alib::bitbuffer::ac_v1::ArrayCompressor::Array< TIntegral >::get ( size_t idx ) const

inline

Returns the value at the given index as an unsigned integer value (for arrays of signed values, zig-zag encoding is performed)

Parameters

idx	The index of the value in the array to retrieve.

Returns: An unsigned representation of the value at the given index.

Definition at line 140 of file ac.inl.

◆ length()

template<typename TIntegral>

size_t alib::bitbuffer::ac_v1::ArrayCompressor::Array< TIntegral >::length ( ) const

inline

Returns the constant array length, given on construction.

Returns: The length of the array to compress/decompress

Definition at line 131 of file ac.inl.

◆ set()

template<typename TIntegral>

void alib::bitbuffer::ac_v1::ArrayCompressor::Array< TIntegral >::set	(	size_t	idx,
		TUI	value )

inline

Writes the given value at the given idx as an unsigned integer value (for arrays of signed values, zig-zag encoding is performed)

Parameters

idx	The index of the value in the array to set.
value	The value to set.

Definition at line 158 of file ac.inl.

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

ac.inl

Description:

Public Type Index:

Public Field Index:

Public Method Index:

Private Field Index:

Type Definition Details:

◆ TUI

Field Details:

◆ distance

◆ firstVal

◆ len

◆ max

◆ maxDec

◆ maxInc

◆ min

◆ minDec

◆ minInc

Constructor(s) / Destructor Details:

◆ Array() [1/2]

◆ Array() [2/2]

Method Details:

◆ calcMinMax()

◆ get()

◆ length()

◆ set()