MinNibbleEntries Class Reference

the entries of a pattern table, the least excess of each group of ranks More...

#include <PBeFS/astar/PatternDatabase.h>

Public Member Functions
int	value (std::uint64_t r, int m) const noexcept
	the value of the rank r, whose placement has Manhattan distance m
std::uint64_t	entries (void) const noexcept
	the number of the entries
unsigned	group (void) const noexcept
	the ranks per group
std::size_t	bytes (void) const noexcept
	the bytes of the entries
std::vector< std::uint8_t >	payload (void) const
	the bytes written in a file

Static Public Member Functions
template<class M>
static MinNibbleEntries	encode (const std::vector< std::uint8_t > &h, M &&m, unsigned c=1)
	the encoding of the distances h, by groups of c ranks
static MinNibbleEntries	decode (std::vector< std::uint8_t > data, std::uint64_t n, unsigned c=1)
	the encoding of n entries read from a file

Static Public Attributes
static constexpr std::uint32_t	code = 4
	the code in a file
static constexpr const char *	name = "min"
	the name
static constexpr bool	relative = false
	absolute values

Detailed Description

the entries of a pattern table, the least excess of each group of ranks

The ranks are grouped by c consecutive ones, c a power of 2, and the group stores the least excess over Manhattan of its placements in 4 bits, saturated at 15, i.e., \( 4 / c \) bits per entry: the lossy compression of Felner, Korf, Meshulam and Holte (JAIR 2007), which here keeps the Manhattan distance of each placement. The value is at most the exact one, hence admissible, but a table so compressed is not consistent in general. Consecutive ranks differ in the cell of the last tile of the pattern only, so that a group holds placements that are close.

Member Function Documentation

bytes()

std::size_t bytes ( void ) const

inlinenodiscardnoexcept

the bytes of the entries

decode()

MinNibbleEntries decode ( std::vector< std::uint8_t > data, std::uint64_t n, unsigned c = 1 )

inlinestaticnodiscard

the encoding of n entries read from a file

encode()

template<class M>

MinNibbleEntries encode ( const std::vector< std::uint8_t > & h, M && m, unsigned c = 1 )

inlinestaticnodiscard

the encoding of the distances h, by groups of c ranks

entries()

std::uint64_t entries ( void ) const

inlinenodiscardnoexcept

the number of the entries

group()

unsigned group ( void ) const

inlinenodiscardnoexcept

the ranks per group

payload()

std::vector< std::uint8_t > payload ( void ) const

inlinenodiscard

the bytes written in a file

value()

int value ( std::uint64_t r, int m ) const

inlinenodiscardnoexcept

the value of the rank r, whose placement has Manhattan distance m

Member Data Documentation

code

std::uint32_t code = 4

staticconstexpr

the code in a file

name

const char* name = "min"

staticconstexpr

the name

relative

bool relative = false

staticconstexpr

absolute values

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

• PBeFS/astar/PatternDatabase.h