hoover_chess_utils::pgn_reader::BitTricks Struct Reference

Collection of bit tricks for 64-bit words. More...

#include <bittricks.h>

Static Public Member Functions
static constexpr std::uint64_t	bits0ToN (std::uint8_t n) noexcept
	Generates a bit mask with bits 0 to N set.
static constexpr std::uint64_t	rangeHalfOpen (std::uint8_t a, std::uint8_t b) noexcept
	Generates a half-open bit mask (min(a,b), max(a,b)].
static constexpr std::uint64_t	isolateLowestSetBit (std::uint64_t mask) noexcept
	Isolates (extracts) the lowest bit set in bit mask.
static constexpr std::uint64_t	isolateHighestSetBit (std::uint64_t mask) noexcept
	Isolates (extracts) the highest bit set in bit mask.
static std::uint64_t	parallelExtract (std::uint64_t data, std::uint64_t mask) noexcept
	Extracts bits of data from bit locations specified by mask.
static std::uint64_t	parallelDeposit (std::uint64_t data, std::uint64_t mask) noexcept
	Deposits bits of data to bit locations specified by mask.

Static Private Member Functions
static std::uint64_t	parallelExtractPortable (std::uint64_t data, std::uint64_t mask) noexcept
static std::uint64_t	parallelDepositPortable (std::uint64_t data, std::uint64_t mask) noexcept

Detailed Description

Collection of bit tricks for 64-bit words.

Member Function Documentation

bits0ToN()

static constexpr std::uint64_t hoover_chess_utils::pgn_reader::BitTricks::bits0ToN ( std::uint8_t  n )

inlinestaticconstexprnoexcept

Generates a bit mask with bits 0 to N set.

Parameters

[in]

n

The highest bit to set. Range: [0, 63]

Returns

Bit mask with bits from 0 to N set

isolateHighestSetBit()

static constexpr std::uint64_t hoover_chess_utils::pgn_reader::BitTricks::isolateHighestSetBit ( std::uint64_t  mask )

inlinestaticconstexprnoexcept

Isolates (extracts) the highest bit set in bit mask.

Parameters

[in]

mask

Bit mask

Returns

Bit mask with highest bit of mask set OR 0 if mask is 0.

isolateLowestSetBit()

static constexpr std::uint64_t hoover_chess_utils::pgn_reader::BitTricks::isolateLowestSetBit ( std::uint64_t  mask )

inlinestaticconstexprnoexcept

Isolates (extracts) the lowest bit set in bit mask.

Parameters

[in]

mask

Bit mask

Returns

Bit mask with lowest bit of mask set OR 0 if mask is 0.

parallelDeposit()

static std::uint64_t hoover_chess_utils::pgn_reader::BitTricks::parallelDeposit ( std::uint64_t  data, std::uint64_t  mask  )

inlinestaticnoexcept

Deposits bits of data to bit locations specified by mask.

Parameters

[in]	data	Data word
[in]	mask	Mask

Returns

Deposited bits

The following implementations are provided:

Build condition	Description
HAVE_X86_BMI2	Fast implementation using x86 PDEP instruction
HAVE_AARCH64_SVE2_BITPERM	Fast implementation using AArch64 BDEP instruction
Otherwise	Generic portable implementation

See also

https://www.chessprogramming.org/BMI2#PDEP

parallelDepositPortable()

static std::uint64_t hoover_chess_utils::pgn_reader::BitTricks::parallelDepositPortable ( std::uint64_t  data, std::uint64_t  mask  )

staticprivatenoexcept

parallelExtract()

static std::uint64_t hoover_chess_utils::pgn_reader::BitTricks::parallelExtract ( std::uint64_t  data, std::uint64_t  mask  )

inlinestaticnoexcept

Extracts bits of data from bit locations specified by mask.

Parameters

[in]	data	Data word
[in]	mask	Mask

Returns

Extracted bits from data

The following implementations are provided:

Build condition	Description
HAVE_X86_BMI2	Fast implementation using x86 PEXT instruction
HAVE_AARCH64_SVE2_BITPERM	Fast implementation using AArch64 BEXT instruction
Otherwise	Generic portable implementation

See also

https://www.chessprogramming.org/BMI2#PEXT

parallelExtractPortable()

static std::uint64_t hoover_chess_utils::pgn_reader::BitTricks::parallelExtractPortable ( std::uint64_t  data, std::uint64_t  mask  )

staticprivatenoexcept

rangeHalfOpen()

static constexpr std::uint64_t hoover_chess_utils::pgn_reader::BitTricks::rangeHalfOpen ( std::uint8_t  a, std::uint8_t  b  )

inlinestaticconstexprnoexcept

Generates a half-open bit mask (min(a,b), max(a,b)].

Parameters

[in]	a	Boundary of the bit mask. Range: [0, 63]
[in]	b	Boundary of the bit mask. Range: [0, 63]

Returns

Half-open bit mask (min(a,b), max(a,b)]

This function is intended to generate a half-open bit mask when it does not matter whether the boundaries are included. That is, the caller sets or resets the boundaries accordingly.

Illustration:

                  a       b
       ----------------------------------------------------------------
ret =  0000000000011111111000000000000000000000000000000000000000000000 

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

• pgn-reader/src/bittricks.h