cxx::Bitmap_base Class Reference

Basic bitmap abstraction. More...

#include <bitmap>

Inheritance diagram for cxx::Bitmap_base:

Collaboration diagram for cxx::Bitmap_base:

Data Structures
class	Bit
	A writeable bit in a bitmap. More...
class	Char
	Helper abstraction for a byte contained in the bitmap. More...
class	Word
	Helper abstraction for a word contained in the bitmap. More...

Public Member Functions
void	bit (long bit, bool on) noexcept
	Set the value of bit bit to on.
void	clear_bit (long bit) noexcept
	Clear bit bit.
void	atomic_clear_bit (long bit) noexcept
	Clear bit bit atomically.
word_type	atomic_get_and_clear (long bit) noexcept
	Clear bit bit atomically and return old state.
void	set_bit (long bit) noexcept
	Set bit bit.
void	atomic_set_bit (long bit) noexcept
	Set bit bit atomically.
word_type	atomic_get_and_set (long bit) noexcept
	Set bit bit atomically and return old state.
word_type	bit (long bit) const noexcept
	Get the truth value of a bit.
word_type	operator[] (long bit) const noexcept
	Get the bit at index bit.
Bit	operator[] (long bit) noexcept
	Get the lvalue for the bit at index bit.
long	scan_zero (long max_bit, long start_bit=0) const noexcept
	Scan for the first zero bit.

Static Public Member Functions
static long	words (long bits) noexcept
	Get the number of Words that are used for the bitmap.
static long	chars (long bits) noexcept
	Get the number of chars that are used for the bitmap.

Protected Types
enum	{ W_bits = sizeof(word_type) * 8 , C_bits = 8 }
typedef unsigned long	word_type
	Data type for each element of the bit buffer.

Static Protected Member Functions
static unsigned	word_index (unsigned bit)
	Get the word index for the given bit.
static unsigned	bit_index (unsigned bit)
	Get the bit index within word_type for the given bit.

Protected Attributes
word_type *	_bits
	Pointer to the buffer storing the bits.

Detailed Description

Basic bitmap abstraction.

This abstraction keeps a pointer to a memory area that is used as bitmap.

Definition at line 29 of file bitmap.

Member Enumeration Documentation

anonymous enum

anonymous enum

protected

Enumerator
W_bits	number of bits in word_type
C_bits	number of bits in char

Definition at line 37 of file bitmap.

Member Function Documentation

atomic_clear_bit()

void cxx::Bitmap_base::atomic_clear_bit ( long  bit )

inlinenoexcept

Clear bit bit atomically.

Use this function for multi-threaded access to the bitmap.

Parameters

bit	The number of the bit to clear.

Definition at line 280 of file bitmap.

atomic_get_and_clear()

Bitmap_base::word_type cxx::Bitmap_base::atomic_get_and_clear ( long  bit )

inlinenoexcept

Clear bit bit atomically and return old state.

Use this function for multi-threaded access to the bitmap.

Parameters

bit	The number of the bit to clear.

Definition at line 290 of file bitmap.

atomic_get_and_set()

Bitmap_base::word_type cxx::Bitmap_base::atomic_get_and_set ( long  bit )

inlinenoexcept

Set bit bit atomically and return old state.

Use this function for multi-threaded access to the bitmap.

Parameters

bit	The number of the bit to set.

Definition at line 319 of file bitmap.

atomic_set_bit()

void cxx::Bitmap_base::atomic_set_bit ( long  bit )

inlinenoexcept

Set bit bit atomically.

Use this function for multi-threaded access to the bitmap.

Parameters

bit	The number of the bit to set.

Definition at line 309 of file bitmap.

bit() [1/2]

Bitmap_base::word_type cxx::Bitmap_base::bit ( long  bit ) const

inlinenoexcept

Get the truth value of a bit.

Parameters

bit	The number of the bit to read.

Return values

0	Bit is not set.
!=	0 Bit is set.

Definition at line 329 of file bitmap.

bit() [2/2]

void cxx::Bitmap_base::bit ( long  bit, bool  on  )

inlinenoexcept

Set the value of bit bit to on.

Parameters

bit	The number of the bit.
on	The boolean value that shall be assigned to the bit.

Definition at line 262 of file bitmap.

Referenced by operator[](), and operator[]().

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bit_index()

static unsigned cxx::Bitmap_base::bit_index ( unsigned  bit )

inlinestaticprotected

Get the bit index within word_type for the given bit.

Parameters

bit	The bit index in the bitmap.

Returns

the bit index within word_type (bit % W_bits).

Definition at line 64 of file bitmap.

References W_bits.

clear_bit()

void cxx::Bitmap_base::clear_bit ( long  bit )

inlinenoexcept

Clear bit bit.

Parameters

bit	The number of the bit to clear.

Definition at line 271 of file bitmap.

operator[]() [1/2]

word_type cxx::Bitmap_base::operator[] ( long  bit ) const

inlinenoexcept

Get the bit at index bit.

Parameters

bit	The number of the bit to read.

Return values

0	Bit is not set.
!=	0 Bit is set.

Definition at line 192 of file bitmap.

References bit().

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operator[]() [2/2]

Bit cxx::Bitmap_base::operator[] ( long  bit )

inlinenoexcept

Get the lvalue for the bit at index bit.

Parameters

bit	The number.

Returns

lvalue for bit

Definition at line 202 of file bitmap.

References bit().

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scan_zero()

long cxx::Bitmap_base::scan_zero ( long  max_bit, long  start_bit = 0  ) const

inlinenoexcept

Scan for the first zero bit.

Parameters

max_bit	Upper bound (exclusive) for the scanning operation.
start_bit	Hint at the number of the first bit to look at. Zero bits below start_bit may or may not be taken into account by the implementation.

Return values

>=	0 Number of first zero bit found.
-1	All bits between start_bit and max_bit are set.

Definition at line 350 of file bitmap.

Referenced by cxx::Bitmap< BITS >::scan_zero().

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set_bit()

void cxx::Bitmap_base::set_bit ( long  bit )

inlinenoexcept

Set bit bit.

Parameters

bit	The number of the bit to set.

Definition at line 300 of file bitmap.

word_index()

static unsigned cxx::Bitmap_base::word_index ( unsigned  bit )

inlinestaticprotected

Get the word index for the given bit.

Parameters

bit	The index of the bit in question.

Returns

the index in Bitmap_base::_bits for the given bit (bit / W_bits).

Definition at line 55 of file bitmap.

References W_bits.

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

• l4/cxx/bitmap