Bit field manipulation. More...

#include <stdint.h>
#include <stdbool.h>

Typedefs
typedef uint32_t *	bit_field_t
	bit_field_t is an arbitrary length bit field (vector of bits) which is used to compactly represent a large number of boolean operations.

typedef uint32_t	size_t
	An unsigned integer used for the size of objects.

typedef uint32_t	index_t
	An unsigned integer used as an index.

typedef uint32_t	counter_t
	An unsigned integer used as a counter or iterator.

Functions
static bool	bit_field_test (bit_field_t b, index_t n)
	This function tests a particular bit of a bit_field.

static void	bit_field_clear (bit_field_t restrict b, index_t n)
	This function clears a particular bit of a bit_field.

static void	bit_field_set (bit_field_t restrict b, index_t n)
	This function sets a particular bit of a bit_field.

static void	not_bit_field (bit_field_t restrict b, size_t s)
	This function negates the bits of an entire bit_field.

static void	and_bit_fields (bit_field_t restrict b1, const bit_field_t restrict b2, size_t s)
	This function ands two bit_fields together.

static void	or_bit_fields (bit_field_t restrict b1, const bit_field_t restrict b2, size_t s)
	This function ors two bit_fields together.

static void	clear_bit_field (bit_field_t restrict b, size_t s)
	This function clears an entire bit_field.

static void	set_bit_field (bit_field_t restrict b, size_t s)
	This function sets an entire bit_field.

static bool	empty_bit_field (const bit_field_t restrict b, size_t s)
	This function tests whether a bit_field is all zeros.

static bool	nonempty_bit_field (const bit_field_t restrict b, size_t s)
	Testing whether a bit_field is non-empty, i.e. if there is at least one bit set.

static size_t	get_bit_field_size (size_t bits)
	A function that calculates the size of a bit_field to hold 'bits' bits.

static int	count_bit_field (const bit_field_t restrict b, size_t s)
	Computes the number of set bits in a bit_field.

void	print_bit_field_bits (const bit_field_t restrict b, size_t s)
	This function prints out an entire bit_field, as a sequence of ones and zeros.

void	print_bit_field (const bit_field_t restrict b, size_t s)
	This function prints out an entire bit_field, as a sequence of hexadecimal numbers, one per line.

void	random_bit_field (bit_field_t restrict b, size_t s)
	Generates a random bit_field for testing purposes.

bit_field_t	bit_field_alloc (uint32_t n_atoms)
	allocates a bit_field_t object

Detailed Description

Bit field manipulation.

A bit field is a vector of machine words which is treated as a vector of bits.

For SpiNNaker each machine word is 32 bits, and so a bit_field for each neuron (assuming 256 neurons) would be 8 words long.

The API includes:

bit_field_test() returns true of false depending on whether bit n is set or clear
bit_field_set() / bit_field_clear() used to set or clear bit n
not_bit_field() logically inverts a bit field of size s.
and_bit_fields() / or_bit_fields() logically ands/ors two bit_fields together. Requires size.
clear_bit_field() / set_bit_field() Initializes bit_field with all false (= clear) or true (= set). Requires size.

There are also support functions for:

printing
randomly setting up a bit field

Author: Dave Lester (david.nosp@m..r.l.nosp@m.ester.nosp@m.@man.nosp@m.chest.nosp@m.er.a.nosp@m.c.uk), Jamie Knight (knigh.nosp@m.tj@c.nosp@m.s.man.nosp@m..ac..nosp@m.uk)

Copyright: Copyright (c) Dave Lester, Jamie Knight and The University of Manchester, 2013. All rights reserved. SpiNNaker Project Advanced Processor Technologies Group School of Computer Science The University of Manchester Manchester M13 9PL, UK

Date: 12 December, 2013

Function Documentation

◆ bit_field_test()

static bool bit_field_test	(	bit_field_t	b,
		index_t	n
	)

inlinestatic

This function tests a particular bit of a bit_field.

Parameters

[in]	b	The sequence of words representing a bit_field.
[in]	n	The size of the bit_field.

Returns: The function returns true if the bit is set or false otherwise.

◆ bit_field_clear()

static void bit_field_clear	(	bit_field_t restrict	b,
		index_t	n
	)

inlinestatic

This function clears a particular bit of a bit_field.

Parameters

[in]	b	The sequence of words representing a bit_field.
[in]	n	The size of the bit_field.

◆ bit_field_set()

static void bit_field_set	(	bit_field_t restrict	b,
		index_t	n
	)

inlinestatic

This function sets a particular bit of a bit_field.

Parameters

[in]	b	The sequence of words representing a bit_field.
[in]	n	The bit in the bit_field of interest.

◆ not_bit_field()

static void not_bit_field	(	bit_field_t restrict	b,
		size_t	s
	)

inlinestatic

This function negates the bits of an entire bit_field.

Parameters

[in]	b	The sequence of words representing a bit_field.
[in]	s	The size of the bit_field.

◆ and_bit_fields()

static void and_bit_fields	(	bit_field_t restrict	b1,
		const bit_field_t restrict	b2,
		size_t	s
	)

inlinestatic

This function ands two bit_fields together.

Parameters

[in,out]	b1	The sequence of words representing the first bit_field; the result is returned in this parameter.
[in]	b2	The sequence of words representing the second bit_field.
[in]	s	The size of the bit_field.

◆ or_bit_fields()

static void or_bit_fields	(	bit_field_t restrict	b1,
		const bit_field_t restrict	b2,
		size_t	s
	)

inlinestatic

This function ors two bit_fields together.

Parameters

[in,out]	b1	The sequence of words representing the first bit_field; the result is returned in this parameter.
[in]	b2	The sequence of words representing the second bit_field.
[in]	s	The size of the bit_field.

◆ clear_bit_field()

static void clear_bit_field	(	bit_field_t restrict	b,
		size_t	s
	)

inlinestatic

This function clears an entire bit_field.

Parameters

[in]	b	The sequence of words representing a bit_field.
[in]	s	The size of the bit_field.

◆ set_bit_field()

static void set_bit_field	(	bit_field_t restrict	b,
		size_t	s
	)

inlinestatic

This function sets an entire bit_field.

Parameters

[in]	b	The sequence of words representing a bit_field.
[in]	s	The size of the bit_field.

◆ empty_bit_field()

static bool empty_bit_field	(	const bit_field_t restrict	b,
		size_t	s
	)

inlinestatic

This function tests whether a bit_field is all zeros.

Parameters

[in]	b	The sequence of words representing a bit_field.
[in]	s	The size of the bit_field.

Returns: The function returns true if every bit is zero, or false otherwise.

◆ nonempty_bit_field()

static bool nonempty_bit_field	(	const bit_field_t restrict	b,
		size_t	s
	)

inlinestatic

Testing whether a bit_field is non-empty, i.e. if there is at least one bit set.

Parameters

[in]	b	The sequence of words representing a bit_field.
[in]	s	The size of the bit_field.

Returns: The function returns true if at least one bit is set; otherwise false.

◆ get_bit_field_size()

static size_t get_bit_field_size ( size_t bits )

inlinestatic

A function that calculates the size of a bit_field to hold 'bits' bits.

Parameters

[in] bits The number of bits required for this bit_field.

Returns: The size (or number of words) in the bit_field.

◆ count_bit_field()

static int count_bit_field	(	const bit_field_t restrict	b,
		size_t	s
	)

inlinestatic

Computes the number of set bits in a bit_field.

Parameters

[in]	b	The sequence of words representing a bit_field.
[in]	s	The size of the bit_field.

Returns: The function returns the number of bits set to 1.

◆ print_bit_field_bits()

void print_bit_field_bits	(	const bit_field_t restrict	b,
		size_t	s
	)

This function prints out an entire bit_field, as a sequence of ones and zeros.

Parameters

[in]	b	The sequence of words representing a bit_field.
[in]	s	The size of the bit_field.

◆ print_bit_field()

void print_bit_field	(	const bit_field_t restrict	b,
		size_t	s
	)

This function prints out an entire bit_field, as a sequence of hexadecimal numbers, one per line.

Parameters

[in]	b	The sequence of words representing a bit_field.
[in]	s	The size of the bit_field.

◆ random_bit_field()

void random_bit_field	(	bit_field_t restrict	b,
		size_t	s
	)

Generates a random bit_field for testing purposes.

Parameters

[in]	b	The sequence of words representing a bit_field.
[in]	s	The size of the bit_field.

◆ bit_field_alloc()

bit_field_t bit_field_alloc ( uint32_t n_atoms )

allocates a bit_field_t object

Parameters

[in] n_atoms the number of atoms to cover with this bitfield

Returns: the allocated bitfield

Typedefs

Functions

Detailed Description

Function Documentation

◆ bit_field_test()

◆ bit_field_clear()

◆ bit_field_set()

◆ not_bit_field()

◆ and_bit_fields()

◆ or_bit_fields()

◆ clear_bit_field()

◆ set_bit_field()

◆ empty_bit_field()

◆ nonempty_bit_field()

◆ get_bit_field_size()

◆ count_bit_field()

◆ print_bit_field_bits()

◆ print_bit_field()

◆ random_bit_field()

◆ bit_field_alloc()