Helper functions for bit arithmetic. More...

Detailed Description

Helper functions for bit arithmetic.

Author: Kaspar Schleiser kaspa.nosp@m.r@sc.nosp@m.hleis.nosp@m.er.d.nosp@m.e; Martine Lenders mlend.nosp@m.ers@.nosp@m.inf.f.nosp@m.u-be.nosp@m.rlin..nosp@m.de

Definition in file bitarithm.h.

#include <stdint.h>
#include "cpu_conf.h"

Include dependency graph for bitarithm.h:

This graph shows which files directly or indirectly include this file:

Go to the source code of this file.

Macros
#define	ARCH_32_BIT (__INT_MAX__ == 2147483647)
	1 for 32 bit architectures, 0 otherwise

Functions
static unsigned	bitarithm_msb (unsigned v)
	Returns the number of the highest '1' bit in a value.

static unsigned	bitarithm_lsb (unsigned v)
	Returns the number of the lowest '1' bit in a value.

unsigned	bitarithm_bits_set (unsigned v)
	Returns the number of bits set in a value.

uint8_t	bitarithm_bits_set_u32 (uint32_t v)
	Returns the (uint32_t version) number of bits set in a value.

unsigned	bitarith_msb_32bit_no_native_clz (unsigned v)
	Returns the number of the highest '1' bit in a value.

static uint8_t	bitarithm_clzb (uint8_t x)
	Returns the number of leading 0-bits in `x`, starting at the most significant bit position.

static unsigned	bitarithm_test_and_clear (unsigned state, uint8_t *index)
	Used for iterating over the bits in `state`.

#define	SETBIT(val, bit) val \|= (bit)
	Sets a bitmask for a bitfield.

#define	CLRBIT(val, bit) val &= (~(bit))
	Clears bitmask for a bitfield.

Single Bit Defines
#define	BIT0 0x00000001
	Bit 0 set define.

#define	BIT1 0x00000002
	Bit 1 set define.

#define	BIT2 0x00000004
	Bit 2 set define.

#define	BIT3 0x00000008
	Bit 3 set define.

#define	BIT4 0x00000010
	Bit 4 set define.

#define	BIT5 0x00000020
	Bit 5 set define.

#define	BIT6 0x00000040
	Bit 6 set define.

#define	BIT7 0x00000080
	Bit 7 set define.

#define	BIT8 0x00000100
	Bit 8 set define.

#define	BIT9 0x00000200
	Bit 9 set define.

#define	BIT10 0x00000400
	Bit 10 set define.

#define	BIT11 0x00000800
	Bit 11 set define.

#define	BIT12 0x00001000
	Bit 12 set define.

#define	BIT13 0x00002000
	Bit 13 set define.

#define	BIT14 0x00004000
	Bit 14 set define.

#define	BIT15 0x00008000
	Bit 15 set define.

#define	BIT16 0x00010000
	Bit 16 set define.

#define	BIT17 0x00020000
	Bit 17 set define.

#define	BIT18 0x00040000
	Bit 18 set define.

#define	BIT19 0x00080000
	Bit 19 set define.

#define	BIT20 0x00100000
	Bit 20 set define.

#define	BIT21 0x00200000
	Bit 21 set define.

#define	BIT22 0x00400000
	Bit 22 set define.

#define	BIT23 0x00800000
	Bit 23 set define.

#define	BIT24 0x01000000
	Bit 24 set define.

#define	BIT25 0x02000000
	Bit 25 set define.

#define	BIT26 0x04000000
	Bit 26 set define.

#define	BIT27 0x08000000
	Bit 27 set define.

#define	BIT28 0x10000000
	Bit 28 set define.

#define	BIT29 0x20000000
	Bit 29 set define.

#define	BIT30 0x40000000
	Bit 30 set define.

#define	BIT31 0x80000000
	Bit 31 set define.

Macro Definition Documentation

◆ ARCH_32_BIT

#define ARCH_32_BIT (__INT_MAX__ == 2147483647)

1 for 32 bit architectures, 0 otherwise

Definition at line 98 of file bitarithm.h.

◆ BIT0

#define BIT0 0x00000001

Bit 0 set define.

Definition at line 59 of file bitarithm.h.

◆ BIT1

#define BIT1 0x00000002

Bit 1 set define.

Definition at line 60 of file bitarithm.h.

◆ BIT10

#define BIT10 0x00000400

Bit 10 set define.

Definition at line 71 of file bitarithm.h.

◆ BIT11

#define BIT11 0x00000800

Bit 11 set define.

Definition at line 72 of file bitarithm.h.

◆ BIT12

#define BIT12 0x00001000

Bit 12 set define.

Definition at line 73 of file bitarithm.h.

◆ BIT13

#define BIT13 0x00002000

Bit 13 set define.

Definition at line 74 of file bitarithm.h.

◆ BIT14

#define BIT14 0x00004000

Bit 14 set define.

Definition at line 75 of file bitarithm.h.

◆ BIT15

#define BIT15 0x00008000

Bit 15 set define.

Definition at line 76 of file bitarithm.h.

◆ BIT16

#define BIT16 0x00010000

Bit 16 set define.

Definition at line 79 of file bitarithm.h.

◆ BIT17

#define BIT17 0x00020000

Bit 17 set define.

Definition at line 80 of file bitarithm.h.

◆ BIT18

#define BIT18 0x00040000

Bit 18 set define.

Definition at line 81 of file bitarithm.h.

◆ BIT19

#define BIT19 0x00080000

Bit 19 set define.

Definition at line 82 of file bitarithm.h.

◆ BIT2

#define BIT2 0x00000004

Bit 2 set define.

Definition at line 61 of file bitarithm.h.

◆ BIT20

#define BIT20 0x00100000

Bit 20 set define.

Definition at line 83 of file bitarithm.h.

◆ BIT21

#define BIT21 0x00200000

Bit 21 set define.

Definition at line 84 of file bitarithm.h.

◆ BIT22

#define BIT22 0x00400000

Bit 22 set define.

Definition at line 85 of file bitarithm.h.

◆ BIT23

#define BIT23 0x00800000

Bit 23 set define.

Definition at line 86 of file bitarithm.h.

◆ BIT24

#define BIT24 0x01000000

Bit 24 set define.

Definition at line 87 of file bitarithm.h.

◆ BIT25

#define BIT25 0x02000000

Bit 25 set define.

Definition at line 88 of file bitarithm.h.

◆ BIT26

#define BIT26 0x04000000

Bit 26 set define.

Definition at line 89 of file bitarithm.h.

◆ BIT27

#define BIT27 0x08000000

Bit 27 set define.

Definition at line 90 of file bitarithm.h.

◆ BIT28

#define BIT28 0x10000000

Bit 28 set define.

Definition at line 91 of file bitarithm.h.

◆ BIT29

#define BIT29 0x20000000

Bit 29 set define.

Definition at line 92 of file bitarithm.h.

◆ BIT3

#define BIT3 0x00000008

Bit 3 set define.

Definition at line 62 of file bitarithm.h.

◆ BIT30

#define BIT30 0x40000000

Bit 30 set define.

Definition at line 93 of file bitarithm.h.

◆ BIT31

#define BIT31 0x80000000

Bit 31 set define.

Definition at line 94 of file bitarithm.h.

◆ BIT4

#define BIT4 0x00000010

Bit 4 set define.

Definition at line 63 of file bitarithm.h.

◆ BIT5

#define BIT5 0x00000020

Bit 5 set define.

Definition at line 64 of file bitarithm.h.

◆ BIT6

#define BIT6 0x00000040

Bit 6 set define.

Definition at line 65 of file bitarithm.h.

◆ BIT7

#define BIT7 0x00000080

Bit 7 set define.

Definition at line 66 of file bitarithm.h.

◆ BIT8

#define BIT8 0x00000100

Bit 8 set define.

Definition at line 67 of file bitarithm.h.

◆ BIT9

#define BIT9 0x00000200

Bit 9 set define.

Definition at line 68 of file bitarithm.h.

◆ CLRBIT

#define CLRBIT	(	val,
		bit
	)	val &= (~(bit))

Clears bitmask for a bitfield.

Parameters

[in]	val	The bitfield
[in]	bit	Specifies the bits to be cleared

Returns: The modified bitfield

Definition at line 52 of file bitarithm.h.

◆ SETBIT

#define SETBIT	(	val,
		bit
	)	val \|= (bit)

Sets a bitmask for a bitfield.

Parameters

[in]	val	The bitfield
[in]	bit	Specifies the bits to be set

Returns: The modified bitfield

Definition at line 41 of file bitarithm.h.

Function Documentation

◆ bitarith_msb_32bit_no_native_clz()

unsigned bitarith_msb_32bit_no_native_clz ( unsigned v )

Returns the number of the highest '1' bit in a value.

     Internal software implementation for 32 bit platforms,
     use @see bitarithm_msb in application code.

Parameters

[in] v Input value

Returns: Bit Number

◆ bitarithm_bits_set()

unsigned bitarithm_bits_set ( unsigned v )

Returns the number of bits set in a value.

Parameters

[in] v Input value with platform-dependent word size

Returns: Number of set bits

◆ bitarithm_bits_set_u32()

uint8_t bitarithm_bits_set_u32 ( uint32_t v )

Returns the (uint32_t version) number of bits set in a value.

Parameters

[in] v Input value with 32 bit size

Returns: Number of set bits

◆ bitarithm_clzb()

static uint8_t bitarithm_clzb ( uint8_t x )

inlinestatic

Returns the number of leading 0-bits in x, starting at the most significant bit position.

If x is 0, the result is undefined.

Parameters

[in] x Input value

Returns: Number of leading zero bits

Definition at line 176 of file bitarithm.h.

◆ bitarithm_lsb()

static unsigned bitarithm_lsb ( unsigned v )

inlinestatic

Returns the number of the lowest '1' bit in a value.

Parameters

[in] v Input value - must be unequal to '0', otherwise the function will produce an infinite loop

Returns: Bit Number

Definition at line 206 of file bitarithm.h.

◆ bitarithm_msb()

static unsigned bitarithm_msb ( unsigned v )

inlinestatic

Returns the number of the highest '1' bit in a value.

Parameters

[in] v Input value

Returns: Bit Number

Source: http://graphics.stanford.edu/~seander/bithacks.html#IntegerLogObvious

Definition at line 153 of file bitarithm.h.

◆ bitarithm_test_and_clear()

static unsigned bitarithm_test_and_clear	(	unsigned	state,
		uint8_t *	index
	)

inlinestatic

Used for iterating over the bits in state.

Returns the index of a set bit in state, returns state with that bit cleared.

Warning: This is a low-level helper function, arguments are not checked. It is intended to iterate over a bit map until all bits are cleared. Whether it starts with the highest or lowest bit will depend on what is fastest on the given hardware.; state must not be zero.

Parameters

[in]	state	Bit Map with at least one bit set
[out]	index	Index of the first set bit. Must be initialized with 0 before the first call to this function, must not be modified between subsequent calls.

Returns: new state value - must be treated as opaque value

Definition at line 254 of file bitarithm.h.

Detailed Description

Macros

Functions

Single Bit Defines

Macro Definition Documentation

◆ ARCH_32_BIT

◆ BIT0

◆ BIT1

◆ BIT10

◆ BIT11

◆ BIT12

◆ BIT13

◆ BIT14

◆ BIT15

◆ BIT16

◆ BIT17

◆ BIT18

◆ BIT19

◆ BIT2

◆ BIT20

◆ BIT21

◆ BIT22

◆ BIT23

◆ BIT24

◆ BIT25

◆ BIT26

◆ BIT27

◆ BIT28

◆ BIT29

◆ BIT3

◆ BIT30

◆ BIT31

◆ BIT4

◆ BIT5

◆ BIT6

◆ BIT7

◆ BIT8

◆ BIT9

◆ CLRBIT

◆ SETBIT

Function Documentation

◆ bitarith_msb_32bit_no_native_clz()

◆ bitarithm_bits_set()

◆ bitarithm_bits_set_u32()

◆ bitarithm_clzb()

◆ bitarithm_lsb()

◆ bitarithm_msb()

◆ bitarithm_test_and_clear()