Bit Manipulation

Collaboration diagram for Bit Manipulation:

Files
file	bitops_arch.h
	amd64 bit manipulation functions
file	bitops.h
	bit manipulation functions
file	bitops_arch.h
	x86 bit manipulation functions

Functions
void	l4util_set_bit (int b, volatile l4_umword_t *dest)
	Set bit in memory.
void	l4util_clear_bit (int b, volatile l4_umword_t *dest)
	Clear bit in memory.
void	l4util_complement_bit (int b, volatile l4_umword_t *dest)
	Complement bit in memory.
int	l4util_test_bit (int b, const volatile l4_umword_t *dest)
	Test bit (return value of bit)
int	l4util_bts (int b, volatile l4_umword_t *dest)
	Bit test and set.
int	l4util_btr (int b, volatile l4_umword_t *dest)
	Bit test and reset.
int	l4util_btc (int b, volatile l4_umword_t *dest)
	Bit test and complement.
int	l4util_bsr (l4_umword_t word)
	Bit scan reverse.
int	l4util_bsf (l4_umword_t word)
	Bit scan forward.
int	l4util_find_first_set_bit (const void *dest, l4_size_t size)
	Find the first set bit in a memory region.
int	l4util_find_first_zero_bit (const void *dest, l4_size_t size)
	Find the first zero bit in a memory region.
int	l4util_next_power2 (unsigned long val)
	Find the next power of 2 for a given number.

Detailed Description

Function Documentation

l4util_bsf()

int l4util_bsf ( l4_umword_t  word )

inline

Bit scan forward.

Parameters

word	value (machine size)

Returns

index of least significant bit set in word, -1 if no bit is set (word == 0)

"bit scan forward", find least significant bit set in word.

Definition at line 318 of file bitops.h.

l4util_bsr()

int l4util_bsr ( l4_umword_t  word )

inline

Bit scan reverse.

Parameters

word	value (machine size)

Returns

index of most significant set bit in word, -1 if no bit is set (word == 0)

"bit scan reverse", find most significant set bit in word (-> LOG2(word))

Definition at line 301 of file bitops.h.

l4util_btc()

int l4util_btc ( int  b, volatile l4_umword_t *  dest  )

inline

Bit test and complement.

Parameters

b	bit position
dest	destination operand

Returns

Old value of bit b.

Complement bit b and return old value.

Definition at line 396 of file bitops.h.

l4util_btr()

int l4util_btr ( int  b, volatile l4_umword_t *  dest  )

inline

Bit test and reset.

Parameters

b	bit position
dest	destination operand

Returns

Old value of bit b.

Reset bit b and return old value.

Definition at line 280 of file bitops.h.

References l4util_cmpxchg().

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l4util_bts()

int l4util_bts ( int  b, volatile l4_umword_t *  dest  )

inline

Bit test and set.

Parameters

b	bit position
dest	destination operand

Returns

Old value of bit b.

Set the b bit of dest to 1 and return the old value.

Definition at line 258 of file bitops.h.

References l4util_cmpxchg().

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l4util_clear_bit()

void l4util_clear_bit ( int  b, volatile l4_umword_t *  dest  )

inline

Clear bit in memory.

Parameters

b	bit position
dest	destination operand

Definition at line 228 of file bitops.h.

References l4util_cmpxchg().

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l4util_complement_bit()

void l4util_complement_bit ( int  b, volatile l4_umword_t *  dest  )

inline

Complement bit in memory.

Parameters

b	bit position
dest	destination operand

Definition at line 361 of file bitops.h.

l4util_find_first_set_bit()

int l4util_find_first_set_bit ( const void *  dest, l4_size_t  size  )

inline

Find the first set bit in a memory region.

Parameters

dest	bit string
size	size of string in bits (must be a multiple of L4_MWORD_BITS!)

Returns

number of the first set bit, >= size if no bit is set

Definition at line 402 of file bitops.h.

l4util_find_first_zero_bit()

int l4util_find_first_zero_bit ( const void *  dest, l4_size_t  size  )

inline

Find the first zero bit in a memory region.

Parameters

dest	bit string
size	size of string in bits (must be a multiple of L4_MWORD_BITS!)

Returns

number of the first zero bit, >= size if no bit is set

Definition at line 335 of file bitops.h.

l4util_next_power2()

int l4util_next_power2 ( unsigned long  val )

inline

Find the next power of 2 for a given number.

Parameters

val	initial value

Returns

next-highest power of 2

Definition at line 375 of file bitops.h.

l4util_set_bit()

void l4util_set_bit ( int  b, volatile l4_umword_t *  dest  )

inline

Set bit in memory.

Parameters

b	bit position
dest	destination operand

Definition at line 209 of file bitops.h.

References l4util_cmpxchg().

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l4util_test_bit()

int l4util_test_bit ( int  b, const volatile l4_umword_t *  dest  )

inline

Test bit (return value of bit)

Parameters

b	bit position
dest	destination operand

Returns

Value of bit b.

Definition at line 246 of file bitops.h.