bitops.h File Reference

#include <ntifs.h>
#include <linux/types.h>

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Macros
#define	find_first_zero_bit(addr, size)   find_next_zero_bit((addr), (size), 0)
#define	ffz(x)   __ffs(~(x))
#define	for_each_bit(bit, addr, size)

Functions
int	find_next_zero_bit (const unsigned long *addr, int size, int offset)
static unsigned long	__ffs (unsigned long word)
static unsigned	find_first_bit (const unsigned long *addr, unsigned size)
static int	ffs (int x)
static int	fls (int x)
static int	fls64 (__u64 x)
static __inline int	get_bitmask_order (unsigned int count)
static __inline int	get_count_order (unsigned int count)
static __u32	rol32 (__u32 word, unsigned int shift)
static __u32	ror32 (__u32 word, unsigned int shift)
static unsigned	fls_long (unsigned long l)
static unsigned long	hweight32 (unsigned long w)
static unsigned long	hweight64 (__u64 w)
static unsigned long	hweight_long (unsigned long w)

Macro Definition Documentation

ffz

#define ffz

(

x

)

__ffs(~(x))

find_next_bit - find the next set bit in a memory region @addr: The address to base the search on @offset: The bitnumber to start searching at @size: The maximum size to search

Definition at line 109 of file bitops.h.

find_first_zero_bit

#define find_first_zero_bit	(		addr,
			size
	)		find_next_zero_bit((addr), (size), 0)

find_first_zero_bit - find the first zero bit in a memory region @addr: The address to start the search at @size: The maximum size to search

Returns the bit number of the first zero bit, not the number of the byte containing a bit.

Definition at line 28 of file bitops.h.

for_each_bit

#define for_each_bit	(		bit,
			addr,
			size
	)

Value:

    for ((bit) = find_first_bit((addr), (size)); \
         (bit) < (size); \
         (bit) = find_next_bit((addr), (size), (bit) + 1))

Definition at line 194 of file bitops.h.

Function Documentation

__ffs()

static unsigned long __ffs ( unsigned long  word )

inlinestatic

__ffs - find first bit in word. @word: The word to search

Undefined if no bit exists, so code should check against 0 first.

Definition at line 44 of file bitops.h.

{
    int num = 0;
 
#if BITS_PER_LONG == 64
    if ((word & 0xffffffff) == 0) {
        num += 32;
        word >>= 32;
    }
#endif
    if ((word & 0xffff) == 0) {
        num += 16;
        word >>= 16;
    }
    if ((word & 0xff) == 0) {
        num += 8;
        word >>= 8;
    }
    if ((word & 0xf) == 0) {
        num += 4;
        word >>= 4;
    }
    if ((word & 0x3) == 0) {
        num += 2;
        word >>= 2;
    }
    if ((word & 0x1) == 0)
        num += 1;
    return num;
}

Referenced by find_first_bit().

ffs()

static int ffs ( int  x )

inlinestatic

ffs - find first bit set @x: the word to search

This is defined the same way as the libc and compiler builtin ffs routines, therefore differs in spirit from the above ffz (man ffs).

Definition at line 120 of file bitops.h.

{
    int r = 1;
 
    if (!x)
        return 0;
    if (!(x & 0xffff)) {
        x >>= 16;
        r += 16;
    }
    if (!(x & 0xff)) {
        x >>= 8;
        r += 8;
    }
    if (!(x & 0xf)) {
        x >>= 4;
        r += 4;
    }
    if (!(x & 3)) {
        x >>= 2;
        r += 2;
    }
    if (!(x & 1)) {
        x >>= 1;
        r += 1;
    }
    return r;
}

find_first_bit()

static unsigned find_first_bit ( const unsigned long *  addr, unsigned  size  )

inlinestatic

find_first_bit - find the first set bit in a memory region @addr: The address to start the search at @size: The maximum size to search

Returns the bit number of the first set bit, not the number of the byte containing a bit.

Definition at line 83 of file bitops.h.

{
    unsigned x = 0;
 
    while (x < size) {
        unsigned long val = *addr++;
        if (val)
            return __ffs(val) + x;
        x += (sizeof(*addr)<<3);
    }
    return x;
}

find_next_zero_bit()

int find_next_zero_bit	(	const unsigned long *	addr,
		int	size,
		int	offset
	)

find_next_zero_bit - find the first zero bit in a memory region @addr: The address to base the search on @offset: The bit number to start searching at @size: The maximum size to search

fls()

static int fls ( int  x )

inlinestatic

fls - find last (most-significant) bit set @x: the word to search

This is defined the same way as ffs. Note fls(0) = 0, fls(1) = 1, fls(0x80000000) = 32.

Definition at line 157 of file bitops.h.

{
    int r = 32;
 
    if (!x)
        return 0;
    if (!(x & 0xffff0000u)) {
        x <<= 16;
        r -= 16;
    }
    if (!(x & 0xff000000u)) {
        x <<= 8;
        r -= 8;
    }
    if (!(x & 0xf0000000u)) {
        x <<= 4;
        r -= 4;
    }
    if (!(x & 0xc0000000u)) {
        x <<= 2;
        r -= 2;
    }
    if (!(x & 0x80000000u)) {
        x <<= 1;
        r -= 1;
    }
    return r;
}

Referenced by __attribute__(), adns__findlabel_next(), adns__findlabel_start(), adns__findrr_anychk(), adns__mkquery_frdgram(), adns__parse_domain(), adns__parse_domain_more(), fls64(), fls_long(), get_bitmask_order(), get_count_order(), pa_ptr(), pap_mailbox822(), test_FiberLocalStorage(), and test_FiberLocalStorageCallback().

fls64()

static int fls64 ( __u64  x )

inlinestatic

Definition at line 186 of file bitops.h.

{
    __u32 h = (__u32) (x >> 32);
    if (h)
        return fls(h) + 32;
    return fls((int)x);
}

Referenced by fls_long().

fls_long()

static unsigned fls_long ( unsigned long  l )

inlinestatic

Definition at line 239 of file bitops.h.

{
    if (sizeof(l) == 4)
        return fls(l);
    return fls64(l);
}

get_bitmask_order()

static __inline int get_bitmask_order ( unsigned int  count )

static

Definition at line 200 of file bitops.h.

{
    int order;
 
    order = fls(count);
    return order;   /* We could be slightly more clever with -1 here... */
}

get_count_order()

static __inline int get_count_order ( unsigned int  count )

static

Definition at line 208 of file bitops.h.

{
    int order;
 
    order = fls(count) - 1;
    if (count & (count - 1))
        order++;
    return order;
}

hweight32()

static unsigned long hweight32 ( unsigned long  w )

inlinestatic

Definition at line 251 of file bitops.h.

{
    unsigned int res = (w & 0x55555555) + ((w >> 1) & 0x55555555);
    res = (res & 0x33333333) + ((res >> 2) & 0x33333333);
    res = (res & 0x0F0F0F0F) + ((res >> 4) & 0x0F0F0F0F);
    res = (res & 0x00FF00FF) + ((res >> 8) & 0x00FF00FF);
    return (res & 0x0000FFFF) + ((res >> 16) & 0x0000FFFF);
}

Referenced by hweight64(), and hweight_long().

hweight64()

static unsigned long hweight64 ( __u64  w )

inlinestatic

Definition at line 260 of file bitops.h.

{
#if BITS_PER_LONG < 64
    return hweight32((unsigned int)(w >> 32)) + hweight32((unsigned int)w);
#else
    u64 res;
    res = (w & 0x5555555555555555U) + ((w >> 1) & 0x5555555555555555U);
    res = (res & 0x3333333333333333U) + ((res >> 2) & 0x3333333333333333U);
    res = (res & 0x0F0F0F0F0F0F0F0FU) + ((res >> 4) & 0x0F0F0F0F0F0F0F0FU);
    res = (res & 0x00FF00FF00FF00FFU) + ((res >> 8) & 0x00FF00FF00FF00FFU);
    res = (res & 0x0000FFFF0000FFFFU) + ((res >> 16) & 0x0000FFFF0000FFFFU);
    return (res & 0x00000000FFFFFFFFU) + ((res >> 32) & 0x00000000FFFFFFFFU);
#endif
}

Referenced by hweight_long().

hweight_long()

static unsigned long hweight_long ( unsigned long  w )

inlinestatic

Definition at line 275 of file bitops.h.

{
    return sizeof(w) == 4 ? hweight32(w) : hweight64(w);
}

rol32()

static __u32 rol32 ( __u32  word, unsigned int  shift  )

inlinestatic

rol32 - rotate a 32-bit value left @word: value to rotate @shift: bits to roll

Definition at line 224 of file bitops.h.

{
    return (word << shift) | (word >> (32 - shift));
}

ror32()

static __u32 ror32 ( __u32  word, unsigned int  shift  )

inlinestatic

ror32 - rotate a 32-bit value right @word: value to rotate @shift: bits to roll

Definition at line 234 of file bitops.h.

{
    return (word >> shift) | (word << (32 - shift));
}