bitops.h

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#ifndef _PERF_LINUX_BITOPS_H_
#define _PERF_LINUX_BITOPS_H_

#include <linux/kernel.h>
#include <linux/compiler.h>
#include <asm/hweight.h>

#ifndef __WORDSIZE
#define __WORDSIZE (__SIZEOF_LONG__ * 8)
#endif

#define BITS_PER_LONG __WORDSIZE
#define BITS_PER_BYTE           8
#define BITS_TO_LONGS(nr)       DIV_ROUND_UP(nr, BITS_PER_BYTE * sizeof(long))
#define BITS_TO_U64(nr)         DIV_ROUND_UP(nr, BITS_PER_BYTE * sizeof(u64))
#define BITS_TO_U32(nr)         DIV_ROUND_UP(nr, BITS_PER_BYTE * sizeof(u32))

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

/* same as for_each_set_bit() but use bit as value to start with */
#define for_each_set_bit_from(bit, addr, size) \
    for ((bit) = find_next_bit((addr), (size), (bit));  \
         (bit) < (size);                    \
         (bit) = find_next_bit((addr), (size), (bit) + 1))

static inline void set_bit(int nr, unsigned long *addr)
{
    addr[nr / BITS_PER_LONG] |= 1UL << (nr % BITS_PER_LONG);
}

static inline void clear_bit(int nr, unsigned long *addr)
{
    addr[nr / BITS_PER_LONG] &= ~(1UL << (nr % BITS_PER_LONG));
}

static __always_inline int test_bit(unsigned int nr, const unsigned long *addr)
{
    return ((1UL << (nr % BITS_PER_LONG)) &
        (((unsigned long *)addr)[nr / BITS_PER_LONG])) != 0;
}

static inline unsigned long hweight_long(unsigned long w)
{
    return sizeof(w) == 4 ? hweight32(w) : hweight64(w);
}

#define BITOP_WORD(nr)      ((nr) / BITS_PER_LONG)

static __always_inline unsigned long __ffs(unsigned long word)
{
    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;
}

/*
 * Find the first set bit in a memory region.
 */
static inline unsigned long
find_first_bit(const unsigned long *addr, unsigned long size)
{
    const unsigned long *p = addr;
    unsigned long result = 0;
    unsigned long tmp;

    while (size & ~(BITS_PER_LONG-1)) {
        if ((tmp = *(p++)))
            goto found;
        result += BITS_PER_LONG;
        size -= BITS_PER_LONG;
    }
    if (!size)
        return result;

    tmp = (*p) & (~0UL >> (BITS_PER_LONG - size));
    if (tmp == 0UL)     /* Are any bits set? */
        return result + size;   /* Nope. */
found:
    return result + __ffs(tmp);
}

/*
 * Find the next set bit in a memory region.
 */
static inline unsigned long
find_next_bit(const unsigned long *addr, unsigned long size, unsigned long offset)
{
    const unsigned long *p = addr + BITOP_WORD(offset);
    unsigned long result = offset & ~(BITS_PER_LONG-1);
    unsigned long tmp;

    if (offset >= size)
        return size;
    size -= result;
    offset %= BITS_PER_LONG;
    if (offset) {
        tmp = *(p++);
        tmp &= (~0UL << offset);
        if (size < BITS_PER_LONG)
            goto found_first;
        if (tmp)
            goto found_middle;
        size -= BITS_PER_LONG;
        result += BITS_PER_LONG;
    }
    while (size & ~(BITS_PER_LONG-1)) {
        if ((tmp = *(p++)))
            goto found_middle;
        result += BITS_PER_LONG;
        size -= BITS_PER_LONG;
    }
    if (!size)
        return result;
    tmp = *p;

found_first:
    tmp &= (~0UL >> (BITS_PER_LONG - size));
    if (tmp == 0UL)     /* Are any bits set? */
        return result + size;   /* Nope. */
found_middle:
    return result + __ffs(tmp);
}

#endif