source: svn/trunk/newcon3bcm2_21bu/toolchain/mips-linux-uclibc/include/asm/bitops.h @ 2

/*
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file "COPYING" in the main directory of this archive
 * for more details.
 *
 * Copyright (c) 1994 - 1997, 1999, 2000  Ralf Baechle (ralf@gnu.org)
 * Copyright (c) 1999, 2000  Silicon Graphics, Inc.
 */

/* non-atomic version which could be used in userspace (but shouldn't anyway) */

#ifndef _ASM_BITOPS_H
#define _ASM_BITOPS_H

#include <linux/types.h>
#include <asm/byteorder.h>              /* sigh ... */

#if (_MIPS_SZLONG == 32)
#define SZLONG_LOG 5
#define SZLONG_MASK 31UL
#define __LL    "ll"
#define __SC    "sc"
#define cpu_to_lelongp(x) cpu_to_le32p((__u32 *) (x)) 
#elif (_MIPS_SZLONG == 64)
#define SZLONG_LOG 6
#define SZLONG_MASK 63UL
#define __LL    "lld"
#define __SC    "scd"
#define cpu_to_lelongp(x) cpu_to_le64p((__u64 *) (x)) 
#endif

/*
 * set_bit - Atomically set a bit in memory
 * @nr: the bit to set
 * @addr: the address to start counting from
 *
 * This function is atomic and may not be reordered.  See __set_bit()
 * if you do not require the atomic guarantees.
 * Note that @nr may be almost arbitrarily large; this function is not
 * restricted to acting on a single-word quantity.
 */
static inline void set_bit(unsigned long nr, volatile unsigned long * addr)
{
        volatile unsigned long *a = addr;
        unsigned long mask;

        a += nr >> SZLONG_LOG;
        mask = 1 << (nr & SZLONG_MASK);
        *a |= mask;
}

/*
 * __set_bit - Set a bit in memory
 * @nr: the bit to set
 * @addr: the address to start counting from
 *
 * Unlike set_bit(), this function is non-atomic and may be reordered.
 * If it's called on the same region of memory simultaneously, the effect
 * may be that only one operation succeeds.
 */
static inline void __set_bit(unsigned long nr, volatile unsigned long * addr)
{
        volatile unsigned long *a = addr;
        unsigned long mask;

        a += nr >> SZLONG_LOG;
        mask = 1 << (nr & SZLONG_MASK);
        *a |= mask;
}

/*
 * clear_bit - Clears a bit in memory
 * @nr: Bit to clear
 * @addr: Address to start counting from
 *
 * clear_bit() is atomic and may not be reordered.  However, it does
 * not contain a memory barrier, so if it is used for locking purposes,
 * you should call smp_mb__before_clear_bit() and/or smp_mb__after_clear_bit()
 * in order to ensure changes are visible on other processors.
 */
static inline void clear_bit(unsigned long nr, volatile unsigned long * addr)
{
        volatile unsigned long *a = addr;
        unsigned long mask;

        a += nr >> SZLONG_LOG;
        mask = 1 << (nr & SZLONG_MASK);
        *a &= ~mask;
}

static inline void __clear_bit(unsigned long nr, volatile unsigned long * addr)
{
        volatile unsigned long *a = addr;
        unsigned long mask;

        a += nr >> SZLONG_LOG;
        mask = 1 << (nr & SZLONG_MASK);
        *a &= ~mask;
}

/*
 * change_bit - Toggle a bit in memory
 * @nr: Bit to change
 * @addr: Address to start counting from
 *
 * change_bit() is atomic and may not be reordered.
 * Note that @nr may be almost arbitrarily large; this function is not
 * restricted to acting on a single-word quantity.
 */
static inline void change_bit(unsigned long nr, volatile unsigned long * addr)
{
        volatile unsigned long *a = addr;
        unsigned long mask;

        a += nr >> SZLONG_LOG;
        mask = 1 << (nr & SZLONG_MASK);
        *a ^= mask;
}

/*
 * __change_bit - Toggle a bit in memory
 * @nr: the bit to change
 * @addr: the address to start counting from
 *
 * Unlike change_bit(), this function is non-atomic and may be reordered.
 * If it's called on the same region of memory simultaneously, the effect
 * may be that only one operation succeeds.
 */
static inline void __change_bit(unsigned long nr, volatile unsigned long * addr)
{
        unsigned long * m = ((unsigned long *) addr) + (nr >> SZLONG_LOG);

        *m ^= 1UL << (nr & SZLONG_MASK);
}

/*
 * test_and_set_bit - Set a bit and return its old value
 * @nr: Bit to set
 * @addr: Address to count from
 *
 * This operation is atomic and cannot be reordered.
 * It also implies a memory barrier.
 */
static inline int test_and_set_bit(unsigned long nr,
        volatile unsigned long * addr)
{
        volatile unsigned long *a = addr;
        unsigned long mask;
        int retval;

        a += nr >> SZLONG_LOG;
        mask = 1 << (nr & SZLONG_MASK);
        retval = (mask & *a) != 0;
        *a |= mask;

        return retval;
}

/*
 * __test_and_set_bit - Set a bit and return its old value
 * @nr: Bit to set
 * @addr: Address to count from
 *
 * This operation is non-atomic and can be reordered.
 * If two examples of this operation race, one can appear to succeed
 * but actually fail.  You must protect multiple accesses with a lock.
 */
static inline int __test_and_set_bit(unsigned long nr,
        volatile unsigned long *addr)
{
        volatile unsigned long *a = addr;
        unsigned long mask;
        int retval;

        a += nr >> SZLONG_LOG;
        mask = 1 << (nr & SZLONG_MASK);
        retval = (mask & *a) != 0;
        *a |= mask;

        return retval;
}

/*
 * test_and_clear_bit - Clear a bit and return its old value
 * @nr: Bit to clear
 * @addr: Address to count from
 *
 * This operation is atomic and cannot be reordered.
 * It also implies a memory barrier.
 */
static inline int test_and_clear_bit(unsigned long nr,
        volatile unsigned long * addr)
{
        volatile unsigned long *a = addr;
        unsigned long mask;
        int retval;

        a += nr >> SZLONG_LOG;
        mask = 1 << (nr & SZLONG_MASK);
        retval = (mask & *a) != 0;
        *a &= ~mask;

        return retval;
}

/*
 * __test_and_clear_bit - Clear a bit and return its old value
 * @nr: Bit to clear
 * @addr: Address to count from
 *
 * This operation is non-atomic and can be reordered.
 * If two examples of this operation race, one can appear to succeed
 * but actually fail.  You must protect multiple accesses with a lock.
 */
static inline int __test_and_clear_bit(unsigned long nr,
        volatile unsigned long * addr)
{
        volatile unsigned long *a = addr;
        unsigned long mask;
        int retval;

        a += (nr >> SZLONG_LOG);
        mask = 1UL << (nr & SZLONG_MASK);
        retval = ((mask & *a) != 0);
        *a &= ~mask;

        return retval;
}

/*
 * test_and_change_bit - Change a bit and return its old value
 * @nr: Bit to change
 * @addr: Address to count from
 *
 * This operation is atomic and cannot be reordered.
 * It also implies a memory barrier.
 */
static inline int test_and_change_bit(unsigned long nr,
        volatile unsigned long * addr)
{
        volatile unsigned long *a = addr;
        unsigned long mask, retval;

        a += nr >> SZLONG_LOG;
        mask = 1 << (nr & SZLONG_MASK);
        retval = (mask & *a) != 0;
        *a ^= mask;

        return retval;
}

/*
 * __test_and_change_bit - Change a bit and return its old value
 * @nr: Bit to change
 * @addr: Address to count from
 *
 * This operation is non-atomic and can be reordered.
 * If two examples of this operation race, one can appear to succeed
 * but actually fail.  You must protect multiple accesses with a lock.
 */
static inline int __test_and_change_bit(unsigned long nr,
        volatile unsigned long * addr)
{
        volatile unsigned long *a = addr;
        unsigned long mask;
        int retval;

        a += (nr >> SZLONG_LOG);
        mask = 1 << (nr & SZLONG_MASK);
        retval = (mask & *a) != 0;
        *a ^= mask;

        return retval;
}

/*
 * test_bit - Determine whether a bit is set
 * @nr: bit number to test
 * @addr: Address to start counting from
 */
static inline int test_bit(unsigned long nr, const volatile unsigned long *addr)
{
        return 1UL & (addr[nr >> SZLONG_LOG] >> (nr & SZLONG_MASK));
}

/*
 * ffz - find first zero in word.
 * @word: The word to search
 *
 * Undefined if no zero exists, so code should check against ~0UL first.
 */
static inline unsigned long ffz(unsigned long word)
{
        int b = 0, s;

        word = ~word;
#if (_MIPS_SZLONG == 32)
        s = 16; if (word << 16 != 0) s = 0; b += s; word >>= s;
        s =  8; if (word << 24 != 0) s = 0; b += s; word >>= s;
        s =  4; if (word << 28 != 0) s = 0; b += s; word >>= s;
        s =  2; if (word << 30 != 0) s = 0; b += s; word >>= s;
        s =  1; if (word << 31 != 0) s = 0; b += s;
#endif
#if (_MIPS_SZLONG == 64)
        s = 32; if (word << 32 != 0) s = 0; b += s; word >>= s;
        s = 16; if (word << 48 != 0) s = 0; b += s; word >>= s;
        s =  8; if (word << 56 != 0) s = 0; b += s; word >>= s;
        s =  4; if (word << 60 != 0) s = 0; b += s; word >>= s;
        s =  2; if (word << 62 != 0) s = 0; b += s; word >>= s;
        s =  1; if (word << 63 != 0) s = 0; b += s;
#endif

        return b;
}

/*
 * __ffs - find first bit in word.
 * @word: The word to search
 *
 * Undefined if no bit exists, so code should check against 0 first.
 */
static inline unsigned long __ffs(unsigned long word)
{
        return ffz(~word);
}

/*
 * fls: find last bit set.
 */

#define fls(x) generic_fls(x)

/*
 * find_next_zero_bit - find the first zero 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
 */
static inline unsigned long find_next_zero_bit(const unsigned long *addr,
        unsigned long size, unsigned long offset)
{
        const unsigned long *p = addr + (offset >> SZLONG_LOG);
        unsigned long result = offset & ~SZLONG_MASK;
        unsigned long tmp;

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

found_first:
        tmp |= ~0UL << size;
        if (tmp == ~0UL)                /* Are any bits zero? */
                return result + size;   /* Nope. */
found_middle:
        return result + ffz(tmp);
}

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

/*
 * 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
 */
static inline unsigned long find_next_bit(const unsigned long *addr,
        unsigned long size, unsigned long offset)
{
        const unsigned long *p = addr + (offset >> SZLONG_LOG);
        unsigned long result = offset & ~SZLONG_MASK;
        unsigned long tmp;

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

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

/*
 * 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.
 */
#define find_first_bit(addr, size) \
        find_next_bit((addr), (size), 0)

#endif /* _ASM_BITOPS_H */