root/include/linux/math64.h

INCLUDED FROM

DEFINITIONS

1. div_u64_rem
2. div_s64_rem
3. div64_u64
4. div_u64_rem
5. div_u64
6. div_s64
7. __iter_div_u64_rem

#ifndef _LINUX_MATH64_H
#define _LINUX_MATH64_H

#include <linux/types.h>
#include <asm/div64.h>

#if BITS_PER_LONG == 64

/**
 * div_u64_rem - unsigned 64bit divide with 32bit divisor with remainder
 *
 * This is commonly provided by 32bit archs to provide an optimized 64bit
 * divide.
 */
static inline u64 div_u64_rem(u64 dividend, u32 divisor, u32 *remainder)
{
        *remainder = dividend % divisor;
        return dividend / divisor;
}

/**
 * div_s64_rem - signed 64bit divide with 32bit divisor with remainder
 */
static inline s64 div_s64_rem(s64 dividend, s32 divisor, s32 *remainder)
{
        *remainder = dividend % divisor;
        return dividend / divisor;
}

/**
 * div64_u64 - unsigned 64bit divide with 64bit divisor
 */
static inline u64 div64_u64(u64 dividend, u64 divisor)
{
        return dividend / divisor;
}

#elif BITS_PER_LONG == 32

#ifndef div_u64_rem
static inline u64 div_u64_rem(u64 dividend, u32 divisor, u32 *remainder)
{
        *remainder = do_div(dividend, divisor);
        return dividend;
}
#endif

#ifndef div_s64_rem
extern s64 div_s64_rem(s64 dividend, s32 divisor, s32 *remainder);
#endif

#ifndef div64_u64
extern u64 div64_u64(u64 dividend, u64 divisor);
#endif

#endif /* BITS_PER_LONG */

/**
 * div_u64 - unsigned 64bit divide with 32bit divisor
 *
 * This is the most common 64bit divide and should be used if possible,
 * as many 32bit archs can optimize this variant better than a full 64bit
 * divide.
 */
#ifndef div_u64
static inline u64 div_u64(u64 dividend, u32 divisor)
{
        u32 remainder;
        return div_u64_rem(dividend, divisor, &remainder);
}
#endif

/**
 * div_s64 - signed 64bit divide with 32bit divisor
 */
#ifndef div_s64
static inline s64 div_s64(s64 dividend, s32 divisor)
{
        s32 remainder;
        return div_s64_rem(dividend, divisor, &remainder);
}
#endif

u32 iter_div_u64_rem(u64 dividend, u32 divisor, u64 *remainder);

static __always_inline u32
__iter_div_u64_rem(u64 dividend, u32 divisor, u64 *remainder)
{
        u32 ret = 0;

        while (dividend >= divisor) {
                /* The following asm() prevents the compiler from
                   optimising this loop into a modulo operation.  */
                asm("" : "+rm"(dividend));

                dividend -= divisor;
                ret++;
        }

        *remainder = dividend;

        return ret;
}

#endif /* _LINUX_MATH64_H */