source: GPL/trunk/include/linux/math64.h@ 479

/*
 * div_u64() compat
 */

#ifndef MATH64_COMPAT_H
#define MATH64_COMPAT_H

#if BITS_PER_LONG >= 64

static inline u64 div_u64_rem(u64 n, u32 div, u32 *rem)
{
        *rem = n % div;
        return n / div;
}

static inline u64 div_u64(u64 n, u32 div)
{
        return n / div;
}

#elif defined(i386)

static inline u64 div_u64_rem(u64 n, u32 div, u32 *rem)
{
        u32 low, high;

        low = (u32)n;
        high = n >> 32;
        if (high) {
                u32 high1 = high % div;
                high /= div;
                asm("divl %2" : "=a" (low), "=d" (*rem) : \
                    "rm" (div), "a" (low), "d" (high1));
                return (u64)high << 32 | low;
        } else {
                *rem = low % div;
                return low / div;
        }
}

static inline u64 div_u64(u64 n, u32 div)
{
        u32 low, high;

        low = (u32)n;
        high = n >> 32;
        if (high) {
                u32 high1 = high % div;
                high /= div;
                asm("divl %2" : "=a" (low) : \
                    "rm" (div), "a" (low), "d" (high1));
                return (u64)high << 32 | low;
        } else
                return low / div;
}

#else

static inline void divl(u32 high, u32 low, u32 div, u32 *q, u32 *r)
{
        u64 n = (u64)high << 32 | low;
        u64 d = (u64)div << 31;
        u32 q1 = 0;
        int c = 32;
        while (n > 0xffffffffUi64) {
                q1 <<= 1;
                if (n >= d) {
                        n -= d;
                        q1 |= 1;
                }
                d >>= 1;
                c--;
        }
        q1 <<= c;
        if (n) {
                low = n;
                *q = q1 | (low / div);
                *r = low % div;
        } else {
                *r = 0;
                *q = q1;
        }
        return;
}

static inline u64 div_u64_rem(u64 n, u32 div, u32 *rem)
{
        u32 low, high;
        low = (u32)n;
        high = n >> 32;
        if (high) {
                u32 high1 = high % div;
                u32 low1 = low;
                high /= div;
                divl(high1, low1, div, &low, rem);
                return (u64)high << 32 | low;
        } else {
                *rem = low % div;
                return low / div;
        }
}

static inline u64 div_u64(u64 n, u32 div)
{
        u32 low, high, rem;
        low = (u32)n;
        high = n >> 32;
        if (high) {
                u32 high1 = high % div;
                u32 low1 = low;
                high /= div;
                divl(high1, low1, div, &low, &rem);
                return (u64)high << 32 | low;
        } else {
                return low / div;
        }
}

#endif

#endif /* MATH64_COMPAT_H */