/*-
 * Copyright (c) 2007 Cisco Systems, Inc.  All rights reserved.
 * Copyright (c) 2014-2015 Mellanox Technologies, Ltd. All rights reserved.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice unmodified, this list of conditions, and the following
 *    disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#ifndef _LINUXKPI_LINUX_MATH64_H
#define _LINUXKPI_LINUX_MATH64_H

#include <sys/stdint.h>
#include <sys/systm.h>

#define do_div(n, base) ({                      \
        uint32_t __base = (base);               \
        uint32_t __rem;                         \
        __rem = ((uint64_t)(n)) % __base;       \
        (n) = ((uint64_t)(n)) / __base;         \
        __rem;                                  \
})

static inline uint64_t
div64_u64_rem(uint64_t dividend, uint64_t divisor, uint64_t *remainder)
{

        *remainder = dividend % divisor;
        return (dividend / divisor);
}

static inline int64_t
div64_s64(int64_t dividend, int64_t divisor)
{

        return (dividend / divisor);
}

static inline uint64_t
div64_u64(uint64_t dividend, uint64_t divisor)
{

        return (dividend / divisor);
}

#define div64_ul(x, y)  div64_u64((x), (y))

static inline uint64_t
div_u64_rem(uint64_t dividend, uint32_t divisor, uint32_t *remainder)
{

        *remainder = dividend % divisor;
        return (dividend / divisor);
}

static inline int64_t
div_s64(int64_t dividend, int32_t divisor)
{

        return (dividend / divisor);
}

static inline uint64_t
div_u64(uint64_t dividend, uint32_t divisor)
{

        return (dividend / divisor);
}

static inline uint64_t
mul_u32_u32(uint32_t a, uint32_t b)
{

        return ((uint64_t)a * b);
}

static inline uint64_t
div64_u64_round_up(uint64_t dividend, uint64_t divisor)
{
        return ((dividend + divisor - 1) / divisor);
}

static inline uint64_t
roundup_u64(uint64_t x1, uint32_t x2)
{
        return (div_u64(x1 + x2 - 1, x2) * x2);
}

#define DIV64_U64_ROUND_UP(...) \
        div64_u64_round_up(__VA_ARGS__)

static inline uint64_t
mul_u64_u32_div(uint64_t x, uint32_t y, uint32_t div)
{
        const uint64_t rem = x % div;

        return ((x / div) * y + (rem * y) / div);
}

static inline uint64_t
mul_u64_u64_div_u64(uint64_t x, uint64_t y, uint64_t z)
{
        uint64_t res, rem;
        uint64_t x1, y1, y1z;

        res = rem = 0;
        x1 = x;
        y1z = y / z;
        y1 = y - y1z * z;

        /*
         * INVARIANT: x * y = res * z + rem + (y1 + y1z * z) * x1
         * INVARIANT: y1 < z
         * INVARIANT: rem < z
         */
        while (x1 > 0) {
                /* Handle low bit. */
                if (x1 & 1) {
                        x1 &= ~1;
                        res += y1z;
                        rem += y1;
                        if ((rem < y1) || (rem >= z)) {
                                res += 1;
                                rem -= z;
                        }
                }

                /* Shift x1 right and (y1 + y1z * z) left */
                x1 >>= 1;
                if ((y1 * 2 < y1) || (y1 * 2 >= z)) {
                        y1z = y1z * 2 + 1;
                        y1 = y1 * 2 - z;
                } else {
                        y1z *= 2;
                        y1 *= 2;
                }
        }

        KASSERT(res * z + rem == x * y, ("%s: res %ju * z %ju + rem %ju != "
            "x %ju * y %ju", __func__, (uintmax_t)res, (uintmax_t)z,
            (uintmax_t)rem, (uintmax_t)x, (uintmax_t)y));
        KASSERT(rem < z, ("%s: rem %ju >= z %ju\n", __func__,
            (uintmax_t)rem, (uintmax_t)z));

        return (res);
}

static inline uint64_t
mul_u64_u32_shr(uint64_t x, uint32_t y, unsigned int shift)
{
        uint32_t hi, lo;
        hi = x >> 32;
        lo = x & 0xffffffff;

        return (mul_u32_u32(lo, y) >> shift) +
                (mul_u32_u32(hi, y) << (32 - shift));
}

#endif /* _LINUXKPI_LINUX_MATH64_H */