// Copyright (c) 2012-2017, The CryptoNote developers, The Bytecoin developers
// Copyright (c) 2018-2019, The TurtleCoin Developers
//
// Please see the included LICENSE file for more information.

#pragma once

#include <assert.h>
#include <stdbool.h>
#include <stdint.h>
#include <string.h>
#include <sys/param.h>

#if defined(_MSC_VER)
#include <stdlib.h>

#define inline __inline

static inline uint32_t rol32(uint32_t x, int r)
{
    static_assert(sizeof(uint32_t) == sizeof(unsigned int), "this code assumes 32-bit integers");
    return _rotl(x, r);
}

static inline uint64_t rol64(uint64_t x, int r)
{
    return _rotl64(x, r);
}

#else

static inline uint32_t rol32(uint32_t x, int r)
{
    return (x << (r & 31)) | (x >> (-r & 31));
}

static inline uint64_t rol64(uint64_t x, int r)
{
    return (x << (r & 63)) | (x >> (-r & 63));
}

#endif

static inline uint64_t hi_dword(uint64_t val)
{
    return val >> 32;
}

static inline uint64_t lo_dword(uint64_t val)
{
    return val & 0xFFFFFFFF;
}

static inline uint64_t mul128(uint64_t multiplier, uint64_t multiplicand, uint64_t *product_hi)
{
    // multiplier   = ab = a * 2^32 + b
    // multiplicand = cd = c * 2^32 + d
    // ab * cd = a * c * 2^64 + (a * d + b * c) * 2^32 + b * d
    uint64_t a = hi_dword(multiplier);

    uint64_t b = lo_dword(multiplier);

    uint64_t c = hi_dword(multiplicand);

    uint64_t d = lo_dword(multiplicand);

    uint64_t ac = a * c;

    uint64_t ad = a * d;

    uint64_t bc = b * c;

    uint64_t bd = b * d;

    uint64_t adbc = ad + bc;

    uint64_t adbc_carry = adbc < ad ? 1 : 0;

    // multiplier * multiplicand = product_hi * 2^64 + product_lo
    uint64_t product_lo = bd + (adbc << 32);

    uint64_t product_lo_carry = product_lo < bd ? 1 : 0;

    *product_hi = ac + (adbc >> 32) + (adbc_carry << 32) + product_lo_carry;
    assert(ac <= *product_hi);

    return product_lo;
}

static inline uint64_t div_with_reminder(uint64_t dividend, uint32_t divisor, uint32_t *remainder)
{
    dividend |= ((uint64_t)*remainder) << 32;
    *remainder = dividend % divisor;
    return dividend / divisor;
}

// Long division with 2^32 base
static inline uint32_t div128_32(
    uint64_t dividend_hi,
    uint64_t dividend_lo,
    uint32_t divisor,
    uint64_t *quotient_hi,
    uint64_t *quotient_lo)
{
    uint64_t dividend_dwords[4];

    uint32_t remainder = 0;

    dividend_dwords[3] = hi_dword(dividend_hi);
    dividend_dwords[2] = lo_dword(dividend_hi);
    dividend_dwords[1] = hi_dword(dividend_lo);
    dividend_dwords[0] = lo_dword(dividend_lo);

    *quotient_hi = div_with_reminder(dividend_dwords[3], divisor, &remainder) << 32;
    *quotient_hi |= div_with_reminder(dividend_dwords[2], divisor, &remainder);
    *quotient_lo = div_with_reminder(dividend_dwords[1], divisor, &remainder) << 32;
    *quotient_lo |= div_with_reminder(dividend_dwords[0], divisor, &remainder);

    return remainder;
}

#define IDENT32(x) ((uint32_t)(x))
#define IDENT64(x) ((uint64_t)(x))

#define SWAP32(x)                                                                                               \
    ((((uint32_t)(x)&0x000000ff) << 24) | (((uint32_t)(x)&0x0000ff00) << 8) | (((uint32_t)(x)&0x00ff0000) >> 8) \
     | (((uint32_t)(x)&0xff000000) >> 24))
#define SWAP64(x)                                                                             \
    ((((uint64_t)(x)&0x00000000000000ff) << 56) | (((uint64_t)(x)&0x000000000000ff00) << 40)  \
     | (((uint64_t)(x)&0x0000000000ff0000) << 24) | (((uint64_t)(x)&0x00000000ff000000) << 8) \
     | (((uint64_t)(x)&0x000000ff00000000) >> 8) | (((uint64_t)(x)&0x0000ff0000000000) >> 24) \
     | (((uint64_t)(x)&0x00ff000000000000) >> 40) | (((uint64_t)(x)&0xff00000000000000) >> 56))

static inline uint32_t ident32(uint32_t x)
{
    return x;
}

static inline uint64_t ident64(uint64_t x)
{
    return x;
}

static inline uint32_t swap32(uint32_t x)
{
    x = ((x & 0x00ff00ff) << 8) | ((x & 0xff00ff00) >> 8);
    return (x << 16) | (x >> 16);
}

static inline uint64_t swap64(uint64_t x)
{
    x = ((x & 0x00ff00ff00ff00ff) << 8) | ((x & 0xff00ff00ff00ff00) >> 8);
    x = ((x & 0x0000ffff0000ffff) << 16) | ((x & 0xffff0000ffff0000) >> 16);
    return (x << 32) | (x >> 32);
}

#if defined(__GNUC__)
#define UNUSED __attribute__((unused))
#else
#define UNUSED
#endif
static inline void mem_inplace_ident(void *mem UNUSED, uint64_t n UNUSED) {}

#undef UNUSED

static inline void mem_inplace_swap32(void *mem, uint64_t n)
{
    uint64_t i;

    for (i = 0; i < n; i++)
    {
        ((uint32_t *)mem)[i] = swap32(((const uint32_t *)mem)[i]);
    }
}

static inline void mem_inplace_swap64(void *mem, uint64_t n)
{
    uint64_t i;

    for (i = 0; i < n; i++)
    {
        ((uint64_t *)mem)[i] = swap64(((const uint64_t *)mem)[i]);
    }
}

static inline void memcpy_ident32(void *dst, const void *src, uint64_t n)
{
    memcpy(dst, src, 4 * n);
}

static inline void memcpy_ident64(void *dst, const void *src, uint64_t n)
{
    memcpy(dst, src, 8 * n);
}

static inline void memcpy_swap32(void *dst, const void *src, uint64_t n)
{
    uint64_t i;

    for (i = 0; i < n; i++)
    {
        ((uint32_t *)dst)[i] = swap32(((const uint32_t *)src)[i]);
    }
}

static inline void memcpy_swap64(void *dst, const void *src, uint64_t n)
{
    uint64_t i;

    for (i = 0; i < n; i++)
    {
        ((uint64_t *)dst)[i] = swap64(((const uint64_t *)src)[i]);
    }
}

#if !defined(BYTE_ORDER) || !defined(LITTLE_ENDIAN) || !defined(BIG_ENDIAN)
static_assert(false, "BYTE_ORDER is undefined. Perhaps, GNU extensions are not enabled");
#endif

#if BYTE_ORDER == LITTLE_ENDIAN
#define SWAP32LE IDENT32
#define SWAP32BE SWAP32
#define swap32le ident32
#define swap32be swap32
#define mem_inplace_swap32le mem_inplace_ident
#define mem_inplace_swap32be mem_inplace_swap32
#define memcpy_swap32le memcpy_ident32
#define memcpy_swap32be memcpy_swap32
#define SWAP64LE IDENT64
#define SWAP64BE SWAP64
#define swap64le ident64
#define swap64be swap64
#define mem_inplace_swap64le mem_inplace_ident
#define mem_inplace_swap64be mem_inplace_swap64
#define memcpy_swap64le memcpy_ident64
#define memcpy_swap64be memcpy_swap64
#endif

#if BYTE_ORDER == BIG_ENDIAN
#define SWAP32BE IDENT32
#define SWAP32LE SWAP32
#define swap32be ident32
#define swap32le swap32
#define mem_inplace_swap32be mem_inplace_ident
#define mem_inplace_swap32le mem_inplace_swap32
#define memcpy_swap32be memcpy_ident32
#define memcpy_swap32le memcpy_swap32
#define SWAP64BE IDENT64
#define SWAP64LE SWAP64
#define swap64be ident64
#define swap64le swap64
#define mem_inplace_swap64be mem_inplace_ident
#define mem_inplace_swap64le mem_inplace_swap64
#define memcpy_swap64be memcpy_ident64
#define memcpy_swap64le memcpy_swap64
#endif