cutlass/include/cute/numeric/uint128.hpp
2024-01-16 14:37:22 -05:00

260 lines
7.4 KiB
C++

/***************************************************************************************************
* Copyright (c) 2023 - 2024 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
* SPDX-License-Identifier: BSD-3-Clause
*
* 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, 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.
*
* 3. Neither the name of the copyright holder nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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#pragma once
#if defined(__CUDACC_RTC__)
#include <cuda/std/cstdint>
#else
#include <cstdint>
#include <cstdlib>
#include <cmath>
#include <type_traits>
#include <stdexcept>
#endif
#include <cute/config.hpp>
/// Optionally enable GCC's built-in type
#if defined(__x86_64) && !defined(__CUDA_ARCH__)
# if defined(__GNUC__) && 0
# define CUTE_UINT128_NATIVE
# elif defined(_MSC_VER)
# define CUTE_INT128_ARITHMETIC
# include <intrin.h>
# endif
#endif
/////////////////////////////////////////////////////////////////////////////////////////////////
namespace cute {
/////////////////////////////////////////////////////////////////////////////////////////////////
///! Unsigned 128b integer type
struct alignas(16) uint128_t
{
/// Size of one part of the uint's storage in bits
static constexpr int storage_bits_ = 64;
struct hilo
{
uint64_t lo;
uint64_t hi;
};
// Use a union to store either low and high parts or, if present, a built-in 128b integer type.
union
{
struct hilo hilo_;
#if defined(CUTE_UINT128_NATIVE)
unsigned __int128 native;
#endif // defined(CUTE_UINT128_NATIVE)
};
//
// Methods
//
/// Default ctor
CUTE_HOST_DEVICE constexpr
uint128_t() : hilo_{0, 0} {}
/// Constructor from uint64
CUTE_HOST_DEVICE constexpr
uint128_t(uint64_t lo_) : hilo_{lo_, 0} {}
/// Constructor from two 64b unsigned integers
CUTE_HOST_DEVICE constexpr
uint128_t(uint64_t lo_, uint64_t hi_) : hilo_{lo_, hi_} {}
/// Optional constructor from native value
#if defined(CUTE_UINT128_NATIVE)
uint128_t(unsigned __int128 value) : native(value) { }
#endif
/// Lossily cast to uint64
CUTE_HOST_DEVICE constexpr
explicit operator uint64_t() const
{
return hilo_.lo;
}
template <class Dummy = bool>
CUTE_HOST_DEVICE constexpr
static void exception()
{
//static_assert(sizeof(Dummy) == 0, "Not implemented exception!");
//abort();
//printf("uint128 not implemented!\n");
}
/// Add
CUTE_HOST_DEVICE constexpr
uint128_t operator+(uint128_t const& rhs) const
{
uint128_t y;
#if defined(CUTE_UINT128_NATIVE)
y.native = native + rhs.native;
#else
y.hilo_.lo = hilo_.lo + rhs.hilo_.lo;
y.hilo_.hi = hilo_.hi + rhs.hilo_.hi + (!y.hilo_.lo && (rhs.hilo_.lo));
#endif
return y;
}
/// Subtract
CUTE_HOST_DEVICE constexpr
uint128_t operator-(uint128_t const& rhs) const
{
uint128_t y;
#if defined(CUTE_UINT128_NATIVE)
y.native = native - rhs.native;
#else
y.hilo_.lo = hilo_.lo - rhs.hilo_.lo;
y.hilo_.hi = hilo_.hi - rhs.hilo_.hi - (rhs.hilo_.lo && y.hilo_.lo > hilo_.lo);
#endif
return y;
}
/// Multiply by unsigned 64b integer yielding 128b integer
CUTE_HOST_DEVICE constexpr
uint128_t operator*(uint64_t const& rhs) const
{
uint128_t y;
#if defined(CUTE_UINT128_NATIVE)
y.native = native * rhs;
#elif defined(CUTE_INT128_ARITHMETIC)
// Multiply by the low part
y.hilo_.lo = _umul128(hilo_.lo, rhs, &y.hilo_.hi);
// Add the high part and ignore the overflow
uint64_t overflow;
y.hilo_.hi += _umul128(hilo_.hi, rhs, &overflow);
#else
exception();
#endif
return y;
}
/// Divide 128b operation by 64b operation yielding a 64b quotient
CUTE_HOST_DEVICE constexpr
uint64_t operator/(uint64_t const& divisor) const
{
uint64_t quotient = 0;
#if defined(CUTE_UINT128_NATIVE)
quotient = uint64_t(native / divisor);
#elif defined(CUTE_INT128_ARITHMETIC)
// implemented using MSVC's arithmetic intrinsics
uint64_t remainder = 0;
quotient = _udiv128(hilo_.hi, hilo_.lo, divisor, &remainder);
#else
exception();
#endif
return quotient;
}
/// Divide 128b operation by 64b operation yielding a 64b quotient
CUTE_HOST_DEVICE constexpr
uint64_t operator%(uint64_t const& divisor) const
{
uint64_t remainder = 0;
#if defined(CUTE_UINT128_NATIVE)
remainder = uint64_t(native % divisor);
#elif defined(CUTE_INT128_ARITHMETIC)
// implemented using MSVC's arithmetic intrinsics
(void)_udiv128(hilo_.hi, hilo_.lo, divisor, &remainder);
#else
exception();
#endif
return remainder;
}
/// Computes the quotient and remainder in a single method.
CUTE_HOST_DEVICE constexpr
uint64_t divmod(uint64_t &remainder, uint64_t divisor) const
{
uint64_t quotient = 0;
#if defined(CUTE_UINT128_NATIVE)
quotient = uint64_t(native / divisor);
remainder = uint64_t(native % divisor);
#elif defined(CUTE_INT128_ARITHMETIC)
// implemented using MSVC's arithmetic intrinsics
quotient = _udiv128(hilo_.hi, hilo_.lo, divisor, &remainder);
#else
exception();
#endif
return quotient;
}
/// Left-shifts a 128b unsigned integer
CUTE_HOST_DEVICE constexpr
uint128_t operator<<(int sh) const
{
if (sh == 0) {
return *this;
}
else if (sh >= storage_bits_) {
return uint128_t(0, hilo_.lo << (sh - storage_bits_));
}
else {
return uint128_t(
(hilo_.lo << sh),
(hilo_.hi << sh) | uint64_t(hilo_.lo >> (storage_bits_ - sh))
);
}
}
/// Right-shifts a 128b unsigned integer
CUTE_HOST_DEVICE constexpr
uint128_t operator>>(int sh) const
{
if (sh == 0) {
return *this;
}
else if (sh >= storage_bits_) {
return uint128_t((hilo_.hi >> (sh - storage_bits_)), 0);
}
else {
return uint128_t(
(hilo_.lo >> sh) | (hilo_.hi << (storage_bits_ - sh)),
(hilo_.hi >> sh)
);
}
}
};
/////////////////////////////////////////////////////////////////////////////////////////////////
} // namespace cute
/////////////////////////////////////////////////////////////////////////////////////////////////