TheRock/math-libs/libhipcxx/include/cuda/__bit/bitfield.h

//===----------------------------------------------------------------------===//
//
// Part of libcu++, the C++ Standard Library for your entire system,
// under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
// SPDX-FileCopyrightText: Copyright (c) 2025 NVIDIA CORPORATION & AFFILIATES.
//
//===----------------------------------------------------------------------===//

// MIT License
//
// Modifications Copyright (C) 2025 Advanced Micro Devices, Inc. All rights reserved.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.

#ifndef _CUDA___BIT_BITFILED_INSERT_EXTRACT_H
#define _CUDA___BIT_BITFILED_INSERT_EXTRACT_H

#include <cuda/std/detail/__config>

#if defined(_CCCL_IMPLICIT_SYSTEM_HEADER_GCC)
#  pragma GCC system_header
#elif defined(_CCCL_IMPLICIT_SYSTEM_HEADER_CLANG)
#  pragma clang system_header
#elif defined(_CCCL_IMPLICIT_SYSTEM_HEADER_MSVC)
#  pragma system_header
#endif // no system header

#include <cuda/__bit/bitmask.h>
#include <cuda/std/__limits/numeric_limits.h>
#include <cuda/std/__type_traits/conditional.h>
#include <cuda/std/__type_traits/is_constant_evaluated.h>
#include <cuda/std/__type_traits/is_unsigned_integer.h>
#include <cuda/std/cstdint>
#include <cuda/std/limits>

_LIBCUDACXX_BEGIN_NAMESPACE_CUDA

#if __cccl_ptx_isa >= 200

_CCCL_NODISCARD _CCCL_HIDE_FROM_ABI _CCCL_DEVICE uint32_t
__bfi(uint32_t __dest, uint32_t __source, int __start, int __width) noexcept
{
  asm("bfi.b32 %0, %1, %2, %3, %4;" : "=r"(__dest) : "r"(__source), "r"(__dest), "r"(__start), "r"(__width));
  return __dest;
}

_CCCL_NODISCARD _CCCL_HIDE_FROM_ABI _CCCL_DEVICE uint64_t
__bfi(uint64_t __dest, uint64_t __source, int __start, int __width) noexcept
{
  asm("bfi.b64 %0, %1, %2, %3, %4;" : "=l"(__dest) : "l"(__source), "l"(__dest), "r"(__start), "r"(__width));
  return __dest;
}

_CCCL_NODISCARD _CCCL_HIDE_FROM_ABI _CCCL_DEVICE uint32_t __bfe(uint32_t __value, int __start, int __width) noexcept
{
  // uint32_t __ret;
  // asm("bfe.u32 %0, %1, %2, %3;" : "=r"(__ret) : "r"(__value), "r"(__start), "r"(__width));
  // return __ret;
  // TODO(HIP/AMD): this builtin seems to not work correctly/as intended here atm
  return __builtin_amdgcn_ubfe(__value, __start, __width);
}

_CCCL_NODISCARD _CCCL_HIDE_FROM_ABI _CCCL_DEVICE uint64_t __bfe(uint64_t __value, int __start, int __width) noexcept
{
  // uint64_t __ret;
  // asm("bfe.u64 %0, %1, %2, %3;" : "=l"(__ret) : "l"(__value), "r"(__start), "r"(__width));
  // return __ret;
  // TODO(HIP/AMD): this builtin seems to not work correctly/as intended here atm
  return __builtin_amdgcn_ubfe(__value, __start, __width);
}

#endif // __cccl_ptx_isa >= 200

template <typename _Tp>
_CCCL_NODISCARD _LIBCUDACXX_HIDE_FROM_ABI constexpr _Tp
bitfield_insert(const _Tp __dest, const _Tp __source, int __start, int __width) noexcept
{
  static_assert(_CUDA_VSTD::__cccl_is_unsigned_integer_v<_Tp>, "bitfield_insert() requires unsigned integer types");
  [[maybe_unused]] constexpr auto __digits = _CUDA_VSTD::numeric_limits<_Tp>::digits;
  _CCCL_ASSERT(__width >= 0 && __width <= __digits, "width out of range");
  _CCCL_ASSERT(__start >= 0 && __start <= __digits, "start position out of range");
  _CCCL_ASSERT(__start + __width <= __digits, "start position + width out of range");
#ifndef __HIP_PLATFORM_AMD__
  if constexpr (sizeof(_Tp) <= sizeof(uint64_t))
  {
    if (!_CUDA_VSTD::__cccl_default_is_constant_evaluated())
    {
      // clang-format off
      NV_DISPATCH_TARGET( // all SM < 70
        NV_PROVIDES_SM_70, (;),
        NV_IS_DEVICE_LIBHIPCXX,      (using _Up = _CUDA_VSTD::_If<sizeof(_Tp) <= sizeof(uint32_t), uint32_t, uint64_t>;
                            return ::cuda::__bfi(static_cast<_Up>(__dest), static_cast<_Up>(__source),
                                                 __start, __width);))
      // clang-format on
    }
  }
#endif
  auto __mask = ::cuda::bitmask<_Tp>(__start, __width);
  return (::cuda::__shl(__source, __start) & __mask) | (__dest & ~__mask);
}

template <typename _Tp>
_CCCL_NODISCARD _LIBCUDACXX_HIDE_FROM_ABI constexpr _Tp
bitfield_extract(const _Tp __value, int __start, int __width) noexcept
{
  static_assert(_CUDA_VSTD::__cccl_is_unsigned_integer_v<_Tp>, "bitfield_extract() requires unsigned integer types");
  [[maybe_unused]] constexpr auto __digits = _CUDA_VSTD::numeric_limits<_Tp>::digits;
  _CCCL_ASSERT(__width >= 0 && __width <= __digits, "width out of range");
  _CCCL_ASSERT(__start >= 0 && __start <= __digits, "start position out of range");
  _CCCL_ASSERT(__start + __width <= __digits, "start position + width out of range");
#ifndef __HIP_PLATFORM_AMD__
  if constexpr (sizeof(_Tp) <= sizeof(uint32_t))
  {
    if (!_CUDA_VSTD::__cccl_default_is_constant_evaluated())
    {
      // clang-format off
      NV_DISPATCH_TARGET( // all SM < 70
        NV_PROVIDES_SM_70, (;),
        NV_IS_DEVICE_LIBHIPCXX,      (using _Up = _CUDA_VSTD::_If<sizeof(_Tp) <= sizeof(uint32_t), uint32_t, uint64_t>;
                            return ::cuda::__bfe(static_cast<_Up>(__value), __start, __width);))
      // clang-format on
    }
  }
#endif
  return ::cuda::__shr(__value, __start) & ::cuda::bitmask<_Tp>(0, __width);
}

_LIBCUDACXX_END_NAMESPACE_CUDA

#endif // _CUDA___BIT_BITFILED_INSERT_EXTRACT_H