Extended <cuda/bit> operations: bitfield_insert, bitfield_extract, bit_reverse, bitmask

libcudacxx/include/cuda/__bit/bitfield.h

@@ -0,0 +1,82 @@
+//===----------------------------------------------------------------------===//
+//
+// 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.
+//
+//===----------------------------------------------------------------------===//
+
+#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/__ptx/instructions/bmsk.h>
+#include <cuda/std/__concepts/concept_macros.h>
+#include <cuda/std/__type_traits/is_constant_evaluated.h>
+#include <cuda/std/__type_traits/is_unsigned_integer.h>
+#include <cuda/std/limits>
+
+_LIBCUDACXX_BEGIN_NAMESPACE_CUDA
+
+template <typename _Tp>
+_CCCL_NODISCARD _LIBCUDACXX_HIDE_FROM_ABI constexpr _Tp
+bitfield_insert(const _Tp __value, int __start, int __width = 1) noexcept
+{
+  static_assert(_CUDA_VSTD::__cccl_is_unsigned_integer_v<_Tp>, "bitfield_insert() requires unsigned integer");
+  constexpr auto __digits = _CUDA_VSTD::numeric_limits<_Tp>::digits;
+  CS_ASSERT(__width > 0 && __width <= __digits, "width out of range");
+  CS_ASSERT(__start >= 0 && __start < __digits, "start position out of range");
+  CS_ASSERT(__start + __width <= __digits, "start position + width out of range");
+  if constexpr (sizeof(_Tp) <= sizeof(uint32_t))
+  {
+    if (!_CUDA_VSTD::__cccl_default_is_constant_evaluated())
+    {
+      NV_IF_TARGET(NV_PROVIDES_SM_70, (return __value | _CUDA_VPTX::bmsk_clamp(__start, __width);))
+    }
+  }
+  if (__width == __digits)
+  {
+    return ~_Tp{0};
+  }
+  auto __mask = (_Tp{1} << __width) - 1;
+  return __value | (__mask << __start);
+}
+
+template <typename _Tp>
+_CCCL_NODISCARD _LIBCUDACXX_HIDE_FROM_ABI constexpr _Tp
+bitfield_extract(const _Tp __value, int __start, int __width = 1) noexcept
+{
+  static_assert(_CUDA_VSTD::__cccl_is_unsigned_integer_v<_Tp>, "bitfield_extract() requires unsigned integer");
+  constexpr auto __digits = _CUDA_VSTD::numeric_limits<_Tp>::digits;
+  CS_ASSERT(__width > 0 && __width <= __digits, "width out of range");
+  CS_ASSERT(__start >= 0 && __start < __digits, "start position out of range");
+  CS_ASSERT(__start + __width <= __digits, "start position + width out of range");
+  if constexpr (sizeof(_Tp) <= sizeof(uint32_t))
+  {
+    if (!_CUDA_VSTD::__cccl_default_is_constant_evaluated())
+    {
+      NV_IF_TARGET(NV_PROVIDES_SM_70, (return __value & _CUDA_VPTX::bmsk_clamp(__start, __width);))
+    }
+  }
+  if (__width == __digits)
+  {
+    return __value;
+  }
+  auto __mask = (_Tp{1} << __width) - 1;
+  return __value & (__mask << __start);
+}
+
+_LIBCUDACXX_END_NAMESPACE_CUDA
+
+#endif // _CUDA___BIT_BITFILED_INSERT_EXTRACT_H

libcudacxx/include/cuda/bit

@@ -0,0 +1,26 @@
+//===----------------------------------------------------------------------===//
+//
+// 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) 2024 NVIDIA CORPORATION & AFFILIATES.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _CUDA_BIT
+#define _CUDA_BIT
+
+#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/bitfield.h>
+
+#endif // _CUDA_BIT