| // Copyright (c) 2015-2016 The Khronos Group Inc. |
| // |
| // Permission is hereby granted, free of charge, to any person obtaining a |
| // copy of this software and/or associated documentation files (the |
| // "Materials"), to deal in the Materials without restriction, including |
| // without limitation the rights to use, copy, modify, merge, publish, |
| // distribute, sublicense, and/or sell copies of the Materials, and to |
| // permit persons to whom the Materials are 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 Materials. |
| // |
| // MODIFICATIONS TO THIS FILE MAY MEAN IT NO LONGER ACCURATELY REFLECTS |
| // KHRONOS STANDARDS. THE UNMODIFIED, NORMATIVE VERSIONS OF KHRONOS |
| // SPECIFICATIONS AND HEADER INFORMATION ARE LOCATED AT |
| // https://www.khronos.org/registry/ |
| // |
| // THE MATERIALS ARE 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 |
| // MATERIALS OR THE USE OR OTHER DEALINGS IN THE MATERIALS. |
| |
| #ifndef LIBSPIRV_UTIL_BITUTILS_H_ |
| #define LIBSPIRV_UTIL_BITUTILS_H_ |
| |
| #include <cstdint> |
| #include <cstring> |
| |
| namespace spvutils { |
| |
| // Performs a bitwise copy of source to the destination type Dest. |
| template <typename Dest, typename Src> |
| Dest BitwiseCast(Src source) { |
| Dest dest; |
| static_assert(sizeof(source) == sizeof(dest), |
| "BitwiseCast: Source and destination must have the same size"); |
| std::memcpy(&dest, &source, sizeof(dest)); |
| return dest; |
| } |
| |
| // SetBits<T, First, Num> returns an integer of type <T> with bits set |
| // for position <First> through <First + Num - 1>, counting from the least |
| // significant bit. In particular when Num == 0, no positions are set to 1. |
| // A static assert will be triggered if First + Num > sizeof(T) * 8, that is, |
| // a bit that will not fit in the underlying type is set. |
| template <typename T, size_t First = 0, size_t Num = 0> |
| struct SetBits { |
| static_assert(First < sizeof(T) * 8, |
| "Tried to set a bit that is shifted too far."); |
| const static T get = (T(1) << First) | SetBits<T, First + 1, Num - 1>::get; |
| }; |
| |
| template <typename T, size_t Last> |
| struct SetBits<T, Last, 0> { |
| const static T get = T(0); |
| }; |
| |
| // This is all compile-time so we can put our tests right here. |
| static_assert(SetBits<uint32_t, 0, 0>::get == uint32_t(0x00000000), |
| "SetBits failed"); |
| static_assert(SetBits<uint32_t, 0, 1>::get == uint32_t(0x00000001), |
| "SetBits failed"); |
| static_assert(SetBits<uint32_t, 31, 1>::get == uint32_t(0x80000000), |
| "SetBits failed"); |
| static_assert(SetBits<uint32_t, 1, 2>::get == uint32_t(0x00000006), |
| "SetBits failed"); |
| static_assert(SetBits<uint32_t, 30, 2>::get == uint32_t(0xc0000000), |
| "SetBits failed"); |
| static_assert(SetBits<uint32_t, 0, 31>::get == uint32_t(0x7FFFFFFF), |
| "SetBits failed"); |
| static_assert(SetBits<uint32_t, 0, 32>::get == uint32_t(0xFFFFFFFF), |
| "SetBits failed"); |
| static_assert(SetBits<uint32_t, 16, 16>::get == uint32_t(0xFFFF0000), |
| "SetBits failed"); |
| |
| static_assert(SetBits<uint64_t, 0, 1>::get == uint64_t(0x0000000000000001LL), |
| "SetBits failed"); |
| static_assert(SetBits<uint64_t, 63, 1>::get == uint64_t(0x8000000000000000LL), |
| "SetBits failed"); |
| static_assert(SetBits<uint64_t, 62, 2>::get == uint64_t(0xc000000000000000LL), |
| "SetBits failed"); |
| static_assert(SetBits<uint64_t, 31, 1>::get == uint64_t(0x0000000080000000LL), |
| "SetBits failed"); |
| static_assert(SetBits<uint64_t, 16, 16>::get == uint64_t(0x00000000FFFF0000LL), |
| "SetBits failed"); |
| |
| } // namespace spvutils |
| |
| #endif // LIBSPIRV_UTIL_BITUTILS_H_ |