1 // Copyright (c) 2015-2016 The Khronos Group Inc. 2 // 3 // Permission is hereby granted, free of charge, to any person obtaining a 4 // copy of this software and/or associated documentation files (the 5 // "Materials"), to deal in the Materials without restriction, including 6 // without limitation the rights to use, copy, modify, merge, publish, 7 // distribute, sublicense, and/or sell copies of the Materials, and to 8 // permit persons to whom the Materials are furnished to do so, subject to 9 // the following conditions: 10 // 11 // The above copyright notice and this permission notice shall be included 12 // in all copies or substantial portions of the Materials. 13 // 14 // MODIFICATIONS TO THIS FILE MAY MEAN IT NO LONGER ACCURATELY REFLECTS 15 // KHRONOS STANDARDS. THE UNMODIFIED, NORMATIVE VERSIONS OF KHRONOS 16 // SPECIFICATIONS AND HEADER INFORMATION ARE LOCATED AT 17 // https://www.khronos.org/registry/ 18 // 19 // THE MATERIALS ARE PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, 20 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF 21 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. 22 // IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY 23 // CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, 24 // TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE 25 // MATERIALS OR THE USE OR OTHER DEALINGS IN THE MATERIALS. 26 27 #ifndef LIBSPIRV_UTIL_BITUTILS_H_ 28 #define LIBSPIRV_UTIL_BITUTILS_H_ 29 30 #include <cstdint> 31 #include <cstring> 32 33 namespace spvutils { 34 35 // Performs a bitwise copy of source to the destination type Dest. 36 template <typename Dest, typename Src> 37 Dest BitwiseCast(Src source) { 38 Dest dest; 39 static_assert(sizeof(source) == sizeof(dest), 40 "BitwiseCast: Source and destination must have the same size"); 41 std::memcpy(&dest, &source, sizeof(dest)); 42 return dest; 43 } 44 45 // SetBits<T, First, Num> returns an integer of type <T> with bits set 46 // for position <First> through <First + Num - 1>, counting from the least 47 // significant bit. In particular when Num == 0, no positions are set to 1. 48 // A static assert will be triggered if First + Num > sizeof(T) * 8, that is, 49 // a bit that will not fit in the underlying type is set. 50 template <typename T, size_t First = 0, size_t Num = 0> 51 struct SetBits { 52 static_assert(First < sizeof(T) * 8, 53 "Tried to set a bit that is shifted too far."); 54 const static T get = (T(1) << First) | SetBits<T, First + 1, Num - 1>::get; 55 }; 56 57 template <typename T, size_t Last> 58 struct SetBits<T, Last, 0> { 59 const static T get = T(0); 60 }; 61 62 // This is all compile-time so we can put our tests right here. 63 static_assert(SetBits<uint32_t, 0, 0>::get == uint32_t(0x00000000), 64 "SetBits failed"); 65 static_assert(SetBits<uint32_t, 0, 1>::get == uint32_t(0x00000001), 66 "SetBits failed"); 67 static_assert(SetBits<uint32_t, 31, 1>::get == uint32_t(0x80000000), 68 "SetBits failed"); 69 static_assert(SetBits<uint32_t, 1, 2>::get == uint32_t(0x00000006), 70 "SetBits failed"); 71 static_assert(SetBits<uint32_t, 30, 2>::get == uint32_t(0xc0000000), 72 "SetBits failed"); 73 static_assert(SetBits<uint32_t, 0, 31>::get == uint32_t(0x7FFFFFFF), 74 "SetBits failed"); 75 static_assert(SetBits<uint32_t, 0, 32>::get == uint32_t(0xFFFFFFFF), 76 "SetBits failed"); 77 static_assert(SetBits<uint32_t, 16, 16>::get == uint32_t(0xFFFF0000), 78 "SetBits failed"); 79 80 static_assert(SetBits<uint64_t, 0, 1>::get == uint64_t(0x0000000000000001LL), 81 "SetBits failed"); 82 static_assert(SetBits<uint64_t, 63, 1>::get == uint64_t(0x8000000000000000LL), 83 "SetBits failed"); 84 static_assert(SetBits<uint64_t, 62, 2>::get == uint64_t(0xc000000000000000LL), 85 "SetBits failed"); 86 static_assert(SetBits<uint64_t, 31, 1>::get == uint64_t(0x0000000080000000LL), 87 "SetBits failed"); 88 static_assert(SetBits<uint64_t, 16, 16>::get == uint64_t(0x00000000FFFF0000LL), 89 "SetBits failed"); 90 91 } // namespace spvutils 92 93 #endif // LIBSPIRV_UTIL_BITUTILS_H_ 94
