mirror of
https://github.com/KhronosGroup/SPIRV-Tools
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94 lines
4.0 KiB
C++
94 lines
4.0 KiB
C++
// Copyright (c) 2015-2016 The Khronos Group Inc.
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//
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// Permission is hereby granted, free of charge, to any person obtaining a
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// copy of this software and/or associated documentation files (the
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// "Materials"), to deal in the Materials without restriction, including
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// without limitation the rights to use, copy, modify, merge, publish,
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// distribute, sublicense, and/or sell copies of the Materials, and to
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// permit persons to whom the Materials are furnished to do so, subject to
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// the following conditions:
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//
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// The above copyright notice and this permission notice shall be included
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// in all copies or substantial portions of the Materials.
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//
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// MODIFICATIONS TO THIS FILE MAY MEAN IT NO LONGER ACCURATELY REFLECTS
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// KHRONOS STANDARDS. THE UNMODIFIED, NORMATIVE VERSIONS OF KHRONOS
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// SPECIFICATIONS AND HEADER INFORMATION ARE LOCATED AT
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// https://www.khronos.org/registry/
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//
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// THE MATERIALS ARE PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
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// IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
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// CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
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// TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
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// MATERIALS OR THE USE OR OTHER DEALINGS IN THE MATERIALS.
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#ifndef LIBSPIRV_UTIL_BITUTILS_H_
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#define LIBSPIRV_UTIL_BITUTILS_H_
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#include <cstdint>
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#include <cstring>
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namespace spvutils {
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// Performs a bitwise copy of source to the destination type Dest.
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template <typename Dest, typename Src>
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Dest BitwiseCast(Src source) {
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Dest dest;
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static_assert(sizeof(source) == sizeof(dest),
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"BitwiseCast: Source and destination must have the same size");
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std::memcpy(&dest, &source, sizeof(dest));
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return dest;
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}
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// SetBits<T, First, Num> returns an integer of type <T> with bits set
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// for position <First> through <First + Num - 1>, counting from the least
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// significant bit. In particular when Num == 0, no positions are set to 1.
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// A static assert will be triggered if First + Num > sizeof(T) * 8, that is,
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// a bit that will not fit in the underlying type is set.
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template <typename T, size_t First = 0, size_t Num = 0>
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struct SetBits {
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static_assert(First < sizeof(T) * 8,
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"Tried to set a bit that is shifted too far.");
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const static T get = (T(1) << First) | SetBits<T, First + 1, Num - 1>::get;
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};
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template <typename T, size_t Last>
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struct SetBits<T, Last, 0> {
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const static T get = T(0);
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};
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// This is all compile-time so we can put our tests right here.
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static_assert(SetBits<uint32_t, 0, 0>::get == uint32_t(0x00000000),
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"SetBits failed");
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static_assert(SetBits<uint32_t, 0, 1>::get == uint32_t(0x00000001),
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"SetBits failed");
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static_assert(SetBits<uint32_t, 31, 1>::get == uint32_t(0x80000000),
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"SetBits failed");
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static_assert(SetBits<uint32_t, 1, 2>::get == uint32_t(0x00000006),
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"SetBits failed");
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static_assert(SetBits<uint32_t, 30, 2>::get == uint32_t(0xc0000000),
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"SetBits failed");
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static_assert(SetBits<uint32_t, 0, 31>::get == uint32_t(0x7FFFFFFF),
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"SetBits failed");
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static_assert(SetBits<uint32_t, 0, 32>::get == uint32_t(0xFFFFFFFF),
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"SetBits failed");
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static_assert(SetBits<uint32_t, 16, 16>::get == uint32_t(0xFFFF0000),
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"SetBits failed");
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static_assert(SetBits<uint64_t, 0, 1>::get == uint64_t(0x0000000000000001LL),
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"SetBits failed");
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static_assert(SetBits<uint64_t, 63, 1>::get == uint64_t(0x8000000000000000LL),
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"SetBits failed");
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static_assert(SetBits<uint64_t, 62, 2>::get == uint64_t(0xc000000000000000LL),
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"SetBits failed");
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static_assert(SetBits<uint64_t, 31, 1>::get == uint64_t(0x0000000080000000LL),
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"SetBits failed");
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static_assert(SetBits<uint64_t, 16, 16>::get == uint64_t(0x00000000FFFF0000LL),
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"SetBits failed");
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} // namespace spvutils
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#endif // LIBSPIRV_UTIL_BITUTILS_H_
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