82 lines
3.2 KiB
C
82 lines
3.2 KiB
C
|
// Copyright (c) 2015-2016 The Khronos Group Inc.
|
||
|
|
//
|
||
|
|
// Licensed under the Apache License, Version 2.0 (the "License");
|
||
|
|
// you may not use this file except in compliance with the License.
|
||
|
|
// You may obtain a copy of the License at
|
||
|
|
//
|
||
|
|
// http://www.apache.org/licenses/LICENSE-2.0
|
||
|
|
//
|
||
|
|
// Unless required by applicable law or agreed to in writing, software
|
||
|
|
// distributed under the License is distributed on an "AS IS" BASIS,
|
||
|
|
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
||
|
|
// See the License for the specific language governing permissions and
|
||
|
|
// limitations under the License.
|
||
|
|
|
||
|
|
#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(static_cast<void*>(&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_
|