mirror of
https://github.com/Atmosphere-NX/Atmosphere.git
synced 2024-11-25 05:12:15 +00:00
72 lines
2 KiB
C
72 lines
2 KiB
C
|
// Tencent is pleased to support the open source community by making RapidJSON available.
|
||
|
|
//
|
||
|
|
// Copyright (C) 2015 THL A29 Limited, a Tencent company, and Milo Yip.
|
||
|
|
//
|
||
|
|
// Licensed under the MIT License (the "License"); you may not use this file except
|
||
|
|
// in compliance with the License. You may obtain a copy of the License at
|
||
|
|
//
|
||
|
|
// http://opensource.org/licenses/MIT
|
||
|
|
//
|
||
|
|
// 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 RAPIDJSON_CLZLL_H_
|
||
|
|
#define RAPIDJSON_CLZLL_H_
|
||
|
|
|
||
|
|
#include "../rapidjson.h"
|
||
|
|
|
||
|
|
#if defined(_MSC_VER) && !defined(UNDER_CE)
|
||
|
|
#include <intrin.h>
|
||
|
|
#if defined(_WIN64)
|
||
|
|
#pragma intrinsic(_BitScanReverse64)
|
||
|
|
#else
|
||
|
|
#pragma intrinsic(_BitScanReverse)
|
||
|
|
#endif
|
||
|
|
#endif
|
||
|
|
|
||
|
|
RAPIDJSON_NAMESPACE_BEGIN
|
||
|
|
namespace internal {
|
||
|
|
|
||
|
|
inline uint32_t clzll(uint64_t x) {
|
||
|
|
// Passing 0 to __builtin_clzll is UB in GCC and results in an
|
||
|
|
// infinite loop in the software implementation.
|
||
|
|
RAPIDJSON_ASSERT(x != 0);
|
||
|
|
|
||
|
|
#if defined(_MSC_VER) && !defined(UNDER_CE)
|
||
|
|
unsigned long r = 0;
|
||
|
|
#if defined(_WIN64)
|
||
|
|
_BitScanReverse64(&r, x);
|
||
|
|
#else
|
||
|
|
// Scan the high 32 bits.
|
||
|
|
if (_BitScanReverse(&r, static_cast<uint32_t>(x >> 32)))
|
||
|
|
return 63 - (r + 32);
|
||
|
|
|
||
|
|
// Scan the low 32 bits.
|
||
|
|
_BitScanReverse(&r, static_cast<uint32_t>(x & 0xFFFFFFFF));
|
||
|
|
#endif // _WIN64
|
||
|
|
|
||
|
|
return 63 - r;
|
||
|
|
#elif (defined(__GNUC__) && __GNUC__ >= 4) || RAPIDJSON_HAS_BUILTIN(__builtin_clzll)
|
||
|
|
// __builtin_clzll wrapper
|
||
|
|
return static_cast<uint32_t>(__builtin_clzll(x));
|
||
|
|
#else
|
||
|
|
// naive version
|
||
|
|
uint32_t r = 0;
|
||
|
|
while (!(x & (static_cast<uint64_t>(1) << 63))) {
|
||
|
|
x <<= 1;
|
||
|
|
++r;
|
||
|
|
}
|
||
|
|
|
||
|
|
return r;
|
||
|
|
#endif // _MSC_VER
|
||
|
|
}
|
||
|
|
|
||
|
|
#define RAPIDJSON_CLZLL RAPIDJSON_NAMESPACE::internal::clzll
|
||
|
|
|
||
|
|
} // namespace internal
|
||
|
|
RAPIDJSON_NAMESPACE_END
|
||
|
|
|
||
|
|
#endif // RAPIDJSON_CLZLL_H_
|