diff options
Diffstat (limited to 'src/s3select/rapidjson/include/rapidjson/internal/clzll.h')
-rw-r--r-- | src/s3select/rapidjson/include/rapidjson/internal/clzll.h | 71 |
1 files changed, 71 insertions, 0 deletions
diff --git a/src/s3select/rapidjson/include/rapidjson/internal/clzll.h b/src/s3select/rapidjson/include/rapidjson/internal/clzll.h new file mode 100644 index 000000000..8fc5118aa --- /dev/null +++ b/src/s3select/rapidjson/include/rapidjson/internal/clzll.h @@ -0,0 +1,71 @@ +// 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_ |