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/*
* Copyright 2015 WebAssembly Community Group participants
*
* 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 wasm_support_bits_h
#define wasm_support_bits_h
#include <climits>
#include <cstdint>
#include <type_traits>
/*
* Portable bit functions.
*
* Not all platforms offer fast intrinsics for these functions, and some
* compilers require checking CPUID at runtime before using the intrinsic.
*
* We instead use portable and reasonably-fast implementations, while
* avoiding implementations with large lookup tables.
*/
namespace wasm::Bits {
int popCount(uint8_t);
int popCount(uint16_t);
int popCount(uint32_t);
int popCount(uint64_t);
inline int popCount(int8_t v) { return popCount(uint8_t(v)); }
inline int popCount(int16_t v) { return popCount(uint16_t(v)); }
inline int popCount(int32_t v) { return popCount(uint32_t(v)); }
inline int popCount(int64_t v) { return popCount(uint64_t(v)); }
uint32_t bitReverse(uint32_t);
int countTrailingZeroes(uint32_t);
int countTrailingZeroes(uint64_t);
inline int countTrailingZeroes(int32_t v) {
return countTrailingZeroes(uint32_t(v));
}
inline int countTrailingZeroes(int64_t v) {
return countTrailingZeroes(uint64_t(v));
}
int countLeadingZeroes(uint32_t);
int countLeadingZeroes(uint64_t);
inline int countLeadingZeroes(int32_t v) {
return countLeadingZeroes(uint32_t(v));
}
inline int countLeadingZeroes(int64_t v) {
return countLeadingZeroes(uint64_t(v));
}
int ceilLog2(uint32_t);
int ceilLog2(uint64_t);
inline int ceilLog2(int32_t v) { return ceilLog2(uint32_t(v)); }
inline int ceilLog2(int64_t v) { return ceilLog2(uint64_t(v)); }
template<typename T> bool isPowerOf2(T v) {
return v != 0 && (v & (v - 1)) == 0;
}
bool isPowerOf2InvertibleFloat(float);
bool isPowerOf2InvertibleFloat(double);
template<typename T, typename U> inline static T rotateLeft(T val, U count) {
auto value = typename std::make_unsigned<T>::type(val);
U mask = sizeof(T) * CHAR_BIT - 1;
count &= mask;
return (value << count) | (value >> (-count & mask));
}
template<typename T, typename U> inline static T rotateRight(T val, U count) {
auto value = typename std::make_unsigned<T>::type(val);
U mask = sizeof(T) * CHAR_BIT - 1;
count &= mask;
return (value >> count) | (value << (-count & mask));
}
uint32_t log2(uint32_t v);
uint32_t pow2(uint32_t v);
} // namespace wasm::Bits
#endif // wasm_support_bits_h
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