mirror of
https://github.com/ClickHouse/ClickHouse.git
synced 2024-12-03 04:52:10 +00:00
a7734672b9
- Introduced with the C++20 <bit> header - The problem with __builtin_c(l|t)z() is that 0 as input has an undefined result (*) and the code did not always check. The std:: versions do not have this issue. - In some cases, we continue to use buildin_c(l|t)z(), (e.g. in src/Common/BitHelpers.h) because the std:: versions only accept unsigned inputs (and they also check that) and the casting would be ugly. (*) https://gcc.gnu.org/onlinedocs/gcc/Other-Builtins.html
37 lines
1000 B
C++
37 lines
1000 B
C++
#include <Functions/FunctionBinaryArithmetic.h>
|
|
#include <Functions/FunctionFactory.h>
|
|
#include <bit>
|
|
|
|
namespace DB
|
|
{
|
|
template <typename A, typename B>
|
|
struct BitHammingDistanceImpl
|
|
{
|
|
using ResultType = UInt8;
|
|
static const constexpr bool allow_fixed_string = false;
|
|
static const constexpr bool allow_string_integer = false;
|
|
|
|
template <typename Result = ResultType>
|
|
static inline NO_SANITIZE_UNDEFINED Result apply(A a, B b)
|
|
{
|
|
UInt64 res = static_cast<UInt64>(a) ^ static_cast<UInt64>(b);
|
|
return std::popcount(res);
|
|
}
|
|
|
|
#if USE_EMBEDDED_COMPILER
|
|
static constexpr bool compilable = false; /// special type handling, some other time
|
|
#endif
|
|
};
|
|
|
|
struct NameBitHammingDistance
|
|
{
|
|
static constexpr auto name = "bitHammingDistance";
|
|
};
|
|
using FunctionBitHammingDistance = BinaryArithmeticOverloadResolver<BitHammingDistanceImpl, NameBitHammingDistance>;
|
|
|
|
REGISTER_FUNCTION(BitHammingDistance)
|
|
{
|
|
factory.registerFunction<FunctionBitHammingDistance>();
|
|
}
|
|
}
|