mirror of
https://github.com/ClickHouse/ClickHouse.git
synced 2024-12-02 04:22:03 +00:00
103 lines
2.7 KiB
C++
103 lines
2.7 KiB
C++
#include <type_traits>
|
|
#include <ext/bit_cast.h>
|
|
#include <Functions/FunctionFactory.h>
|
|
#include <Functions/FunctionUnaryArithmetic.h>
|
|
|
|
namespace DB
|
|
{
|
|
namespace ErrorCodes
|
|
{
|
|
extern const int NOT_IMPLEMENTED;
|
|
}
|
|
|
|
namespace
|
|
{
|
|
|
|
template <typename T>
|
|
inline std::enable_if_t<std::is_integral_v<T> && (sizeof(T) <= sizeof(UInt32)), T>
|
|
roundDownToPowerOfTwo(T x)
|
|
{
|
|
return x <= 0 ? 0 : (T(1) << (31 - __builtin_clz(x)));
|
|
}
|
|
|
|
template <typename T>
|
|
inline std::enable_if_t<std::is_integral_v<T> && (sizeof(T) == sizeof(UInt64)), T>
|
|
roundDownToPowerOfTwo(T x)
|
|
{
|
|
return x <= 0 ? 0 : (T(1) << (63 - __builtin_clzll(x)));
|
|
}
|
|
|
|
template <typename T>
|
|
inline std::enable_if_t<std::is_same_v<T, Int128>, T>
|
|
roundDownToPowerOfTwo(T x)
|
|
{
|
|
if (x <= 0)
|
|
return 0;
|
|
|
|
if (Int64 x64 = Int64(x >> 64))
|
|
return Int128(roundDownToPowerOfTwo(x64)) << 64;
|
|
return roundDownToPowerOfTwo(Int64(x));
|
|
}
|
|
|
|
template <typename T>
|
|
inline std::enable_if_t<std::is_same_v<T, Float32>, T>
|
|
roundDownToPowerOfTwo(T x)
|
|
{
|
|
return ext::bit_cast<T>(ext::bit_cast<UInt32>(x) & ~((1ULL << 23) - 1));
|
|
}
|
|
|
|
template <typename T>
|
|
inline std::enable_if_t<std::is_same_v<T, Float64>, T>
|
|
roundDownToPowerOfTwo(T x)
|
|
{
|
|
return ext::bit_cast<T>(ext::bit_cast<UInt64>(x) & ~((1ULL << 52) - 1));
|
|
}
|
|
|
|
template <typename T>
|
|
inline std::enable_if_t<is_big_int_v<T>, T>
|
|
roundDownToPowerOfTwo(T)
|
|
{
|
|
throw Exception("roundToExp2() for big integers is not implemented", ErrorCodes::NOT_IMPLEMENTED);
|
|
}
|
|
|
|
/** For integer data types:
|
|
* - if number is greater than zero, round it down to nearest power of two (example: roundToExp2(100) = 64, roundToExp2(64) = 64);
|
|
* - otherwise, return 0.
|
|
*
|
|
* For floating point data types: zero out mantissa, but leave exponent.
|
|
* - if number is greater than zero, round it down to nearest power of two (example: roundToExp2(3) = 2);
|
|
* - negative powers are also used (example: roundToExp2(0.7) = 0.5);
|
|
* - if number is zero, return zero;
|
|
* - if number is less than zero, the result is symmetrical: roundToExp2(x) = -roundToExp2(-x). (example: roundToExp2(-0.3) = -0.25);
|
|
*/
|
|
|
|
template <typename T>
|
|
struct RoundToExp2Impl
|
|
{
|
|
using ResultType = T;
|
|
static constexpr const bool allow_fixed_string = false;
|
|
|
|
static inline T apply(T x)
|
|
{
|
|
return roundDownToPowerOfTwo<T>(x);
|
|
}
|
|
|
|
#if USE_EMBEDDED_COMPILER
|
|
static constexpr bool compilable = false;
|
|
#endif
|
|
};
|
|
|
|
struct NameRoundToExp2 { static constexpr auto name = "roundToExp2"; };
|
|
using FunctionRoundToExp2 = FunctionUnaryArithmetic<RoundToExp2Impl, NameRoundToExp2, false>;
|
|
|
|
}
|
|
|
|
template <> struct FunctionUnaryArithmeticMonotonicity<NameRoundToExp2> : PositiveMonotonicity {};
|
|
|
|
void registerFunctionRoundToExp2(FunctionFactory & factory)
|
|
{
|
|
factory.registerFunction<FunctionRoundToExp2>();
|
|
}
|
|
|
|
}
|