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//
//
// Copyright 2015 gRPC authors.
//
// 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 GRPC_SRC_CORE_LIB_GPR_USEFUL_H
#define GRPC_SRC_CORE_LIB_GPR_USEFUL_H
#include <grpc/support/port_platform.h>
#include <cstddef>
#include "y_absl/strings/string_view.h"
#include "y_absl/types/variant.h"
/// useful utilities that don't belong anywhere else
namespace grpc_core {
template <typename T>
T Clamp(T val, T min, T max) {
if (val < min) return min;
if (max < val) return max;
return val;
}
/// rotl, rotr assume x is unsigned
template <typename T>
constexpr T RotateLeft(T x, T n) {
return ((x << n) | (x >> (sizeof(x) * 8 - n)));
}
template <typename T>
constexpr T RotateRight(T x, T n) {
return ((x >> n) | (x << (sizeof(x) * 8 - n)));
}
// Set the n-th bit of i
template <typename T>
T SetBit(T* i, size_t n) {
return *i |= (T(1) << n);
}
// Clear the n-th bit of i
template <typename T>
T ClearBit(T* i, size_t n) {
return *i &= ~(T(1) << n);
}
// Get the n-th bit of i
template <typename T>
bool GetBit(T i, size_t n) {
return (i & (T(1) << n)) != 0;
}
namespace useful_detail {
inline constexpr uint32_t HexdigitBitcount(uint32_t x) {
return (x - ((x >> 1) & 0x77777777) - ((x >> 2) & 0x33333333) -
((x >> 3) & 0x11111111));
}
} // namespace useful_detail
inline constexpr uint32_t BitCount(uint32_t i) {
return (((useful_detail::HexdigitBitcount(i) +
(useful_detail::HexdigitBitcount(i) >> 4)) &
0x0f0f0f0f) %
255);
}
inline constexpr uint32_t BitCount(uint64_t i) {
return BitCount(static_cast<uint32_t>(i)) +
BitCount(static_cast<uint32_t>(i >> 32));
}
inline constexpr uint32_t BitCount(uint16_t i) {
return BitCount(static_cast<uint32_t>(i));
}
inline constexpr uint32_t BitCount(uint8_t i) {
return BitCount(static_cast<uint32_t>(i));
}
inline constexpr uint32_t BitCount(int64_t i) {
return BitCount(static_cast<uint64_t>(i));
}
inline constexpr uint32_t BitCount(int32_t i) {
return BitCount(static_cast<uint32_t>(i));
}
inline constexpr uint32_t BitCount(int16_t i) {
return BitCount(static_cast<uint16_t>(i));
}
inline constexpr uint32_t BitCount(int8_t i) {
return BitCount(static_cast<uint8_t>(i));
}
// This function uses operator< to implement a qsort-style comparison, whereby:
// if a is smaller than b, a number smaller than 0 is returned.
// if a is bigger than b, a number greater than 0 is returned.
// if a is neither smaller nor bigger than b, 0 is returned.
template <typename T>
int QsortCompare(const T& a, const T& b) {
if (a < b) return -1;
if (b < a) return 1;
return 0;
}
template <typename... X>
int QsortCompare(const y_absl::variant<X...>& a, const y_absl::variant<X...>& b) {
const int index = QsortCompare(a.index(), b.index());
if (index != 0) return index;
return y_absl::visit(
[&](const auto& x) {
return QsortCompare(x, y_absl::get<y_absl::remove_cvref_t<decltype(x)>>(b));
},
a);
}
inline int QsortCompare(y_absl::string_view a, y_absl::string_view b) {
return a.compare(b);
}
inline int QsortCompare(const TString& a, const TString& b) {
return a.compare(b);
}
template <typename A, typename B>
int QsortCompare(const std::pair<A, B>& a, const std::pair<A, B>& b) {
const int first = QsortCompare(a.first, b.first);
if (first != 0) return first;
return QsortCompare(a.second, b.second);
}
template <typename T>
constexpr size_t HashPointer(T* p, size_t range) {
return (((reinterpret_cast<size_t>(p)) >> 4) ^
((reinterpret_cast<size_t>(p)) >> 9) ^
((reinterpret_cast<size_t>(p)) >> 14)) %
range;
}
// Compute a+b.
// If the result is greater than INT64_MAX, return INT64_MAX.
// If the result is less than INT64_MIN, return INT64_MIN.
inline int64_t SaturatingAdd(int64_t a, int64_t b) {
if (a > 0) {
if (b > INT64_MAX - a) {
return INT64_MAX;
}
} else if (b < INT64_MIN - a) {
return INT64_MIN;
}
return a + b;
}
inline uint32_t MixHash32(uint32_t a, uint32_t b) {
return RotateLeft(a, 2u) ^ b;
}
inline uint32_t RoundUpToPowerOf2(uint32_t v) {
v--;
v |= v >> 1;
v |= v >> 2;
v |= v >> 4;
v |= v >> 8;
v |= v >> 16;
v++;
return v;
}
} // namespace grpc_core
#define GPR_ARRAY_SIZE(array) (sizeof(array) / sizeof(*(array)))
#endif // GRPC_SRC_CORE_LIB_GPR_USEFUL_H
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