IntegerMath.h

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#pragma once
#include <cstdint>
#include <limits>
#include <type_traits>
 
namespace catapult { namespace utils {
 
    template<typename T>
    bool CheckedAdd(T& value, T delta) {
        if (value > std::numeric_limits<T>::max() - delta)
            return false;
 
        value += delta;
        return true;
    }
 
    template<typename T, typename X = std::enable_if_t<std::is_integral_v<T>>>
    constexpr T GetNumBits() {
        return static_cast<T>(8u * sizeof(T));
    }
 
    template<typename T, typename X = std::enable_if_t<std::is_unsigned_v<T>>>
    constexpr T Log2(T value) {
#ifdef _MSC_VER
        unsigned long result;
        if (!_BitScanReverse(&result, value))
            return std::numeric_limits<T>::max();
 
        return static_cast<T>(result);
#else
        if (!value)
            return std::numeric_limits<T>::max();
 
        return static_cast<T>(63 - __builtin_clzll(value));
#endif
    }
 
    uint64_t Log2TimesPowerOfTwo(uint64_t value, uint64_t n);
 
    template<typename T, typename X = std::enable_if_t<std::is_unsigned_v<T>>>
    constexpr T Pow2(T value) {
        return value >= GetNumBits<T>() ? 0 : static_cast<T>(static_cast<T>(1) << value);
    }
 
    template<typename T, typename X = std::enable_if_t<std::is_unsigned_v<T>>>
    constexpr T DivideAndGetRemainder(T& value, T divisor) {
        auto remainder = static_cast<T>(value % divisor);
        value /= divisor;
        return remainder;
    }
 
    template<typename T, typename X = std::enable_if_t<std::is_unsigned_v<T>>>
    constexpr bool IsPowerMultiple(T lhs, T rhs, T base) {
        if (lhs > rhs || 0 != rhs % lhs)
            return false;
 
        T quotient = rhs / lhs;
        while (quotient > 1) {
            if (0 != DivideAndGetRemainder(quotient, base))
                return false;
        }
 
        return true;
    }
}}