integral_traits.h

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#pragma once
#include "../utility/assert.h"
#include "../utility/bits.h"
#include "../utility/meta.h"
#include "../utility/parameter.h"
 
#include "../stream/serialize_traits.h"
 
#include <cstdint>
#include <limits>
#include <type_traits>
 
namespace bitstream
{
    template<typename T, T = (std::numeric_limits<T>::min)(), T = (std::numeric_limits<T>::max)()>
    struct bounded_int;
 
#pragma region integral types
    template<typename T>
    struct serialize_traits<T, typename std::enable_if_t<std::is_integral_v<T> && !std::is_const_v<T>>>
    {
        static_assert(sizeof(T) <= 8, "Integers larger than 8 bytes are currently not supported. You will have to write this functionality yourself");
 
        template<typename Stream>
        typename utility::is_writing_t<Stream>
        static serialize(Stream& writer, in<T> value, T min = (std::numeric_limits<T>::min)(), T max = (std::numeric_limits<T>::max)()) noexcept
        {
            BS_ASSERT(min < max);
            
            BS_ASSERT(value >= min && value <= max);
 
            uint32_t num_bits = utility::bits_in_range(min, max);
 
            BS_ASSERT(num_bits <= sizeof(T) * 8);
 
            if constexpr (sizeof(T) > 4)
            {
                if (num_bits > 32)
                {
                    // If the given range is bigger than a word (32 bits)
                    uint32_t unsigned_value = static_cast<uint32_t>(value - min);
                    BS_ASSERT(writer.serialize_bits(unsigned_value, 32));
 
                    unsigned_value = static_cast<uint32_t>((value - min) >> 32);
                    BS_ASSERT(writer.serialize_bits(unsigned_value, num_bits - 32));
 
                    return true;
                }
            }
 
            // If the given range is smaller than or equal to a word (32 bits)
            uint32_t unsigned_value = static_cast<uint32_t>(value - min);
            BS_ASSERT(writer.serialize_bits(unsigned_value, num_bits));
 
            return true;
        }
 
        template<typename Stream>
        typename utility::is_reading_t<Stream>
        static serialize(Stream& reader, T& value, T min = (std::numeric_limits<T>::min)(), T max = (std::numeric_limits<T>::max)()) noexcept
        {
            BS_ASSERT(min < max);
 
            uint32_t num_bits = utility::bits_in_range(min, max);
 
            BS_ASSERT(num_bits <= sizeof(T) * 8);
 
            if constexpr (sizeof(T) > 4)
            {
                if (num_bits > 32)
                {
                    // If the given range is bigger than a word (32 bits)
                    value = 0;
                    uint32_t unsigned_value;
 
                    BS_ASSERT(reader.serialize_bits(unsigned_value, 32));
                    value |= static_cast<T>(unsigned_value);
 
                    BS_ASSERT(reader.serialize_bits(unsigned_value, num_bits - 32));
                    value |= static_cast<T>(unsigned_value) << 32;
 
                    value += min;
 
                    BS_ASSERT(value >= min && value <= max);
 
                    return true;
                }
            }
 
            // If the given range is smaller than or equal to a word (32 bits)
            uint32_t unsigned_value;
            BS_ASSERT(reader.serialize_bits(unsigned_value, num_bits));
 
            value = static_cast<T>(unsigned_value) + min;
            
            BS_ASSERT(value >= min && value <= max);
 
            return true;
        }
    };
#pragma endregion
 
#pragma region const integral types
    template<typename T, T Min, T Max>
    struct serialize_traits<bounded_int<T, Min, Max>, typename std::enable_if_t<std::is_integral_v<T> && !std::is_const_v<T>>>
    {
        static_assert(sizeof(T) <= 8, "Integers larger than 8 bytes are currently not supported. You will have to write this functionality yourself");
 
        template<typename Stream>
        typename utility::is_writing_t<Stream>
        static serialize(Stream& writer, in<T> value) noexcept
        {
            static_assert(Min < Max);
            
            BS_ASSERT(value >= Min && value <= Max);
 
            constexpr uint32_t num_bits = utility::bits_in_range(Min, Max);
 
            static_assert(num_bits <= sizeof(T) * 8);
 
            if constexpr (sizeof(T) > 4 && num_bits > 32)
            {
                // If the given range is bigger than a word (32 bits)
                uint32_t unsigned_value = static_cast<uint32_t>(value - Min);
                BS_ASSERT(writer.serialize_bits(unsigned_value, 32));
 
                unsigned_value = static_cast<uint32_t>((value - Min) >> 32);
                BS_ASSERT(writer.serialize_bits(unsigned_value, num_bits - 32));
            }
            else
            {
                // If the given range is smaller than or equal to a word (32 bits)
                uint32_t unsigned_value = static_cast<uint32_t>(value - Min);
                BS_ASSERT(writer.serialize_bits(unsigned_value, num_bits));
            }
 
            return true;
        }
 
        template<typename Stream>
        typename utility::is_reading_t<Stream>
        static serialize(Stream& reader, T& value) noexcept
        {
            static_assert(Min < Max);
 
            constexpr uint32_t num_bits = utility::bits_in_range(Min, Max);
 
            static_assert(num_bits <= sizeof(T) * 8);
 
            if constexpr (sizeof(T) > 4 && num_bits > 32)
            {
                // If the given range is bigger than a word (32 bits)
                value = 0;
                uint32_t unsigned_value;
 
                BS_ASSERT(reader.serialize_bits(unsigned_value, 32));
                value |= static_cast<T>(unsigned_value);
 
                BS_ASSERT(reader.serialize_bits(unsigned_value, num_bits - 32));
                value |= static_cast<T>(unsigned_value) << 32;
 
                value += Min;
            }
            else
            {
                // If the given range is smaller than or equal to a word (32 bits)
                uint32_t unsigned_value;
                BS_ASSERT(reader.serialize_bits(unsigned_value, num_bits));
 
                value = static_cast<T>(unsigned_value) + Min;
            }
            
            BS_ASSERT(value >= Min && value <= Max);
 
            return true;
        }
    };
#pragma endregion
}