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#ifndef _ROMID_HPP
#define _ROMID_HPP

#include <cstdint>

#include "array.hpp"

/// Standard container for a 1-Wire ROM ID.
class RomId
{
public:
    /// Length of the buffer in bytes.
    static const std::size_t byteLen = 8;
    
    /// Built-in array representation.
    typedef array<std::uint8_t, byteLen>::Buffer ByteBuffer;

    /// Perform a CRC8 calculation.
    /// @param crc8 Beginning state of the CRC generator.
    /// @param data Data to pass though the CRC generator.
    /// @returns The calculated CRC8.
    static std::uint8_t calculateCRC8(std::uint8_t crc8, std::uint8_t data);
    
    /// Perform a CRC8 calculation with variable length data.
    /// @param[in] data Data array to pass through the CRC generator.
    /// @param data_len Length of the data array to process.
    /// @param crc Beginning state of the CRC generator.
    /// @returns The calculated CRC8.
    static std::uint8_t calculateCRC8(const std::uint8_t * data, std::size_t data_len, std::uint8_t crc = 0);

private:
    static const std::size_t familyCodeIdx = 0;
    static const std::size_t crc8Idx = 7;
    
    /// Default starting value is all bytes 0x00.
    static const std::uint8_t defaultByteVal = 0x00;

    array<std::uint8_t, byteLen> m_romId;

public:
    const RomId & operator=(const RomId & rhs)
    {
        this->m_romId = rhs.m_romId;
        return rhs;
    }
    
    bool operator==(const RomId & rhs) const
    {
        return (this->m_romId == rhs.m_romId);
    }
    
    bool operator!=(const RomId & rhs) const
    {
        return !operator==(rhs);
    }
    
    /// Conversion to array reference.
    operator ByteBuffer &()
    {
        return m_romId;
    }
    
    /// Conversion to const array reference.
    operator const ByteBuffer &() const
    {
        return m_romId;
    }

    /// Reset to the default starting value.
    void reset()
    {
        std::memset(m_romId, defaultByteVal, byteLen);
    }

    RomId() { reset(); }
    RomId(const RomId & romId) : m_romId(romId.m_romId) { }
    RomId(const ByteBuffer & romIdBytes) : m_romId(romIdBytes) { }

    /// Read the Family Code byte.
    std::uint8_t familyCode() const
    {
        return m_romId[familyCodeIdx];
    }
    
    /// Set the family code byte.
    void setFamilyCode(std::uint8_t familyCode)
    {
        m_romId[familyCodeIdx] = familyCode;
    }

    /// Read the CRC8 byte.
    std::uint8_t crc8() const
    {
        return m_romId[crc8Idx];
    }
    
    /// Set the CRC8 byte.
    void setCrc8(std::uint8_t crc8)
    {
        m_romId[crc8Idx] = crc8;
    }
    
    /// Check if the CRC8 is valid for the ROM ID.
    /// @returns True if the CRC8 is valid.
    bool crc8Valid() const
    {
        return (calculateCRC8(m_romId, (byteLen - 1), 0x00) == crc8());
    }
    
    /// Calculate and set the CRC8 for the ROM ID.
    void setValidCrc8()
    {
        setCrc8(calculateCRC8(m_romId, (byteLen - 1), 0x00));
    }

    /// Check if the ROM ID is valid (Family Code and CRC8 are both valid).
    /// @returns True if the ROM ID is valid.
    bool valid() const
    {
        return (crc8Valid() && (familyCode() != defaultByteVal));
    }
};

#endif