tlvCommon.h

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#pragma once

#include <cstdint>
#include <cstdio>

namespace Tlv
{
// Type (T of TLV) is encoded on 4 bytes
typedef uint32_t type_t;

// Can be used passed as size argument to API function
constexpr size_t UNLIMITED = UINT32_MAX;

// TLV is padded to 4-octet alignment
constexpr size_t alignmentSize = 4;

// TLV header (TL part)
#pragma pack(push, 1)
struct __attribute__((packed)) header_s {
        type_t type;
        uint32_t length;
};
#pragma pack(pop)

// TLV stucture (warning: the sizeof will _not_ include value, which is of variable size)
#pragma pack(push, 1)
struct __attribute__((packed)) tlv_s {
    private:
        header_s header;
        uint8_t value[]; // Number of bytes is specified by header.length

    public:
        // Return type of TLV
        inline type_t getType() const
        {
                return header.type;
        }

        // Return length of TLV
        inline size_t getLength() const
        {
                return header.length;
        }

        // Return buffer of TLV
        inline const uint8_t *getValue() const
        {
                return value;
        }
};
#pragma pack(pop)

// Returns number of padding bytes to be added depending on non-padded size
static inline size_t getPadding(size_t size)
{
        size_t n = size % alignmentSize;
        return (n == 0) ? 0 : alignmentSize - n;
}

// Return size of TLV, it differs from length since it includes header size and padding
static inline size_t getSize(const tlv_s &tlv)
{
        size_t unpadded_size = sizeof(header_s) + tlv.getLength();
        return unpadded_size + getPadding(unpadded_size);
}

} // namespace Tlv