I really hope you could give me some interesting viewpoints for my situation,

my ways to approach my issue are not to my liking .

I am writing an mp3 parser , starting with an ID3v2 parser .

Right now I`m working on the extended header parsing , my issue is that the optional header is defined differently in version 2.3 and 2.4 of the tag .

The 2.3 version optional header is defined as follows :

struct ID3_3_EXTENDED_HEADER{
DWORD dwExtHeaderSize;          //Extended header size (either 6 or 8 bytes , excluded)
WORD  wExtFlags;                //Extended header flags
DWORD dwSizeOfPadding;          //Size of padding (size of the tag excluding the frames and headers)
};

While the 2.4 version is defined :

struct ID3_4_EXTENDED_HEADER{
DWORD dwExtHeaderSize;          //Extended header size (synchsafe int)
BYTE  bNumberOfFlagBytes;       //Number of flag bytes
BYTE  bFlags;                   //Flags
};

How could I parse the header while minimizing code duplication ?

Using two different functions to parse each version sounds less great ,

using a single function with a different flow for each occasion is similar ,

any good practices for this kind of issues ? any tips for avoiding code duplication ?

anything would be great .