> I need to perform a file read function to implement decoder.
That is a very, very demanding task:
you will have to implement a hardware interface to your media (hard
disc, SD card, USB stick,...). Then you will have to implement the
controller for that specific media. After that you will have to
implement a controller for the file system. Then you will have to access
the desired file, read its content, interpret it and transfer the values
to your registers.
If you are a beginner, then you can easily say "happy new year" before
finishing the work...
Let me ask you: why do you want to access a file in hardware?