Avalon-ST data width adapter

There is an ST data adapter but it's not going to do what you want. It does things like take a 32-bit input containing 4 symbols (bytes) and converts it down to an 8-bit output (four beats of a single symbol at a time).

Instead what you need is a custom core that has a 32-bit sink, and a 10-bit source that truncates the bits away for you. Alternatively you can just do this at the input of the next core in the ST chain assuming you wrote the core and can modify it.

So no there is no adapter available for doing this but it's dirt simple to create one. If you want to see an example take a look at any of the designs for the NEEK and look at the video pipeline. There will be a core that takes 32-bit RGBA and outputs RGB with the A channel ripped out.