Freertos compatible iconv or icu4c

I have a requirement to covert Unicode plane 0 content to one of the code pages
gb2312,shift_ jis,cp1251,cp1252,wr_cp1250
What will be the compatible solution for Freetos?

Anything written in C or C++ that is small enough and doesn’t assume it’s running on a hosted (i.e. Linux) should work.