I recommend 2 things 1 statically analyzer,Lint etc This will takeout in advance some problems in the migration 2 maybe create part of the toolchain for the mig

I recommend 2 things 1 statically analyzer,Lint etc This will takeout in advance some problems in the migration 2 maybe create part of the toolchain for the migration, some of the new compilers are modulars and can make the c99 to c11 transition easier, if you don't want to re-implement the code by hand (wich is always a option) https://m.youtube.com/watch?v=_cIVa-RctcA&t=325s https://m.youtube.com/watch?v=_cIVa-RctcA&t=325s