Creating & Linking library for C function / program in Codesys V2.3

[asifdip]

Dear All,
I am using CodeSys 2.3 with Target Codesys SP RTE. I want to create /link external library for C function. Actually I have a C program but I can not write it in ST langauge as It is too big. I hope, there should some library that can use C code or read C code and i can use it in Codesys .  Or any way to  link C code in Codesys 2.3. or is there any oscat library for link C code?
Actually I am very new  in this group and PLC programing.

Best Regards,
Asif