CCS/MSP430FR5969: Error: Unresolved symbol..., first referenced...

The errors are basically saying that the source file (in this case crypto_util.c) is referencing symbols fpadd1271, fpcopy1271, etc. but the linker cannot find a definition for those symbols. The definition could come from a source file that defines those functions or from a library file. Your first step is to identify which file/library contains definitions for those symbols. Then if it is in a source file, make sure it is added to the project, or if it is in a library file, make sure it is linked into the project. 

*help! another issue!*

Thank you for the swift reply! Your instructions are very clear and I have included an Include guard (#include "fp.h") in the crypto_ultil.c file and it seems to have removed the problems. Here's how I did it:

However, I am now stuck with a new problem and it's telling me that there are redefined symbols in the files.

Here's a few more screenshots for the context:

fpmul1271 in fp.h:

fpmul1271 in eccp.c:

fpmul1271 in crypto_ultil.c:

fpmull1271 references:

I have read through the internet that this problem has something to do with declaration and definition but from what I'm looking at, I'm not sure if that's the case. I also did not include any .c guard in the crypto_ultil.c or eccp2.c files. 

This is what I understand regarding definitions and declaration:

• extern unsigned char x;     is a declaration;
•        unsigned char x;     is a declaration and may also become a definition;
•        unsigned char x = 0; is a definition.

- Shawn

Take a look at this FAQ for guidance on how/where to declare and define variables and functions.

As mentioned in the FAQ, you may want to consider moving the definition of fpmul1271 to a C source file, and putting an external declaration in the fp.h header file. Then #include the fp.h file in all C files that need it. Note there should only be one definition of the function seen by the compiler tools.