"tc" "th" files for C program

I first encountered files ended with .tc and .th in a C library (http://www.vlfeat.org/api/files.html, only .tc files are listed there. To see .th file, one has to download its source code http://www.vlfeat.org/download/vlfeat-0.9.5-开发者_运维百科bin.tar.gz. They are under vl directory.). Just wonder what do they mean and relation with normal .h and .c files ?

Thanks and regards!

They use those as a template and the files are not compiled directly, but by being #included in the corresponding .c or .h file after setting #defines that affect the final result.

One example is what happens in mathop_sse2.c. They include the same mathop_sse2.tc twice, but the first time FLT is defined as VL_TYPE_DOUBLE and the second time is VL_TYPE_FLOAT. That way they avoid duplicating the exact same code for different types.

Seems most likely these files were written using the Borland compiler.