interface code for matlab coder-generated .dll

On Matlab 2014b, when compiling a .dll on Windows x64, coder generates a directory under the main source directory named "interface" containing files with names like coder<function>_api.c, coder<function>_api.c, coder<function>_mex.c (where function stands for the main function name built into the dll). What are these files, and what are they for? They don't appear to be documented anywhere, and don't appear to be included in the main library build. I suspect the _mex file is intended to provide a mex interface to allow the generated .dll to be called from matlab, which is useful for test purposes, and exactly what I want. However, it is not clear exactly what one must do to compile this so that it may be used.

Can anyone tell me more about these files, and how to make use of them?