Retrieve algorithm from function in Fortran obj file

I have an object file written in Lahey Fortran in 1993-1995 that I need to recover the math out of. There are 8 x real*4 and 1 x integer*4 values passed to the function and a real*4 returned. There should only be 1 function in the obj file. The function itself should be relatively short and simple and made up primarily of math operations.