The Promula FORTRAN to C Translator
First published in 1987, this tool is the best-of-breed FORTRAN to C translator around -- according to independent reviews.
This tool can be used to produce custom C translations that are both correct (functionally equivalent to the original FORTRAN) and C-readable (i.e., of high C-code quality, subject to the client's C programming standards or custom preferences).
Over the past thirty years, we have applied this tool in several hundred migration projects around the world and have helped our clients in the porting of their legacy applications (millions of lines of third-generation code) from mainframes and other proprietary systems to more contemporary, open platforms.
This tool is also a general-purpose, multi-dialect and portable FORTRAN compiler. It runs on multiple platforms and supports both the ANSI FORTRAN 66 and ANSI FORTRAN 77 standard dialects. It also supports a large number of common extensions such as those found in several commercial compilers, such as VAX FORTRAN, PDP FORTRAN, and PRIME FORTRAN. Some Fortran 90 extensions are also supported.
Validated by the GSA FORTRAN Compiler Validation Test Suite, the Promula FORTRAN compiler works by compiling FORTRAN source code to compilable C source code (from where it derives its portability). It requires a C compiler to produce executable code and is the ideal processor for hybrid FORTRAN/C applications.