Running Fortran on ARM

Generally and very briefly, there is no official Fortran compiler available for the ARM architecture. The easiest way to get Fortran code (specifically Fortran 77) to run on the ARM architecture, or any other architecture that doesn’t have a Fortran compiler, is to convert the Fortran code to C. In order to do that efficiently, we can use Netlib’s f2c command line tool, available for Linux, Unix and Windows.

The steps that need to be followed are:

1) Compile the library – source at http://www.netlib.org/f2c/libf2c.zip
Rename makefile.u to makefile and do make. Copy the generated libf2c.a to /usr/lib and the f2c.h header under /usr/include.
2) Compile the binary – source at http://www.netlib.org/f2c/src/
Rename makefile.u to makefile and do make. Copy the binary f2c under /usr/local/bin.

Supposing we have the foo.f file we can generate the C version by running f2c foo.f, giving us foo.c. It can now be compiled using ‘gcc foo.c -o foo -lf2c‘.

In order to automate this process a while, the following script can be used. It accepts only one argument, the Fortran source file.

#!/bin/bash
fortranFile=$1
fileName=`echo $1 | sed 's/\(.*\)\..*/\1/'`
echo $fileName
f2c $fortranFile
gcc ${fileName}.c -o $fileName -lf2c

UPDATE: There is GCC Fortran compiler for ARM Fedora and Debian and I presume for other distros as well. The issue now is that these distributions are compiled for ARMv5, while the latest ARM processors (Cortex-A8, A9, A15) are of the ARMv7 architecture. The compilers, and the OS in general is therefore unable to make use of the additional instructions sets and FPU. Other distros, such as Slackware, are compiled on even older architecture, ARMv4.

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