Fortran

Fortran, as derived from Formula Translating System, is a general-purpose, imperative programming language. It is used for numeric and scientific computing.

Compiling the source code

But the basics are simple enough. Take the gfortran compiler, part of the GNU compiler collection. To compile a simple program as the one above, that consists of one source file, you run the following command, assuming the source code is stored in the file “hello.f90”:

gfortran -c hello.f90

This results in a file “hello.o” (as the gfortran compiler uses “.o” as the extension for the object files).

The option “-c” means: only compile the source files. If you were to leave it out, then the default action of the compiler is to compile the source file and start the linker to build the actual executable program. The command:

gfortran hello.f90

gfortran hello.f90 -o main

Building Dynamic-Link Libraries

Building Dynamic-Link Libraries

There is one more thing to be aware of: On Windows you must explicitly specify that a procedure is to be exported, i.e. is visible in the dynamic library. There are several ways — depending on the compiler you use — to achieve this. One method is via a so-called compiler directive:

subroutine myroutine( ... )
!GCC$ ATTRIBUTES DLLEXPORT:: myroutine

Or, with the Intel Fortran compiler:

subroutine myroutine( ... )
!DEC$ ATTRIBUTES DLLEXPORT:: myroutine

Sample program: C calling Fortran

cmd.exe "/K" '"C:\Program Files (x86)\Intel\oneAPI\setvars.bat" && powershell'

Temporarily change the value of the environment variable PATH

$env:path += ";d:\work\fortran_work\ModernFortran\codes\windows\shared-lib\01\"

Building Shared Libraries

Fortran Formats

Fortran Formats

Mixed-Programming

fortran2018-examples

FORTRAN系列链接整理(FORTRAN series link)

main.c

extern void show_N1();
extern void show_N2();
extern void show_N3();

int main(int argc, char *argv[])
{
    show_N1();
    show_N2();
    show_N3();

    return 0;
}

onemod.f90

module onemod
implicit none

   integer, parameter :: N = 1024

contains
   subroutine show_N() bind(C, name='show_N')
      print*, "N = ", N
   end subroutine show_N

end module onemod

Ubuntu+gcc+gfortran

$ gfortran -c onemod.f90
$ gfortran -c twomods.f90
$ ar r mods.a onemod.o twomods.o
------------------------------------------
check mods.a
------------------------------------------
$ nm mods.a
------------------------------------------
test(fortran)
$ gfortran -c main.f90 -I../
$ gfortran -o testprj main.o ../mods.a
------------------------------------------
test(c)
$ gcc -c main.c
$ gcc -o testprj main.o ../mods.a -lgfortran

Windows11+oneAPI+icx+ifort

$ cmd.exe "/K" '"C:\Program Files (x86)\Intel\oneAPI\setvars.bat" && powershell'

$ ifort -c onemod.f90
$ lib /OUT:onemod.lib onemod.obj
----------------------------------
check onemod.lib
------------------------------------------
$ dumpbin /symbols onemod.lib
------------------------------------------
test(fortran)
$ ifort -c main.f90
$ ifort -o testprj main.obj ../onemod.lib
-------------------------------------
test(c)
$ icx -c main.c
$ icx -o testprj main.obj ../onemod.lib

Dumpbin

PS D:\work\fortran_work\ModernFortran\codes\windows\c-call-fortran-lib\static\01> dumpbin /symbols sub.lib
Microsoft (R) COFF/PE Dumper Version 14.37.32825.0
Copyright (C) Microsoft Corporation.  All rights reserved.


Dump of file sub.lib

File Type: LIBRARY

COFF SYMBOL TABLE
000 00000000 SECT1  notype       Static       | .text
    Section length   50, #relocs    3, #linenums    0, checksum        0
002 00000000 SECT1  notype ()    External     | sub_
003 00000000 SECT2  notype       Static       | .rdata
    Section length   10, #relocs    0, #linenums    0, checksum        0
005 00000008 SECT2  notype       Static       | __STRLITPACK_1
006 00000000 UNDEF  notype ()    External     | for_write_seq_lis
007 00000000 SECT3  notype       Static       | .xdata
    Section length    8, #relocs    0, #linenums    0, checksum        0
009 00000000 SECT4  notype       Static       | .pdata
    Section length    C, #relocs    3, #linenums    0, checksum        0
00B 00000000 SECT2  notype       Static       | __STRLITPACK_3.0.1
00C 00000000 UNDEF  notype ()    External     | __ImageBase
00D 00000000 SECT5  notype       Static       | .drectve
    Section length   B9, #relocs    0, #linenums    0, checksum        0

String Table Size = 0x44 bytes

  Summary

          B9 .drectve
           C .pdata
          10 .rdata
          50 .text
           8 .xdata

Example1

main.c

extern void hello_print();
int main( int argc, char**argv )
{
      hello_print();
      return 0;
}

sub.c

#include <stdio.h>

void hello_print()
{
    printf("hello!\n");
}

Windows11+oneAPI+icx

cd d:\work\modern_cmake_work\ModernCMake\codes\cmake\add_library\test\07b\build\
$ cmd.exe "/K" '"C:\Program Files (x86)\Intel\oneAPI\setvars.bat" && powershell'
$ icx -c ../sub.c
$ icx -c ../main.c
$ icx -o testprj main.obj sub.obj

Windows11+oneAPI+icx static lib

cd d:\work\modern_cmake_work\ModernCMake\codes\cmake\add_library\test\07c\build\
$ cmd.exe "/K" '"C:\Program Files (x86)\Intel\oneAPI\setvars.bat" && powershell'
$ icx -c ../sub.c
$ lib /OUT:sub.lib sub.obj
$ icx -c ../main.c
$ icx -o testprj main.obj sub.lib

Windows11+oneAPI+icx static lib+CMake

cmake_minimum_required ( VERSION 3.28 )

project ( testprj )

add_library(sub OBJECT sub.c)

add_executable ( ${PROJECT_NAME}
    main.c
)

target_link_libraries( ${PROJECT_NAME}
    PRIVATE
        sub
)

Windows11+oneAPI+icx static lib+CMake v1

cmake_minimum_required ( VERSION 3.28 )

project ( testprj )

add_library(sub OBJECT sub.c)

add_executable ( ${PROJECT_NAME}
    main.c
)

target_link_libraries( ${PROJECT_NAME}
    PRIVATE
        $<TARGET_OBJECTS:sub>
)

get_target_property(prj_LINK_LIBRARIES ${PROJECT_NAME}  LINK_LIBRARIES)

add_custom_target ( print
    ${CMAKE_COMMAND} -E
    echo
    prj_LINK_LIBRARIES = ${prj_LINK_LIBRARIES} &
    echo
    TARGET_OBJECTS:sub = $<TARGET_OBJECTS:sub>
)

Windows11+oneAPI+icx static lib+CMake v2

cmake_minimum_required ( VERSION 3.28 )

project ( testprj )

add_library(sub OBJECT sub.c)

add_executable ( ${PROJECT_NAME}
    main.c
    $<TARGET_OBJECTS:sub>
)

message ( STATUS "sub = ${sub}" )

get_target_property(prj_LINK_LIBRARIES ${PROJECT_NAME}  LINK_LIBRARIES)

add_custom_target ( print
    ${CMAKE_COMMAND} -E
    echo
    prj_LINK_LIBRARIES = ${prj_LINK_LIBRARIES} &
    echo
    TARGET_OBJECTS:sub = $<TARGET_OBJECTS:sub>
)

cmake ..
cmake --build . --target print
cmake --build . --config Debug --target print
cmake --build . --config Release --target print

Example2

sub.c

#include <stdio.h>

void hello_print()
{
    printf("hello!\n");
}

main.c

extern void hello_print();
int main( int argc, char**argv )
{
      hello_print();
      return 0;
}

fmain.f90

program main
  implicit none

  interface
    subroutine fortran_hello_print() bind(C,name='hello_print')
    end subroutine fortran_hello_print
  end interface

  call fortran_hello_print()

end program main

Windows11+oneAPI+icx+ifort+CMake

cmake_minimum_required ( VERSION 3.28 )

project ( testprj )

add_library(sub OBJECT sub.c)

add_executable ( CPrj
    main.c
)

enable_language(Fortran)

add_executable ( FPrj
    fmain.f90
)

target_link_libraries( CPrj
    PRIVATE
        $<TARGET_OBJECTS:sub>
)

target_link_libraries( FPrj
    PRIVATE
        $<TARGET_OBJECTS:sub>
)

get_target_property(cprj_LINK_LIBRARIES CPrj LINK_LIBRARIES)
get_target_property(fprj_LINK_LIBRARIES FPrj LINK_LIBRARIES)

add_custom_target ( print
    ${CMAKE_COMMAND} -E
    echo
    cprj_LINK_LIBRARIES = ${cprj_LINK_LIBRARIES} &
    echo
    fprj_LINK_LIBRARIES = ${fprj_LINK_LIBRARIES} &
    echo
    TARGET_OBJECTS:sub = $<TARGET_OBJECTS:sub>
)

cmake ..
cmake --build . --target print
cmake --build . --config Debug --target print
cmake --build . --config Release --target print

Run Build Command(s): "C:/Program Files/Microsoft Visual Studio/2022/Community/Common7/IDE/devenv.com" IntelFortranImplicit.sln /build Debug /project ALL_BUILD

C:\ProgramData\Microsoft\Windows\Start Menu\Programs\Visual Studio 2022\Visual Studio Tools
C:\ProgramData\Microsoft\Windows\Start Menu\Programs\Visual Studio 2022\Visual Studio Tools\Developer Command Prompt for VS 2022.lnk
%comspec% /k "C:\Program Files\Microsoft Visual Studio\2022\Community\Common7\Tools\VsDevCmd.bat"