Makefile Updated – 1) No Need to Modify main.f any more; 2) A Single Makefile; 3) 64-bit Build

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Makefile Generator, Makefile

The Makefile is updated again. Main changes are:

  1. Don’t compile modparm.f any more to keep SWAT codes unchange.
  2. Don’t generate separated Makefiles for debug and release any more. A single Makefile is generated instead to include four make targets: debug32, debug64, rel32 and rel64, which matches the four official SWAT executables.
  3. 64-bit build added to the Makefile.

No Need to Modify main.f any more

In previous version of Makefile, to compile SWAT successfully, the first line of main.f (include ‘modparm.f’) must be comment/deleted, which is not so convenient but not so bad.

It has been found that the problem is in the compilation of modparm.f and main.f. The parm.mod would be generated when either modparm.f or main.f is compiled. The key here is the effect of include statement., which could be found in gnu website.

The effect of the INCLUDE directive is as if the included text directly replaced the directive in the source file prior to interpretation of the program.

So, include ‘modparm.f’ means adding all the contents of modparm.f to main.f, i.e. all the variables are also defined in main.f. If both of modparm.f and main.f are compiled to object files and used to in the link operation, all the variables would be defined twice and the linker would give error message shown below.

Solution is just very simple: don’t compile modparm.f at all. Thus, all the variable would be just defined in main.f and include ‘modparm.f’ doesn’t need to be comment/deleted.

A Single Makefile

The new Makefile would be put in the source codes folder rather than the debug and release folder. Sub-folders (debug32, debug64, rel32 and rel64) would be created to hold all the object files and mod file. The final executable files will be in the source codes folder and given different name similar as official SWAT executables. More details are list in the following table.

Command 32-bit or 64-bit debug or release executable name Comment
make debug32 32 debug swat_debug32
make debug64 64 debug swat_debug64 Doesn’t support by MinGW
make rel32 32 release swat_rel32
make rel64 64 release swat_rel64 Doesn’t support by MinGW

64-bit Build

64-bit build is added to the Makefile though flag -m64, although MinGW doesn’t support it. To compile 6-bit SWAT, either use MinGW-w64 or Rtools instead. More details would be published shortly in an integrated document.


Debug SWAT in Eclipse – Utilize Makefile

Don’t Want to Go through all these Processes?

No problem. The Eclipse project created in this post is uploaded to Google Code: Just check out and open in Eclipse. It’s done!

This version also add Make Target, which is a quick way to build and clean the project. Just double-click to build or clean specific version.

It’s recommended to use SVN Plugin for Eclipse to do this work. I would have another post on this topic in the near future. Please stay tuned.


  • Find Fortran Project… Menu
  • Create an Empty Makefile Project
  • Setup the Project
    • Binary Parser
    • Error Parsers
    • Fortran Build Configuration
  • Copy SWAT Source Codes and Generate Makefile
  • Build Project
  • Debug/Run SWAT.exe

Please note

  1. To compile SWAT, MinGW needs to be installed first. Please refer to another post MinGW Installation Guide for SWAT Debugging
  2. Eclipse KEPLER and PTP 7.0.3 was used in this post. These steps should also be able to be used in other version of Eclipse and PTP. For more information, please refer to my previous post Compile and Run SWAT with Photran + MinGW – the easiest way to remove mathematical errors from SWAT.

A Makefile is created in previous post. To use it in Eclipse (Photran/PTP), instead of Executable (Gnu Fortran on Windows) project, we should use the Makefile project, which would allow use of user-defined Makefile.

This post will show you how to create and configure a SWAT Makefile project to utilize the makefile.

Find Fortran Project… Menu

The Fortran Project is not list in menu File -> New when PTP is used the first time. In this case, select Projects… to open New Project window. In this window, you would find Fortran project under Fotran folder. Select it and click Next to create the project. When it’s done, you will be asked if you want to open Fortran perspective. Select Yes. The Fotran Project option would be list in menu File -> New.

Create an Empty Makefile Project

File -> New -> Fortran Project

The project name is SWAT. Select Empty Project under Makefile project and select — Other Toolchain —. Click finish to create the project..

Setup the Project

Open the Property window through right click on the project and select “Properties” to setup the project.

Binary Parser

In Fotran -> Build -> Setting, select PE Windows Parser for Binary Parsers (I’m working a Windows machine)..

Error Parsers

Select Photran Error Parser for GNU Fortran (gfortran) for Error Parsers and move it to the top. This option is not selected when the project is created.

Fortran Build Configuration

Select Fortran Build in the left panel, un-check Use default build command and change Build Command to mingw32-make.

Add debug/ to build directory as there will be two versions of Makefile, one is located in debug folder and another is located in release folder. This one is for debug version.

Change configuration name from Default to Debug.

The default configuration name is Default. It would be nice to rename it to debug. Click Manage Configurations… to open Manage Configurations window. Select default and click Rename… to change name to Debug.

Create Release Configuration

As mentioned before, there is also a release version of Makefile. It’s necessary to make a configuration for it. Here, we could copy all the settings from debug configuration to save time.

Click New… on Manage Configurations window to open Create New Configuration window. Input name as Release and select to copy settings from Debug configuration.

Change the Build directory to ${workspace_loc:/SWAT}/release/.

Copy SWAT Source Codes and Generate Makefile

Copy all the SWAT source codes to the project folder and refresh the project in Eclipse. It would show all the files. Remember to comment the first line in main.f.

Download the GenerateMakefile program and save it into the project folder. Run it to generate the Makefile for debug and release version.

Build Project

Now, it’s ready to build the project, i.e. compile SWAT source codes. Right-click the project and select Build Project to start compile SWAT source codes. You would see some output information from Console window in the bottom. From there, you would know whether or not the process is finished. All the warnings and errors would also be found in this window.

Debug/Run SWAT.exe

After SWAT is compiled successfully, it’s ready to run SWAT. Before that, there is one thing to do: setup Run/Debug Settings, which could be completed in Properties window.

Select Run/Debug Settings in the left panel and click New… to create a Run/Debug Settings. We will first create the settings for debug version. Same as the build configuration, the setting for release version could be also copied from debug version.

In the Main tab, input Fortran Application as debug\SWAT.exe.

In Arguments table, change Working directory to the model txtinout folder.

In Debugger tab, select MinGW gdb for Debugger and uncheck Stop on startup at: option.

In Common tab, select Debug in Display in favorites menu to show the setting in debug menu.

Click debug menu in the toolbar to start running SWAT.

The output information would be display in the Console window.

If some breakpoints are set, SWAT would stop running on breakpoints and ask if want to change to Debug perspective. Click yes to change to Debug perspective, which would re-arrange the windows to facilitate debugging.

You would has change to check all the variable values in Variables window under debugging mode.

Click Fortran button on the up right corner, Eclipse would go back to Fortran perspective, which is designed for coding.

Click the Debug button in the up right corner to return to Debug perspective.

SWAT Makefile Updated – Stop running when overflow happens

Note: This version is updated in next post SWAT Makefile Updated – Ignore Underflow, where underflow flag is removed.

The Makefile published in previous blog Makefile – Compile SWAT using gfortran without modification is updated. It’s highly recommended to update.

Download Link

Makefile Generator, Debug Makefile, Release Makefile


  1. More gfortran flags are added to make sure the SWAT will stop running when errors happen.

In previous version, SWAT would ignore all the errors (e.g. overflow) and run to the end. It’s impossible to know if there are some errors. For some cases, the results are not safe to use.

The official SWAT would stop whenever an error happens and give where the error comes from. It’s the right way to compile SWAT.

In gfortran, the flag -ffpe-trap could used to do this work. The following command flag is added to the Makefile, which would stop the program whenever invalid, zero, overflow or underflow happens.


  1. rm command is used to replace del command in the clean target.

The del command could only be called from cmd.exe. Eclipse don’t know where is this command and would fail to clean the project.

rm.exe comes along with MSYS in MinGW (package mingw-developer-toolkit and msys-base) and is usually located at C:\MinGW\msys\1.0\bin. Adding this location to the PATH variable in Windows setting or Eclipse project setting would allow Eclipse to call this function when “Clear Project” is used.

Makefile – Compile SWAT using gfortran without modification

Note: The makefile here is an older version. For the latest version, please visit another post SWAT Makefile Updated – Stop running when overflow happens.

Quick Download Link

Makefile Generator, Debug Makefile, Release Makefile

Next post will be: Use Makefile in Photran to Debug SWAT

Please note that the modparm.f doesn’t need to be compiled as parm.mod any more. That process is already included in the Makefile.


  • Why some files fail to be compiled in Photran?
  • Use additional gfortran command options to compile problematic files
  • Makefile
  • Generate Makefile
  • The only modification
  • Use Makefile

In my previous post Compile and Run SWAT with Photran + MinGW – the easiest way to remove mathematical errors from SWAT, several swat source code files need to be modified to be able to compilable within Photran. It’s nice, but it’s even better if the source codes could be compiled without any modification.

Why some files fail to be compiled in Photran?

Compare the original source codes and the modified source codes through Google codes, and find that only following files need to be modified.

  • biozone.f
  • bmpinit.f
  • carbon_zhang2.f90
  • main.f
  • modparm.f
  • ovr_sed.f
  • percmain.f
  • rthsed.f

Except for main.f, these files have a common problem: one or more lines exceed the default line length set for Fotran fix format file (*.f) and free format file (*.f90). The default limitation of the line length for *.f is 72 and for *.f90 is 132. The default Fortran compile command (shown below) in Photran doesn’t consider this situable. If the length of one line exceed the limitation, the compiler (gfortran) would give errors.

  • Debug version: gfortran -funderscoring -O0 -g -Wall -c -fmessage-length=0
  • Release version: gfortran -funderscoring -O3 -Wall -c -fmessage-length=0

Use additional gfortran command options to compile problematic files

To solve this problem, these files are modified to make sure they meet the requirement on line length in previous post. Besides this, there is also another solution: change the line length limitation using gfortran command options.

  • Fixed format (*.f): add -ffixed-line-length-132 option to set the line length limitation of fixed format Fortran file to 132
  • Freeformat (*.f): add -ffree-line-length-200
    option to set the line length limitation of free format Fortran file to 200

For example, the gfortran command for debug version of biozone.f would be

gfortran -funderscoring -O0 -g -Wall -c -fmessage-length=0 -ffixed-line-length-132

And the gfortran command for release version of carbon_zhang2.f90 would be

gfortran -funderscoring -O0 -g -Wall -c -fmessage-length=0 -ffree-line-length-200

These files could be compiled successfully with the new command.


In default Photran settings, it’s impossible to use different command options for different source files. Applying -ffixed-line-length-132 to other *.f files would also generate compile errors. How to solve this? Using Makefile.

Makefile defines how to compile and link a program. With it, it’s possible to define different commands for different source files and compile SWAT source codes without modification. For more information, please refer to GNU make document.

Generate Makefile

There are more than 300 Fortran source files in SWAT. It’s time-consuming work to write the Makefile manually. We already know the gfortran commands and the files which need to re-set the line length limitation. A program, which would get all *.f and *.f90 in the SWAT source codes folder and generate the compile commands in the makefile, is a quite straightforward and simple way to do the work.

Based on this, a .NET console application is created (source codes, executable). It’s fairly easy to use. Copy the program file to the source codes folder and double-click.

A prompt window would pop-up to ask which version should be the Makefile generated for, debug or release. Input d or debug for debug version, r or release for release version. Then the program would start to work and generate the corresponding Makefile in debug or release folder. The debug/release folder would be created if it doesn’t exist.

The two version of Makefile for rev 615 are also available to be download directly (debug version, release version). These two files could be also used for also version as long as the number and name of source codes files is same. Create the debug/release folder in the source codes folder and put the file into the corresponding folder.

The only modification

The only modification is to comment the first line of main.f (include modparm.f). There should be some command option to ignore this line but haven’t found it:)

Use Makefile

Makefile is fairly easy to use. Just use the GNU make command which comes along with MinGW. There are two version of make in MinGW: mingw32-make and make. Either one is ok.

Open cmd.exe and navigate to the Makefile folder. Execute mingw32-make or make. It’s done!