build.gradle

// Common Build file for AddNumbers
// This gradle build file is a derivative of the work by Willie Wheer
// https://medium.com/wwblog/java-fortran-integration-using-jni-7376879f45cd

// pre-requisites
// gfortran should be installed in the system.  
// java should be installed in the system

plugins {
  	id 'application'

}

def currentOS = org.gradle.internal.os.OperatingSystem.current()

def platform = 'linux'


// define if to compile 32b or 64b.
// for 32b , set arch as -m32.  for 64b set arch as -m64
ext.arch = '-m64'
// set the jdk version.  use jdk 1.8 for 32b and jdk11 of or above for 64b.
ext.jdkver = 11

apply plugin: 'java'
apply plugin: 'eclipse'

compileJava {
	sourceCompatibility = jdkver
   	targetCompatibility = jdkver
   	options.fork = true
}

	
repositories {
    mavenLocal()
    jcenter()
}	

// define location of platform specific libraries.
if (currentOS.isWindows()) {
    platform = 'win'

	// If you are building for 32 bit systems, you need to use 32 bit version of jdk 1.8 or earlier. 
	if (arch == '-m32') {
		ext.jdkver = 1.8
		
		// find the location of libgfortran-4.dll and put it here.  it will be in your mingw directory
		ext.fortranLib = 
			file("C:/Program Files (x86)/mingw-w64/i686-7.3.0-posix-sjlj-rt_v5-rev0/mingw32/bin/libgfortran-4.dll")
		ext.sysHeadersDir = 
			file("c:/program files (x86)/java/zulujdk-8u222-b10/include")
  		ext.sysHeadersDir2 = 
  			file("c:/program files (x86)/java/zulujdk-8u222-b10/include/win32") 

		
  		ext.lib = file("build/libs/win-x86")
  		ext.jarName =  "AddNumbers-w32.jar"
	}

	// If you are building for 64 bit systems, you need to use 64 bit version of jdk 9 or later.
	// In this example we are using jdk11  
	if (arch == '-m64') { 
		// find the location of libgfortran-4.dll and put it here.  it will be in your mingw directory
    	ext.fortranLib = file("C:/Program Files/mingw-w64/mingw64/bin/libgfortran-4.dll")
		ext.sysHeadersDir = file("c:/program files/java/openjdk-11u-11.0.3+7/include/")
    	ext.sysHeadersDir2 = file("c:/program files/java/openjdk-11u-11.0.3+7/include/win32")
  		ext.lib = file("build/libs/win-x64")
  		ext.jarName =  "AddNumbers-w64.jar"
	}
    
    ext.platformFlag = '-mwindows'
    ext.gfortran = 'gfortran'
    
} else if (currentOS.isMacOsX()) {
	
    platform = 'mac'
    // for mac, the java is usually installed in the below directory
  	ext.sysHeadersDir =
      file("/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.15.sdk/System/Library/Frameworks/JavaVM.framework/Versions/A/Headers")  
    ext.sysHeadersDir2 = ''  
    ext.lib = file("${buildDir}/libs/mac")
    ext.jarName =  "AddNumbers-mac.jar"    
    ext.platformFlag =''
	ext.gfortran = '/usr/local/bin/gfortran'
    
} else if (currentOS.isLinux()) {
    platform = 'linux'
  	ext.sysHeadersDir = file("/usr/lib/jvm/adoptopenjdk-11-hotspot-amd64/include")  
    
    ext.sysHeadersDir2 = file("/usr/lib/jvm/adoptopenjdk-11-hotspot-amd64/include/linux")
    ext.lib = file("${buildDir}/libs/linux-amd64")
    ext.jarName =  "AddNumbers-linux.jar"    
    ext.platformFlag ='-O2'
//	ext.gfortran = '/usr/bin/gfortran'

}

ext.forCommonLibHeader = file("./src/main/c/")    



sourceSets {
	main {
		java {
        	srcDirs= ["src/main/java"]
            outputDir = file("${buildDir}/classes")
         }
		resources {
        	srcDirs= ["src/main/java/"]
         }
	}
}

mainClassName = 'appFortranExample.Main'

// Create directory for storing fortran object files
task prepareFortran {
  
	mkdir "${buildDir}/fortran"
}


// Compile the fortran source code
task compileFortran(type: Exec) {
  	ext.src = file("src/main/fortran/AddNumbers.FOR")
  	ext.obj = file("${buildDir}/fortran/AddNumbers.o")

  	group "Build"
  	description "Compiles the Fortran sources for Add Numbers"
	
	if (platform == 'win') { 
		executable "cmd"
		commandLine 'gfortran',arch,platformFlag,'-I',sysHeadersDir2,
		'-finit-local-zero', '-finit-real=zero','-finit-integer=0',
	  	'-o',  obj,  '-c', src
	} else if (platform == 'mac') { 
		commandLine '/usr/local/bin/gfortran',arch,
		  '-finit-local-zero', '-finit-real=zero','-finit-integer=0',
	  	'-o',  obj,  '-c', src 	  

	} else if (platform == 'linux' ) { 
		commandLine '/usr/bin/gfortran',arch,
		  '-finit-local-zero', '-finit-real=zero','-finit-integer=0',
	  	'-o',  obj,  '-c', src 	  
	}
}

// Create build directory to store C object files
task prepareC {
	mkdir "${buildDir}/c"
}

// Create JNI header files
task generateJniHeaders(type: Exec) {

  def classpath = sourceSets.main.java.outputDir
  def jniHeadersDir = file("${buildDir}/c/jni-headers")

  group "Build"
  description "Generates the JNI headers for Pygen."
  
  
  // with jdk8.x  
	if (jdkver == 1.8) { 
	  commandLine 'javah'  ,'-d', jniHeadersDir, '-classpath', classpath,
	      'appFortranExample.AddNumbers'
	}

	// changes with jdk 10
	if (jdkver >= 10) {
 		commandLine 'javac', '-h', jniHeadersDir, '-classpath', classpath,
      		'src/main/java/appFortranExample/AddNumbers.java' 
	}
      
  dependsOn classes, prepareC
}



// Compile the C common lib which contains routines for converting 
// 2 dimensional arrays from java format to fortran format and back

task compileCForCommonLib(type: Exec) {

  ext.src = file("./src/main/c/forCommonLib.c")
  ext.forCommonLib = file("${buildDir}/c/forCommonLib.o")

  group "Build"
  description "Compiles the C sources for common header"
	 commandLine 'gcc', '-c', '-o', forCommonLib, '-I', sysHeadersDir, '-I' ,sysHeadersDir2,
      '-I', forCommonLibHeader, src,  '-std=c99',platformFlag ,arch
      
  dependsOn prepareC
}

// Compile the C code for add numbers
task compileC(type: Exec) {

  ext.forCommonLib = file("${buildDir}/c/forCommonLib.o")  
  ext.jniHeadersDir = file("${buildDir}/c/jni-headers")
  ext.src = file("./src/main/c/add_numbers.c")
  ext.obj = file("${buildDir}/c/add_numbers.o")

  group "Build"
  description "Compiles the C sources for add numbers"
	 commandLine 'gcc', '-c', '-o', obj, '-I', sysHeadersDir, '-I' ,sysHeadersDir2,
      '-I', jniHeadersDir, src,  '-std=c99',arch,platformFlag
      
  dependsOn generateJniHeaders, compileFortran, compileCForCommonLib
}

// create directories for storing the jnilib files
task prepareJniLib {

	mkdir "${buildDir}/libs/win-x86"
	mkdir "${buildDir}/libs/win-x64"
	mkdir "${buildDir}/libs/mac"
	mkdir "${buildDir}/libs/linux-amd64"
}

task copyLibs(type: Copy) {

	if (arch == '-m64' && platform == 'win') {
	    from ('c:/Program Files/mingw-w64/mingw64/bin/') {
    		include 'libgfortran-4.dll'
      		include 'libgcc_s_sjlj-1.dll'
      		include 'libquadmath-0.dll'
     	}
    	into lib
    } else if (arch == '-m32' && platform == 'win') { 
    	from ('c:/Program Files (x86)/mingw-w64/mingw64/bin/') {
     	 	include 'libgfortran-4.dll'
      	 	include 'libgcc_s_sjlj-1.dll'
      		include 'libquadmath-0.dll'       
    	}	 
    	into lib
    } else if (platform == 'mac') { 
	
    }
    
    dependsOn prepareJniLib    
}

// build the jnilib files.  For windows its created as dll's.  for mac its created as .so

task buildJniLib(type: Exec) {

 	if (platform=='win') {
 		ext.jniLib = file("${lib}/lib_addnumbers_driver.dll")
 		ext.fortranLib = file("${lib}/libgfortran-4.dll")
	 	ext.cLib = file("${lib}/libgcc_s_sjlj-1.dll")
 		ext.qmath = file("${lib}/libquadmath-0.dll")
 		
 		  commandLine(
    'gcc','-Wall','-D_JNI_IMPLEMENTATION_', '-Wl,--kill-at', '-shared',arch, '-o', jniLib, fortranLib,cLib,qmath,
    "${buildDir}/c/forCommonLib.o","${buildDir}/fortran/AddNumbers.o", "${buildDir}/c/add_numbers.o")
 		
 	} else if (platform == 'mac') { 
 		ext.jniLib = file("${lib}/lib_addnumbers_driver.so")	
	    ext.fortranLib = file("/usr/local/gfortran/lib/libgfortran.dylib")
 
     commandLine( 'g++', '-dynamiclib', arch,'-o', jniLib, fortranLib,
    "${buildDir}/c/forCommonLib.o","${buildDir}/fortran/AddNumbers.o", "${buildDir}/c/add_numbers.o",
    '-framework', 'JavaVM')
 		
	} else if (platform == 'linux') { 
 		ext.jniLib = file("${lib}/lib_addnumbers_driver.so")	
		ext.fortranLib = file("/usr/lib/gcc/x86_64-linux-gnu/7/libgfortran.so")
 
     commandLine( 'g++','-shared', '-dynamiclib', arch,'-o', jniLib, fortranLib,
    "${buildDir}/c/forCommonLib.o","${buildDir}/fortran/AddNumbers.o", "${buildDir}/c/add_numbers.o")
 		
	}
	

  dependsOn copyLibs,compileFortran, compileC, prepareJniLib
}

task copyJars (type: Copy) {
    def fromDir = "build/libs/"
	def toDir = "./"
	include jarName
 
    // copy jars to lib folder:
    from fromDir
    into toDir
}


tasks.withType(JavaCompile) {
    options.warnings = false
}

build.dependsOn buildJniLib,copyJars


// create a final jar build file
jar {

    archiveName = jarName

    from {

      configurations.runtime.collect {
            it.isDirectory() ? it : zipTree(it)
       }

      configurations.compile.collect {
            it.isDirectory() ? it : zipTree(it)
       }
     }
     
     manifest {
        attributes (
        'Main-Class': 'appFortranExample.Main',
         // add classpath to Manifest; see http://stackoverflow.com/questions/30087427/add-classpath-in-manifest-file-of-jar-in-gradle
         //"Class-Path": '. lib/' + configurations.default.collect { it.getName() }.join(' lib/')
        )
        
     }

   exclude 'META-INF/*.RSA', 'META-INF/*.SF','META-INF/*.DSA'
}