Cross Compiling C and Fortran - Revision history

Root: /* My Advice */

2010-04-01T19:00:48Z

My Advice

← Older revision		Revision as of 19:00, 1 April 2010
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	# If you know something, anything, about working with Linux do yourself a favour and develop in Linux with Sun Studio. Do this even if you deploy (later) in windows. (If you don't know any Linux of course you are missing a world of fun. Go and download [[wikipedia:Linux Mint\|Linux Mint]] -- a very user friendly Ubuntu variant and burn a [[wikipedia:live-cd\|Live CD]]. You don't even have to install it to try!)		# If you know something, anything, about working with Linux do yourself a favour and develop in Linux with Sun Studio. Do this even if you deploy (later) in windows. (If you don't know any Linux of course you are missing a world of fun. Go and download [[wikipedia:Linux Mint\|Linux Mint]] -- a very user friendly Ubuntu variant and burn a [[wikipedia:live-cd\|Live CD]]. You don't even have to install it to try!)
	# Whatever you do, develop in a platform that has 1) easy IEEE Floating Point trapping 2) a decent debugger.		# Whatever you do, develop in a platform that has 1) easy IEEE Floating Point trapping 2) a decent debugger.
	# First try something like the obligatory 'hello world' to learn the tricks and to test your build environment before trying the complicated code. [http://stackoverflow.com/questions/354182/calling-c-code-from-fortran http://stackoverflow.com/questions/354182/calling-c-code-from-~~fortranHere~~'s a tutorial].		# First try something like the obligatory 'hello world' to learn the tricks and to test your build environment before trying the complicated code. [http://stackoverflow.com/questions/354182/calling-c-code-from-fortran http://stackoverflow.com/questions/354182/calling-c-code-from-fortran Here's a tutorial].

Root: /* My Advice */

2010-04-01T19:00:37Z

My Advice

← Older revision		Revision as of 19:00, 1 April 2010
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	# If you know something, anything, about working with Linux do yourself a favour and develop in Linux with Sun Studio. Do this even if you deploy (later) in windows. (If you don't know any Linux of course you are missing a world of fun. Go and download [[wikipedia:Linux Mint\|Linux Mint]] -- a very user friendly Ubuntu variant and burn a [[wikipedia:live-cd\|Live CD]]. You don't even have to install it to try!)		# If you know something, anything, about working with Linux do yourself a favour and develop in Linux with Sun Studio. Do this even if you deploy (later) in windows. (If you don't know any Linux of course you are missing a world of fun. Go and download [[wikipedia:Linux Mint\|Linux Mint]] -- a very user friendly Ubuntu variant and burn a [[wikipedia:live-cd\|Live CD]]. You don't even have to install it to try!)
	# Whatever you do, develop in a platform that has 1) easy IEEE Floating Point trapping 2) a decent debugger.		# Whatever you do, develop in a platform that has 1) easy IEEE Floating Point trapping 2) a decent debugger.
			# First try something like the obligatory 'hello world' to learn the tricks and to test your build environment before trying the complicated code. [http://stackoverflow.com/questions/354182/calling-c-code-from-fortran http://stackoverflow.com/questions/354182/calling-c-code-from-fortranHere's a tutorial].

Root: /* First the Theory */

2010-04-01T18:58:31Z

First the Theory

← Older revision		Revision as of 18:58, 1 April 2010
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	;For Example:		;For Example:
	<source lang="bash">		<source lang="bash">
	g++ -c ctest.c ~~<br/>~~		g++ -c ctest.c
	gfortran -c ftest.f90 ~~<br/>~~		gfortran -c ftest.f90
	gfortran *.o -lstdc++ -o test_prog ~~<br/>~~		gfortran *.o -lstdc++ -o test_prog

	</source>		</source>

Root: /* First the Theory */

2010-04-01T18:58:07Z

First the Theory

← Older revision		Revision as of 18:58, 1 April 2010
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	* Compile C code with C compiler, Fortran with Fortran compiler (kind of obvious!), but '''always link with the Fortran linker'''.		* Compile C code with C compiler, Fortran with Fortran compiler (kind of obvious!), but '''always link with the Fortran linker'''.

			;For Example:
			<source lang="bash">
			g++ -c ctest.c <br/>
			gfortran -c ftest.f90 <br/>
			gfortran *.o -lstdc++ -o test_prog <br/>

			</source>

	==Now the practice==		==Now the practice==

Root: /* First the Theory */

2010-04-01T18:56:40Z

First the Theory

← Older revision		Revision as of 18:56, 1 April 2010
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	call get_swmm_dt(swmmdt)		call get_swmm_dt(swmmdt)
	</source>		</source>

			* Compile C code with C compiler, Fortran with Fortran compiler (kind of obvious!), but '''always link with the Fortran linker'''.

	==Now the practice==		==Now the practice==

Root: /* My Advice */

2010-04-01T18:54:54Z

My Advice

← Older revision		Revision as of 18:54, 1 April 2010
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	==My Advice==		==My Advice==
	Here's my two cents' worth based on experience:		Here's my two cents' worth based on experience:
	# If you know something, anything, about working with Linux do yourself a favour and develop in Linux with Sun Studio. Do this even if you deploy (later) in windows. (If you don't know any Linux of course you are missing a world of fun. Go and download [[wikipedia:Linux Mint\|Linux Mint]] -- a very user friendly Ubuntu variant and burn a [[wikipedia:live-cd\|~~live-cd~~]]. You don't even have to install it to try!)		# If you know something, anything, about working with Linux do yourself a favour and develop in Linux with Sun Studio. Do this even if you deploy (later) in windows. (If you don't know any Linux of course you are missing a world of fun. Go and download [[wikipedia:Linux Mint\|Linux Mint]] -- a very user friendly Ubuntu variant and burn a [[wikipedia:live-cd\|Live CD]]. You don't even have to install it to try!)
	# Whatever you do, develop in a platform that has 1) easy IEEE Floating Point trapping 2) a decent debugger.		# Whatever you do, develop in a platform that has 1) easy IEEE Floating Point trapping 2) a decent debugger.

	#

Root: /* Now the practice */

2010-04-01T18:54:18Z

Now the practice

← Older revision		Revision as of 18:54, 1 April 2010
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	Now this is a demonstration of the wisdom of doing a little, but doing that well. The system works like a dream (I tried it on my 64-bit Ubuntu Karmic installation) and allowed me to compile C and Fotran in a single IDE project (with [[wikipedia:automake\|automake]] -- a kind of system that the IDE writes the [[wikipedia:makefile\|makefile]]s for you.), debug code across both languages, trap IEE floating point exceptions. What more can one hope for!		Now this is a demonstration of the wisdom of doing a little, but doing that well. The system works like a dream (I tried it on my 64-bit Ubuntu Karmic installation) and allowed me to compile C and Fotran in a single IDE project (with [[wikipedia:automake\|automake]] -- a kind of system that the IDE writes the [[wikipedia:makefile\|makefile]]s for you.), debug code across both languages, trap IEE floating point exceptions. What more can one hope for!

			Since I needed to give the compiled code to my students, who use only windows system, later I compiled the (already properly working) code on Windows using Intel Compilers + Visual Studio 2008. But, Intel/Microsoft system has several limitations compared to Sun Studio.
			# You can have only one language in one IDE project. So, I needed to create a C static libarary project, compile the C code to a static library, compile the Fortran code and link with the created static library in another project. Of course the build process can be automated. But, its an unnecessary complication. Debugging also can be a bit difficult.
			# Here you face a situation similar to Eclipse+CDT+Photran combo. Three tools (Intel Fortran, Intel C/C++, Visual Studio 2008) that has to be taught to work together -- a bit messy. Then, it is provided by two companies and the system is expensive!
			# I learned (the hard way) that Intel C and Fortran compilers refused to do anything with each other (e.g. linking a library created by Intel C version 11.x.y with Fortran linker version 11.k.p). So, if you must go the Intel path, download compilers of identical version.
			# The system is huge! I ended up downloading more than 3GB of programs!

			==My Advice==
			Here's my two cents' worth based on experience:
			# If you know something, anything, about working with Linux do yourself a favour and develop in Linux with Sun Studio. Do this even if you deploy (later) in windows. (If you don't know any Linux of course you are missing a world of fun. Go and download [[wikipedia:Linux Mint\|Linux Mint]] -- a very user friendly Ubuntu variant and burn a [[wikipedia:live-cd\|live-cd]]. You don't even have to install it to try!)
			# Whatever you do, develop in a platform that has 1) easy IEEE Floating Point trapping 2) a decent debugger.

			#

Root: /* First the Theory */

2010-04-01T18:39:02Z

First the Theory

← Older revision		Revision as of 18:39, 1 April 2010
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	call get_swmm_dt(swmmdt)		call get_swmm_dt(swmmdt)
	</source>		</source>

			==Now the practice==
			Following are the things I learned the hard way.

			My first platform to try this on was [[wikipedia:Eclipse_(software)\|Eclipse ]]. Eclipse has a C-development environment (CDT) that use [[wikipedia:GNU Compiler Collection\|GNU compilers]] gcc, g++ and their excellent debugger gdb. Then there is the Fortran extension, [[wikipedia:Photran\|Photran]] that provides support for GNU fortran compilers (Fortran 77, 90, 95, and 2003). All these work on both Linux and Windows. I could get the system to compile my code properly. But, things started to get uncomfortable when the program started producing some NaNs. The GNU compilers do not support Floating Point Exception Trapping ([[wikipedia:Floating_point#IEEE_754:_floating_point_in_modern_computers\|Floating_point]]), except with platform dependant API calls. Debugging across C and Fortran code also did not work very well for me.

			What came to rescue was the [[wikipedia:Sun_Studio_(software)\|Sun Studio]] which is a proprietary, but free platform that works on Linux and Solaris. Now this provides only
			# A C/C++ Compiler
			# A Fortran Compiler
			# A debugger
			# An an extremely simple IDE based on [[wikipedia:NetBeans\|NetBeans]] system.

			Now this is a demonstration of the wisdom of doing a little, but doing that well. The system works like a dream (I tried it on my 64-bit Ubuntu Karmic installation) and allowed me to compile C and Fotran in a single IDE project (with [[wikipedia:automake\|automake]] -- a kind of system that the IDE writes the [[wikipedia:makefile\|makefile]]s for you.), debug code across both languages, trap IEE floating point exceptions. What more can one hope for!

Root: /* First the Theory */

2010-04-01T18:19:35Z

First the Theory

← Older revision		Revision as of 18:19, 1 April 2010
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	</source>		</source>
	;Fortran:		;Fortran:
	<source lang="~~fortran~~" line start="100" highlight="5">		<source lang="FORTRAN" line start="100" highlight="5">

	real*8 swmmdt		real*8 swmmdt

Root: /* First the Theory */

2010-04-01T18:19:03Z

First the Theory

← Older revision		Revision as of 18:19, 1 April 2010
Line 46:		Line 46:

	For example look at the C function get_swmm_dt and how it is called from Fortran.		For example look at the C function get_swmm_dt and how it is called from Fortran.
			;C:
	<source lang="c" line start="10" highlight="5">		<source lang="c" line start="10" highlight="5">
	void get_swmm_dt_(double * dt){		void get_swmm_dt_(double * dt){
Line 52:		Line 52:
	}		}
	</source>		</source>
			;Fortran:
	<source lang="fortran" line start="100" highlight="5">		<source lang="fortran" line start="100" highlight="5">