Citeseerx extending high performance fortran for the. See the sun fortran users guide and the fortran programming guide for details on the specific directives available with f77. Using fpp preprocessor directives intel fortran compiler 19. Parallelization directives are only recognized when compilation options parallel or explicitpar are used. It allows users to define compile time operations that can examine and modify the source tree before it is compiled with a traditional compiler. Then pass options to the prepreprocessor by including them after d on the compile line, e. The fortran preprocessor, fpp, is provided as part of the intel fortran product. Using fpp preprocessor directives intel developer zone. Then you can identify the os outside of fortran and pass the information to the fortran program. Many fortran compilers including gnu fortran allow passing the source code through a c preprocessor cpp. The following preprocessor options are available if you use the fpp compiler option. Using gnu fortran southeastern louisiana university.
Preprocessor symbols macros let you substitute values in a program before it is compiled. Only one directive name can be specified per directive note that this includes combined directives, see section 2. The mpopenmp and openmp f95 compiler flags enable these directives. Fortran is a key programming language used by high performance computing developers. Name fpp the fortran language preprocessor for fortran 77 and fortran 90. We give an overview of the implemented runtime preprocessing mechanisms and evaluate the efficiency of compilergenerated code on an nec cenju3 multico. In general, source code preprocessors permit the user to define special variables.
Fortran compilers that support fpp or cpp generally define preprocessor macros that can be used to adapt code based on compilerdependent features. A read is counted each time someone views a publication summary such as the title, abstract, and list of authors, clicks on a figure, or views or downloads the fulltext. The sun fortran 95 compiler supports the openmp version 1. The main advantage of using a preprocessor is that. Fortunately, for this kind of dilemma there is the preprocessor, that although not part of the standard, is understood by several fortran compiler at least gfortran, ifort and xlf. The amount and kind of processing done depends on the nature of the preprocessor. For details about parallel programming with openmp, see the. Syntax for preprocessor directives is based on that of the c preprocessor.
Intel offers a fortran preprocessor, fpp, for use with the ifort compiler, which has similar capabilities. In order to allow the user to choose specific implementation details, compiler directives can be used to set attributes of variables and procedures which are not part of the standard. The first set of examples are for the fortran ii, iv, and 77 compilers. Mar 03, 2012 following last post on fortran and preprocessing, we ll try to see other use of preprocessing instructions.
Numeric literal constants must be integer literal constants or real literal constants, as defined for fortran. It is an entirely new program that has been designed to provide fortran 95 support and extensibility for future fortran language standards, as well as providing backwards compatibility for fortran 77 and nearly all of the gnu language extensions supported by g77. Around the same time, fortran 95 defined an optional conditionalcompilation preprocessor, called coco. Feb 16, 2012 fortunately, for this kind of dilemma there is the preprocessor, that although not part of the standard, is understood by several fortran compiler at least gfortran, ifort and xlf. Preprocessing of the current gdl file is paused until the included file has been processed. I am using matlab r20a on linux 64 platform, trying to mex fortran code. Gfortran preprocessor directives for different operating systems. Comments written in the style of the c language, beginning with and ending with, can appear anywhere within a source preprocessing directive in which blanks or tabs can. Preprocessing performs such tasks as preprocessor symbol macro substitution, conditional compilation, and file inclusion. Preprocessing and conditional compilation the gnu fortran.
Fortran originally had no proper preprocessor, so it became common to use cpp. Some of fpps capabilities could, potentially, be reapplied in other tools. This is more general then gfortran most fortran compilers will process cstyle preprocessor directives. The preprocessor is automatically invoked if the file extension is. Source preprocessing identifier names are case sensitive. Preprocessor symbols macros substitute values in a program before it is compiled. Eventually, this could be expanded to show values for different host architectures and compilation options. The output is said to be a preprocessed form of the input data, which is often used by some subsequent programs like compilers. Many fortran compilers including gnu fortran allow passing the source code. For more information on optimization, see the fortran programming guide parallelization directives. The proposed fortran preprocessor, fpp, would provide fortranspeci. Mar 30, 2020 preprocessor symbols macros substitute values in a program before it is compiled. The compiler includes a limited conditional compilation capability, based on.
Fortran 95 openmp directives the sun fortran 95 compiler supports the openmp 2. Directives unique to f90 are described in appendix c. Developer guide for intel math kernel library for windows. You can save the intermediate file by specifying the d compiler option. Symbols can also be defined on the compilers command line, generally with the d. Fortranfortran examples wikibooks, open books for an open. This section lists the openmp directives, library routines, and environment variables supported by f95. The preprocessor may cause lines of code to be inserted or deleted. Ive got a large fortran codebase that originally targeted intels compiler. Preprocessing directive article about preprocessing. These lines are not program statements but directives for the preprocessor. Preprocessing and conditional compilation the gnu fortran compiler. Use this option to manually enable preprocessing of any kind of fortran file.
Cocoprovides preprocessing as per part 3 of the fortran standard coco is short for conditional compilation. The gnu fortran compiler automatically calls cpp before compiling fortran code if certain file extensions are used. Preprocessor directives are not part of the fortran language and not subject to the rules for fortran statements. It is the language of choice in many application domains including computational fluid dynamics including weather and ocean modeling, finiteelement analysis, molecular dynamics, and quantum chemistry. It implements the auxiliary third part of isoiec 1539 better known as programming languages fortran, and supports several extensions. Some preprocessor symbols are predefined by the compiler system and are available to compiler directives and to fpp. A directive passes information to a compiler in a special form of comment. See section preprocessing and conditional compilation for more detailed information on preprocessing in gfortran.
Zero or more spaces or tabs can appear after the exclamation point, for indentation. Use this option to manually enable preprocessing of any. Most c systems have an option to pass code through the preprocessor only, and send the edited output to another place. The only exception is the prohibition of fpp directives within a macro call divided on several lines by means of continuation symbols. The following fortran code examples or sample programs show different situations depending on the compiler. For details on openmp, see the openmp fortran specification at. For preprocessing fortran, a more flexible variant of the c preprocessor is preferred, gpp. There are numerous cpp options that can be activated in header files cppdefs.
Below are examples for some compilers that support fpp or cpp. Nonconfidential pdf versionarm dui0375h arm compiler v5. The preprocessor examines the code before actual compilation of code begins and resolves all these directives before any code is actually generated by regular statements. Using the fpp preprocessor japan advanced institute of. Passing fortran files through the c preprocessor ibm. Because fortran and c differ in their treatment of some sequences of characters, be careful when using or. The preprocessor directives are removed from the code before it is sent to the compiler, so it would function as a simple text editor. On windows systems, the preprocessor options must start with a slash.
The gnu fortran compiler is the successor to g77, the fortran 77 front end included in gcc prior to version 4. Synopsis fpp options inputfile outputfile description fpp is the preprocessor for fortran 77 and fortran 90. The fortran preprocessor fpp may be invoked automatically or by specifying the fpp compiler option. Typically, these special directives may appear as comment lines to a compiler. Preprocessor article about preprocessor by the free. Fortran accept several preprocessor instructions, weve illustrated the conditional preprocessors instructions, lets look now at some case studies and how preprocessors instructions can help. The preprocessing directives control the behavior of the preprocessor. Thempopenmpand openmpcompiler flags enable these directives. Cuda fortran is supported on linux, mac os x and windows. Preprocessor directives must begin in column 1 of any fortran source files. An implementation of fpp would have to parse and analyze fortran source, evaluate fortran expressions and generate.
Filename, size file type python version upload date hashes. These identifiers can simply be constants or a macro function. The substitution is performed in the preprocessing phase. When you use a preprocessor for intel fortran source files, the generated output files are used as input source files by the compiler. Community help resources for users of pgi compilers including the free pgi community edition. Roms extensively uses the c preprocessor cpp during compilation to replace code statements, insert files into the code, and select relevant parts of the code depending on its directives. In order to simplify the presentation, free form is used for the syntax of openmp directives for fortran in the remainder of this document, except as noted. There is nothing to stop you from using the c preprocessor with fortran too. However, cpp is not fully compatible with fortran source, so sun developed fpp, a fortran compatible version of cpp.
It can be used for any programming languages but its primary aim is to offer a fortran preprocessor, which helps to extend fortran with condititional compiling and template metaprogramming capabilities. In computer science, a preprocessor is a program that processes its input data to produce output that is used as input to another program. The remaining examples can be compiled and run with any newer standard fortran compiler see the end of the main fortran article for lists of compilers. Each directive occupies one line and has the following format. Compilers that support cpp or fpp usually support predefined preprocessor macros that aid compilerspecific code requirements. The basic idea of preprocessing is to allow conditional compilation. Libraries for intel em64tbased applications are now provided, and the crosscompiler for itaniumbased applications is now supported for use with the imsl libraries. Use a source code directive, a form of fortran comment, to pass specific information to the compiler regarding special optimization or parallelization choices. On linux and os x systems, the preprocessor options must start with a dash.
In the case of a compiler, the input is source code. Parallelization directives explicitly request the compiler attempt to parallelize the do loop that follows the directive. In the case of gnu fortran, this is the gnu c preprocessor in the traditional mode. The f95, f2003, f2008, and f2018 values specify strict conformance to the fortran 95, fortran 2003, fortran 2008 and fortran 2018 standards, respectively.
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