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Languages

Languages

• Standard Compiled languages
  • C

  • C++

  • GCC

  • G++

  • Fortran 77, G77

  • Fortran 90

  • HPF

• Source to source code restructuring
  • HPF - Southampton Translator

  • Fortran 77 to 90 Converter

  • Adaptor

C

• C is the most common language used for systems programming on UNIX workstations.

• A powerful middle-level language as it enables high-level programming constructs to be used

• These constructs are used in conjunction with access to registers and memory locations
  • provides C with a flexibility not available in other languages

• Added complexity increases the scope for programmer error

• Availability: Available from many sources both commercial and in the public domain.

C++

• C++ is an object-oriented superset of C introduced to provide the encapsulation and data abstraction facilities lacking in C

• C++ provides a reasonable implementation of the object-oriented concepts (encapsulation, inheritance, polymorphism).

• Availability: Available from many sources both commercial and in the public domain.

GCC and G++

• A generic version of C - not machine specific, doesn't contain any optimizations for a particular machine architecture

• GNU C provides ANSI standard C.

• "GCC" is a common shorthand term for the GNU C compiler.

• REFERENCE: http://www.ns.utk.edu/gnu/gnu.html

• The C, C++, and Objective C versions of the compiler are integrated; the GNU C compiler can compile programs written in C, C++, or Objective C.

FORTRAN - HISTORY

• Fortran (FORmula TRANslation system) - developed by IBM in 1954

• 1958 - second version which included subroutines, functions, common blocks.

• 1962 - Fortran IV was an attempt to standardize the language in order to work independent of the computer

• Fortran 66 - first standard in 1966, by the American National Standards Association

• Fortran 77 - a revised standard, released in 1978, providing extended features - removing the need for pre-processors

• Fortran 8x - ANSI began developing a new standard additional to rather than a replacement for Fortran 77.

• Fortran 90 - the third ANSI standard eventually released in 1991 which concentrated on language development.

• A new revision is expected within 10 years.

• HPF is the latest language that combines Fortran 90 with enhanced user defined data distribution.

FORTRAN 77

• The preferred programming language of scientists and engineers and has massive support across that community in terms of library support.

• The Fortran Market gives details for all products and services related to Fortran some of which are free
  • http://www.fortran.com/fortran/market.html

• GNU Fortran (g77) - still being developed but f2c (a FORTRAN-to-C translator) and gcc (the GNU C compiler) may be used if g77 proves insufficient.

• f2c provides a free Fortran 77 compiler

• g77 is available now via anonymous ftp to prep.ai.mit.edu:/pub/gnu.

FORTRAN 90

• Fortran 90 is a superset of Fortran 77

• New facilities include:
  • array operations - a new concise and powerful notation

  • new methods for specifying precision

  • free form

  • dynamic arrays - called allocatable arrays

  • the ability to define and manipulate user-defined data types.

  • marks features which are to disappear in the next version as `obsolescent' etc

• Fortran90 is an extension of the FORTRAN standard to include features for large scale computing and data abstraction.

HPF

• HPF combines Fortran 90 with enhanced user defined data distribution

• HPF extends Fortran 90 in several areas
  • Data distribution features - compiler able to arrange the computation to minimise communications but retain parallelism

  • Data parallel execution features - offers a new statement, FORALL, and new directive, INDEPENDENT, to express parallel computation explicitly

  • Extended intrinsic functions and standard library - added parallel operations.

  • EXTRINSIC procedures - define an explicit interface to procedures written in other paradigms e.g. explicit message passing subroutine libraries.

  • Changes in sequence and storage association.