PhD Thesis - staffweb - University of Greenwich

APPENDIX 2 : Journal Paper "Case Study : An Incremental Approach to Re-Engineeringa Legacy FORTRAN C.F.D. Code in C++", Ewer J., Knight B. and Cowell D.,Advances in Engineering Software, Vol. 22, pp 153-168, 1995seemingly arbitrary valued numbers represent, particularly in light of the meagre codedocumentation. Figure 2 shows the two types of literal values used in CWNN. These arearray indexing by integer values and physical constants entered explicitly withoutdefinition.A re-engineering strategy was sought that would remove the problems inherent in theFORTRAN implementation of CWNN whilst providing an extensible framework forcontinued research into CFD techniques. The approach described here was planned andrefined during the re-engineering of the legacy code. Example test cases were used to checkcode consistency throughout each stage of the development.As an investigation an attempt was made to translate the FORTRAN code into C orC++ using two proprietary tools. The results of the translations were very disappointing.The translated code was noted to be less clear than the original with little or noimprovement in structure. In some instances there was considerable degeneration in codeclarity with awkward and non-portable handling or certain library routines. The translatorswere clearly designed to allow compilation in C rather than to support continueddevelopment. This was the major reason for the manual translation strategy adopted in thiscase study.4. The multi-stage re-engineering processFORTRANCWNNAutomatictranslationC++Smartfire(1)Ensure dataconsistencyand make global(9)Optimisationsandenhancementstestruntestrun(2)Name andalgorithmclarificationtestrun(8)Create classmember functionsfor proceduralroutinestestrun(3)Removal ofredundant codeand simplification(7)Create classdata structuresas in design(4)testrunEnsure consistentuse of controlReplace logicalsfinaltest(5)Manualtranslation(6)testrunModify all fileI / O and rewritefor compatibilitycompileFigure 3 :Stages of re-engineering.Appendix 11.2 Page 142-8 8