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Transformation of C code to Matlab/Simulink models Approach based on parsing Vilmos Zsombori 4.01.2005, Shanghai Motivation • Considerations: • The amount of source code to be transformed • Transformation patterns • Existence of third party parser generators that allow to automatically generate a customized parser for a user defined grammar • Prerequisite of automatic transformation: • Customized lexical analyzer • Customized syntactic analyzer • Implementation of output actions • Benefits: • The tool would reduce a large amount of transformation time • The automatic transformation is not susceptible to “human” errors • The actions are attached to language structures, in consequence the transformation is uniform, based on patterns and modeling guidelines • In case of library upgrades, name changes or pattern changes, the model update requests incomparably less time than the manual approach Vilmos Zsombori 4.01.2005 Approach Key concept Based on lexical and syntactic analysis Automatic parser generation Action specification according to the transformation patterns and the modeling guidelines General architecture cpp.jj grammar specification parser specification action specification Synthesis (JavaCC) CPPParser.java and C2Model.java Customized parser and code generator Vilmos Zsombori 4.01.2005 General architecture cpp.jj grammar specification parser specification action specification Synthesis (JavaCC) CPPParser.java and C2Model.java Customized parser and code generator Vilmos Zsombori 4.01.2005 Lexical and Syntactic analysis (I) Lexical analysis (tokens – regular expressions) SKIP : { “ ” | “\n” | <“/*” … “/”> } TOKEN : { <#DECIMAL_LITERAL: ["1"-"9"] (["0"-"9"])*> | <STRING_LITERAL: "\"" … "\""> … } TOKEN : { <CONTINUE: "continue"> | <VOLATILE: "volatile"> | <TYPEDEF: "typedef"> | <IF: "if"> | <DO: "do"> … } TOKEN : { <IDENTIFIER: <LETTER> (<LETTER> | <DIGIT>)*> | <#LETTER: ["$","A"-"Z","_","a"-"z"]> | <#DIGIT: ["0"-"9"]> } Vilmos Zsombori 4.01.2005 Lexical and Syntactic analysis (II) Syntactic analysis (C grammar) translation_unit : external_declaration | translation_unit external_declaration; external_declaration : function_definition | declaration; function_definition : declaration_specifiers declarator declaration_list compound_statement | declaration_specifiers declarator compound_statement | declarator declaration_list compound_statement | declarator compound_statement; selection_statement : IF '(' expression ')' statement | IF '(' expression ')' statement ELSE statement | SWITCH '(' expression ')' statement; Vilmos Zsombori 4.01.2005 General architecture cpp.jj grammar specification parser specification action specification Synthesis (JavaCC) CPPParser.java and C2Model.java Customized parser and code generator Vilmos Zsombori 4.01.2005 Parser generation (I) • Based on lexical and syntactic descriptions • Available parser generators: • Lex + Yacc • Generation of C code for the parser • Tool freely available for Linux but NOT for Windows • Needs a C compiler (gcc) • JavaCC • • • • Generation of Java code for the parser Needs a Java compiler and a Java Virtual Machine at runtime Both, JDK and JavaCC are FREE-ly available The generated parser is platform independent • The current work is based on JavaCC Vilmos Zsombori 4.01.2005 Parser generation (II) How JavaCC works JavaCC Source cpp.jj Vilmos Zsombori Lexical Analyzer CPPParserTokens.java CPPParserConstants.java TokenManagerError.java Syntax Analyzer CPPParser.java ParseException.java JavaCC Compiler 4.01.2005 General architecture cpp.jj grammar specification parser specification action specification Synthesis (JavaCC) CPPParser.java and C2Model.java Customized parser and code generator Vilmos Zsombori 4.01.2005 Action specification (I) • The actions are attached to the syntactic structures • Based on: • Transformation patterns: • • Function: void sign_init(void) { … } If-then-else structure: if ( expression ) { statement1 } else { statement2 } • Modeling guidelines • Vilmos Zsombori Data flow, naming, colors, … 4.01.2005 Action specification (II) • Block construction is possible through the Matlab script language: add_block(…) { blocks for the logical expression } add_block(‘built-in/Subsystem’, ‘{prefix}/statement1’) add_block(‘built-in/Subsystem’, ‘{prefix}/statement2’) add_block(‘built-in/Logical Operator’, ‘…/not’, ‘Operation’, ‘NOT’) add_line(‘{prefix}’, ‘{logical exprn out}/1’, ‘statement1/Enable’) add_line(‘{prefix}’, ‘{logical exprn out}/1’, ‘not/1’) add_line(‘{prefix}’, ‘not/1’, ‘statement2/Enable’) • Implementation of the actions: • Java class hierarchy – Node class subtype • Each class implements the process() method in a specific way, wrapping the output action; e.g. EqualityExpression: String process ( PrintWriter outputStream, String prefix ) { String rightHandSide = getChild(0).process(outputStream, prefix); // process the right-hand side String rightHandSide = getChild(1).process(outputStream, prefix); // process the left-hand side outputStream.print(“add_block(built-in/Relational Operator‘“ + ”, ‘” + prefix + ”/eq’, Operator’, ‘==’)”); outputStream.print(“add_line(‘” + prefix + ”’, “ + rightHandSide + ”/1’, ‘eq/1’)”); outputStream.print(“add_line(‘” + prefix + ”’, “ + leftHandSide + ”/1’, ‘eq/2’)”); // interconnect the blocks return “eq/1”; // return the output port } Vilmos Zsombori 4.01.2005 General architecture cpp.jj grammar specification parser specification action specification Synthesis (JavaCC) CPPParser.java and C2Model.java Customized parser and code generator Vilmos Zsombori 4.01.2005 The translation process Process overview Source code sign.c C2Model.jar (customized parser and code generator) Matlab script sign.m Matlab Simulink model sign.mdl C2Model.jar – customized parser and code generator • Builds up • a parse tree from the source code according to the lexical/syntactic definitions • consists of Node class subtypes • the nodes wrap the appropriate output actions • symbol tables – attached to Scopes: • type-, variable-, function- and port-table • efficient - using hash map Vilmos Zsombori 4.01.2005 The translation process – example Parse tree Source C file (test.c) typedef struct { int i, j; } stru; void fcn1(void) { a = b; } int fcn2(int u, int v) { if ((a<b) && (c+d <= e)) stru.i = u + v; } int fcn3(int h) { if (a == b) { u = c + d; } else { v = r + t; } } Vilmos Zsombori C2Model.jar TranslationUnit [4] … ExternalDeclaration [1] FunctionDefinition [3] DeclarationSpecifiers [1] TypeSpecifier [0] Declarator [1] DirectDeclarator [1] token: fcn1 … CompoundStatement [1] StatementList [1] Statement [1] ExpressionStatement [1] Expression [1] AssignmentExpression [3] UnaryExpression [1] PostfixExpression [1] PrimaryExpression [0] token: a AssignmentOperator [0] AssignmentExpression [1] … PrimaryExpression [0] token: b … 4.01.2005 The translation process – example (ctd.) Matlab script (test.m) Parse tree C2Model.jar new_system('test') add_block('built-in/Subsystem','test/fcn1') add_block('built-in/Outport','test/fcn1/a') set_param('test/fcn1/a', …) add_block('built-in/Inport','test/fcn1/b') set_param('test/fcn1/b', …) add_line('test/fcn1', 'b/1', 'a/1') … save_system('test') Simulink model Matlab Vilmos Zsombori 4.01.2005 Achievements and open questions • The lexical and syntactic definitions are complete • The symbol tables for each scope are constructed correctly • Type-, variable-, function- and port-table • The actions are implemented for: • All binary and n-ary operations • Assignment and conditional expressions • Selection statement, jump statement, iteration statement • Bus systems are created for structures • Bus selectors are used for operations on structure members • Operational on the entire sign.c • Open questions: • Handling of function-calls • Handling of arrays Vilmos Zsombori 4.01.2005 Results – Bus systems Vilmos Zsombori 4.01.2005 Results – Conditional operations Vilmos Zsombori 4.01.2005 Results – If-then-else structure Vilmos Zsombori 4.01.2005 Results – Functions Vilmos Zsombori 4.01.2005 Conclusion • A new automated translation method has been explored, based on parsing and a third party compiler generator, which transforms source code written in C/C++ to Matlab/Simulink models. • This yields fast and error-free operation, and has proven capable of handling large source codes without human intervention. • Although there are some issues concerning the organization of the output models (localization and positioning), results at this stage are encouraging. • Switching the implemented actions, the parser can be adapted to any “bit-by-bit transformation”. • However, the focus of this approach is the pure source code, not the logic and the functionality. • This is the reason, why it is unable to meet the simplification and the re-engineering issues, which are among the essential objectives of the entire project. • Therefore the developed tool could only assist the transformation work. Vilmos Zsombori 4.01.2005