Download Contributions to the Development of an Environment for

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