/// <summary>
/// Parse Loop statement
/// </summary>
private void LOOP()
{
if (c_bParserASMDebug) m_Em.asm(";;;;;; LOOP statement begin ;;;;;;");
// Labels
string sBeginLabel = m_LABEL_BASE + m_iLabelLevel++;
string sEndLabel = m_LABEL_BASE + m_iLabelLevel++;
// consume LOOP token
m_tok = m_Tknzr.NextToken();
// Beginning of loop
m_Em.Label(sBeginLabel);
// Parse until IF
ParseLoop(Token.TOKENTYPE.IF);
// IF
Match(Token.TOKENTYPE.IF);
List<Token> inFix = new List<Token>();
for (; m_tok.m_tokType != Token.TOKENTYPE.THEN; m_tok = m_Tknzr.NextToken())
inFix.Add(m_tok);
//// LOOP instantiation
// Match tokens
Match(Token.TOKENTYPE.THEN);
// parse after condition
ParseLoop();
Match(Token.TOKENTYPE.SEMI_COLON);
Match(Token.TOKENTYPE.END);
Match(Token.TOKENTYPE.SEMI_COLON);
// eval conditional expression
EvalPostFix(InFixToPostFix(inFix));
// if EAX is one then statement is true and jump to IF
m_Em.Compare("EAX", "1");
m_Em.Jump("jge", sEndLabel);
//// evaluate inside loop
ParseLoop();
//m_Em.RDINT(); // trace
// jump to top of loop
m_Em.Jump("jmp", sBeginLabel);
// label if condition fails jump over
m_Em.Label(sEndLabel);
// consume remaining "END;"
Match(Token.TOKENTYPE.END);
Match(Token.TOKENTYPE.SEMI_COLON);
if (c_bParserASMDebug) m_Em.asm(";;;;;; end LOOP statement ;;;;;;");
}
/// <summary>
/// Returns true if type is one of: (, AND, OR, =, !=, >, >=, <, <=
/// </summary>
/// <param name="type"></param>
/// <returns></returns>
private bool InfixPlusMinusCondition(Token.TOKENTYPE type)
{
return (type == Token.TOKENTYPE.AND || type == Token.TOKENTYPE.OR
|| type == Token.TOKENTYPE.EQUAL || type == Token.TOKENTYPE.NOT_EQ
|| type == Token.TOKENTYPE.GRTR_THAN || type == Token.TOKENTYPE.GRTR_THAN_EQ
|| type == Token.TOKENTYPE.LESS_THAN || type == Token.TOKENTYPE.LESS_THAN_EQ);
}
/// <summary>
/// Parse tokens from infix to postfix, including conditionals and logical operators
/// </summary>
private List<Token> InFixToPostFix(List<Token> tokList = null)
{
// InFix to PostFix
Stack<Token> stkInToPost = new Stack<Token>(); // infix to postfix stack
List<Token> lsExpression = new List<Token>(); // get the whole expression as seperate list
List<Token> lsPostFix = new List<Token>(); // postfix statement
Token tok; // temp
// get expression into list
// Use passed in list if possible
if (tokList == null)
for (; m_tok.m_tokType != Token.TOKENTYPE.SEMI_COLON; m_tok = m_Tknzr.NextToken())
lsExpression.Add(m_tok);
else
lsExpression = tokList;
// loop through expression
for (int j = 0; j < lsExpression.Count; ++j)
{
switch (lsExpression[j].m_tokType)
{
case Token.TOKENTYPE.RIGHT_PAREN:
// Pop elements until '(' is found
if (stkInToPost.Count > 0)
{
tok = stkInToPost.Pop();
while (stkInToPost.Count > 0 && tok.m_tokType != Token.TOKENTYPE.LEFT_PAREN)
{
lsPostFix.Add(tok);
tok = stkInToPost.Pop();
} // while not '('
} // if stack no empty
break;
//** HIGHEST PRECEDENCE
case Token.TOKENTYPE.MOD:
case Token.TOKENTYPE.MULT:
case Token.TOKENTYPE.DIV:
case Token.TOKENTYPE.LEFT_PAREN:
// Highest precedence, push onto stack
if (!checkNeg(ref lsPostFix, ref lsExpression, ref j))
stkInToPost.Push(lsExpression[j]); // push onto stack
break;
//** MIDDLE PRECEDENCE
case Token.TOKENTYPE.AND:
case Token.TOKENTYPE.OR:
case Token.TOKENTYPE.NOT:
case Token.TOKENTYPE.EQUAL:
case Token.TOKENTYPE.NOT_EQ:
case Token.TOKENTYPE.GRTR_THAN:
case Token.TOKENTYPE.GRTR_THAN_EQ:
case Token.TOKENTYPE.LESS_THAN:
case Token.TOKENTYPE.LESS_THAN_EQ:
// if previous token was operator then check if number should be negative
if (!checkNeg(ref lsPostFix, ref lsExpression, ref j))
{
if (stkInToPost.Count > 0)
{
tok = stkInToPost.Peek();
// check top of stack and compare precedence
while (true)
{
// left paren on top is like having an empty stack
if (tok.m_tokType == Token.TOKENTYPE.LEFT_PAREN)
{
stkInToPost.Push(lsExpression[j]); // push onto stack
break;
} // if '('
// Current lower / top higher
if (tok.m_tokType == Token.TOKENTYPE.MULT || tok.m_tokType == Token.TOKENTYPE.DIV
|| tok.m_tokType == Token.TOKENTYPE.MOD)
{
tok = stkInToPost.Pop();
lsPostFix.Add(tok);
if (stkInToPost.Count > 0)
tok = stkInToPost.Peek();
else // stack empty push
{
stkInToPost.Push(lsExpression[j]); // push onto stack
break;
} // else
continue; // not needed, but kept for readability
} // Higher
// equal
if (InfixPlusMinusCondition(tok.m_tokType))
{
tok = stkInToPost.Pop();
lsPostFix.Add(tok);
stkInToPost.Push(lsExpression[j]); // push onto stack
break;
} // Equal
// Current higher / top lower
if (tok.m_tokType == Token.TOKENTYPE.PLUS || tok.m_tokType == Token.TOKENTYPE.MINUS)
{
stkInToPost.Push(lsExpression[j]); // push onto stack
break;
} // Lower
} // while
} // if stack not empty
else // stack empty
stkInToPost.Push(lsExpression[j]); // push onto stack
} // if not neg
break;
//** LOWEST PRECEDENCE
case Token.TOKENTYPE.PLUS:
case Token.TOKENTYPE.MINUS:
// if previous token was operator then check if number should be negative
if (!checkNeg(ref lsPostFix, ref lsExpression, ref j))
{
if (stkInToPost.Count > 0)
{
tok = stkInToPost.Peek();
// check top of stack and compare precedence
while (true)
{
// left paren on top is like having an empty stack
if (tok.m_tokType == Token.TOKENTYPE.LEFT_PAREN)
{
stkInToPost.Push(lsExpression[j]); // push onto stack
break;
}
// Current lower / top higher
if (InfixPlusMinusCondition(tok.m_tokType) || tok.m_tokType == Token.TOKENTYPE.MULT
|| tok.m_tokType == Token.TOKENTYPE.DIV || tok.m_tokType == Token.TOKENTYPE.MOD)
{
tok = stkInToPost.Pop();
lsPostFix.Add(tok);
// check stack
if (stkInToPost.Count > 0)
tok = stkInToPost.Peek();
else // stack empty push
{
stkInToPost.Push(lsExpression[j]); // push onto stack
break;
} // else
continue; // not needed, but kept for readability
} // Top higher
// equal
if (tok.m_tokType == Token.TOKENTYPE.PLUS || tok.m_tokType == Token.TOKENTYPE.MINUS)
{
tok = stkInToPost.Pop();
lsPostFix.Add(tok);
stkInToPost.Push(lsExpression[j]); // push onto stack
break;
} // Equal / Lower
} // while
} // if stack not empty
else // stack empty
stkInToPost.Push(lsExpression[j]); // push onto stack
} // if not neg
break;
case Token.TOKENTYPE.ID:
// Check if ARRAY
if (j + 1 < lsExpression.Count && lsExpression[j + 1].m_tokType /*m_Tknzr.PeekToken().m_tokType*/
== Token.TOKENTYPE.LEFT_BRACK)
{
lsPostFix.Add(lsExpression[j]); // add ID
++j; // only skip over ID, [ is current token
lsPostFix.Add(lsExpression[j]); // add [
++j; // move to next
// Add array as ID [ postfix index exp ]
// ex: list[23*]
List<Token> ltTemp = new List<Token>();
// Add everything in brackets and convert to postfix
for (; lsExpression[j].m_tokType != Token.TOKENTYPE.RIGHT_BRACK; ++j)
ltTemp.Add(lsExpression[j]);
lsPostFix.AddRange(InFixToPostFix(ltTemp)); // add post fix expression
lsPostFix.Add(lsExpression[j]); // add ]
break;
}
goto case Token.TOKENTYPE.INT_NUM;
case Token.TOKENTYPE.INT_NUM:
lsPostFix.Add(lsExpression[j]);
break;
default:
ErrorHandler.Error(ERROR_CODE.TOKEN_INVALID, lsExpression[j].m_iLineNum,
"Expected (,),+,-,*,/,MOD,INT_NUM, or ID token");
break;
} // switch
} // for all tokens in lsExpression
while (stkInToPost.Count > 0)
lsPostFix.Add(stkInToPost.Pop()); // get last element out
return lsPostFix;
}
/// <summary>
/// Parse Assignment function
/// ex. ID := Expression ;
/// </summary>
private void ID()
{
// lookup in symbol table
Symbol sym = FindSymbol(m_tok.m_strName);
switch (sym.SymType)
{
case Symbol.SYMBOL_TYPE.TYPE_CONST:
ErrorHandler.Error(ERROR_CODE.CONST_REDEFINITION, m_tok.m_iLineNum, "Cannot redefine a CONST value");
return; // get out of function
case Symbol.SYMBOL_TYPE.TYPE_REFPROC:
case Symbol.SYMBOL_TYPE.TYPE_PROC:
ProcID(sym);
return;
default:
break;
} // SymType
// consume token
m_tok = m_Tknzr.NextToken(); // ID
// Check if ARRAY, get proper offset
if (m_tok.m_tokType == Token.TOKENTYPE.LEFT_BRACK)
ArrayID(sym);
else // type INT
{
m_Em.CalcIntAddress(sym.Offset.ToString(), sym.ParamType);
m_Em.pushReg("EAX");
}
Match(Token.TOKENTYPE.ASSIGN); // :=
// Get value to be stored
if (m_tok.m_tokType == Token.TOKENTYPE.RDINT)
{
m_Em.RDINT();
m_tok = m_Tknzr.NextToken();
Match(Token.TOKENTYPE.LEFT_PAREN);
Match(Token.TOKENTYPE.RIGHT_PAREN);
} // RDINT
else
EvalPostFix(InFixToPostFix()); // evaluate expression, emit asm in process
// Value to be stored should be in EAX
// store the value at proper place:
m_Em.popReg("EDI");
m_Em.movReg("[EDI]", "EAX");
Match(Token.TOKENTYPE.SEMI_COLON);
}
/// <summary>
/// Parse IF statement
/// </summary>
private void IF()
{
if (c_bParserASMDebug) m_Em.asm(";;;;;; IF statement begin ;;;;;;");
// labels
string sIfLabel = m_LABEL_BASE + m_iLabelLevel++;
string sElseLabel = m_LABEL_BASE + m_iLabelLevel++;
string sEndLabel = m_LABEL_BASE + m_iLabelLevel++;
// consume token (IF)
m_tok = m_Tknzr.NextToken();
List<Token> inFix = new List<Token>();
for (; m_tok.m_tokType != Token.TOKENTYPE.THEN; m_tok = m_Tknzr.NextToken())
inFix.Add(m_tok);
// eval conditional expression
EvalPostFix(InFixToPostFix(inFix));
// if EAX is one then statement is true and jump to IF
m_Em.Compare("EAX", "1");
m_Em.Jump("je", sIfLabel);
// Force jump to else
m_Em.Jump("jmp", sElseLabel);
// consume token (THEN)
m_tok = m_Tknzr.NextToken();
///// run code in IF section
if (c_bParserASMDebug) m_Em.asm(";;; IF");
m_Em.Label(sIfLabel); // IF Label
ParseLoop(); // Parse inside of IF until ELSE or END is reached
m_Em.Jump("jmp", sEndLabel); // jump around else code
// Else label, put even if no ELSE token
m_Em.Label(sElseLabel); // ELSE Label
if (m_tok.m_tokType == Token.TOKENTYPE.ELSE) // if END then there is no ELSE section
{
// consume token (ELSE)
m_tok = m_Tknzr.NextToken();
//// else code
if (c_bParserASMDebug) m_Em.asm(";;; ELSE");
ParseLoop(Token.TOKENTYPE.ELSE); // Parse inside of ELSE until END token
} // ELSE
m_Em.Label(sEndLabel); // END Label
// consume remaining "END;"
Match(Token.TOKENTYPE.END);
Match(Token.TOKENTYPE.SEMI_COLON);
if (c_bParserASMDebug) m_Em.asm(";;;;;; end IF statement ;;;;;;");
}
/// <summary>
/// Parses a modula-2 file. File must be open.
/// </summary>
public void ParseFile()
{
// make sure tokenizer is reset
m_Tknzr.Reset();
// reset emitter
m_Em.Reset();
// reset symbol table
m_SymTable.Reset();
// reset offset and label count
m_iOff = 4;
m_iLabelLevel = 0;
m_iArithmeticLevel = 0;
m_tok = m_Tknzr.NextToken();
// Force jump to main when first run
m_Em.Jump("jmp", "__MAIN");
// Loop through file
while (m_tok.m_tokType != Token.TOKENTYPE.EOF || m_tok == null)
{
Module();
while (m_tok.m_tokType != Token.TOKENTYPE.BEGIN)
{
switch (m_tok.m_tokType)
{
case Token.TOKENTYPE.CONST:
Const();
break;
case Token.TOKENTYPE.TYPE:
Type();
break;
case Token.TOKENTYPE.VAR:
Vars();
break;
case Token.TOKENTYPE.PROCEDURE:
Procedure();
break;
default:
//error
break;
}
}
// print symbol table
Function();
} // while
}
/// <summary>
/// Parse array on left side of :=. Address is pushed onto the stack
/// </summary>
/// <param name="sym"></param>
private void ArrayID(Symbol sym)
{
// ***** ARRAY ID() ***** //
if (c_bParserASMDebug) m_Em.asm(";;;; ARRAY Assignment ;;;;");
m_tok = m_Tknzr.NextToken();
List<Token> lsIndex = new List<Token>();
// get index expression (contents between [ ] )
for (; m_tok.m_tokType != Token.TOKENTYPE.RIGHT_BRACK; m_tok = m_Tknzr.NextToken())
lsIndex.Add(m_tok);
// get index value
EvalPostFix(InFixToPostFix(lsIndex));
// calculate address
m_Em.CalcArrayAddress(sym.ArrayEnd.ToString(), sym.Offset.ToString(), sym.ParamType, "ID() ADDRESS: ");
// push for assignment
m_Em.pushReg("EAX");
Match(Token.TOKENTYPE.RIGHT_BRACK);
}
/// <summary>
/// Parse and emit WRINT module keyword
/// ex. WRINT(42);
/// </summary>
private void WRINT()
{
// consume token
m_tok = m_Tknzr.NextToken();
// eat '('
Match(Token.TOKENTYPE.LEFT_PAREN);
// evaluate expression
// consumes RIGHT_PAREN and SEMICOLON tokens
List<Token> exp = new List<Token>();
for (; m_tok.m_tokType != Token.TOKENTYPE.SEMI_COLON; m_tok = m_Tknzr.NextToken())
exp.Add(m_tok);
exp.RemoveAt(exp.Count - 1); // remove ')' in WRINT(exp)
// Get value of INT
EvalPostFix(InFixToPostFix(exp));
// write to console
// - int to print should be in EAX
m_Em.WRINT(); // prints what is in EAX
Match(Token.TOKENTYPE.SEMI_COLON);
// consume token
//m_tok = m_Tknzr.NextToken();
}
/// <summary>
/// Parse and emit WRLN modula keyword
/// ex. WRLN;
/// </summary>
private void WRLN()
{
// consume token
m_tok = m_Tknzr.NextToken();
m_Em.WRLN();
Match(Token.TOKENTYPE.SEMI_COLON);
}
/// <summary>
/// Parses the TYPE section
/// </summary>
private void Type()
{
Match(Token.TOKENTYPE.TYPE);
List<int> intList = new List<int>(); // type values
List<string> lsIDs = new List<string>(); // type IDs
// ID, Equal, ARRAY, LEFT_BRACK, INT, .., INT, RIGHT_BRACK, OF, INTEGER, ;
// prListType = ARRAY [11 .. 30] OF INTEGER ;
while (m_tok.m_tokType != Token.TOKENTYPE.CONST && m_tok.m_tokType != Token.TOKENTYPE.VAR)
{
// ID = ARRAY
if (m_tok.m_tokType == Token.TOKENTYPE.ID)
{
// check if it exists already
if (lsIDs.Contains(m_tok.m_strName))
{
ErrorHandler.Error(ERROR_CODE.TYPE_REDECLARATION, m_tok.m_iLineNum, "TYPE ID already exists");
break;
}
// store ID in temp string
lsIDs.Add(m_tok.m_strName);
Match(Token.TOKENTYPE.ID);
Match(Token.TOKENTYPE.EQUAL);
// Determine which type being defined (Eventually refactor cases into separate functions)
switch (m_tok.m_tokType)
{
case Token.TOKENTYPE.ARRAY:
m_tok = m_Tknzr.NextToken(); // eat ARRAY
if (m_tok.m_tokType == Token.TOKENTYPE.LEFT_BRACK)
{
m_tok = m_Tknzr.NextToken(); // eat '['
// Add ARRAY bounds to intlist -> [INT .. INT]
intList.Add(int.Parse(m_tok.m_strName));
m_tok = m_Tknzr.NextToken();
Match(Token.TOKENTYPE.DOT_DOT); // ..
intList.Add(int.Parse(m_tok.m_strName));
m_tok = m_Tknzr.NextToken();
Match(Token.TOKENTYPE.RIGHT_BRACK); // ]
Match(Token.TOKENTYPE.OF);
// Match type
switch (m_tok.m_tokType)
{
case Token.TOKENTYPE.INTEGER:
m_tok = m_Tknzr.NextToken(); // eat token
break;
default:
ErrorHandler.Error(ERROR_CODE.INVALID_TYPE, m_tok.m_iLineNum,
string.Format("Invalid type:{0}, should be INTEGER", m_tok.m_tokType));
break;
} // ARRAY data type
Match(Token.TOKENTYPE.SEMI_COLON);
} // If LEFT_BRACK
// Add "template" to symbol table
foreach (string id in lsIDs)
m_SymTable.AddSymbol(new Symbol(id, 0, Symbol.SYMBOL_TYPE.TYPE_ARRAY, Symbol.STORAGE_TYPE.TYPE_INT,
Symbol.PARAMETER_TYPE.LOCAL_VAR, 0, 0, intList[intList.Count - 2], intList[intList.Count - 1]));
break;
default:
ErrorHandler.Error(ERROR_CODE.INVALID_TYPE, m_tok.m_iLineNum, string.Format("Invalid type:{0}, should be ARRAY",
m_tok.m_tokType));
break;
} // switch TYPE
} // ID =
} // != CONST
}
/// <summary>
/// Parses:
/// ID : TYPE
/// and adds the appropriate symbols to the table at scope.
/// NOTE: m_tok is now the token after TYPE
/// </summary>
/// <param name="scope"></param>
private void VarDef(int scope = 0, int baseoffset = -1, Symbol.PARAMETER_TYPE Paramater_Type = Symbol.PARAMETER_TYPE.LOCAL_VAR)
{
List<string> lsIDs = new List<string>();
// stack offset to access variable
// check if using local or global offset
int iOffset = (baseoffset < 0) ? m_iOff : baseoffset;
// loop through all var definitions (ex. i, k, j : INTEGER)
while (m_tok.m_tokType != Token.TOKENTYPE.COLON)
{
// check for identifier
if (m_tok.m_tokType == Token.TOKENTYPE.ID)
{
// check if it exists
if (lsIDs.Contains(m_tok.m_strName))
{
ErrorHandler.Error(ERROR_CODE.VAR_REDECLARATION, m_tok.m_iLineNum, "VAR ID already exists");
break;
}
// store ID in temp string
lsIDs.Add(m_tok.m_strName);
} // If ID
// consume ID token
Match(Token.TOKENTYPE.ID);
// check if last VAR to be declared
if (m_tok.m_tokType == Token.TOKENTYPE.COMMA)
// consume token
m_tok = m_Tknzr.NextToken();
} // while not COLON
Match(Token.TOKENTYPE.COLON);
// add symbol for each var to symbol table
// - probably not the best way to implement the loop and switch
foreach (string s in lsIDs)
{
switch (m_tok.m_tokType)
{
case Token.TOKENTYPE.INTEGER:
// Add symbol
m_SymTable.AddSymbol(new Symbol(s, scope, Symbol.SYMBOL_TYPE.TYPE_SIMPLE, Symbol.STORAGE_TYPE.TYPE_INT,
Paramater_Type, iOffset));
iOffset += 4; // inc offset by 32bits
break;
case Token.TOKENTYPE.CARDINAL:
// not implemented
break;
case Token.TOKENTYPE.REAL:
// not implemented
break;
default:
// Look for user defined type in symbol type
Symbol sym = m_SymTable.FindSymbol(m_tok.m_strName);
if (sym == null)
ErrorHandler.Error(ERROR_CODE.TOKEN_INVALID, m_tok.m_iLineNum,
"Expecting INTEGER, CARDINAL, or REAL token");
else
// ARRAY
m_SymTable.AddSymbol(new Symbol(s, scope, Symbol.SYMBOL_TYPE.TYPE_ARRAY, Symbol.STORAGE_TYPE.TYPE_INT,
Paramater_Type, iOffset, 0, sym.BaseOffset, sym.ArrayEnd));
iOffset += (sym.ArrayEnd - sym.BaseOffset) * 4; // memory offset of array-> sizeof(int)*(EndIndex - BeginIndex)
break;
} // switch
} // foreach
// update m_iOff if using global scope
if (baseoffset < 0) m_iOff = iOffset;
// consume token
m_tok = m_Tknzr.NextToken();
}
/// <summary>
/// Parse/emit procedure call
/// </summary>
/// <param name="sym"></param>
private void ProcID(Symbol sym)
{
// ***** PROCEDURE ***** //
// Parse argument list, pushing each value onto the stack
// little ( k ) ;
int iArgCount = 0;
m_tok = m_Tknzr.NextToken();
Match(Token.TOKENTYPE.LEFT_PAREN);
// Parse arguments into list of token lists
// each list in the token list is an argument for the function being parsed
List<List<Token>> lslsArgs = new List<List<Token>>(); // hold the arguments, list of token (expression) lists
for (; m_tok.m_tokType != Token.TOKENTYPE.SEMI_COLON; m_tok = m_Tknzr.NextToken())
{
// parse argument into EAX
List<Token> lsArg = new List<Token>();
for (; m_tok.m_tokType != Token.TOKENTYPE.COMMA && m_tok.m_tokType != Token.TOKENTYPE.RIGHT_PAREN;
m_tok = m_Tknzr.NextToken())
lsArg.Add(m_tok);
lslsArgs.Add(lsArg); // add argument expression to list of arg expressions
++iArgCount; // used when restoring the stack
} // Get arguments
// Must push arguments in reverse order
for (int i = iArgCount; i > 0; --i)
{
// if proc is reference then push pointer to variable
if (sym.SymType == Symbol.SYMBOL_TYPE.TYPE_REFPROC)
{
Symbol symRefArg = m_SymTable.FindSymbol(lslsArgs[i - 1][0].m_strName);
m_Em.asm(";// Push REF addresses for: " + symRefArg.Name + " in PROCEDURE: " + sym.Name);
m_Em.asm(";// PARAM: " + symRefArg.ParamType.ToString());
// int
if (lslsArgs[i - 1].Count == 1)
m_Em.CalcIntAddress(symRefArg.Offset.ToString(), symRefArg.ParamType);
// array
else
{
// Evaluate index
List<Token> ltIndex = lslsArgs[i - 1].GetRange(2, lslsArgs[i - 1].Count - 3);
EvalPostFix(InFixToPostFix(ltIndex));
m_Em.CalcArrayAddress(symRefArg.BaseOffset.ToString(), symRefArg.Offset.ToString(),
symRefArg.ParamType, ";///ProcID Offset: ");
}
m_Em.pushReg("EAX");
continue;
}
// Get value into EAX then push onto stack
EvalPostFix(InFixToPostFix(lslsArgs[i - 1]));
m_Em.pushReg("EAX");
} // Push parameters for function
Match(Token.TOKENTYPE.SEMI_COLON);
// Call function
m_Em.asm(string.Format("call {0} ; PROCEDURE {0}", sym.Name));
m_Em.Add("SP", (lslsArgs.Count * 4).ToString());
}
private void ProcFunction(int callingscope, string procname)
{
// *********************
// ***** PROCEDURE *****
// skip BEGIN
m_tok = m_Tknzr.NextToken();
// Find PROCEDURE symbol in one below top scope
Scope scpActive = m_SymTable.GetCurrentScope();
Scope scpCalling = m_SymTable.GetScope(callingscope);
Symbol symProc = null;
foreach (Symbol sym in scpCalling.Symbols)
if (sym.Name == procname)
{
symProc = sym;
break;
} // get procedure symbol
// error
if (symProc == null)
ErrorHandler.Error(ERROR_CODE.SYMBOL_UNDEFINED, m_tok.m_iLineNum,
"Expecting PROCEDURE name");
// procedure header
if (c_bParserASMDebug) m_Em.asm(string.Format(";======= PROCEDURE: {0} =======", symProc.Name));
// Print jump label
m_Em.Label(symProc.Name);
// Prep procedure stack, save old stack info
m_Em.pushReg("BP"); // save old stack base
m_Em.movReg("BP", "SP"); // stack pointer now points to "bottom" of procedure stack
// Make room for local variables
// Get number of local variables
if (c_bParserASMDebug) m_Em.asm("; Make room for local variables ;;;;;;;;");
int iArg = 0, iLocalVarSpace = 0;
foreach (Symbol sym in scpActive.Symbols)
if (sym.ParamType == Symbol.PARAMETER_TYPE.LOCAL_VAR
&& sym.SymType == Symbol.SYMBOL_TYPE.TYPE_SIMPLE) ++iArg;
iLocalVarSpace = 4 + (4 * (iArg)); // integer variables
List<int> liArraySizes = new List<int>();
List<Symbol> lsArrays = new List<Symbol>();
/////
// If array is REF_PARM only needs 4 bytes of space
// Just the address of the lowest is passed
// if VAL_PARM
// WOOH LAMBDAS!
// Get all Array symbols into a list
lsArrays.AddRange(scpActive.Symbols.ToList().FindAll(sym => sym.SymType.Equals(Symbol.SYMBOL_TYPE.TYPE_ARRAY)));
// Get all offsets
lsArrays.ForEach(sym =>
{
if (sym.ParamType == Symbol.PARAMETER_TYPE.LOCAL_VAR)
iLocalVarSpace += (sym.ArrayEnd - sym.BaseOffset) * 4; ;
});
// space for local variables
m_Em.Sub("SP", iLocalVarSpace.ToString());
if (c_bParserASMDebug) m_Em.asm("; Function Body ;;;;;;;;");
// Parse/Emit until END
ParseLoop();
if (c_bParserASMDebug) m_Em.asm("; Epilogue ;;;;;;;;");
// Deallocate variables (readjust stack)
//m_Em.movReg("SP", "BP");
m_Em.Add("SP", (iLocalVarSpace).ToString());
// Restore old basepointer
m_Em.popReg("BP");
//// restore calling stack
//int iOffset = 0;
//scpActive.Symbols.ToList().ForEach(s =>
//{
// if (s.ParamType != Symbol.PARAMETER_TYPE.LOCAL_VAR)
// iOffset += 4;//(s.ArrayEnd - s.BaseOffset) * 4;
// //else
// // iOffset += 4;
//});
//m_Em.Add("SP", (iLocalVarSpace).ToString());
// Print return instruction
m_Em.asm("ret ; Return to calling code");
// procedure footer
if (c_bParserASMDebug) m_Em.asm(string.Format(";======= END PROCEDURE: {0} =======", symProc.Name));
// match end
Match(Token.TOKENTYPE.END);
Match(Token.TOKENTYPE.ID);
Match(Token.TOKENTYPE.SEMI_COLON);
// remove active scope, set next active
m_SymTable.RemoveScope();
}
/// <summary>
/// Parses the PROCEDURE header of a modula-2 file
/// EX:
/// PROCEDURE ID ( ID : TYPE ) ;
/// </summary>
private void Procedure()
{
// PROCEDURE little
//( i : INTEGER ) ;
// store calling scope
int iCallScope = m_SymTable.ActiveScope;
// consume PROCEDURE token
m_tok = m_Tknzr.NextToken();
// look up proc ID, check for redeclaration
Symbol procSym = m_SymTable.FindSymbol(m_tok.m_strName);
if (procSym != null)
ErrorHandler.Error(ERROR_CODE.PROC_REDECLARATION, m_tok.m_iLineNum, "PROCEDURE already declared");
Token tkProcID = m_tok; // save proc ID
// Consume ID token
m_tok = m_Tknzr.NextToken();
// Parse arguments if any
if (m_tok.m_tokType == Token.TOKENTYPE.LEFT_PAREN)
{
m_tok = m_Tknzr.NextToken();
// check for passed by reference
// if VAR token exists then parameters are reference types
if (m_tok.m_tokType == Token.TOKENTYPE.VAR)
{
// Add PROC to symbol table to calling scope
m_SymTable.AddSymbol(new Symbol(tkProcID.m_strName, iCallScope, Symbol.SYMBOL_TYPE.TYPE_REFPROC,
Symbol.STORAGE_TYPE.STORE_NONE, Symbol.PARAMETER_TYPE.LOCAL_VAR, 0));
// Create new scope for procedure
m_SymTable.AddScope();
m_tok = m_Tknzr.NextToken(); // consume VAR token
while (m_tok.m_tokType != Token.TOKENTYPE.RIGHT_PAREN)
VarDef(m_SymTable.ActiveScope, 4, Symbol.PARAMETER_TYPE.REF_PARM);
// Add Proc sym with TYPE_REFPROC so that we know the parameters are of reference type
// in the ID() function. Do so by overwriting the symbol
}
// Pass by value
else
{
// Add PROC to symbol table to calling scope
m_SymTable.AddSymbol(new Symbol(tkProcID.m_strName, iCallScope, Symbol.SYMBOL_TYPE.TYPE_PROC,
Symbol.STORAGE_TYPE.STORE_NONE, Symbol.PARAMETER_TYPE.LOCAL_VAR, 0));
// Create new scope for procedure
m_SymTable.AddScope();
// Parse procedure paramaters (arguments)
while (m_tok.m_tokType != Token.TOKENTYPE.RIGHT_PAREN) // while not )
VarDef(m_SymTable.ActiveScope, 4, Symbol.PARAMETER_TYPE.VAL_PARM); // baseoffset for scope starts at 4
}
m_tok = m_Tknzr.NextToken(); // Consume )
}
Match(Token.TOKENTYPE.SEMI_COLON);
while (m_tok.m_tokType != Token.TOKENTYPE.BEGIN)
{
switch (m_tok.m_tokType)
{
// CONST
case Token.TOKENTYPE.CONST:
Const(m_SymTable.ActiveScope);
break;
// VAR Parse PROCEDURE's local vars
case Token.TOKENTYPE.VAR:
Vars(m_SymTable.ActiveScope, 4);
break;
}
}
// Parse PROCEDURE's contents
m_Em.asm(string.Format("\r\n\r\n;// START Procedure: {0}", tkProcID.m_strName));
ProcFunction(iCallScope, tkProcID.m_strName);
m_Em.asm(string.Format(";// END Procedure: {0}\r\n\r\n", tkProcID.m_strName));
}
/// <summary>
/// True has been returned if tokType matches the current token, false if not.
/// One token has been consumed.
/// </summary>
/// <param name="tokType"></param>
/// <returns></returns>
private bool Match(Token.TOKENTYPE tokType)
{
bool b = (m_tok.m_tokType == tokType);
// Throw error if not expected token
if (!b) ErrorHandler.Error(ERROR_CODE.TOKEN_INVALID, m_tok.m_iLineNum,
string.Format("Expected token: {0}", tokType.ToString()));
m_tok = m_Tknzr.NextToken();
return b;
}
// *********************************************************************************
// *********************************************************************************
// K E Y W O R D H E L P E R F U N C T I O N S
// *********************************************************************************
/// <summary>
/// Parse and emit WRSTR modula keyword
/// ex. WRSTR("string contents");
/// </summary>
private void WRSTR()
{
// consume token
m_tok = m_Tknzr.NextToken();
Match(Token.TOKENTYPE.LEFT_PAREN);
// Check for parse error
if (m_tok.m_tokType != Token.TOKENTYPE.STRING) ErrorHandler.Error(ERROR_CODE.TOKEN_INVALID,
m_tok.m_iLineNum, "Expected STRING token");
m_Em.WRSTR(m_tok.m_strName);
Match(Token.TOKENTYPE.STRING);
Match(Token.TOKENTYPE.RIGHT_PAREN);
Match(Token.TOKENTYPE.SEMI_COLON);
}
/// <summary>
/// Loops and parses keywords of functions
/// </summary>
private void ParseLoop(Token.TOKENTYPE endType = Token.TOKENTYPE.END)
{
bool runloop = true;
// While not endType and no error
while (m_tok.m_tokType != endType && ErrorHandler.LastError == (ERROR_CODE)0
&& runloop)
{
switch (m_tok.m_tokType)
{
case Token.TOKENTYPE.WRSTR:
WRSTR();
break;
case Token.TOKENTYPE.WRLN:
WRLN();
break;
case Token.TOKENTYPE.WRINT:
WRINT();
break;
case Token.TOKENTYPE.ID:
ID();
break;
case Token.TOKENTYPE.IF:
IF();
break;
case Token.TOKENTYPE.LOOP:
LOOP();
break;
case Token.TOKENTYPE.EXIT:
m_tok = m_Tknzr.NextToken(); // consume token
goto case Token.TOKENTYPE.END;
case Token.TOKENTYPE.ELSE:
case Token.TOKENTYPE.END:
runloop = false;
break; // exit
default:
// Invalid token
ErrorHandler.Error(ERROR_CODE.TOKEN_INVALID, m_tok.m_iLineNum,
string.Format("Token {0} invalid\r\nExpected a proper keyword",
m_tok.m_tokType));
break;
} // switch
} // while
}
/// <summary>
/// normal constructor with tokentype, lexeme and line number
/// </summary>
/// <param name="tok"></param>
/// <param name="inName"></param>
/// <param name="inLine"></param>
public Token(Token.TOKENTYPE tok, string inName, int inLine)
{
m_tokType = tok;
m_strName = inName;
m_iLineNum = inLine;
}
