/**** parser.c ***************************************************/ #include "global.h" extern void emit(int t, int tval, float rval); extern void error(char *m); extern int lexan(void); extern int GlobalInsert(char s[], int tok, int type, int size, int function, int functionlabel); extern void CheckMain(void); extern void AllBodsParsed(void); extern void LocalReset(void); extern int LocalInsert(char s[], int tok, int type, int size,int function, int functionlabel); extern void ParamInt(void); int term(void); void match(int t); int expr(void); void PushArrayCellAddr(void); void DeclOrF(void); void GlobalScopeAndInsert(int type); void GlobalVarList(int type); void exprTest(void); void exprAssg(void); void parseAStmt(void); void parse(void); int factor(void); void ExprList(void); void FunctionList(void); void FunctionDef(int type); void MoreParams(void); void ParamList(void); void DecList(void); void VarList(int type); void FstmtList(void); int term(void) { int t; /* temporary holder of tokens */ int leftExpr, rightExpr; leftExpr = factor(); if (ErrorFlag) return -99; while(lookahead == '*' || lookahead == '/') { t = lookahead; match(lookahead); if (ErrorFlag) return -99; rightExpr = factor(); if (ErrorFlag) return -99; if (leftExpr == rightExpr) { if (leftExpr) { if (t == '*') emit(RMUL, 0, 0.0); else emit(RDIV, 0, 0.0); leftExpr = 1; } else { if (t == '*') emit(MUL, 0, 0.0); else emit(DIV, 0, 0.0); leftExpr = 0; } } else { if (leftExpr) { emit(FLOAT, 0, 0.0); if (t == '*') emit(RMUL, 0, 0.0); else emit(RDIV, 0, 0.0); } else { emit(NUM, 1, 0.0); emit(IST, 0, 0.0); emit(FLOAT, 0, 0.0); emit(NUM, 1, 0.0); emit(VAL, 0, 0.0); if (t == '*') emit(RMUL, 0, 0.0); else emit(RDIV, 0, 0.0); } leftExpr = 1; } /* end else leftExpr == rightExpr */ } if (FloatFlag) return(1); else return (leftExpr); } /* ========================================================================= */ void match(int t) /* verify that t was the last token, then get next token */ /* token to verify as last found */ { if (lookahead == t) { PreviousLookahead = lookahead; PreviousTokenval = tokenval; PreviousFtokenval = ftokenval; lookahead = NextLookahead; tokenval = NextTokenval; ftokenval = NextFtokenval; if (NextLookahead != DONE) NextLookahead = lexan(); } else { switch (lookahead) { case WHILE: case IF: error("Missing ; at end of previous statement"); break; } if (ErrorFlag) return; switch (t) { case ')': error("Missing right parenthesis or illegal operator"); break; default: printf("\n In default of match lookahead = %d",lookahead); error("syntax error"); break; } /* end switch */ } /* else */ } /* ------------------------------------------------------------------- */ int expr(void) { int t; /* temporary holder of tokens */ int leftExpr, rightExpr; leftExpr = term(); if (ErrorFlag) return -99; while(lookahead == '+' || lookahead == '-') { t = lookahead; match(lookahead); if (ErrorFlag) return -99; rightExpr = term(); if (ErrorFlag) return -99; if (leftExpr == rightExpr) { if (leftExpr) { if (t == '+') emit(RADD, 0, 0.0); else emit(RSUB, 0, 0.0); leftExpr = 1; } else { if (t == '+') emit(ADD, 0, 0.0); else emit(SUB, 0, 0.0); leftExpr = 0; } } else { if (leftExpr) { emit(FLOAT, 0, 0.0); if (t == '+') emit(RADD, 0, 0.0); else emit(RSUB, 0, 0.0); } else { emit(NUM, 1, 0.0); emit(IST, 0, 0.0); emit(FLOAT, 0, 0.0); emit(NUM, 1, 0.0); emit(VAL, 0, 0.0); if (t == '+') emit(RADD, 0, 0.0); else emit(RSUB, 0, 0.0); } leftExpr = 1; } /* end else leftExpr == rightExpr */ } if (FloatFlag) return(1); else return(leftExpr); } /* ========================================================================= */ void PushArrayCellAddr(void) /* calculate address of array cell on stack */ { int tempTokenval; if ( !(ArrayParsed)) { ArrayParsed = 1; tempTokenval = tokenval; if (LocalIndex) emit(PUSH_LOC_VAR_ADDR, LocalIndex, 0.0); else if (GlobalIndex) emit(PUSH_GLO_VAR_ADDR, GlobalIndex, 0.0); else { error("Compiler error, array lexeme not found in any table"); return; } match(ARRAY); if (ErrorFlag) return; match('['); if (ErrorFlag) return; FloatFlag = 0; FloatFlag = expr(); if (ErrorFlag) return; if (lookahead != ']') { error("Missing ']'"); return; } if (FloatFlag) { error("Array index must be an integer value"); return; } emit(ADD, 0, 0.0); lookahead = ARRAY; tokenval = tempTokenval; } /* end if !ArrayParsed */ else ArrayParsed = 0; } /* end PushArrayCellAddr */ /* ============================================================= */ void DeclOrF(void) { int type; /* stores type to call other functions with */ int temp; Scope = 0; /* set scope to zero to mean global variables */ while(1) { if (lookahead == ID) { emit(BEGIN, 0, 0.0); LabelCounter = 4; /* first 3 label used by emit BEGIN */ /* insert an implicit call to main into the symbol tabel */ temp = GlobalInsert ("main",ID,INT,0,1,1); if (ErrorFlag) return; if (strcmp("main", lexbuf) == 0) GlobalIndex = temp; FunctionDef (INT); if (ErrorFlag) return; return; } else if (lookahead == INT) { match (INT); if (ErrorFlag) return; } else { match (FLOAT); if (ErrorFlag) return; } if (NextLookahead == '(') { emit(BEGIN, 0, 0.0); LabelCounter = 4; /* first 3 labels used by emit BAGIN */ /* insert an implicit call to main into the symbol tabel */ temp = GlobalInsert ("main",ID,INT,0,1,1); if (ErrorFlag) return; if (strcmp("main", lexbuf) == 0) GlobalIndex = temp; FunctionDef(PreviousLookahead); if (ErrorFlag) return; return; } else { type = PreviousLookahead; GlobalScopeAndInsert (type); if (ErrorFlag) return; GlobalVarList (type); if (ErrorFlag) return; match(';'); if (ErrorFlag) return; } /* end if != '(' */ } /* end while(1) */ } /* end DeclOrF */ /* ============================================================= */ void GlobalScopeAndInsert(int type) { int tempGlobalIndex; if (LocalIndex) { error("Compiler error! global lexeme found in local symbol table"); return; } /* end LocalIndex */ else if (GlobalIndex) { if (GlobalTable[GlobalIndex].function) { error("Attempting to define a function name as an identifier"); return; } /* end if */ else { error("Attempting to define a global variable twice"); return; } /* end else */ } /* end else ifGlobalIndex */ else { if (NextLookahead == '[') { tempGlobalIndex = GlobalIndex = GlobalInsert(lexbuf, ARRAY, type,0,0,0); if (ErrorFlag) return; match(ID); if (ErrorFlag) return; match('['); if (ErrorFlag) return; if (lookahead == NUM) { GlobalTable[tempGlobalIndex].size = tokenval; match(NUM); } /* end if (lookahead == num) */ else { error("Improperly formed array definition"); return; } /* end else */ match(']'); if (ErrorFlag) return; emit(GLO_DECL, tempGlobalIndex, 0.0); DecCount += GlobalTable[tempGlobalIndex].size; } /* end if next == '[' */ else /* regular ID */ { GlobalIndex = GlobalInsert(lexbuf, ID, type, 1, 0, 0); if (ErrorFlag) return; emit(GLO_DECL, GlobalIndex, 0.0); ++DecCount; match(ID); if (ErrorFlag) return; } /* end else */ } /* end else */ } /* end GlobalScopeAndInsert */ /* ============================================================= */ void GlobalVarList(int type) { while (lookahead == ',') { match(','); if (ErrorFlag) return; if (lookahead == ID || lookahead == ARRAY) { GlobalScopeAndInsert (type); if (ErrorFlag) return; } /* end if ID or ARRAY */ else { error("Expected an identifier or array"); return; } /* end else */ } /* end while loop */ } /* end GlobalVarList */ /* ============================================================= */ void exprTest(void) { int tempTrue, tempDone; int tempOperation; int TempFloatFlag; FloatFlag = 0; FloatFlag = expr(); if (ErrorFlag) return; while ((lookahead == EQUAL) || (lookahead == NEQUAL)) { tempOperation = lookahead; if (lookahead == EQUAL) match(EQUAL); else match(NEQUAL); if (ErrorFlag) return; TempFloatFlag = FloatFlag; if (TempFloatFlag) { FloatFlag = 0; FloatFlag = expr(); if (!(FloatFlag)) { emit(FLOAT, 0, 0.0); FloatFlag = 1; } } else { FloatFlag = expr(); if (FloatFlag) { emit(NUM, 1, 0.0); emit(IST, 0, 0.0); emit(FLOAT, 0, 0.0); emit(NUM, 1, 0.0); emit(VAL, 0, 0.0); } } if (ErrorFlag) return; emit(COMP, 0, 0.0); tempTrue = LabelCounter; ++LabelCounter; tempDone = LabelCounter; ++LabelCounter; emit(PUSH_CODE_LABEL, tempTrue, 0.0); if (tempOperation == EQUAL) emit(BEQ, 0, 0.0); else emit(BNE, 0, 0.0); emit(NUM, 0, 0.0); emit(PUSH_CODE_LABEL, tempDone, 0.0); emit(B, 0, 0.0); emit(LABEL_CODE, tempTrue, 0.0); emit(NUM, 1, 0.0); emit(LABEL_CODE, tempDone, 0.0); } /* end if */ } /* end exprTest */ /* ========================================================================= */ void exprAssg(void) { int tempLocalIndex, tempGlobalIndex; /* temp indices during recursion */ switch (lookahead) { case ARRAY: tempLocalIndex = LocalIndex; tempGlobalIndex = GlobalIndex; PushArrayCellAddr(); if (ErrorFlag) return; if (NextLookahead == '=') { ArrayParsed = 0; match(ARRAY); if (ErrorFlag) return; match('='); if (ErrorFlag) return; FloatFlag = 0; exprAssg(); if (ErrorFlag) return; if (tempLocalIndex) { if ((LocalTable[tempLocalIndex].type == INT) && (FloatFlag)) { emit(INT, 0, 0.0); FloatFlag = 0; } else if ((LocalTable[tempLocalIndex].type == FLOAT) && ( !FloatFlag)) { emit(FLOAT, 0, 0.0); FloatFlag = 1; } emit(STHB ,0 ,0.0); } else if (tempGlobalIndex) { if ((GlobalTable[tempGlobalIndex].type == INT) && (FloatFlag)) { emit(INT, 0, 0.0); FloatFlag = 0; } else if((GlobalTable[tempGlobalIndex].type == FLOAT) && (!FloatFlag)) { emit(FLOAT, 0, 0.0); FloatFlag = 1; } emit(STH, 0, 0.0); } emit(SWAP, 0, 0.0); emit(POP, 0, 0.0); } /* end if NextLookahead == '=' */ else { exprTest(); if (ErrorFlag) return; } /* end else of if lookahead == '=' */ break; case ID: tempLocalIndex = LocalIndex; tempGlobalIndex = GlobalIndex; if (NextLookahead == '=') { if (LocalIndex) emit(PUSH_LOC_VAR_ADDR, LocalIndex, 0.0); else if (GlobalIndex) emit(PUSH_GLO_VAR_ADDR, GlobalIndex, 0.0); else { error("Compiler error, variable lexeme not found in any table"); return; } match(ID); if (ErrorFlag) return; match('='); if (ErrorFlag) return; FloatFlag = 0; exprAssg(); if (ErrorFlag) return; if (tempLocalIndex) { if ((LocalTable[tempLocalIndex].type == INT) && (FloatFlag)) { emit(INT, 0, 0.0); FloatFlag = 0; } else if ((LocalTable[tempLocalIndex].type == FLOAT) && ( !FloatFlag)) { emit(FLOAT, 0, 0.0); FloatFlag = 1; } emit(STHB, 0, 0.0); } else if (tempGlobalIndex) { if ((GlobalTable[tempGlobalIndex].type == INT) && (FloatFlag)) { emit(INT, 0, 0.0); FloatFlag = 0; } else if((GlobalTable[tempGlobalIndex].type == FLOAT) && (!FloatFlag)) { emit(FLOAT, 0, 0.0); FloatFlag = 1; } emit(STH, 0, 0.0); } emit(SWAP, 0, 0.0); emit(POP, 0, 0.0); } else { exprTest(); if (ErrorFlag) return; } break; default: exprTest(); if (ErrorFlag) return; } /* end switch */ return; } /* end exprAssg */ /* ========================================================================= */ void parseAStmt(void) /* parse a single statement */ { int tempLabel1, tempLabel2; switch (lookahead) { case WHILE: match(WHILE); if (ErrorFlag) return; tempLabel1 = LabelCounter; ++LabelCounter; tempLabel2 = LabelCounter; ++LabelCounter; emit(LABEL_CODE, tempLabel1, 0.0); emit(PUSH_CODE_LABEL, tempLabel2, 0.0); match('('); if (ErrorFlag) return; FloatFlag = 0; exprAssg(); if (ErrorFlag) return; match(')'); if (ErrorFlag) return; if (FloatFlag) emit(RNUM, 0, 0.0); /* push 0.0 */ else emit(NUM, 0 ,0.0); /* push 0 */ emit(COMP, 0, 0.0); emit(BEQ, 0, 0.0); parseAStmt(); if (ErrorFlag) return; emit(PUSH_CODE_LABEL, tempLabel1, 0.0); emit(B, 0, 0.0); emit(LABEL_CODE, tempLabel2, 0.0); break; case IF: match(IF); if (ErrorFlag) return; tempLabel1 = LabelCounter; ++LabelCounter; emit(PUSH_CODE_LABEL, tempLabel1, 0.0); match('('); if (ErrorFlag) return; FloatFlag = 0; exprAssg(); if (ErrorFlag) return; match(')'); if (ErrorFlag) return; if (FloatFlag) emit(RNUM, 0, 0.0); /* push 0.0 */ else emit(NUM, 0, 0.0); /* push 0 */ emit(COMP, 0, 0.0); emit(BEQ, 0, 0.0); parseAStmt(); if (ErrorFlag) return; if (lookahead == ELSE) { match (ELSE); if (ErrorFlag) return; tempLabel2 = LabelCounter; ++LabelCounter; emit(PUSH_CODE_LABEL, tempLabel2, 0.0); emit(B, 0, 0.0); emit(LABEL_CODE, tempLabel1, 0.0); parseAStmt(); if (ErrorFlag) return; emit(LABEL_CODE, tempLabel2, 0.0); } /* end if lookahead == ELSE */ else { emit(LABEL_CODE, tempLabel1, 0.0); } /* end else lookahead == ELSE */ break; case '{': match('{'); do { parseAStmt(); if (ErrorFlag) ErrorFlag = 0; } while ((lookahead != '}') && (lookahead != DONE)); match('}'); if (ErrorFlag) return; break; case RETURN: if (NextLookahead == ';') { match(RETURN); if (ErrorFlag) return; match(';'); if (ErrorFlag) return; if (GlobalTable[FuncNameIndex].type == INT) emit(NUM, 1, 0.0); else emit(RNUM, 0, 1.0); } /* end if */ else { match(RETURN); if (ErrorFlag) return; exprAssg(); if (ErrorFlag) return; match(';'); if (ErrorFlag) return; } /* end else */ emit(PUSH_CODE_LABEL, ReturnLabel, 0.0); emit(B, 0, 0.0); break; default: /* assignment statement */ exprAssg(); if (ErrorFlag) return; emit(POP, 0, 0.0); match(';'); return; } /* end switch */ return; } /* end parseAStmt */ /* ========================================================================= */ void parse(void) /* parse a list of functions */ { /* prime NextLookahead */ lookahead = 1; match (lookahead); if (ErrorFlag) ErrorFlag = 0; /* prime lookahead */ lookahead = 1; match (lookahead); if (ErrorFlag) ErrorFlag = 0; DeclOrF(); /* parses the global var. declarations and the first function */ if (ErrorFlag) return; FunctionList(); if (ErrorFlag) return; CheckMain(); AllBodsParsed(); if (ErrorFlag) return; emit(END, 0, 0.0); return; } /* end parse */ /* ========================================================================= */ int factor(void) { int temp; int tempLocalIndex, tempGlobalIndex; char templexbuf[30]; switch(lookahead) { case '(': match('('); if (ErrorFlag) return -99; switch (lookahead) { case INT: match (INT); if (ErrorFlag) return -99; match (')'); if (ErrorFlag) return -99; temp = factor(); if (ErrorFlag) return -99; if (temp) emit(INT, 0, 0.0); return(0); break; case FLOAT: match (FLOAT); if (ErrorFlag) return -99; match (')'); if (ErrorFlag) return -99; temp = factor(); if (ErrorFlag) return -99; if ( !temp) emit(FLOAT, 0, 0.0); return(1); break; default: FloatFlag = 0; exprAssg(); if (ErrorFlag) return -99; match(')'); if (ErrorFlag) return -99; if (FloatFlag) return(1); else return(0); break; } /* end switch */ break; case NUM: emit(NUM, tokenval, 0.0); match(NUM); if (ErrorFlag) return -99; return(0); /* meaning false float flag */ break; case RNUM: emit(RNUM, tokenval, ftokenval); match(RNUM); if (ErrorFlag) return -99; return(1); /* meaning true float flag */ break; case ID: if (NextLookahead == '(') { /* function call */ tempLocalIndex = LocalIndex; tempGlobalIndex = GlobalIndex; strcpy (templexbuf, lexbuf); match(ID); if (ErrorFlag) return -99; match('('); if (ErrorFlag) return -99; ExprList(); if (ErrorFlag) return -99; match(')'); if (ErrorFlag) return -99; /* prepare to branch to function */ CallReturnAddr = LabelCounter; ++LabelCounter; emit(PUSH_CODE_LABEL, CallReturnAddr, 0.0); emit(PUSH_FRAMESIZE, FuncNameIndex, 0.0); emit(IB, 0, 0.0); /* branch to function */ if (tempLocalIndex) { error("Function called is to a local variable"); return -99; } /* end LocalIndex */ else if (tempGlobalIndex) { if (!(GlobalTable[tempGlobalIndex].function)) { error("Function called is to a global variable"); return -99; } /* end if !function */ else { emit(PUSH_CODE_LABEL,GlobalTable[tempGlobalIndex].functionlabel,0.0); } /* end else !function */ } /* end GlobalIndex */ else /* lexeme not in any symbol table */ { tempGlobalIndex = GlobalInsert (templexbuf,ID,INT,0,1,LabelCounter); if (ErrorFlag) ErrorFlag = 0; ++LabelCounter; emit(PUSH_CODE_LABEL, GlobalTable[tempGlobalIndex].functionlabel, 0.0); } /* end insert function name */ emit(B, 0, 0.0); /* return sequence */ emit(LABEL_CODE, CallReturnAddr, 0.0); emit(PUSH_FRAMESIZE, FuncNameIndex, 0.0); emit(DB, 0, 0.0); if (GlobalTable[tempGlobalIndex].function < 0) /* function defined */ { if (GlobalTable[tempGlobalIndex].type == INT) return(0); else return(1); } else /* default return type of undefined function is INT */ return(0); } /* end if NextLookahead == ')' */ else if ( !(LocalIndex || GlobalIndex)) { error("attempting to use an undefined variable"); return -99; } if (LocalIndex) emit(PUSH_LOC_VAR_VALUE, LocalIndex, 0.0); else if (GlobalIndex) emit(PUSH_GLO_VAR_VALUE, GlobalIndex, 0.0); else { error("Compiler error, lexeme was not found in any table"); break; } tempLocalIndex = LocalIndex; tempGlobalIndex = GlobalIndex; match(ID); if (ErrorFlag) return -99; if (tempLocalIndex) { if (LocalTable[tempLocalIndex].type == FLOAT) return(1); else return(0); } else { if (GlobalTable[tempGlobalIndex].type == FLOAT) return(1); else return(0); } break; case ARRAY: tempLocalIndex = LocalIndex; tempGlobalIndex = GlobalIndex; PushArrayCellAddr(); if (ErrorFlag) return -99; ArrayParsed = 0; match(ARRAY); if (ErrorFlag) return -99; if (tempLocalIndex) emit(VALB, 0, 0.0); else if (tempGlobalIndex) emit(VAL, 0, 0.0); else { error("using an undefined array referance"); return -99; } if (tempLocalIndex) { if (LocalTable[tempLocalIndex].type == FLOAT) return(1); else return(0); } else { if (GlobalTable[tempGlobalIndex].type == FLOAT) return(1); else return(0); } break; case '-': match('-'); if (ErrorFlag) return -99; temp=factor(); if (ErrorFlag) return -99; if (temp) emit(RNEG, 0, 0.0); else emit(NEG, 0, 0.0); return(temp); break; case READF: match(READF); if (ErrorFlag) return -99; match ('('); if (ErrorFlag) return -99; match (')'); if (ErrorFlag) return -99; emit(READ, 0, 0.0); emit(FLOAT, 0, 0.0); return(1); break; case READI: match(READI); if (ErrorFlag) return -99; match('('); if (ErrorFlag) return -99; match(')'); if (ErrorFlag) return -99; emit(READ, 0, 0.0); emit(INT, 0, 0.0); return(0); break; case WRITEF: match (WRITEF); if (ErrorFlag) return -99; match('('); if (ErrorFlag) return -99; FloatFlag = 0; exprAssg(); if (ErrorFlag) return -99; if ( !(FloatFlag)) { emit(FLOAT, 0, 0.0); FloatFlag = 1; } match(')'); if (ErrorFlag) return -99; emit(WRITEF, 0, 0.0); emit(RNUM, 1, 1.0); return(1); break; case WRITEI: match(WRITEI); if (ErrorFlag) return -99; match('('); if (ErrorFlag) return -99; FloatFlag = 0; exprAssg(); if (ErrorFlag) return -99; if (FloatFlag) { emit(INT, 0, 0.0); FloatFlag = 0; } match(')'); if (ErrorFlag) return -99; emit(WRITEI, 0, 0.0); emit(NUM, 1, 0.0); return(0); break; case WRITELN: match(WRITELN); if (ErrorFlag) return -99; match('('); if (ErrorFlag) return -99; match(')'); if (ErrorFlag) return -99; emit(WRITELN, 0, 0.0); emit(NUM, 1, 0.0); return(0); break; default: /* error used to be called from here */ error("Illegal operator"); return(0); } return -99; } /* ------------------------------------------------------------------ */ void ExprList(void) { if (lookahead != ')') { exprAssg(); if (ErrorFlag) return; while (lookahead == ',') { match(','); if (ErrorFlag) return; exprAssg(); if (ErrorFlag) return; } /* end while */ } /* end if ) */ } /* end ExprList */ /* ========================================================================= */ void FunctionList(void) { do { ErrorFlag = 0; FloatFlag = 0; LocalReset(); switch(lookahead) { case ID: FunctionDef(INT); if (ErrorFlag) return; break; case INT: match(INT); if (ErrorFlag) return; FunctionDef(INT); if (ErrorFlag) return; break; case FLOAT: match(FLOAT); if (ErrorFlag) return; FunctionDef(FLOAT); if (ErrorFlag) return; case DONE: break; default: error("Unexpected token found"); return; break; } /* end for switch statement */ } while (lookahead != DONE); } /* end FunctionList */ /* ----------------------------------------------------------------------- */ void FunctionDef(int type) { offset = 1; if (lookahead != ID) { error("Invalid function defintion structure. Expected ID"); return; } /* end if lookahead */ if (LocalIndex) { error("Compiler error, function name in local symbol table"); return; } /* end if LocalIndex */ else if (GlobalIndex) { if (!(GlobalTable[GlobalIndex].function)) { error("Attempting to redefine a global variable as a function name"); return; } /* end if GlobalTable */ else if (GlobalTable[GlobalIndex].function < 0) { error("Redefining a function."); return; } /* end else if GlobalTable */ else if (GlobalTable[GlobalIndex].function > 0) /* function is a postive value, already called not defined */ { GlobalTable[GlobalIndex].type = type; FuncNameIndex = GlobalIndex; GlobalTable[GlobalIndex].function = -1; } /* end else if function > 0 */ else { error("Compiler error, functiondef is confused"); return; } } /* end else if (GlobalIndex) */ else /* ID not in any tabel */ { GlobalIndex = GlobalInsert (lexbuf,ID,type,0,-1,LabelCounter); if (ErrorFlag) ErrorFlag = 0; FuncNameIndex = GlobalIndex; ++LabelCounter; } /* end else */ Scope = GlobalTable[GlobalIndex].functionlabel; /* label function */ emit(LABEL_FUNC, GlobalIndex, 0.0); emit(LABEL_CODE, Scope, 0.0); /* store return address */ emit(STORE_RA, FuncNameIndex, 0.0); ReturnLabel = LabelCounter; ++LabelCounter; match(ID); if (ErrorFlag) ErrorFlag = 0; match('('); if (ErrorFlag) ErrorFlag = 0; if ( strcmp(GlobalTable[FuncNameIndex].lexptr, "main") == 0) { if (lookahead == ')') { match(')'); if (ErrorFlag) return; } /* end if lookahead == ')' */ else { error("Function main cannot have parameters."); return; } /* end else */ } /* end if function is main */ else { ParamList(); if (ErrorFlag) ErrorFlag = 0; match(')'); if (ErrorFlag) ErrorFlag = 0; } /* end else (function is something other than main) */ DecList(); if (ErrorFlag) ErrorFlag = 0; emit(SAVE_FRAMESIZE, FuncNameIndex, 0.0); FstmtList(); if (ErrorFlag) return; if (GlobalTable[FuncNameIndex].type == INT) emit(NUM, 1, 0.0); else emit(RNUM, 0, 1.0); emit(LABEL_CODE, ReturnLabel, 0.0); emit(PUSH_RA, FuncNameIndex, 0.0); emit(B, 0, 0.0); } /* end function Def */ /* ---------------------------------------------------------------------- */ void MoreParams(void) { int tempLocalIndex; if (lookahead == ',') { match(','); if (ErrorFlag) return; if (lookahead != ID) { error("Improperly formed parameter list"); return; } if (GlobalIndex) { if (GlobalTable[GlobalIndex].function) { error("Cannot use a function name as parameter"); return; } /* end if GlobalTable */ } /* GlobalIndex */ if (LocalIndex) { error("Trying to use a prameter twice"); return; } /* end else if (LocalIndex) */ else { tempLocalIndex = LocalIndex = LocalInsert (lexbuf,ID,PARAM,1,0,0); if (ErrorFlag) return; } /* end else */ match (ID); if (ErrorFlag) return; MoreParams(); if (ErrorFlag) return; emit(LOC_DECL, tempLocalIndex, 0.0); emit(PUSH_LOC_VAR_ADDR, tempLocalIndex, 0.0); emit(ISTB, 0, 0.0); ++offset; } /* end if lookahead == ',' */ } /* end MoreParams() */ /* ---------------------------------------------------------------------- */ void ParamList(void) { int tempLocalIndex; if (lookahead == ID) { if (GlobalIndex) { if (GlobalTable[GlobalIndex].function) { error("Cannot use a function name as parameter"); return; } /* end if GlobalTable */ } /* GlobalIndex */ if (LocalIndex) { error("Trying to use a parameter twice"); return; } /* end else if (LocalIndex) */ else { tempLocalIndex = LocalIndex = LocalInsert (lexbuf,ID,PARAM,1,0,0); if (ErrorFlag) return; } /* end else */ match (ID); if (ErrorFlag) return; MoreParams(); if (ErrorFlag) return; emit(LOC_DECL, tempLocalIndex, 0.0); emit(PUSH_LOC_VAR_ADDR, tempLocalIndex, 0.0); emit(ISTB, 0, 0.0); ++offset; } /* end if lookahead == ID */ } /* end paramlist() */ /* ------------------------------------------------------------------ */ void DecList(void) { while ((lookahead == INT) || (lookahead == FLOAT)) { match (lookahead); /* obviously must be INT or FLOAT */ if (ErrorFlag) return; VarList (PreviousLookahead); if (ErrorFlag) return; } /* end while ((lookahead == INT) || (loookahead == FLOAT)) */ ParamInt(); } /* end function DecList */ /* --------------------------------------------------------------------- */ void VarList(int type) { int tempLocalIndex; do { if (GlobalIndex) { if (GlobalTable[GlobalIndex].function) { error ("Cannot use a function name as a parameter"); return; } /* end if GlogalTable */ } /* end if (GlobalIndex) */ if (LocalIndex) { if (LocalTable[LocalIndex].type == PARAM) { if (NextLookahead == '[') error ("Cannot pass an array as a parameter"); else { LocalTable[LocalIndex].type = type; match(ID); if (ErrorFlag) return; } /* end else */ } /* end if LocalTable[LocalIndex] */ else { error ("Trying to redefine a variable"); return; } /* end else */ } /* end if LocalIndex */ else /* variable is not entered as a local so insert */ { if (NextLookahead == '[') { tempLocalIndex = LocalIndex = LocalInsert (lexbuf,ARRAY,type,0,0,0); if (ErrorFlag) return; lookahead = ARRAY; match (ARRAY); if (ErrorFlag) return; match ('['); if (ErrorFlag) return; if (lookahead == NUM) { LocalTable[tempLocalIndex].size = tokenval; if (ErrorFlag) return; } else { error("Array declarations requires an integer within []"); return; } match (NUM); if (ErrorFlag) return; match (']'); if (ErrorFlag) return; emit(LOC_DECL, tempLocalIndex, 0.0); offset += LocalTable[tempLocalIndex].size; } /* end if nextlook */ else { LocalIndex = LocalInsert(lexbuf,ID,type,1,0,0); if (ErrorFlag) return; emit(LOC_DECL, LocalIndex, 0.0); ++offset; match (ID); if (ErrorFlag) return; } /* end else */ } /* end else */ switch (lookahead) { case ',': match (','); if (ErrorFlag) return; break; case ';': match (';'); if (ErrorFlag) return; return; break; default: error ("badly formed declarations"); return; } /* end switch (lookahead) */ } while ((lookahead == ID) || (lookahead == ARRAY)); error("can only use ID or ARRAAY"); return; } /* end function VarList */ /* ------------------------------------------------------------------- */ void FstmtList(void) { match ('{'); if (ErrorFlag) ErrorFlag = 0; do { parseAStmt(); if (ErrorFlag) ErrorFlag = 0; } while ((lookahead != '}') && (lookahead != DONE)); if (lookahead == DONE) { error("Unexpected end of file"); return; } /* end if */ else { match ('}'); if (ErrorFlag) return; } /* end else */ } /* end function FstmtList */