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compiler.c
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// Ryan Weisman
// COP 3402 Spring 2023
// All libraries included
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
// defines the maximum table size and maximum code size
#define MAX_SYMBOL_TABLE_SIZE 500
#define CODE_SIZE 500
// Data structures for symbol table and assembly code array
typedef struct
{
int kind;
char name[12];
int val;
int level;
int addr;
int mark;
} symbol;
typedef struct
{
char OP[4];
int L;
int M;
} code;
// Initializes arrays for the assembly code (text) and the symbol table
symbol symbolTable[MAX_SYMBOL_TABLE_SIZE];
code text[CODE_SIZE];
// These global variables are used to keep uniform indexes throughout the entire program
int lexLevel = -1;
int lexIndex = 0;
int tableIndex = 0;
int cx = 0;
char token[12] = "";
// An enumerator for all symbols
typedef enum
{
skipsym = 1,
identsym,
numbersym,
plussym,
minussym,
multsym,
slashsym,
oddsym,
eqlsym,
neqsym,
lessym,
leqsym,
gtrsym,
geqsym,
lparentsym,
rparentsym,
commasym,
semicolonsym,
periodsym,
becomessym,
beginsym,
endsym,
ifsym,
thensym,
whilesym,
dosym,
callsym,
constsym,
varsym,
procsym,
writesym,
readsym,
elsesym
} tokens;
// Helper functions declared
int checkValid(char programString[]);
int printLexList(char *programString, char **word, char *lexList);
void printText();
// Symbol Table functions
void addSymbol(int kind, char *name, int val, int level, int addr, int mark);
int checkSymbolTable(char *name, int level);
// Functions for each non-terminal symbol
int programCheck(char *lexList);
int blockCheck(char *lexList);
int constCheck(char *lexList);
int varCheck(char *lexList);
int procedureCheck(char *lexList);
int statementCheck(char *lexList);
int checkCondition(char *lexList);
int checkExpression(char *lexList);
int checkTerm(char *lexList);
int checkFactor(char *lexList);
// Functions for emitting, error, and getting the next token
int emit(char *OP, int L, int M);
int error(int errorCode, char *symbol);
void getToken(char *lexList, char *token);
// Main function
int main(int argc, char *argv[])
{
// Variable defined for this function
FILE *ifp = fopen(argv[1], "r");
int count = 1;
int i = 0;
char c;
char *word[] = {"begin", "const", "do", "end", "if", "odd", "read", "then", "var",
"while", "write", "call", "procedure"};
// Checks for null pointers
if (ifp == NULL)
{
printf("Error: File not found.");
return -1;
}
// Gets first character from input file
c = fgetc(ifp);
// Copys content of input file to ouput file
printf("\nSource Program:\n\n");
while (!feof(ifp))
{
printf("%c", c);
if (c != ' ' && c != '\t' && c != '\n')
count++;
c = fgetc(ifp);
}
// Creates a string to hold all valid scanner characters with bars at terminal character
char programString[count * 2];
rewind(ifp);
c = fgetc(ifp);
while (1)
{
if (c == '.' || feof(ifp))
{
if (feof(ifp))
{
programString[i] = '\0';
break;
}
programString[i] = '|';
programString[i + 1] = c;
programString[i + 2] = '\0';
break;
}
if (c == ',' || c == ';' || c == '+' || c == '-' || c == '/' || c == '*' || c == ':' || c == '<' || c == '>' || c == '=')
{
if (i >= 1)
{
char tempChar = programString[i - 1];
if ((tempChar >= 'A' && tempChar <= 'Z') || (tempChar >= 'a' && tempChar <= 'z') || (tempChar >= '0' && tempChar <= '9'))
{
programString[i] = '|';
i += 1;
}
}
programString[i] = c;
i += 1;
programString[i] = '|';
}
else if (c == ' ' || c == '\t' || c == '\n')
{
if (programString[i - 1] != '|')
programString[i] = '|';
else
{
c = fgetc(ifp);
continue;
}
}
else if (c != ' ' && c != '\t' && c != '\n')
{
programString[i] = c;
}
c = fgetc(ifp);
i++;
}
fclose(ifp);
// This calls a function to check to invalid characters and length of numbers and identifiers
if (checkValid(programString) == -1)
return -1;
char lexList[strlen(programString)];
lexList[0] = '\0';
// Function to create the lexeme list
if (printLexList(programString, word, lexList) == 0)
return -1;
// Adds main function and JMP call to symbol table and text respectively
addSymbol(3, "main", 0, 0, 0, 0);
// This call begins our parser. First with a check that the program is valid
if (programCheck(lexList) == -1)
return -1;
printf("\n\nNo errors, program is syntactically correct.\n");
// This is where everything prints to the terminal
printf("\nAssembly Code:\n\n");
printText();
printf("\n");
return 1;
}
// This function is used to check the input string for invalid characters and numbers and
// identifiers that are too long
int checkValid(char programString[])
{
// All variables for this function
char c;
int i = 0;
int numCounter = 0;
int charCounter = 0;
int trueNum = 0;
// This while loop is used to iterate over the programString
while (1)
{
c = programString[i];
// If we reach the end the program we break out of the loop
if (c == '.' || c == '\0')
{
if (c == '\0')
return error(9, "");
break;
}
// This if statement checks for valid characters. The inner while loop skips over comments
if ((c >= '(' && c <= '>') || (c >= 'A' && c <= 'Z') || (c >= 'a' && c <= 'z') || c == '|')
{
if (programString[i] == '/' && programString[i + 1] == '|' && programString[i + 2] == '*')
{
while (1)
{
if (programString[i - 2] == '*' && programString[i - 1] == '|' && programString[i] == '/')
{
i++;
c = programString[i];
break;
}
i++;
}
}
// This if statement checks if each lexeme is within the contraints
if (c == '|')
{
if (numCounter > 5)
return error(25, "");
if (charCounter > 11)
return error(26, "");
numCounter = 0;
trueNum = 0;
charCounter = 0;
}
// This is for finding number rather than identifiers
if ((c >= '0' && c <= '9') && programString[i - 1] == '|')
trueNum = 1;
if (trueNum == 1)
numCounter++;
else
charCounter++;
}
else
{
// This prints any invalid characters
char invalid[2];
invalid[0] = c;
return error(27, invalid);
}
i++;
}
return 1;
}
// This function prints the Lexeme List
int printLexList(char *programString, char **word, char *lexList)
{
// Some variable defined for this function
char c;
int i = 0, j = 0;
// This while loop is used to iterate over the programString
while (1)
{
// Here a temporary string is made to hold each lexeme as it is read in
c = programString[i];
j = 0;
char tempString[12] = "";
char tempIdent[12] = "";
// If a '.' is found the while loop breaks
if (c == '.')
{
sprintf(tempIdent, "%d", periodsym);
strcat(lexList, tempIdent);
break;
}
// This if statement iterates over comments because they can be ignored
if (programString[i] == '/' && programString[i + 1] == '|' && programString[i + 2] == '*')
{
while (1)
{
if (programString[i - 2] == '*' && programString[i - 1] == '|' && programString[i] == '/')
{
i++;
c = programString[i];
break;
}
i++;
}
}
// This is where keywords and identifiers are detected and put into the lexeme list
if ((c >= 'A' && c <= 'Z') || (c >= 'a' && c <= 'z'))
{
// This while loop creates a temporary string to hold the current lexeme
while (1)
{
if (programString[i] != '|')
{
tempString[j] = programString[i];
j++;
i++;
}
else
break;
}
// These if statements determine what the lexeme is, either a keyword or identifier
if (strcmp(tempString, word[0]) == 0)
{
sprintf(tempIdent, "%d", beginsym);
strcat(lexList, tempIdent);
strcat(lexList, "|");
}
else if (strcmp(tempString, word[1]) == 0)
{
sprintf(tempIdent, "%d", constsym);
strcat(lexList, tempIdent);
strcat(lexList, "|");
}
else if (strcmp(tempString, word[2]) == 0)
{
sprintf(tempIdent, "%d", dosym);
strcat(lexList, tempIdent);
strcat(lexList, "|");
}
else if (strcmp(tempString, word[3]) == 0)
{
sprintf(tempIdent, "%d", endsym);
strcat(lexList, tempIdent);
strcat(lexList, "|");
}
else if (strcmp(tempString, word[4]) == 0)
{
sprintf(tempIdent, "%d", ifsym);
strcat(lexList, tempIdent);
strcat(lexList, "|");
}
else if (strcmp(tempString, word[5]) == 0)
{
sprintf(tempIdent, "%d", oddsym);
strcat(lexList, tempIdent);
strcat(lexList, "|");
}
else if (strcmp(tempString, word[6]) == 0)
{
sprintf(tempIdent, "%d", readsym);
strcat(lexList, tempIdent);
strcat(lexList, "|");
}
else if (strcmp(tempString, word[7]) == 0)
{
sprintf(tempIdent, "%d", thensym);
strcat(lexList, tempIdent);
strcat(lexList, "|");
}
else if (strcmp(tempString, word[8]) == 0)
{
sprintf(tempIdent, "%d", varsym);
strcat(lexList, tempIdent);
strcat(lexList, "|");
}
else if (strcmp(tempString, word[9]) == 0)
{
sprintf(tempIdent, "%d", whilesym);
strcat(lexList, tempIdent);
strcat(lexList, "|");
}
else if (strcmp(tempString, word[10]) == 0)
{
sprintf(tempIdent, "%d", writesym);
strcat(lexList, tempIdent);
strcat(lexList, "|");
}
else if (strcmp(tempString, word[11]) == 0)
{
sprintf(tempIdent, "%d", callsym);
strcat(lexList, tempIdent);
strcat(lexList, "|");
}
else if (strcmp(tempString, word[12]) == 0)
{
sprintf(tempIdent, "%d", procsym);
strcat(lexList, tempIdent);
strcat(lexList, "|");
}
else
{
sprintf(tempIdent, "%d", identsym);
strcat(lexList, tempIdent);
strcat(lexList, "|");
strcat(lexList, tempString);
strcat(lexList, "|");
}
}
// This else if activates when a operation, terminal character, or number is detected
else if (c >= '(' && c <= '>')
{
if (c >= '0' && c <= '9')
{
// This while loop creates a temporary string to hold the current lexeme
while (1)
{
if (programString[i] != '|')
{
tempString[j] = programString[i];
j++;
i++;
}
else
break;
}
sprintf(tempIdent, "%d", numbersym);
strcat(lexList, tempIdent);
strcat(lexList, "|");
sprintf(tempString, "%s", tempString);
strcat(lexList, tempString);
strcat(lexList, "|");
}
else
{
// This switch is used to detect operators and terminal characters
switch (c)
{
case '+':
sprintf(tempString, "%d", plussym);
strcat(lexList, tempString);
strcat(lexList, "|");
break;
case '-':
sprintf(tempString, "%d", minussym);
strcat(lexList, tempString);
strcat(lexList, "|");
break;
case '*':
sprintf(tempString, "%d", multsym);
strcat(lexList, tempString);
strcat(lexList, "|");
break;
case '/':
sprintf(tempString, "%d", slashsym);
strcat(lexList, tempString);
strcat(lexList, "|");
break;
case '(':
sprintf(tempString, "%d", lparentsym);
strcat(lexList, tempString);
strcat(lexList, "|");
break;
case ')':
sprintf(tempString, "%d", rparentsym);
strcat(lexList, tempString);
strcat(lexList, "|");
break;
case ',':
sprintf(tempString, "%d", commasym);
strcat(lexList, tempString);
strcat(lexList, "|");
break;
case ';':
sprintf(tempString, "%d", semicolonsym);
strcat(lexList, tempString);
strcat(lexList, "|");
break;
case '=':
sprintf(tempString, "%d", eqlsym);
strcat(lexList, tempString);
strcat(lexList, "|");
break;
case '>':
if (programString[i + 2] == '=')
{
sprintf(tempString, "%d", geqsym);
strcat(lexList, tempString);
strcat(lexList, "|");
i += 3;
}
else
{
sprintf(tempString, "%d", gtrsym);
strcat(lexList, tempString);
strcat(lexList, "|");
}
break;
case '<':
if (programString[i + 2] == '=')
{
sprintf(tempString, "%d", leqsym);
strcat(lexList, tempString);
strcat(lexList, "|");
i += 3;
}
else if (programString[i + 2] == '>')
{
sprintf(tempString, "%d", neqsym);
strcat(lexList, tempString);
strcat(lexList, "|");
i += 3;
}
else
{
sprintf(tempString, "%d", lessym);
strcat(lexList, tempString);
strcat(lexList, "|");
}
break;
case ':':
if (programString[i + 2] == '=')
{
sprintf(tempString, "%d", becomessym);
strcat(lexList, tempString);
strcat(lexList, "|");
i += 3;
}
else
return error(27, ":");
break;
}
}
}
i++;
}
return 1;
}
// This function is used to search the symbol table for a name
int checkSymbolTable(char *identName, int mode)
{
for (int i = tableIndex - 1; i > 0; i--)
{
if (symbolTable[i].mark != 1)
{
if (mode == 1)
{
if ((strcmp(symbolTable[i].name, identName) == 0) && (symbolTable[i].level == lexLevel))
return i;
}
else
{
if (strcmp(symbolTable[i].name, identName) == 0)
return i;
}
}
}
return -1;
}
// This function is used to add symbols to the symbol table
void addSymbol(int kind, char *name, int val, int level, int addr, int mark)
{
symbolTable[tableIndex].kind = kind;
strcpy(symbolTable[tableIndex].name, name);
symbolTable[tableIndex].val = val;
symbolTable[tableIndex].level = level;
symbolTable[tableIndex].addr = addr;
symbolTable[tableIndex].mark = mark;
tableIndex++;
}
// Functions for parser and code generation
// This is the program function. It calls the block function and checks for a
// period at the end of the input file
int programCheck(char *lexList)
{
// Here we call the Block function, if theres an error we return -1;
if (blockCheck(lexList) != -1)
{
char buffer[3] = "";
int j = 0;
for (int i = 2; i > 0; i--)
{
buffer[j] = lexList[strlen(lexList) - i];
j++;
}
// This checks for a period at the end
if (atoi(buffer) != periodsym)
return error(9, "");
}
else
return -1;
// This emits the halt OP
if (emit("SYS", 0, 3) == -1)
return -1;
return 1;
}
// This is the block function, it checks for constants, variables, and statements
int blockCheck(char *lexList)
{
// A jump address is kept for each procedure
// the lexicographical level is also incremented
int jmpAddress = cx;
lexLevel++;
if (emit("JMP", 0, 0) == -1)
return -1;
int numVars = 0;
getToken(lexList, token);
// Here are the other function calls
if (constCheck(lexList) == -1)
return -1;
if ((numVars = varCheck(lexList)) == -1)
return -1;
if (procedureCheck(lexList) == -1)
return -1;
// the procedure JMP is updated with the current code index
text[jmpAddress].M = cx;
if (emit("INC", 0, numVars + 3) == -1)
return -1;
if (statementCheck(lexList) == -1)
return -1;
if (lexLevel != 0)
{
if (emit("OPR", 0, 0) == -1)
return -1;
}
// The lexicographical level is decremented
lexLevel--;
return 1;
}
// This is the constant function, it checks for a valid constant assignment
int constCheck(char *lexList)
{
int num;
if (atoi(token) == constsym)
{
while (1)
{
num = 0;
char name[12] = "";
getToken(lexList, token);
// Checks for an identifier
if (atoi(token) != identsym)
return error(4, "");
getToken(lexList, token);
strcpy(name, token);
// Checks the symbol table for the indentifier passed
if (checkSymbolTable(name, 1) != -1)
return error(3, name);
getToken(lexList, token);
// Checks for an assignment using the = symbol
if (atoi(token) != eqlsym)
return error(1, "");
getToken(lexList, token);
// Checks for a number
if (atoi(token) != numbersym)
return error(2, "");
// Here we add the constant to the symbol table
getToken(lexList, token);
num = atoi(token);
addSymbol(1, name, num, lexLevel, 0, 0);
getToken(lexList, token);
// This checks for a comma or a semicolon after the assignment,
// otherwise throws an error
if (atoi(token) == commasym || atoi(token) == semicolonsym)
{
if (atoi(token) == semicolonsym)
break;
}
else
return error(5, "");
}
getToken(lexList, token);
}
return 1;
}
// This is the variable function, it checks for a valid constant assignment
int varCheck(char *lexList)
{
int numVars = 0;
if (atoi(token) == varsym)
{
// This while loop is used to count the varaible in an assignment statement
while (1)
{
numVars++;
char name[12] = "";
getToken(lexList, token);
// Checks for an identifier
if (atoi(token) != identsym)
return error(4, "");
getToken(lexList, token);
strcpy(name, token);
// Checks for the identifier in the symbol table
if (checkSymbolTable(name, 1) != -1)
return error(3, name);
// Adds the variable to the symbol table
addSymbol(2, name, 0, lexLevel, numVars + 2, 0);
getToken(lexList, token);
// This checks for a comma or a semicolon after the assignment,
// otherwise throws an error
if (atoi(token) == commasym || atoi(token) == semicolonsym)
{
if (atoi(token) == semicolonsym)
break;
}
else
return error(5, "");
}
getToken(lexList, token);
}
return numVars;
}
// This is the procedure chech function, it makes sure the procedure is impemented correctly
int procedureCheck(char *lexList)
{
// A mark index is initialized for later use
int markIndex = 0;
if (atoi(token) == procsym)
{
while (1)
{
// Checks for an identifier
getToken(lexList, token);
if (atoi(token) != identsym)
return error(4, "");
char name[12] = "";
getToken(lexList, token);
strcpy(name, token);
// Checks for the identifier in the symbol table
if (checkSymbolTable(name, 1) != -1)
return error(3, "");
// Adds the procedure name to the symbol table and set the mark index
addSymbol(3, name, 0, lexLevel, cx, 0);
getToken(lexList, token);
markIndex = tableIndex;
if (atoi(token) != semicolonsym)
return error(6, "");
if (blockCheck(lexList) == -1)
return -1;
// Marks all the finished symbols
for (int i = markIndex; i < tableIndex; i++)
symbolTable[i].mark = 1;
if (atoi(token) != semicolonsym)
return error(8, "");
getToken(lexList, token);
if (atoi(token) != procsym)
break;
}
}
return 1;
}
// This is the statement function, it will call other non-terminal functions,
// otherwise it will return -1
int statementCheck(char *lexList)
{
int symIdx = 0;
int i = 0;
int jpcIdx = 0;
int loopIdx = 0;
// Checks if token it an identifier
if (atoi(token) == identsym)
{
char name[12] = "";
getToken(lexList, token);
strcpy(name, token);
symIdx = checkSymbolTable(name, 0);
// This throws an error if the identifier was not declared
if (symIdx == -1)
return error(11, name);
// This throws an error if the identifier is not a variable
if (symbolTable[symIdx].kind != 2)
return error(12, "");
getToken(lexList, token);
// This throws an error is the next token is not :=
if (atoi(token) != becomessym)
return error(13, "");
getToken(lexList, token);
// Checks for a valid expression
if (checkExpression(lexList) == -1)
return -1;
// Emits the STO instruction
if (emit("STO", (lexLevel - symbolTable[symIdx].level), symbolTable[symIdx].addr) == -1)
return -1;
return 1;
}
// Checks if token is the 'call' keyword
if (atoi(token) == callsym)
{
getToken(lexList, token);
// Checks for an identifier
if (atoi(token) != identsym)
return error(14, "");
char name[12] = "";
getToken(lexList, token);
strcpy(name, token);
symIdx = checkSymbolTable(name, 0);
// This throws an error if the identifier was not declared
if (symIdx == -1)
return error(11, name);
// This throws an error if the identifier is not a procedure
if (symbolTable[symIdx].kind != 3)
return error(15, "");
// Emits a CAL OP
if (emit("CAL", (lexLevel - symbolTable[symIdx].level), symbolTable[symIdx].addr) == -1)
return -1;
getToken(lexList, token);
return 1;
}
// Checks if token is the 'begin' keyword
if (atoi(token) == beginsym)
{
// Loops until the 'end' keyword
while (1)
{
getToken(lexList, token);
// Calls the statement function again
if (statementCheck(lexList) == -1)
return -1;
// Checks for a semicolon or 'end' keyword, otherwise it throws an error
if (atoi(token) == semicolonsym || atoi(token) == endsym)
{
if (atoi(token) == endsym)
break;
}
else
return error(17, "");
}
getToken(lexList, token);
return 1;
}
// Checks for the 'if' keyword
if (atoi(token) == ifsym)
{
getToken(lexList, token);
// Calls the condition function
if (checkCondition(lexList) == -1)
return -1;
// Emits JPC
jpcIdx = cx;
if (emit("JPC", 0, 0) == -1)
return -1;
// Checks for the 'then' keyword
if (atoi(token) != thensym)
return error(16, "");
getToken(lexList, token);
// Calls the statement function
if (statementCheck(lexList) == -1)
return -1;
text[jpcIdx].M = cx;
return 1;
}
// Checks if token is 'while' keyword
if (atoi(token) == whilesym)
{
getToken(lexList, token);
loopIdx = cx;
// Calls condition function
if (checkCondition(lexList) == -1)
return -1;
// Checks if token is 'do' keyword
if (atoi(token) != dosym)
return error(18, "");
getToken(lexList, token);
// Emits JPC
jpcIdx = cx;
if (emit("JPC", 0, 0) == -1)
return -1;
// Calls statement check
if (statementCheck(lexList) == -1)
return -1;
// Emits JMP
if (emit("JMP", 0, loopIdx) == -1)
return -1;
text[jpcIdx].M = cx;
return 1;
}
// Checks if the token is 'read' symbol table
if (atoi(token) == readsym)