Pass 1: Generating Symbol Table

Pass 1 Code: to generate symbol table and IR file

#include <stdio.h>

#include <string.h>

#include <stdlib.h>

#define MAX_LINES 100

#define MAX_LABELS 50

#define MAX_LINE_LENGTH 100

typedef struct {

    char label[50];

    int address;

} Symbol;

Symbol symbolTable[MAX_LABELS];

int symbolCount = 0;

typedef struct {

    int address;

    char instruction[MAX_LINE_LENGTH];

} IR;

IR irTable[MAX_LINES];

int irCount = 0;

int currentAddress = 0;

void addSymbol(const char *label, int address) {

    strcpy(symbolTable[symbolCount].label, label);

    symbolTable[symbolCount].address = address;

    symbolCount++;

}

int isLabel(const char *line) {

    int len = strlen(line);

    if (len > 1 && line[len - 1] == ':') {

        return 1;

    }

    return 0;

}

int isThumbInstruction(const char *instruction) {

    // Check for "Thumb" instructions by looking for specific patterns or keywords

    return (strstr(instruction, "MOVS") || strstr(instruction, "ADDS") || strstr(instruction, "SUBS") ||

            strstr(instruction, "CMP") || strstr(instruction, "BEQ") || strstr(instruction, "B") ||

            strstr(instruction, "ANDS") || strstr(instruction, "ORRS") || strstr(instruction, "EORS"));

}

int isIgnoredLine(const char *line) {

    // Skip lines containing specific keywords

    return (strstr(line, "AREA") || strstr(line, "ENTRY") || strstr(line, "CODE") || strstr(line, "READONLY") || strstr(line, "END"));

}

void processLine(const char *line) {

    char trimmedLine[MAX_LINE_LENGTH];

    strcpy(trimmedLine, line);

    // Remove comments

    char *comment = strchr(trimmedLine, ';');

    if (comment) {

        *comment = '\0';

    }

    // Trim leading and trailing whitespace

    char *start = trimmedLine;

    while (*start == ' ' || *start == '\t') start++;

    char *end = trimmedLine + strlen(trimmedLine) - 1;

    while (end > start && (*end == ' ' || *end == '\t' || *end == '\n')) *end-- = '\0';

    // Skip empty lines or ignored lines

    if (*start == '\0' || isIgnoredLine(start)) return;

    // Check if line is a label

    if (isLabel(start)) {

        char label[50];

        strncpy(label, start, strlen(start) - 1);

        label[strlen(start) - 1] = '\0';

        addSymbol(label, currentAddress);

        return;

    }

    // Add to IR table

    irTable[irCount].address = currentAddress;

    strcpy(irTable[irCount].instruction, start);

    irCount++;

    // Increment address based on instruction type

    if (isThumbInstruction(start)) {

        currentAddress += 2; // Thumb instructions are 2 bytes

    } else {

        currentAddress += 4; // Non-Thumb instructions are 4 bytes

    }

}

void printSymbolTable() {

    printf("Symbol Table:\n");

    for (int i = 0; i < symbolCount; i++) {

        printf("%06X\t%s\n", symbolTable[i].address, symbolTable[i].label);

    }

}

void printIRTable() {

    printf("\nIntermediate Representation (IR):\n");

    for (int i = 0; i < irCount; i++) {

        printf("%06X\t%s\n", irTable[i].address, irTable[i].instruction);

    }

}

int main() {

    FILE *file = fopen("input.txt", "r");

    if (!file) {

        printf("Error: Could not open file.\n");

        return 1;

    }

    char line[MAX_LINE_LENGTH];

    currentAddress = 0; // Start address from 000000

    while (fgets(line, sizeof(line), file)) {

        processLine(line);

    }

    fclose(file);

    printSymbolTable();

    printIRTable();

    return 0;

}