program7.c

#include <stdio.h>
#include <string.h>
#include <stdlib.h>

int main() {
    char opcode[10], operand[10], label[10], code[10], mnemonic[3];
    int locctr, start, length;
    FILE *fp1, *fp2, *fp3, *fp4;

    fp1 = fopen("Input.txt", "r");
    fp2 = fopen("Optab.txt", "r");
    fp3 = fopen("Symtabl.txt", "w");
    fp4 = fopen("Out.txt", "w");

    fscanf(fp1, "%s\t%s\t%s", label, opcode, operand);

    if (strcmp(opcode, "START") == 0) {
        start = atoi(operand);
        locctr = start;
        fprintf(fp4, "\t%s\t%s\t%s\n", label, opcode, operand);
        fscanf(fp1, "%s\t%s\t%s", label, opcode, operand);
    } else
        locctr = 0;

    while (strcmp(opcode, "END") != 0) {
        if (strcmp(label, "**") != 0)
            fprintf(fp3, "%s\t%d\n", label, locctr);

        fscanf(fp2, "%s\t%s", code, mnemonic);

        while (strcmp(code, "END") != 0) {
            if (strcmp(opcode, code) == 0) {
                locctr += 3;
                break;
            }
            fscanf(fp2, "%s\t%s", code, mnemonic);
        }

        if (strcmp(opcode, "WORD") == 0)
            locctr += 3;
        else if (strcmp(opcode, "RESW") == 0)
            locctr += (3 * (atoi(operand)));
        else if (strcmp(opcode, "RESB") == 0)
            locctr += atoi(operand);
        else if (strcmp(opcode, "BYTE") == 0)
            ++locctr;

        fprintf(fp4, "%s\t%s\t%s\t\n", label, opcode, operand);
        fscanf(fp1, "%s\t%s\t%s", label, opcode, operand);
    }

    fprintf(fp4, "%d\t%s\t%s\t%s\n", locctr, label, opcode, operand);
    length = locctr - start;
    printf("The length of the code:%d\n", length);

    fclose(fp1);
    fclose(fp2);
    fclose(fp3);
    fclose(fp4);
}