Untitled

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

void display();

void swap(char *x, char *y) {
  char t = *x; *x = *y; *y = t;
}
 
char* reverse(char *buffer, int i, int j)
{  while (i < j) {
     swap(&buffer[i++], &buffer[j--]);
   }
 return buffer;
}

char* itoa(int value, char* buffer, int base)
{  if (base < 2 || base > 32) {
    return buffer;
   }
 int n = abs(value);
 int i = 0;
 while (n)
  { int r = n % base;
    if (r >= 10) {
      buffer[i++] = 65 + (r - 10);
    }
    else {
       buffer[i++] = 48 + r;
     }
    n = n / base;
   }
 if (i == 0) {
    buffer[i++] = '0';
  }
 if (value < 0 && base == 10) {
    buffer[i++] = '-';
  }
  buffer[i] = '\0';
  return reverse(buffer, 0, i - 1);
}

int main()
{ char a[10], ad[10], label[10], opcode[10], operand[10], symbol[10];
  int start, diff, i, address, add, len, actual_len, finaddr, prevaddr, j = 0;
  char mnemonic[15][15] = {"LDA", "STA", "LDCH", "STCH"};
  char code[15][15] = {"03", "0F", "53", "57"};

   FILE *fp1, *fp2, *fp3, *fp4;
   fp1 = fopen("output.txt", "w");
   fp2 = fopen("symtab.txt", "r");
   fp3 = fopen("intermediate.txt", "r");
   fp4 = fopen("objcode.txt", "w");
   fscanf(fp3, "%s\t%s\t%s", label, opcode, operand);
   while (strcmp(opcode, "END") != 0)
   { prevaddr = address;
     fscanf(fp3, "%d%s%s%s", &address, label, opcode, operand);
    }
    finaddr = address;
    fclose(fp3);
    fp3 = fopen("intermediate.txt", "r");

    fscanf(fp3, "\t%s\t%s\t%s", label, opcode, operand);
    if (strcmp(opcode, "START") == 0)
    {fprintf(fp1, "\t%s\t%s\t%s\n", label, opcode, operand);
     fprintf(fp4, "H^%s^00%s^00%d\n", label, operand, finaddr);
     fscanf(fp3, "%d%s%s%s", &address, label, opcode, operand);
     start = address;
     diff = prevaddr - start;
     fprintf(fp4, "T^00%d^%d", address, diff);
    }
    
    while (strcmp(opcode, "END") != 0)
    { if (strcmp(opcode, "BYTE") == 0)
        { fprintf(fp1, "%d\t%s\t%s\t%s\t", address, label, opcode, operand);
          len = strlen(operand);
          actual_len = len - 3;
          fprintf(fp4, "^");
          for (i = 2; i < (actual_len + 2); i++)
          { itoa(operand[i], ad, 16);
            fprintf(fp1, "%s", ad);
            fprintf(fp4, "%s", ad);
           }
           fprintf(fp1, "\n");
        }
      else if (strcmp(opcode, "WORD") == 0)
      { len = strlen(operand);
        itoa(atoi(operand), a, 10);
        fprintf(fp1, "%d\t%s\t%s\t%s\t00000%s\n", address, label, opcode, operand, a);
        fprintf(fp4, "^00000%s", a);
      }
      else if ((strcmp(opcode, "RESB") == 0) || (strcmp(opcode, "RESW") == 0)) {
        fprintf(fp1, "%d\t%s\t%s\t%s\n", address, label, opcode, operand);
      }
      else
      {  while (strcmp(opcode, mnemonic[j]) != 0)      
            j++;
         if (strcmp(operand, "COPY") == 0)
            fprintf(fp1, "%d\t%s\t%s\t%s\t%s0000\n", address, label, opcode, operand, code[j]);
         else {
               rewind(fp2);
               fscanf(fp2, "%s%d", symbol, &add);
               while (strcmp(operand, symbol) != 0)
                    fscanf(fp2, "%s%d", symbol, &add);
               fprintf(fp1, "%d\t%s\t%s\t%s\t%s%d\n", address, label, opcode, operand, code[j], add);
               fprintf(fp4, "^%s%d", code[j], add);
         }
      }
      fscanf(fp3, "%d%s%s%s", &address, label, opcode, operand);
    }
   fprintf(fp1, "%d\t%s\t%s\t%s\n", address, label, opcode, operand);
   fprintf(fp4, "\nE^00%d\n", start);
   fclose(fp4);
   fclose(fp3);
   fclose(fp2);
   fclose(fp1);
   display();

   return 0;
}

void display() {
  char ch;
  FILE *fp1, *fp2, *fp3, *fp4;
  printf("\nIntermediate file is converted into object code");

  printf("\n\nThe contents of Intermediate file:\n\n");
  fp3 = fopen("intermediate.txt", "r");
  ch = fgetc(fp3);
  while (ch != EOF)
   { printf("%c", ch);
     ch = fgetc(fp3);
   }
  fclose(fp3);

  printf("\n\nThe contents of Symbol Table :\n\n");
  fp2 = fopen("symtab.txt", "r");
  ch = fgetc(fp2);
  while (ch != EOF)
   { printf("%c", ch);
     ch = fgetc(fp2);
   }
   fclose(fp2);

   printf("\n\nThe contents of Output file :\n\n");
   fp1 = fopen("output.txt", "r");
   ch = fgetc(fp1);
   while (ch != EOF)
   { printf("%c", ch);
      ch = fgetc(fp1);
   }
   fclose(fp1);

   printf("\n\nThe contents of Object code file :\n\n");
   fp4 = fopen("objcode.txt", "r");
   ch = fgetc(fp4);
   while (ch != EOF)
   { printf("%c", ch);
     ch = fgetc(fp4);
    }
   fclose(fp4);
 }