#include<stdio.h>

#include<string.h>

#include<stdlib.h>

void main(){

FILE *f1,*f2,*f3,*f4;//file pointers

int start,location_counter,length,f=0;

char label[10],opcode[10],operand[10],mnemonic[10],code[10],extra[10];

//input file,symbol table and intermediate file

f1=fopen("input.txt","r");

f3=fopen("symtab.txt","w");

f4=fopen("output.txt","w");

printf("SYMTAB IS:\n");

fscanf(f1,"%s\t%s\t%s",label,opcode,operand);

if (strcmp(opcode,"START")==0)

{

start=atoi(operand);

location_counter=start;

fprintf(f4,"\t%s\t%s\t%s\n",label,opcode,operand);

fscanf(f1,"%s\t%s\t%s",label,opcode,operand);

}

else

{

location_counter=0;

}

while(!feof(f1)){//end of input filr

fprintf(f4,"\t%d",location_counter);

if(strcmp(label,"--")!=0){

fprintf(f3,"%d\t%s\n",location_counter,label);

printf("\t%d\t%s\n",location_counter,label);

}

f2=fopen("optab.txt","r");

fscanf(f2,"%s\t%s",code,mnemonic);

while (!feof(f2))//end of optab

{

if(strcmp(code,opcode)==0){

location_counter+=3;

break;

}

fscanf(f2,"%s\t%s",code,mnemonic);

}

fclose(f2);

if(strcmp(opcode,"WORD")==0)

location_counter+=3;

else if(strcmp(opcode,"RESW")==0)

location_counter+=(3*(atoi(operand)));

else if(strcmp(opcode,"RESB")==0)

{

location_counter+=(atoi(operand));

}

else if(strcmp(opcode,"BYTE")==0)

{

location_counter+=strlen(operand);

}

fprintf(f4,"\t%s\t%s\n",label,opcode,operand);//write to file

fscanf(f1,"%s\t%s\t%s",label,opcode,operand);//read to file

}

fprintf(f4,"\t%d\t%s\t%s",location_counter,label,opcode,operand);

//compute length of input source code and display it

length=location_counter-start;

printf("Length of the input source code is: %d",length);

fclose(f1);

fclose(f3);

fclose(f4);

}