Design suitable data structures and implement pass-I of a two-pass assembler for pseudo-machine in Java using object oriented feature. Implementation should consist of a few instructions from each category and few assembler directives.

-

 /*

Problem Statement: Design suitable data structures and implement pass-I of a two-pass assembler for pseudo-

machine in Java using object oriented feature. Implementation should consist of a few

instructions from each category and few assembler directives.

*/

import java.io.*;

class SymTab

{

public static void main(String args[])throws Exception

{

FileReader FP=new FileReader(args[0]);

BufferedReader bufferedReader = new BufferedReader(FP);

String line=null;

int line_count=0,LC=0,symTabLine=0,opTabLine=0,litTabLine=0,poolTabLine=0;

  

//Data Structures

final int MAX=100;

String SymbolTab[][]=new String[MAX][3];

String OpTab[][]=new String[MAX][3];

String LitTab[][]=new String[MAX][2];

int PoolTab[]=new int[MAX];

int litTabAddress=0;

/*---------------------------------------------------------------------------------------------------*/

 

System.out.println("___________________________________________________");

    while((line = bufferedReader.readLine()) != null)

     {

      String[] tokens = line.split("\t");

      if(line_count==0)

      {

      LC=Integer.parseInt(tokens[2]);

//set LC to operand of START

      for(int i=0;i<tokens.length;i++) //for printing the input program

      System.out.print(tokens[i]+"\t");

      System.out.println("");

      }

      else

      {

      for(int i=0;i<tokens.length;i++) //for printing the input program

      System.out.print(tokens[i]+"\t");

      System.out.println("");

      if(!tokens[0].equals(""))

      {

 

      //Inserting into Symbol Table

      SymbolTab[symTabLine][0]=tokens[0];

      SymbolTab[symTabLine][1]=Integer.toString(LC);

      SymbolTab[symTabLine][2]=Integer.toString(1);

      symTabLine++;

      }

else if(tokens[1].equalsIgnoreCase("DS")||tokens[1].equalsIgnoreCase("DC"))

{

//Entry into symbol table for declarative statements

SymbolTab[symTabLine][0]=tokens[0];

      SymbolTab[symTabLine][1]=Integer.toString(LC);

      SymbolTab[symTabLine][2]=Integer.toString(1);

      symTabLine++;

}


if(tokens.length==3 && tokens[2].charAt(0)=='=')

{

//Entry of literals into literal table

LitTab[litTabLine][0]=tokens[2];

      LitTab[litTabLine][1]=Integer.toString(LC);

      litTabLine++;

}

else if(tokens[1]!=null)

{

//Entry of Mnemonic in opcode table

OpTab[opTabLine][0]=tokens[1];

if(tokens[1].equalsIgnoreCase("START")||tokens[1].equalsIgnoreCase("END")||tokens[1].equalsIgnoreCase("ORIGIN")||tokens[1].equalsIgnoreCase("EQU")||tokens[1].equalsIgnoreCase("LTORG")) //if Assembler Directive

{

      OpTab[opTabLine][1]="AD";

OpTab[opTabLine][2]="R11";

}      

else if(tokens[1].equalsIgnoreCase("DS")||tokens[1].equalsIgnoreCase("DC"))

{

OpTab[opTabLine][1]="DL";

OpTab[opTabLine][2]="R7";

}

else

{

OpTab[opTabLine][1]="IS";

OpTab[opTabLine][2]="(04,1)";

}

      opTabLine++;

}

        }

        line_count++;

        LC++;

    }   


System.out.println("___________________________________________________");  


//print symbol table

System.out.println("\n\n SYMBOL TABLE ");

System.out.println("--------------------------");

System.out.println("SYMBOL\tADDRESS\tLENGTH");

System.out.println("--------------------------");

for(int i=0;i<symTabLine;i++)

System.out.println(SymbolTab[i][0]+"\t"+SymbolTab[i][1]+"\t"+SymbolTab[i][2]);

System.out.println("--------------------------");



//print opcode table

System.out.println("\n\n OPCODE TABLE ");

System.out.println("----------------------------");

System.out.println("MNEMONIC\tCLASS\tINFO");

System.out.println("----------------------------");

for(int i=0;i<opTabLine;i++)

System.out.println(OpTab[i][0]+"\t\t"+OpTab[i][1]+"\t"+OpTab[i][2]);

System.out.println("----------------------------");


//print literal table

System.out.println("\n\n   LITERAL TABLE ");

System.out.println("-----------------");

System.out.println("LITERAL\tADDRESS");

System.out.println("-----------------");

for(int i=0;i<litTabLine;i++)

System.out.println(LitTab[i][0]+"\t"+LitTab[i][1]);

System.out.println("------------------");


//intialization of POOLTAB

for(int i=0;i<litTabLine;i++)

{

if(LitTab[i][0]!=null && LitTab[i+1][0]!=null ) //if literals are present

{

if(i==0)

{

PoolTab[poolTabLine]=i+1;

poolTabLine++;

}

else if(Integer.parseInt(LitTab[i][1])<(Integer.parseInt(LitTab[i+1][1]))-1)

{

PoolTab[poolTabLine]=i+2;

poolTabLine++;

}

}

}

//print pool table

System.out.println("\n\n   POOL TABLE ");

System.out.println("-----------------");

System.out.println("LITERAL NUMBER");

System.out.println("-----------------");

for(int i=0;i<poolTabLine;i++)

System.out.println(PoolTab[i]);

System.out.println("------------------");

    // Always close files.

    bufferedReader.close();

}

}


/*

OUTPUT-

$ javac SymTab.java 

$ java SymTab input.txt

___________________________________________________

START 100

READ A

LABLE MOVER A,B

LTORG

='5'

='1'

='6'

='7'

MOVEM A,B

LTORG

='2'

LOOP READ B

A DS 1

B DC '1'

='1'

END

___________________________________________________



SYMBOL TABLE

--------------------------

SYMBOL ADDRESS LENGTH

--------------------------

LABLE 102 1

LOOP 111 1

A 112 1

B 113 1

--------------------------



OPCODE TABLE

----------------------------

MNEMONIC CLASS INFO

----------------------------

READ IS (04,1)

MOVER IS (04,1)

LTORG AD R11

MOVEM IS (04,1)

LTORG AD R11

READ IS (04,1)

DS DL R7

DC DL R7

END AD R11

----------------------------



   LITERAL TABLE

-----------------

LITERAL ADDRESS

-----------------

='5' 104

='1' 105

='6' 106

='7' 107

='2' 110

='1' 114

------------------



   POOL TABLE

-----------------

LITERAL NUMBER

-----------------

1

5

6

------------------

*/

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