Assembler

/*
 * COA Pipelining assignment 
 * Code written by- Umesh Poswal(13CS01010)
 * 
 * Code description:
 *   Given code take an assembly file as an input, then convert the given assembly code into the object code(machine code), saves
 *   object code into another file called output file(here).
 *   
 *  
 *   Description of my ISA:
 *     1. Total number of registers is 10 including SP and PC
 *     2. 8 GPRs are numbered as 0,1,2,3,...,7
 *     4. Memory size is 64, processor stack size is 64
 *     5. Each instruction size is 16 bits
 *     6. There are a total of 16 instructions
 *     7. First four bits(opcode) determine the operation to be performed
 *     8. Depending upon the operation other bits are given values as:
 *        Note: Register numbers used in below examples are for reference only, you can use any register out of 8 registers
 *        
 *          1. ADD 5 1 4           R5 = R1 + R4    three bits to determine each register, so bits used are 13,rest 3 bits are 000
 *          2. SUB 4 5 2           R4 = R5 - R2         same as for addition
 *          3. Similarly           MUL and DIV    are used to multiply and divide respectively 
 *          4. SLL 4 5 imm.value     (Shift logical left) R5 value is logically shift by imm.value and result stored in reg.4
 *          5. Similarly SLR        to shift right
 *          6. MOV1I  imm.value      12 bit imm.value(12 bits) is given to register number 1
 *          7. JMP label           jump to label(12 bits) 
 *          8. JAL label           jump to label and link to present PC address, register 7 is used as linking register
 *          9. BEQ label           jump to label if R0 = 1
 *         10. MOVR 1 2            Content of R2 given to R1, i.e R1=R2  (rest 6 bits are 0s)
 *         11. MOVI 5 imm.value    imm.value(9 bits) is given to R5
 *         12. JR 7                Jump to address stored in R7
 *         13. LD 5 location       load value in R5 from memory location 'location'(6 bits) rest 3 bits are 0s
 *         14. ST 5 location       store value R5 at memory location 'location'
 *         15. SLT 4 5             (Set less than) if R4 < R5 then R0 = 1,else R0 = 0  rest 6 bits are 0s
 *          
 * 
 * 
 * N.B: Do not give any empty lines in input file, input file must also not have empty lines at the end
 *      Labels are used without colons, i.e uuoo is a label and will be used as uuoo
 *      kkoo: is a label and will be used as kkoo:  e.g jmp kkoo: and not jmp kkoo
 *      label name should not have space in between 
 */

package coa_pipelining;

import java.util.Scanner;
import java.io.*;

public class Assembler {

	static String IfileName = "src/input.txt";
	static String OfileName = "src/output.txt";
	static PrintWriter out = null;
	static int PC = 0;
	static int[] memory;
	static int SP = 0;
	static int[] register;

	public static void main(String args[]) {
		File Ifile = new File(IfileName);
		File Ofile = new File(OfileName);
		register = new int[8];
		memory = new int[128];		
		SP = memory.length;
		
		
		print("\nRead comments in source code to know how to use.\n\nMemory size is 64(from 0 to 63), to add data in memory give memory address\n");
		print("and then data value(separated by sapce(give memory add = 100 to exit\n)");
		Scanner ini  =new Scanner(System.in);
		int mA = ini.nextInt();
		int mV=0;
		while(mA!=100){	
			mV=ini.nextInt();
			if(mA>=0 && mA<64)
				memory[mA]=mV;
			else{
				print("Wrong memory address..try again or enter 100 to execute your code\n");
			}
			mA=ini.nextInt();
		}

		if (!Ifile.exists()) {
			System.out
					.println("Input file(Assembly code) doesn't exist..!!\nExiting..");
			System.exit(1);
		}

		Scanner inFile = null;
		try {
			inFile = new Scanner(Ifile);
		} catch (FileNotFoundException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}

		try {
			out = new PrintWriter(Ofile);
			ToMachine machineCode = new ToMachine();
			ToMachine.labels = new label[15];
			
			while (inFile.hasNextLine()) {
				machineCode.fillLabels(inFile.nextLine());
			}
			
			
			
			inFile = new Scanner(Ifile);
			
			while (inFile.hasNextLine()) {
				out.println(machineCode.AssemblyToMachine(inFile.nextLine()));
			}
			
		

			out.close();
			inFile.close();
		} catch (FileNotFoundException E) {
			print("Error ...output file not created successfully\n\nExiting..");
			System.exit(2);
		}

		// Fetching object code in RAM
		try {
			inFile = new Scanner(Ofile);
		} catch (FileNotFoundException e) {
			// TODO Auto-generated catch block
			print("Object code isn't found\n Exiting..");
			System.exit(3);
		}
		int inslength = ToMachine.lAdd;
		String Instruction[] = new String[inslength];
		int i = 0;
		while (inFile.hasNextLine()) {
			Instruction[i] = inFile.nextLine();
			i++;
		}
		inFile.close();
		
		//for(i=0;i<inslength;i++)
		//	print(Instruction[i]+"\n");
		
		// Fetching Instructions and decoding
		
		while (PC < inslength) {
			if(SP < 64 || SP > 128){
				print("Stack overflow...\nExiting...");
				System.exit(3);
			}
			String ins = Instruction[PC];
			PC++;
			decode(ins);
		}

		//Show register contents
		showRegister();
		
		// Show Memory contents
		showMemory();
		
		//Show stack Contents
		
		showStack();
		
		
	}

	

	public static void print(String s) {
		System.out.print(s);
	}

	public static void decode(String str) {
		String opcode, restCode;
		opcode = str.substring(0, 4);
		restCode = str.substring(4, 16);
		int[] op = new int[3];

		switch (opcode) {
		case "0000":
		case "0001":
		case "0010":
		case "0011":
			op[0] = Integer.parseInt(restCode.substring(0, 3), 2);
			op[1] = Integer.parseInt(restCode.substring(3, 6), 2);
			op[2] = Integer.parseInt(restCode.substring(6, 9), 2);
			if (opcode.contentEquals("0000"))
				register[op[0]] = register[op[1]] + register[op[2]];
			if (opcode.contentEquals("0001"))
				register[op[0]] = register[op[1]] - register[op[2]];
			if (opcode.contentEquals("0010"))
				register[op[0]] = register[op[1]] * register[op[2]];
			if (opcode.contentEquals("0011"))
				register[op[0]] = register[op[1]] / register[op[2]];
			break;

		case "0100":
		case "0101":
			op[0] = Integer.parseInt(restCode.substring(0, 3), 2);
			op[1] = Integer.parseInt(restCode.substring(3, 6), 2);
			op[2] = Integer.parseInt(restCode.substring(6, 12), 2);
			if (opcode.contentEquals("0100"))
				register[op[0]] = register[op[1]] << op[2];
			if (opcode.contentEquals("0101"))
				register[op[0]] = register[op[1]] >> op[2];
			break;
			
		case "0110":
			op[0]=Integer.parseInt(restCode.substring(0, 12), 2);
			register[1] = op[0];
			break;
			
		case "0111":
		case "1000":
			op[0]=Integer.parseInt(restCode.substring(0, 12), 2);
			if(opcode.contentEquals("0111"))PC = op[0];
			if(opcode.contentEquals("1000"))register[7] = PC;PC=op[0];
			break;
			
		case "1001":
			op[0] = Integer.parseInt(restCode.substring(0, 3), 2);
			op[1] = Integer.parseInt(restCode.substring(3, 6), 2);
			register[op[0]] = register[op[1]];
			break;
			
		case "1010":
			op[0] = Integer.parseInt(restCode.substring(0, 3), 2);
			op[1] = Integer.parseInt(restCode.substring(3, 12), 2);
			register[op[0]] = op[1];
			break;
			
		case "1011":
			op[0] = Integer.parseInt(restCode.substring(0, 3), 2);
			PC = register[op[0]];
			break;

		case "1100":
		case "1101":
			op[0] = Integer.parseInt(restCode.substring(0, 3), 2);
			op[1] = Integer.parseInt(restCode.substring(3, 9), 2);
			if(opcode.contentEquals("1100"))register[op[0]] = memory[op[1]];
			if(opcode.contentEquals("1101"))memory[op[1]]  = register[op[0]];
			break;				
			
		case "1110":
			if(register[0]==1){
				op[0] = Integer.parseInt(restCode, 2);
				PC = op[0];
			}
			break;
			
		case "1111":
			if(!restCode.substring(10, 12).contentEquals("11")){
				op[0] = Integer.parseInt(restCode.substring(0, 3), 2);
				op[1] = Integer.parseInt(restCode.substring(3, 6), 2);
				register[0]=0;
				if(register[op[0]]<register[op[1]])
					register[0]=1;
			}
			break;
			
			
			
		}
	}
	
	
	
	
	private static void showRegister(){
		print("Final register contents:\n");
		for(int i=0;i<8;i++)
			print("R"+i+": "+register[i]+"\n");
		print("SP: "+SP+"\nPC: "+PC+"\n\n\n");
	}
	
	
	private static void showStack() {
		// TODO Auto-generated method stub
		print("Final stack contents:\n");
		for(int i=64;i<128;i++)
			print("S"+(i-64)+": "+memory[i]+"\n");
		print("\n\n");
	}

	private static void showMemory() {
		// TODO Auto-generated method stub
		print("Final memory contents:\n");
		for(int i=0;i<64;i++)
			print("M"+i+": "+memory[i]+"\n");
		print("\n\n\n");
	}
	
	
	
}