# Lab 09
Name: CHATSE SIDDHANT MADHUKAR
Roll No.: CS22B016

---
## Question 1
**Verilog Code**

module ALU #(parameter n=4)(a,b,controller,result);
	input [n-1:0]a,b;
	input [1:0]controller;
	output [n-1:0]result;
	wire [n-1:0]addition_result,subtraction_result,and_result,or_result;
	assign addition_result = a+b;
	assign subtraction_result = a-b;
	assign and_result = a&b;
	assign or_result = a|b;
	assign result = (controller==2'b00) ? addition_result :
			(controller==2'b01) ? subtraction_result :
			(controller==2'b10) ? and_result :
			(controller==2'b11) ? or_result :
			0;
endmodule

module ALU_test;
	reg [3:0]a,b;
	reg [1:0]controller;
	wire [3:0]result;
	ALU uut(.a(a),.b(b),.controller(controller),.result(result));
	initial begin
		a=4'b0000;
		b=4'b0000;
		controller=2'b00;
	end
	always #2 a=a+1'b1;
	always #1 b=b+1'b1;
	always #16 controller=controller+1'b1;
	initial #100 $finish;
endmodule

Output is as shown:
1.

2.

3.

---
## Question 2

**Verilog Code**

module simple_processor(input [7:0]instruction);
	reg [7:0] memory [255:0];
	reg [7:0] reg_file [15:0];
	reg opcode;
	reg [1:0] reg_dest;
	reg [1:0] reg_source;
	reg [2:0] offset;

	reg [7:0] data_out;
	reg [7:0] address;
	
	always @(*)
	begin
		opcode = instruction[7];
		reg_dest = instruction[6:5];
		offset = instruction[4:2];
		reg_source = instruction[1:0];
	end

	always @(*) begin
		case(opcode)
			1'b0: begin
				memory[address] = reg_file[reg_source]+offset;
				data_out = memory[address];
				reg_file[reg_dest] = data_out;
			end
			1'b1: begin
				address = reg_file[reg_source]+offset;
				memory[address] = reg_file[reg_dest];
				data_out = 8'b00000000;
			end
			default: begin
				data_out = 8'b00000000;
			end
		endcase
	end
endmodule

---

## Question 3

#include<stdio.h>

int fact(int n)
{
	if(n==0) 
	{
		return 1;
	}
	return n * fact(n-1);
}

int main()
{
	int a=5;
	printf("%d\n",fact(5));
	return 0;
}

The number of instructions are counted in this program using inscount0 tool.

Commands executed are as follows:

../../../pin -t obj-intel64/inscount0.so -o inscount0.log -- /home/system/Desktop/Computer_Organisation_Lab/Lab9/first.out
cat inscount0.log

Output is as follows:

Count 125605

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