Rearchitect into separate projects.main

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+/**
+  * Collatz Conjecture module.
+  *
+  * Takes a start integer and calculates the number of steps
+  * required for that number to get down to 1 using the collatz
+  * conjecture.
+  */
+module collatz #(
+    parameter integer WIDTH = 16
+) (
+    /* Input clock and reset pin. */
+    input clk,
+    input rst,
+
+    /* The number to calculate. */
+    input wire [WIDTH-1:0] in_start,
+    /* Pulsing the start_int pin will start the calculation. */
+    input wire start_int,
+
+    /* Output count. */
+    output reg [WIDTH-1:0] o_count,
+
+    /* Set to high when the module is idle and ready to start.
+     * While computing, this output is set to low.
+     *
+     * A positive edge of this will indicate the output is ready
+     * to be consumed. */
+    output idle
+);
+
+  // Define some state parameters.
+  localparam integer IDLE = 0;
+  localparam integer SPINNING = 1;
+
+  reg state = 0;
+  reg [WIDTH-1:0] count = 0;
+  reg [WIDTH-1:0] n = 0;
+
+  wire is_even = ~n[0];  // Is the current value even.
+  assign idle = state == IDLE;
+
+  // When the start_int input is set to high, copy the in_start to the current
+  // number and set the state to SPINNING.
+  always @(posedge start_int) begin
+    if (state == IDLE) begin
+      state <= SPINNING;
+      n <= in_start;
+    end
+  end
+
+  // Each clock cycle, determine what needs to happen.
+  always @(posedge clk or posedge rst) begin
+    // On reset, reset the state.
+    if (rst == 1'b1) begin
+      count = 0;
+      state <= IDLE;
+      n <= 0;
+
+      // If the state is idle, reset the count to 0.
+    end else if (state == SPINNING) begin
+      // If n is 1, then  set the output and go back to the IDLE state.
+      if (n <= 1) begin
+        o_count = count;
+        n <= 0;
+        state   = IDLE;
+      end else begin
+        // If is_even, divide by two, otherwise multiply by 3 and add 1.
+        if (is_even) begin
+          n <= n >> 1;
+        end else begin
+          n <= n * 3 + 1;
+        end
+        // Increment the count.
+        count <= count + 1;
+      end
+    end
+  end
+
+endmodule