Added playback controller and testbench

design/playback_controller.sv

@@ -14,10 +14,79 @@ module playback_controller(
     output SPEED speed
 );
 
+typedef enum logic [2:0] {
+    PAUSE, PLAY, FF2, FF4, FF8
+} state_t;
+
+state_t current, next;
+
 wire play_pulse,ff_pulse;
 
 // NOTE: These might need to be hooked to an even lower clock? Not sure
 debouncer playDebouncer (clk,reset,play,play_pulse);
 debouncer ffDebouncer (clk,reset,ff,ff_pulse);
 
+//next state logic
+always_comb
+begin
+    unique case (current)
+        PAUSE: 
+            begin
+                if (play_pulse) next = PLAY;
+                else if (ff_pulse) next = FF2;
+                else next = PAUSE;
+            end
+        PLAY: 
+            begin
+                if (play_pulse) next = PAUSE;
+                else if (ff_pulse) next = FF2;
+                else next = PLAY;
+            end
+        FF2:
+            begin
+                if (play_pulse) next = PAUSE;
+                else if (ff_pulse) next = FF4;
+                else next = FF2;
+            end
+        FF4:
+            begin
+                if (play_pulse) next = PAUSE;
+                else if (ff_pulse) next = FF8;
+                else next = FF4;
+            end
+        FF8:
+            begin
+                if (play_pulse) next = PAUSE;
+                else if (ff_pulse) next = FF8;
+                else next = FF8;
+            end
+        default:
+            next = PAUSE;
+    endcase
+end
+
+//output logic
+always_comb
+begin
+    unique case (current)
+        PAUSE:  speed = 0; 
+        PLAY:   speed = 1;
+        FF2:    speed = 2;
+        FF4:    speed = 4;
+        FF8:    speed = 8;
+        default:speed = 0;
+    endcase
+end
+
+//sequential logic
+always_ff @(posedge clk)
+begin    
+    if (reset)
+        current <= PAUSE;
+    else
+        current <= next;
+end
 endmodule
+
+
+