Implement button mmap

sim/state/buttons.ts

@@ -1,6 +1,6 @@
 namespace pxsim {
 
-    export class EV3ButtonState extends CommonButtonState{
+    export class EV3ButtonState extends CommonButtonState {
 
         constructor() {
             super();
@@ -13,6 +13,24 @@ namespace pxsim {
                 new CommonButton(DAL.BUTTON_ID_ESCAPE),
                 new CommonButton(DAL.BUTTON_ID_ALL)
             ];
+            let data = new Uint8Array(this.buttons.length)
+            MMapMethods.register("/dev/lms_ui", {
+                data,
+                beforeMemRead: () => {
+                    for (let i = 0; i < this.buttons.length; ++i)
+                        data[i] = this.buttons[i].isPressed() ? 1 : 0
+                },
+                read: buf => {
+                    let v = "vSIM"
+                    for (let i = 0; i < buf.data.length; ++i)
+                        buf.data[i] = v.charCodeAt(i) || 0
+                    return buf.data.length
+                },
+                write: buf => {
+                    pxsim.output.setLights(buf.data[0] - 48)
+                    return 2
+                }
+            })
         }
     }
 }