Add syscall 3, home button exit VM on choice media

docs/dev-firmware-micro-vm.md

@@ -95,9 +95,28 @@ This system call is used to wait for machine events. Use R0 to mask events to wa
 Example:
 
 ```
-    mov r0, 
+    mov r0, 0b1000
+    syscall 2
 ```
 
+## SYSCALL  3 (Send signal)
+
+Send a specific signal event to the machine.
+Use R0 register to pass the signal argument.
+
+```
+    mov r0, 42
+    syscall 3
+```
+
+Supported signals:
+
+| Signal  |    Number   |
+|-------       |--------    |
+| reserved |   0   |
+| Quit story |   1    |
+
+
 # Assembler
 
 Basic grammar

story-editor/scripts/media.chip32

@@ -29,7 +29,7 @@
     mov t5, r0  ; save it
     
     ; wait for event
-    lcons r0, 0b111 ; mask for OK, previous and next buttons
+    lcons r0, 0b100111 ; mask for OK, previous and next buttons, home button
     syscall 2
     ; Event is stored in R0
 
@@ -45,6 +45,11 @@
     skipz r1 ; not OK, skip jump
     jump .media_previous
 
+    lcons r1, 0b100000 ; mask for home button
+    and r1, r0 ; r1 = r1 AND r0
+    skipz r1 ; not Home, skip jump
+    jump .media_exit
+
     ; all other events mean: next node
     eq  r0, t0, t4   ;  t4 est le dernier élément
     skipz r0   ;  zéro, on peut incrémenter l'adresse
@@ -71,4 +76,9 @@
     call t5 ; jump to the node
     lcons r0, 0b10000100001 ; mask for end of audio, Ok, and home buttons
     syscall 2 ; wait for event (OK, home or end of audio), return to choice loop
-    jump .media_loop
+    jump .media_loop
+
+.media_exit:
+    lcons r0, 1 ; Home button pressed, send signal to exit story
+    syscall 3 ; exit story, we should never return from this call
+    halt ; just in case

story-player/lib/libstory/storyvm.dart

@@ -22,6 +22,12 @@ class MediaEvent {
   MediaEvent(this.image, this.sound);
 }
 
+class SignalEvent {
+  int signal;
+
+  SignalEvent(this.signal);
+}
+
 Completer<bool> periodic(Duration interval, Function(int cycle) callback) {
   final done = Completer<bool>();
   () async {
@@ -96,8 +102,10 @@ class StoryVm {
 
     if (i == 0) {
         eventBus.fire(MediaEvent(file, ""));
-    } else {
+    } else if (i == 1) {
         eventBus.fire(MediaEvent("", file));
+    } else if (i == 2) {
+        eventBus.fire(SignalEvent(1));
     }
     
   }

story-player/lib/main.dart

@@ -160,6 +160,14 @@ class _MyHomePageState extends State<MyHomePage> {
         }
     });
 
+    eventBus.on<SignalEvent>().listen((event) {
+      if (event.signal == 1) {
+        state = PlayerState.indexFile;
+        showCurrentStoryIndex();
+      }
+    });
+
+
     audioPlayerSub = player.onPlayerComplete.listen((event) {
       if (state == PlayerState.inStory) {
         // Send end of music event

story-player/storyvm/storyvm.cpp

@@ -118,6 +118,19 @@ uint8_t story_player_syscall(chip32_ctx_t *ctx, uint8_t code)
         event_mask = ctx->registers[R0];
         retCode = SYSCALL_RET_WAIT_EV; // set the VM in pause
     }
+    else if (code == 3) // Signal
+    {
+        if (ctx->registers[R0] == 1)
+        {
+            // EXIT
+            std::cout << "[STORYVM] Syscall 3 (exit)" << std::endl;
+            if (gMediaCallback)
+            {
+                std::cout << "[STORYVM] Execute callback (sound)" << std::endl;
+                gMediaCallback(2, "");
+            }
+        }
+    }
     return retCode;
 }