Display error number on the screen upon panic

libs/core/linux.cpp

@@ -139,11 +139,24 @@ void sendSerial(const char *data, int len) {
     sendUsb(USB_SERIAL, data, len);
 }
 
+volatile bool paniced;
+extern "C" void drawPanic(int code);
+
 extern "C" void target_panic(int error_code) {
     char buf[50];
+    paniced = true;
+    pthread_mutex_trylock(&execMutex);
+
     snprintf(buf, sizeof(buf), "\nPANIC %d\n", error_code);
-    sendSerial(buf, strlen(buf));
+
+    drawPanic(error_code);
     DMESG("PANIC %d", error_code);
+
+    for (int i = 0; i < 10; ++i) {
+        sendSerial(buf, strlen(buf));
+        sleep_core_us(500 * 1000);
+    }
+
     target_reset();
 }
 
@@ -284,12 +297,16 @@ static void *evtDispatcher(void *dummy) {
     while (true) {
         pthread_cond_wait(&newEventBroadcast, &eventMutex);
         while (eventHead != NULL) {
+            if (paniced)
+                return 0;
             Event *ev = eventHead;
             eventHead = ev->next;
             if (eventHead == NULL)
                 eventTail = NULL;
 
             for (auto thr = allThreads; thr; thr = thr->next) {
+                if (paniced)
+                    return 0;
                 if (thr->waitSource == 0)
                     continue;
                 if (thr->waitValue != ev->value && thr->waitValue != DEVICE_EVT_ANY)
@@ -346,11 +363,15 @@ static void runPoller(Thread *thr) {
 
     while (true) {
         sleep_core_us(us);
+        if (paniced)
+            break;
         TValue curr = pxt::runAction0(query);
         if (curr != prev) {
             startUser();
             pxt::runAction2(thr->act, prev, curr);
             stopUser();
+            if (paniced)
+                break;
             decr(prev);
             prev = curr;
         }

libs/core/pxt.h

@@ -25,6 +25,7 @@ class MMap : public RefObject {
     void print();
 };
 
+extern volatile bool paniced;
 
 }
 

libs/core/screen.cpp

@@ -9,7 +9,6 @@
 #include <fcntl.h>
 #include <sys/ioctl.h>
 
-
 /**
 * Drawing modes
 */
@@ -265,6 +264,56 @@ void init() {
     pthread_create(&pid, NULL, screenRefresh, NULL);
     pthread_detach(pid);
 }
+
+static const uint8_t numbers[] = {
+    0x06, 0x09, 0x09, 0x09, 0x06, 0x04, 0x06, 0x04, 0x04, 0x0e, 0x07, 0x08, 0x06, 0x01, 0x0f, 0x0f,
+    0x08, 0x04, 0x09, 0x06, 0x0c, 0x0a, 0x09, 0x1f, 0x08, 0x1f, 0x01, 0x0f, 0x10, 0x0f, 0x08, 0x04,
+    0x0e, 0x11, 0x0e, 0x1f, 0x08, 0x04, 0x02, 0x01, 0x0e, 0x11, 0x0e, 0x11, 0x0e, 0x0e, 0x11, 0x0e,
+    0x04, 0x02,
+    // face
+    0b11011, 0b11011, 0b00000, 0b11111, 0b11011,
+};
+
+static void drawNumber(int off, int idx) {
+    const uint8_t *src = &numbers[idx * 5];
+    uint8_t *dst = &bitBuffer[off];
+    for (int i = 0; i < 5; i++) {
+        uint8_t ch = *src++;
+        for (int jj = 0; jj < 8; ++jj) {
+            for (int j = 0; j < 5; j++) {
+                if (ch & (1 << j))
+                    *dst = 0xff;
+                dst++;
+            }
+            dst += ROW_SIZE - 5;
+        }
+    }
+}
+
+extern "C" void drawPanic(int code) {
+    clear();
+
+    int ptr = ROW_SIZE * 16 + 3 + 6;
+    drawNumber(ptr, 10);
+    ptr += 6;
+
+    ptr = ROW_SIZE * 70 + 3;
+
+    drawNumber(ptr, (code / 100) % 10);
+    ptr += 6;
+    drawNumber(ptr, (code / 10) % 10);
+    ptr += 6;
+    drawNumber(ptr, (code / 1) % 10);
+    ptr += 6;
+
+    updateLCD();
+
+    int fd = open("/dev/lms_ui", O_RDWR);
+    uint8_t cmd[] = { 48 + 5, 0 };
+    write(fd, cmd, 2);
+    close(fd);
+}
+
 }
 
 namespace pxt {