mbv: debugging the async app

mbv/apps/async/uart.cc

@@ -27,6 +27,8 @@ std::array<std::byte, kUartTxBufferSize> tx_buffer = {};
 RingBuffer tx_ring_buffer{.buffer = tx_buffer};
 
 XUartLite* uart0 = &uart0_inst;
+
+bool sending;
 }  // namespace
 
 void InitUarts() {
@@ -35,9 +37,12 @@ void InitUarts() {
     XUartLite_SetSendHandler(uart0, HandleUartTxFromIsr, nullptr);
     XUartLite_SetRecvHandler(uart0, HandleUartRxFromIsr, nullptr);
     XUartLite_EnableInterrupt(uart0);
+
+    sending = false;
 }
 
 void UartWriteCrash(std::span<const std::byte> data) {
+    XUartLite_DisableInterrupt(uart0);
     while (data.size() > 0) {
         while (XUartLite_IsSending(uart0)) {
         }
@@ -48,6 +53,7 @@ void UartWriteCrash(std::span<const std::byte> data) {
     }
     while (XUartLite_IsSending(uart0)) {
     }
+    XUartLite_EnableInterrupt(uart0);
 }
 
 async::task<> UartWrite(std::span<const std::byte> data) {
@@ -79,10 +85,11 @@ async::task<> UartWriteLoop(
 
         {
             InterruptLock lock;
-            if (!XUartLite_IsSending(uart0)) {
+            if (!sending) {
                 tracing::trace(tracing::TraceEvent::kUartSend);
                 XUartLite_Send(uart0, tx_ring_buffer.RawReadPointer(),
                                tx_ring_buffer.ContiguousAvailableData());
+                sending = true;
             }
         }
     }
@@ -139,11 +146,13 @@ async::task<buffer> UartRead(int size) {
 }
 
 void HandleUartTxFromIsr(void*, unsigned int transmitted) {
+    sending = false;
     tx_ring_buffer.Pop(transmitted);
     if (tx_ring_buffer.AvailableData() > 0) {
         tracing::trace(tracing::TraceEvent::kUartSend);
         XUartLite_Send(uart0, tx_ring_buffer.RawReadPointer(),
                        tx_ring_buffer.ContiguousAvailableData());
+        sending = true;
     }
     async::resume(AwaitableType::kUartTx);
 }