arm: more uart async & debug stuff

arm/async.h

@@ -30,6 +30,64 @@ struct task_final_suspend {
     std::coroutine_handle<> parent;
 };
 
+template <typename T>
+struct gimme {
+    // child interface
+    bool await_ready() { return false; }
+    void await_suspend(std::coroutine_handle<> h) {
+        ha = h;
+        waiting = true;
+        TRACE(tracing::TraceEvent::kAsyncGimmeWaiting);
+
+        if (parent) {
+            TRACE(tracing::TraceEvent::kAsyncCallParent);
+            parent.resume();
+            TRACE(tracing::TraceEvent::kAsyncCallParentDone);
+        }
+    }
+    T await_resume() {
+        waiting = false;
+        TRACE(tracing::TraceEvent::kAsyncGimmeResume);
+        return std::move(stuff);
+    }
+
+    // parent interface
+    auto feed(T&& s) {
+        struct awaitable {
+            bool await_ready() {
+                if (g.waiting) {
+                    return true;
+                }
+                // TODO: handle g.ha.done()
+                return false;
+            }
+            void await_suspend(std::coroutine_handle<> h) {
+                g.parent = h;
+            }
+            void await_resume() {}
+
+            gimme<T>& g;
+        };
+
+        if (!waiting) {
+           __builtin_trap();
+        }
+        if (!ha) {
+           __builtin_trap();
+        }
+        stuff = s;
+        parent = {};
+        ha.resume();
+
+        return awaitable{.g = *this};
+    }
+
+    bool waiting = false;
+    std::coroutine_handle<> ha;
+    T stuff;
+    std::coroutine_handle<> parent;
+};
+
 template <typename T = void>
 struct task;
 

arm/uart.cc

@@ -1,10 +1,11 @@
 #include "uart.h"
-#include "uart_async.h"
 
 #include "async.h"
 #include "gpio.h"
+#include "lock.h"
 #include "ring_buffer.h"
 #include "trace.h"
+#include "uart_async.h"
 #include "xuartlite.h"
 
 namespace {
@@ -54,38 +55,93 @@ void UartWriteCrash(std::span<const std::byte> data) {
 
 async::task<> UartWrite(std::span<const std::byte> data) {
     while (!tx_ring_buffer.Store(data)) {
+        tracing::trace(tracing::TraceEvent::kUartTxBufferFull);
         co_await async::await(AwaitableType::kUartTx);
+        tracing::trace(tracing::TraceEvent::kUartTxBufferNotFull);
     }
 
-    if (!XUartLite_IsSending(uart0)) {
-        XUartLite_Send(uart0, tx_ring_buffer.RawReadPointer(),
-                       tx_ring_buffer.ContiguousAvailableData());
+    {
+        InterruptLock lock;
+        if (!XUartLite_IsSending(uart0)) {
+            tracing::trace(tracing::TraceEvent::kUartSend);
+            XUartLite_Send(uart0, tx_ring_buffer.RawReadPointer(),
+                           tx_ring_buffer.ContiguousAvailableData());
+        }
     }
 }
 
+#define GCC_HAS_BUG_101133 1  // https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101133
+#if !GCC_HAS_BUG_101133
+async::task<> UartWriteLoop(async::gimme<std::span<const std::byte>>& data_gen) {
+    while (1) {
+        auto data = co_await data_gen;
+        while (!tx_ring_buffer.Store(data)) {
+            tracing::trace(tracing::TraceEvent::kUartTxBufferFull);
+            co_await async::await(AwaitableType::kUartTx);
+            tracing::trace(tracing::TraceEvent::kUartTxBufferNotFull);
+        }
+
+        {
+            InterruptLock lock;
+            if (!XUartLite_IsSending(uart0)) {
+                tracing::trace(tracing::TraceEvent::kUartSend);
+                XUartLite_Send(uart0, tx_ring_buffer.RawReadPointer(),
+                        tx_ring_buffer.ContiguousAvailableData());
+            }
+        }
+    }
+}
+#endif  // !GCC_HAS_BUG_101133
+
 void UartReadBlocking(std::span<std::byte> data) {
     size_t bytes_received = 0;
     while (bytes_received < data.size()) {
         auto* buffer = reinterpret_cast<uint8_t*>(data.data() + bytes_received);
+        tracing::trace(tracing::TraceEvent::kUartRecv);
         bytes_received +=
             XUartLite_Recv(uart0, buffer, data.size() - bytes_received);
     }
 }
 
 void UartWriteBlocking(std::span<const std::byte> data) {
+    if (__get_PRIMASK() != 0) {
+        UartWriteCrash("\r\nUartWriteBlocking called with interupts disabled!\r\n");
+        __builtin_trap();
+    }
+
     while (!tx_ring_buffer.Store(data)) {
     }
 
-    if (!XUartLite_IsSending(uart0)) {
-        XUartLite_Send(uart0, tx_ring_buffer.RawReadPointer(),
-                       tx_ring_buffer.ContiguousAvailableData());
+    {
+        InterruptLock lock;
+        if (!XUartLite_IsSending(uart0)) {
+            tracing::trace(tracing::TraceEvent::kUartSend);
+            XUartLite_Send(uart0, tx_ring_buffer.RawReadPointer(),
+                           tx_ring_buffer.ContiguousAvailableData());
+        }
+    }
+}
+
+async::task<uint8_t> UartReadLoop() {
+    uint8_t c;
+    while (1) {
+        tracing::trace(tracing::TraceEvent::kUartRecv);
+        size_t received = XUartLite_Recv(uart0, &c, 1);
+        // some data may already be in the fifo, but if not, wait:
+        if (received < 1) {
+            co_await async::await(AwaitableType::kUartRx);
+        }
+
+        co_yield c;
     }
 }
 
 async::task<buffer> UartRead(int size) {
     auto buff = buffer::make(size);
     auto* data = reinterpret_cast<uint8_t*>(buff.data.data());
+    tracing::trace(tracing::TraceEvent::kUartRecv);
     size_t received = XUartLite_Recv(uart0, data, buff.data.size());
+    // some data may already be in the fifo, but if not, wait:
     if (received < buff.data.size()) {
         co_await async::await(AwaitableType::kUartRx);
     }
@@ -93,9 +149,9 @@ async::task<buffer> UartRead(int size) {
 }
 
 void HandleUartTxFromIsr(void*, unsigned int transmitted) {
-    tracing::trace(tracing::TraceEvent::kUartTxCb);
     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());
     }
@@ -103,8 +159,17 @@ void HandleUartTxFromIsr(void*, unsigned int transmitted) {
 }
 
 void HandleUartRxFromIsr(void*, unsigned int) {
-    tracing::trace(tracing::TraceEvent::kUartRxCb);
     async::resume(AwaitableType::kUartRx);
 }
 
 void HandleUartIsr() { XUartLite_InterruptHandler(uart0); }
+
+extern "C" uint8_t XUartLite_GetSR(XUartLite*);
+
+uint8_t UartStatus() { return XUartLite_GetSR(uart0); }
+
+void LogStuff() {
+    uint8_t data = gpio0->data;
+    data |= (uart0->ReceiveBuffer.RemainingBytes & 0xf) << 4;
+    gpio0->data = data;
+}

arm/uart.h

@@ -28,3 +28,7 @@ inline void UartWriteBlocking(std::string_view s) {
 void HandleUartTxFromIsr(void*, unsigned int transmitted);
 void HandleUartRxFromIsr(void*, unsigned int);
 void HandleUartIsr();
+
+uint8_t UartStatus();
+
+void LogStuff();

arm/uart_async.h

@@ -7,7 +7,9 @@
 #include "buffer.h"
 
 async::task<buffer> UartRead(int size);
+async::task<uint8_t> UartReadLoop();
 async::task<> UartWrite(std::span<const std::byte> data);
 inline async::task<> UartWrite(std::string_view s) {
     co_await UartWrite(std::as_bytes(std::span{s.data(), s.size()}));
 }
+async::task<> UartWriteLoop(async::gimme<std::span<const std::byte>>& data);