From faa1685e183476a1db1f2e21e70319ee20115101 Mon Sep 17 00:00:00 2001
From: Erki <erki.meinberg@gmail.com>
Date: Sun, 21 Mar 2021 17:03:06 +0200
Subject: [PATCH] Add async UART logger (running on DMA).

---
 Utility/Inc/utility_asyncaurtlogger.hpp  | 49 ++++++++++++++++
 Utility/Inc/utility_atomicscopeguard.hpp | 31 ++++++++++
 Utility/Src/utility_asynchuartlogger.cpp | 73 ++++++++++++++++++++++++
 Utility/Src/utility_atomicscopeguard.cpp | 32 +++++++++++
 4 files changed, 185 insertions(+)
 create mode 100644 Utility/Inc/utility_asyncaurtlogger.hpp
 create mode 100644 Utility/Inc/utility_atomicscopeguard.hpp
 create mode 100644 Utility/Src/utility_asynchuartlogger.cpp
 create mode 100644 Utility/Src/utility_atomicscopeguard.cpp

diff --git a/Utility/Inc/utility_asyncaurtlogger.hpp b/Utility/Inc/utility_asyncaurtlogger.hpp
new file mode 100644
index 0000000..58d2353
--- /dev/null
+++ b/Utility/Inc/utility_asyncaurtlogger.hpp
@@ -0,0 +1,49 @@
+/*
+ * utility_asyncaurtlogger.hpp
+ *
+ *  Created on: Mar 20, 2021
+ *      Author: erki
+ */
+
+#ifndef SKULLC_UTILITY_ASYNCAURTLOGGER_HPP_
+#define SKULLC_UTILITY_ASYNCAURTLOGGER_HPP_
+
+#include "utility_ilogger.hpp"
+#include "utility_ringbuffer.hpp"
+
+#include "usart.h"
+
+namespace Utility
+{
+
+class AsyncUARTLogger : public ILogger
+{
+public:
+  explicit AsyncUARTLogger(UART_HandleTypeDef* huart);
+  AsyncUARTLogger() = delete;
+  AsyncUARTLogger(const AsyncUARTLogger&) = delete;
+  AsyncUARTLogger(AsyncUARTLogger&&) = delete;
+
+  void log(const char* format, ...);
+
+private:
+  struct _Data
+  {
+    std::array<char, 255> buffer;
+    std::int32_t length;
+  };
+
+  Ringbuffer<_Data, 10> _buffer_queue;
+  UART_HandleTypeDef* _huart;
+  bool _in_flight = false;
+
+  static AsyncUARTLogger* _this;
+  static void _txCompleteCallback(UART_HandleTypeDef* huart);
+
+  void _sendNextLog();
+};
+
+}
+
+
+#endif /* SKULLC_UTILITY_ASYNCAURTLOGGER_HPP_ */
diff --git a/Utility/Inc/utility_atomicscopeguard.hpp b/Utility/Inc/utility_atomicscopeguard.hpp
new file mode 100644
index 0000000..beef132
--- /dev/null
+++ b/Utility/Inc/utility_atomicscopeguard.hpp
@@ -0,0 +1,31 @@
+/*
+ * utility_atomicscopeguard.hpp
+ *
+ *  Created on: Mar 21, 2021
+ *      Author: erki
+ */
+
+#ifndef UTILITY_INC_UTILITY_ATOMICSCOPEGUARD_HPP_
+#define UTILITY_INC_UTILITY_ATOMICSCOPEGUARD_HPP_
+
+#include <cstdint>
+
+namespace Utility
+{
+
+class AtomicScopeGuard
+{
+public:
+  AtomicScopeGuard();
+  AtomicScopeGuard(const AtomicScopeGuard&) = delete;
+  AtomicScopeGuard(AtomicScopeGuard&&) = delete;
+
+  ~AtomicScopeGuard();
+
+private:
+  static std::int32_t _reentrancy_counter;
+};
+
+}
+
+#endif /* UTILITY_INC_UTILITY_ATOMICSCOPEGUARD_HPP_ */
diff --git a/Utility/Src/utility_asynchuartlogger.cpp b/Utility/Src/utility_asynchuartlogger.cpp
new file mode 100644
index 0000000..a529789
--- /dev/null
+++ b/Utility/Src/utility_asynchuartlogger.cpp
@@ -0,0 +1,73 @@
+/*
+ * utility_asynchuartlogger.cpp
+ *
+ *  Created on: Mar 20, 2021
+ *      Author: erki
+ */
+
+#include "utility_asyncaurtlogger.hpp"
+
+#include <cstdlib>
+#include <cstdarg>
+#include <cassert>
+
+#include "utility_atomicscopeguard.hpp"
+
+namespace Utility
+{
+
+AsyncUARTLogger* AsyncUARTLogger::_this = nullptr;
+
+AsyncUARTLogger::AsyncUARTLogger(UART_HandleTypeDef* huart)
+  : _huart(huart)
+{
+  assert(!_this);
+
+  _this = this;
+  _huart->TxCpltCallback = &AsyncUARTLogger::_txCompleteCallback;
+}
+
+void AsyncUARTLogger::log(const char* format, ...)
+{
+  {
+    AtomicScopeGuard s;
+
+    if (_buffer_queue.size() == _buffer_queue.max_size())
+      return;
+  }
+
+  std::va_list args;
+  va_start(args, format);
+
+  auto tail = _buffer_queue.end();
+  std::array<char, 255>& buffer = tail->buffer;
+
+  tail->length = vsnprintf(buffer.data(), buffer.size(), format, args);
+
+  {
+    AtomicScopeGuard s;
+    _buffer_queue.increment_tail();
+
+    if (!_in_flight)
+      _sendNextLog();
+  }
+}
+
+void AsyncUARTLogger::_txCompleteCallback(UART_HandleTypeDef*)
+{
+  if (!AsyncUARTLogger::_this->_buffer_queue.empty())
+    AsyncUARTLogger::_this->_sendNextLog();
+  else
+    AsyncUARTLogger::_this->_in_flight = false;
+}
+
+void AsyncUARTLogger::_sendNextLog()
+{
+  _in_flight = true;
+
+  _Data& head = _buffer_queue.front();
+  HAL_UART_Transmit_DMA(_huart, reinterpret_cast<uint8_t*>(head.buffer.data()), head.length);
+  _buffer_queue.pop_front();
+}
+
+}
diff --git a/Utility/Src/utility_atomicscopeguard.cpp b/Utility/Src/utility_atomicscopeguard.cpp
new file mode 100644
index 0000000..17ca0b6
--- /dev/null
+++ b/Utility/Src/utility_atomicscopeguard.cpp
@@ -0,0 +1,32 @@
+/*
+ * utility_atomicscopeguard.cpp
+ *
+ *  Created on: Mar 21, 2021
+ *      Author: erki
+ */
+
+#include "utility_atomicscopeguard.hpp"
+
+#include "cmsis_gcc.h"
+
+namespace Utility
+{
+
+std::int32_t AtomicScopeGuard::_reentrancy_counter;
+
+AtomicScopeGuard::AtomicScopeGuard()
+{
+  __disable_irq();
+  _reentrancy_counter++;
+}
+
+AtomicScopeGuard::~AtomicScopeGuard()
+{
+  _reentrancy_counter--;
+
+  if (!_reentrancy_counter)
+    __enable_irq();
+}
+
+}
+