cores: Replace HardwareSerial.cpp with master version.

Signed-off-by: Frederikwag <frederik.wagner@infineon.com>

Author: Frederikwag

cores/HardwareSerial.cpp

@@ -32,7 +32,7 @@ HardwareSerial::HardwareSerial(XMC_UART_t *xmc_uart_config,
                                RingBuffer *tx_buffer) {
     _XMC_UART_config = xmc_uart_config;
     _rx_buffer = rx_buffer;
-    _tx_buffer = tx_buffer; // TODO: replaced by TBUF (hardware register), can be actually removed
+    _tx_buffer = tx_buffer;
 }
 
 // Public Methods //////////////////////////////////////////////////////////////
@@ -119,12 +119,10 @@ int HardwareSerial::available(void) {
 }
 
 int HardwareSerial::availableForWrite(void) {
-    int available = XMC_USIC_CH_GetTransmitBufferStatus(_XMC_UART_config->channel);
-    if (available == XMC_USIC_CH_TBUF_STATUS_IDLE) {
-        return 0;
-    } else {
-        return 1;
-    } // TODO: should return bytes avaliable to write! need to enable txFIFO in the future
+    int tail = _tx_buffer->_iTail; // Snapshot index affected by irq
+    if (_tx_buffer->_iHead >= tail)
+        return SERIAL_BUFFER_SIZE - 1 - _tx_buffer->_iHead + tail;
+    return tail - _tx_buffer->_iHead - 1;
 }
 
 int HardwareSerial::peek(void) {
@@ -146,19 +144,59 @@ int HardwareSerial::read(void) {
 }
 
 void HardwareSerial::flush(void) {
+    while (_tx_buffer->_iHead != _tx_buffer->_iTail)
+        ; // wait for transmit data to be sent
+
     while (XMC_USIC_CH_GetTransmitBufferStatus(_XMC_UART_config->channel) ==
            XMC_USIC_CH_TBUF_STATUS_BUSY)
         ;
 }
 
 size_t HardwareSerial::write(const uint8_t uc_data) {
-    // Is the hardware currently busy?
-
-    // Make sure TX interrupt is enabled
-    XMC_UART_CH_EnableEvent(_XMC_UART_config->channel, XMC_UART_CH_EVENT_TRANSMIT_BUFFER);
-    // Bypass buffering and send character directly
-    XMC_UART_CH_Transmit(_XMC_UART_config->channel, uc_data);
-
+// Is the hardware currently busy?
+#if defined(SERIAL_USE_U1C1)
+    if (_tx_buffer->_iTail != _tx_buffer->_iHead)
+#else
+    if ((XMC_USIC_CH_GetTransmitBufferStatus(_XMC_UART_config->channel) ==
+         XMC_USIC_CH_TBUF_STATUS_BUSY) ||
+        (_tx_buffer->_iTail != _tx_buffer->_iHead))
+#endif
+    {
+        // If busy we buffer
+        int nextWrite = _tx_buffer->_iHead + 1;
+        if (nextWrite >= SERIAL_BUFFER_SIZE)
+            nextWrite = 0;
+
+        // This should always be false but in case transmission is completed before buffer, we need
+        // to reenable IRQ
+        if (XMC_USIC_CH_GetTransmitBufferStatus(_XMC_UART_config->channel) !=
+            XMC_USIC_CH_TBUF_STATUS_BUSY) {
+            XMC_UART_CH_EnableEvent(_XMC_UART_config->channel, XMC_UART_CH_EVENT_TRANSMIT_BUFFER);
+            XMC_UART_CH_Transmit(_XMC_UART_config->channel,
+                                 _tx_buffer->_aucBuffer[_tx_buffer->_iTail]);
+            _tx_buffer->_iTail++;
+            if (_tx_buffer->_iTail >= SERIAL_BUFFER_SIZE)
+                _tx_buffer->_iTail %= SERIAL_BUFFER_SIZE; // If iTail is larger than Serial Buffer
+                                                          // Size calculate the correct index value
+        }
+
+        unsigned long startTime = millis();
+        while (_tx_buffer->_iTail == nextWrite) {
+            if (millis() - startTime > 1000) {
+                return 0; // Spin locks if we're about to overwrite the buffer. This continues once
+                          // the data is
+                          // sent
+            }
+        }
+
+        _tx_buffer->_aucBuffer[_tx_buffer->_iHead] = uc_data;
+        _tx_buffer->_iHead = nextWrite;
+    } else {
+        // Make sure TX interrupt is enabled
+        XMC_UART_CH_EnableEvent(_XMC_UART_config->channel, XMC_UART_CH_EVENT_TRANSMIT_BUFFER);
+        // Bypass buffering and send character directly
+        XMC_UART_CH_Transmit(_XMC_UART_config->channel, uc_data);
+    }
     return 1;
 }
 
@@ -182,11 +220,20 @@ void HardwareSerial::IrqHandler(void) {
         XMC_UART_CH_ClearStatusFlag(_XMC_UART_config->channel,
                                     XMC_UART_CH_STATUS_FLAG_TRANSMIT_BUFFER_INDICATION);
 
-        // Mask off transmit interrupt so we don't get it any more
-        XMC_UART_CH_DisableEvent(_XMC_UART_config->channel, XMC_UART_CH_EVENT_TRANSMIT_BUFFER);
+        if (_tx_buffer->_iTail != _tx_buffer->_iHead) {
+            XMC_UART_CH_Transmit(_XMC_UART_config->channel,
+                                 _tx_buffer->_aucBuffer[_tx_buffer->_iTail]);
+            _tx_buffer->_iTail++;
+            if (_tx_buffer->_iTail >= SERIAL_BUFFER_SIZE)
+                _tx_buffer->_iTail %= SERIAL_BUFFER_SIZE; // If iTail is larger than Serial Buffer
+                                                          // Size calculate the correct index value
+        } else {
+            // Mask off transmit interrupt so we don't get it any more
+            XMC_UART_CH_DisableEvent(_XMC_UART_config->channel, XMC_UART_CH_EVENT_TRANSMIT_BUFFER);
+        }
     }
 }
 
 //****************************************************************************
 //                                 END OF FILE
-//****************************************************************************
+//****************************************************************************