From 3d5c54e344ee8d8f769c318d034dd567da6ba25f Mon Sep 17 00:00:00 2001
From: edogaldo <edogaldo@gmail.com>
Date: Tue, 16 May 2017 00:00:59 +0200
Subject: [PATCH] Make HardwareSerial.flush() compatible with Arduino 1.0 api

---
 STM32F1/cores/maple/HardwareSerial.cpp                 | 5 +++--
 STM32F1/system/libmaple/include/libmaple/ring_buffer.h | 6 +++---
 2 files changed, 6 insertions(+), 5 deletions(-)

diff --git a/STM32F1/cores/maple/HardwareSerial.cpp b/STM32F1/cores/maple/HardwareSerial.cpp
index c993bdf..024efbc 100644
--- a/STM32F1/cores/maple/HardwareSerial.cpp
+++ b/STM32F1/cores/maple/HardwareSerial.cpp
@@ -193,7 +193,8 @@ size_t HardwareSerial::write(unsigned char ch) {
 	return 1;
 }
 
+/* edogaldo: Waits for the transmission of outgoing serial data to complete (Arduino 1.0 api specs) */
 void HardwareSerial::flush(void) {
-    usart_reset_rx(this->usart_device);
-    usart_reset_tx(this->usart_device);
+    while(!rb_is_empty(this->usart_device->wb)); // wait for TX buffer empty
+    while(!((this->usart_device->regs->SR) & (1<<USART_SR_TC_BIT))); // wait for TC (Transmission Complete) flag set 
 }
diff --git a/STM32F1/system/libmaple/include/libmaple/ring_buffer.h b/STM32F1/system/libmaple/include/libmaple/ring_buffer.h
index eb38634..e99fe62 100644
--- a/STM32F1/system/libmaple/include/libmaple/ring_buffer.h
+++ b/STM32F1/system/libmaple/include/libmaple/ring_buffer.h
@@ -52,9 +52,9 @@ extern "C"{
  * One byte is left free to distinguish empty from full. */
 typedef struct ring_buffer {
     volatile uint8 *buf; /**< Buffer items are stored into */
-    uint16 head;         /**< Index of the next item to remove */
-    uint16 tail;         /**< Index where the next item will get inserted */
-    uint16 size;         /**< Buffer capacity minus one */
+    volatile uint16 head;         /**< Index of the next item to remove */
+    volatile uint16 tail;         /**< Index where the next item will get inserted */
+    volatile uint16 size;         /**< Buffer capacity minus one */
 } ring_buffer;
 
 /**