From d6f62943d4b511e7d5fe6147096c8979890416f5 Mon Sep 17 00:00:00 2001
From: Markus Sattler <help.markus+git@gmail.com>
Date: Fri, 19 Jun 2015 10:41:20 +0200
Subject: [PATCH] fix problems with serial and cbuf (some times freeze on high
 load)

---
 cores/esp8266/HardwareSerial.cpp | 1 +
 cores/esp8266/cbuf.h             | 8 ++++++--
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/cores/esp8266/HardwareSerial.cpp b/cores/esp8266/HardwareSerial.cpp
index 970b16c50..fcca84687 100644
--- a/cores/esp8266/HardwareSerial.cpp
+++ b/cores/esp8266/HardwareSerial.cpp
@@ -608,6 +608,7 @@ size_t HardwareSerial::write(uint8_t c) {
 
     while(_tx_buffer->room() == 0) {
         yield();
+        uart_arm_tx_interrupt(_uart);
     }
 
     _tx_buffer->write(c);
diff --git a/cores/esp8266/cbuf.h b/cores/esp8266/cbuf.h
index 87642510b..ceb6a7b6d 100644
--- a/cores/esp8266/cbuf.h
+++ b/cores/esp8266/cbuf.h
@@ -39,8 +39,12 @@ class cbuf {
         }
 
         size_t room() const {
-            if(_end >= _begin) return _size - (_end - _begin) - 1;
-
+            if(_end >= _begin) {
+                return _size - (_end - _begin) - 1;
+            }
+            if(_begin == _end) {
+                return _size;
+            }
             return _begin - _end - 1;
         }