1 files changed, 6 insertions, 1 deletions
diff --git a/cores/arduino/Print.h b/cores/arduino/Print.h
index d099a3b..4d8a2f5 100644
--- a/cores/arduino/Print.h
+++ b/cores/arduino/Print.h
@@ -22,6 +22,7 @@
 
 #include <inttypes.h>
 #include <stdio.h> // for size_t
+#include <limits.h> // for INT_MAX
 
 #include "WString.h"
 #include "Printable.h"
@@ -57,7 +58,11 @@ class Print
     size_t write(const char *buffer, size_t size) {
       return write((const uint8_t *)buffer, size);
     }
-    
+
+    // default to zero, meaning "a single write may block"
+    // should be overriden by subclasses with buffering
+    virtual int availableForWrite() { return 0; }
+
     size_t print(const __FlashStringHelper *);
     size_t print(const String &);
     size_t print(const char[]);