From 92ec97338d287278e6f0fc67e846a1863bade4bd Mon Sep 17 00:00:00 2001
From: MCUdude <hansibull@gmail.com>
Date: Wed, 6 May 2020 07:36:17 +0200
Subject: [PATCH] Update corefiles

---
 avr/cores/MCUdude_corefiles/HardwareSerial.h | 2 +-
 avr/cores/MCUdude_corefiles/Print.h          | 8 +++++++-
 avr/cores/MCUdude_corefiles/USBAPI.h         | 2 +-
 3 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/avr/cores/MCUdude_corefiles/HardwareSerial.h b/avr/cores/MCUdude_corefiles/HardwareSerial.h
index 8a5bf95e6..17000c2cc 100755
--- a/avr/cores/MCUdude_corefiles/HardwareSerial.h
+++ b/avr/cores/MCUdude_corefiles/HardwareSerial.h
@@ -124,7 +124,7 @@ class HardwareSerial : public Stream
     virtual int available(void);
     virtual int peek(void);
     virtual int read(void);
-    int availableForWrite(void);
+    virtual int availableForWrite(void);
     virtual void flush(void);
     virtual size_t write(uint8_t);
     inline size_t write(unsigned long n) { return write((uint8_t)n); }
diff --git a/avr/cores/MCUdude_corefiles/Print.h b/avr/cores/MCUdude_corefiles/Print.h
index 9b91f0ca1..2fdd687f7 100755
--- a/avr/cores/MCUdude_corefiles/Print.h
+++ b/avr/cores/MCUdude_corefiles/Print.h
@@ -57,7 +57,13 @@ 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; }
+
+    virtual void flush() { /* Empty implementation for backward compatibility */ }
+
     size_t print(const __FlashStringHelper *);
     size_t print(const String &);
     size_t print(const char[]);
diff --git a/avr/cores/MCUdude_corefiles/USBAPI.h b/avr/cores/MCUdude_corefiles/USBAPI.h
index 0e25b29a8..cdcc8addb 100755
--- a/avr/cores/MCUdude_corefiles/USBAPI.h
+++ b/avr/cores/MCUdude_corefiles/USBAPI.h
@@ -98,7 +98,7 @@ class Serial_ : public Stream
   virtual int available(void);
   virtual int peek(void);
   virtual int read(void);
-  int availableForWrite(void);
+  virtual int availableForWrite(void);
   virtual void flush(void);
   virtual size_t write(uint8_t);
   virtual size_t write(const uint8_t*, size_t);