Some updates on Stream and Print class.

cores/arduino/Print.cpp

@@ -238,14 +238,14 @@ size_t Print::printFloat(double number, uint8_t digits)
 
   // Print the decimal point, but only if there are digits beyond
   if (digits > 0) {
-    n += print(".");
+    n += print('.');
   }
 
   // Extract digits from the remainder one at a time
   while (digits-- > 0)
   {
     remainder *= 10.0;
-    unsigned int toPrint = (unsigned int)remainder;
+    unsigned int toPrint = (unsigned int)(remainder);
     n += print(toPrint);
     remainder -= toPrint;
   }

cores/arduino/Print.h

@@ -28,6 +28,9 @@
 #define DEC 10
 #define HEX 16
 #define OCT 8
+#ifdef BIN // Prevent warnings if BIN is previously defined in "iotnx4.h" or similar
+#undef BIN
+#endif
 #define BIN 2
 
 class Print
@@ -54,6 +57,10 @@ class Print
       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[]);
@@ -78,6 +85,8 @@ class Print
     size_t println(double, int = 2);
     size_t println(const Printable&);
     size_t println(void);
+
+    virtual void flush() { /* Empty implementation for backward compatibility */ }
 };
 
 #endif

cores/arduino/Stream.h

@@ -59,7 +59,6 @@ class Stream : public Print
     virtual int available() = 0;
     virtual int read() = 0;
     virtual int peek() = 0;
-    virtual void flush() = 0;
 
     Stream() {_timeout=1000;}
 

libraries/I2S/src/I2S.cpp

@@ -280,7 +280,7 @@ size_t I2SClass::write(const uint8_t *buffer, size_t size)
   return write((const void*)buffer, size);
 }
 
-size_t I2SClass::availableForWrite()
+int I2SClass::availableForWrite()
 {
   if (_state != I2S_STATE_TRANSMITTER) {
     enableTransmitter();

libraries/I2S/src/I2S.h

@@ -51,7 +51,7 @@ class I2SClass : public Stream
   virtual size_t write(uint8_t);
   virtual size_t write(const uint8_t *buffer, size_t size);
 
-  virtual size_t availableForWrite();
+  virtual int availableForWrite();
 
   int read(void* buffer, size_t size);