Adding Client::peek() in Ethernet library (issue #349).

libraries/Ethernet/Client.cpp

@@ -83,6 +83,14 @@ int Client::read() {
   return b;
 }
 
+int Client::peek() {
+  uint8_t b;
+  if (!available())
+    return -1;
+  ::peek(_sock, &b);
+  return b;
+}
+
 void Client::flush() {
   while (available())
     read();

libraries/Ethernet/Client.h

@@ -17,6 +17,7 @@ public:
   virtual void write(const uint8_t *buf, size_t size);
   virtual int available();
   virtual int read();
+  virtual int peek();
   virtual void flush();
   void stop();
   uint8_t connected();

libraries/Ethernet/utility/socket.cpp

@@ -158,6 +158,19 @@ uint16_t recv(SOCKET s, uint8_t *buf, uint16_t len)
 }
 
 
+/**
+ * @brief	Returns the first byte in the receive queue (no checking)
+ * 		
+ * @return
+ */
+uint16_t peek(SOCKET s, uint8_t *buf)
+{
+  W5100.recv_data_processing(s, buf, 1, 1);
+
+  return 1;
+}
+
+
 /**
  * @brief	This function is an application I/F function which is used to send the data for other then TCP mode. 
  * 		Unlike TCP transmission, The peer's destination address and the port is needed.

libraries/Ethernet/utility/socket.h

@@ -10,6 +10,7 @@ extern void disconnect(SOCKET s); // disconnect the connection
 extern uint8_t listen(SOCKET s);	// Establish TCP connection (Passive connection)
 extern uint16_t send(SOCKET s, const uint8_t * buf, uint16_t len); // Send data (TCP)
 extern uint16_t recv(SOCKET s, uint8_t * buf, uint16_t len);	// Receive data (TCP)
+extern uint16_t peek(SOCKET s, uint8_t *buf);
 extern uint16_t sendto(SOCKET s, const uint8_t * buf, uint16_t len, uint8_t * addr, uint16_t port); // Send data (UDP/IP RAW)
 extern uint16_t recvfrom(SOCKET s, uint8_t * buf, uint16_t len, uint8_t * addr, uint16_t *port); // Receive data (UDP/IP RAW)
 

libraries/Ethernet/utility/w5100.cpp

@@ -88,13 +88,16 @@ void W5100Class::send_data_processing(SOCKET s, uint8_t *data, uint16_t len)
 }
 
 
-void W5100Class::recv_data_processing(SOCKET s, uint8_t *data, uint16_t len)
+void W5100Class::recv_data_processing(SOCKET s, uint8_t *data, uint16_t len, uint8_t peek)
 {
   uint16_t ptr;
   ptr = readSnRX_RD(s);
   read_data(s, (uint8_t *)ptr, data, len);
-  ptr += len;
+  if (!peek)
-  writeSnRX_RD(s, ptr);
+  {
+    ptr += len;
+    writeSnRX_RD(s, ptr);
+  }
 }
 
 void W5100Class::read_data(SOCKET s, volatile uint8_t *src, volatile uint8_t *dst, uint16_t len)

libraries/Ethernet/utility/w5100.h

@@ -155,7 +155,7 @@ public:
    * and after copy the data from receive buffer update the Rx write pointer register.
    * User should read upper byte first and lower byte later to get proper value.
    */
-  void recv_data_processing(SOCKET s, uint8_t *data, uint16_t len);
+  void recv_data_processing(SOCKET s, uint8_t *data, uint16_t len, uint8_t peek = 0);
 
   inline void setGatewayIp(uint8_t *_addr);
   inline void getGatewayIp(uint8_t *_addr);