From 2de7630a25d875986b79f406e2dcc41cf754d9b5 Mon Sep 17 00:00:00 2001
From: Bernd Giesecke <bernd@giesecke.tk>
Date: Mon, 30 Sep 2019 17:33:26 +0800
Subject: [PATCH] Added printf to Print class to have Serial.printf()
 functionality

---
 cores/arduino/Print.cpp | 10 ++++++++++
 cores/arduino/Print.h   |  4 ++++
 2 files changed, 14 insertions(+)

diff --git a/cores/arduino/Print.cpp b/cores/arduino/Print.cpp
index 9fc5c3116..2d5ca358a 100644
--- a/cores/arduino/Print.cpp
+++ b/cores/arduino/Print.cpp
@@ -183,6 +183,16 @@ size_t Print::println(const Printable& x)
   return n;
 }
 
+void Print::printf(const char format[], ...)
+{
+  char buf[PRINTF_BUF];
+  va_list ap;
+  va_start(ap, format);
+  vsnprintf(buf, sizeof(buf), format, ap);
+  write(buf);
+  va_end(ap);
+}
+
 // Private Methods /////////////////////////////////////////////////////////////
 
 size_t Print::printNumber(unsigned long n, uint8_t base)
diff --git a/cores/arduino/Print.h b/cores/arduino/Print.h
index dfb645cbb..abda4679b 100644
--- a/cores/arduino/Print.h
+++ b/cores/arduino/Print.h
@@ -21,6 +21,8 @@
 
 #include <inttypes.h>
 #include <stdio.h> // for size_t
+#include <stdarg.h> // for printf
+#define PRINTF_BUF 80
 
 #include "WString.h"
 #include "Printable.h"
@@ -86,6 +88,8 @@ class Print
     size_t println(const Printable&);
     size_t println(void);
 
+    void printf(const char[], ...);
+
     virtual void flush() { /* Empty implementation for backward compatibility */ }
 };