From 2661608ba4e9df9ef87bad56d97e72dac375dcb2 Mon Sep 17 00:00:00 2001
From: "David A. Mellis" <d.mellis@arduino.cc>
Date: Wed, 26 Nov 2008 14:15:24 +0000
Subject: [PATCH] Adding support for printing floats and doubles (defaulting to
 2 decimal places)

---
 hardware/cores/arduino/Print.cpp | 30 ++++++++++++++++++++++++++++++
 hardware/cores/arduino/Print.h   |  3 +++
 2 files changed, 33 insertions(+)

diff --git a/hardware/cores/arduino/Print.cpp b/hardware/cores/arduino/Print.cpp
index feff940a5..143f15d11 100755
--- a/hardware/cores/arduino/Print.cpp
+++ b/hardware/cores/arduino/Print.cpp
@@ -22,6 +22,7 @@
 #include <stdio.h>
 #include <string.h>
 #include <inttypes.h>
+#include <math.h>
 #include "wiring.h"
 
 #include "Print.h"
@@ -78,6 +79,11 @@ void Print::print(long n, int base)
     printNumber(n, base);
 }
 
+void Print::print(double n)
+{
+  printFloat(n*100, 2);
+}
+
 void Print::println(void)
 {
   print('\r');
@@ -132,6 +138,12 @@ void Print::println(long n, int base)
   println();
 }
 
+void Print::println(double n)
+{
+  print(n);
+  println();
+}
+
 // Private Methods /////////////////////////////////////////////////////////////
 
 void Print::printNumber(unsigned long n, uint8_t base)
@@ -154,3 +166,21 @@ void Print::printNumber(unsigned long n, uint8_t base)
       '0' + buf[i - 1] :
       'A' + buf[i - 1] - 10));
 }
+
+void Print::printFloat(double number, uint8_t scale) 
+{ 
+  double mult = pow(10,scale); 
+  double rounded = floor(number /mult); 
+  double biground = rounded * mult; 
+  double remainder = (number - biground);  
+  remainder = remainder / mult; 
+  print(long(rounded)); 
+  print("."); 
+
+  while (scale--) {  
+    double toPrint = floor(remainder * 10); 
+    print(int(toPrint)); 
+    remainder -= (toPrint/10); 
+    remainder *= 10; 
+  } 
+} 
\ No newline at end of file
diff --git a/hardware/cores/arduino/Print.h b/hardware/cores/arduino/Print.h
index 8cec23567..c95a0dc09 100755
--- a/hardware/cores/arduino/Print.h
+++ b/hardware/cores/arduino/Print.h
@@ -32,6 +32,7 @@ class Print
 {
   private:
     void printNumber(unsigned long, uint8_t);
+    void printFloat(double, uint8_t);
   public:
     virtual void write(uint8_t);
     void print(char);
@@ -42,6 +43,7 @@ class Print
     void print(long);
     void print(unsigned long);
     void print(long, int);
+    void print(double);
     void println(void);
     void println(char);
     void println(const char[]);
@@ -51,6 +53,7 @@ class Print
     void println(long);
     void println(unsigned long);
     void println(long, int);
+    void println(double);
 };
 
 #endif