From f52570e01191f2a4397284c70433b1206d6b20cb Mon Sep 17 00:00:00 2001
From: "rjbatista@gmail.com"
 <rjbatista@gmail.com@f0354187-03e1-8ba3-851e-26a5c8714c44>
Date: Mon, 20 Feb 2012 22:17:47 +0000
Subject: [PATCH] ISSUE #20: Support for negative decimal numbers

---
 CHANGES.txt   |  1 +
 TM1638.cpp    | 27 ++++++++++++++++++++++++---
 TM1638.h      |  5 +++++
 TM16XXFonts.h |  2 ++
 4 files changed, 32 insertions(+), 3 deletions(-)

diff --git a/CHANGES.txt b/CHANGES.txt
index 7f1d8ee..84d9ff1 100644
--- a/CHANGES.txt
+++ b/CHANGES.txt
@@ -1,3 +1,4 @@
+- ISSUE #20: Support for negative decimal numbers;
 - ISSUE #19: Corrected setDisplayToString dot bug.
 
 Version 2.0.1
diff --git a/TM1638.cpp b/TM1638.cpp
index 4784b4d..02aad4e 100644
--- a/TM1638.cpp
+++ b/TM1638.cpp
@@ -44,18 +44,18 @@ void TM1638::setDisplayToHexNumber(unsigned long number, byte dots, boolean lead
   }
 }
 
-void TM1638::setDisplayToDecNumber(unsigned long number, byte dots, boolean leadingZeros,
+void TM1638::setDisplayToDecNumberAt(unsigned long number, byte dots, byte startingPos, boolean leadingZeros,
 	const byte numberFont[])
 {
   if (number > 99999999L) {
     setDisplayToError();
   } else {
-    for (int i = 0; i < displays; i++) {
+    for (int i = 0; i < displays - startingPos; i++) {
       if (number != 0) {
         setDisplayDigit(number % 10, displays - i - 1, (dots & (1 << i)) != 0, numberFont);
         number /= 10;
       } else {
-		  if (leadingZeros) {
+		if (leadingZeros) {
 		  setDisplayDigit(0, displays - i - 1, (dots & (1 << i)) != 0, numberFont);
 		} else {
 		  clearDisplayDigit(displays - i - 1, (dots & (1 << i)) != 0);
@@ -65,6 +65,27 @@ void TM1638::setDisplayToDecNumber(unsigned long number, byte dots, boolean lead
   }
 }
 
+void TM1638::setDisplayToDecNumber(unsigned long number, byte dots, boolean leadingZeros,
+	const byte numberFont[])
+{
+	setDisplayToDecNumberAt(number, dots, leadingZeros, 0, numberFont);
+}
+
+void TM1638::setDisplayToSignedDecNumber(signed long number, byte dots, boolean leadingZeros,
+		const byte numberFont[])
+{
+	if (number >= 0) {
+		setDisplayToDecNumberAt(number, dots, 0, leadingZeros, numberFont);
+	} else {
+		if (-number > 9999999L) {
+		    setDisplayToError();
+		} else {
+			setDisplayToDecNumberAt(-number, dots, 1, leadingZeros, numberFont);
+			sendChar(0, MINUS, (dots & (0x80)) != 0);
+		}
+	}
+}
+
 void TM1638::setDisplayToBinNumber(byte number, byte dots, const byte numberFont[])
 {
   for (int i = 0; i < displays; i++) {
diff --git a/TM1638.h b/TM1638.h
index a6d59c5..46bd80f 100644
--- a/TM1638.h
+++ b/TM1638.h
@@ -43,6 +43,9 @@ class TM1638 : public TM16XX
     /** Set the display to a unsigned decimal number (with or without leading zeros) */
     void setDisplayToDecNumber(unsigned long number, byte dots, boolean leadingZeros = true,
 		const byte numberFont[] = NUMBER_FONT);
+    /** Set the display to a signed decimal number (with or without leading zeros) */
+    void setDisplayToSignedDecNumber(signed long number, byte dots, boolean leadingZeros = true,
+		const byte numberFont[] = NUMBER_FONT);
     /** Set the display to a unsigned binary number */
     void setDisplayToBinNumber(byte number, byte dots,
 		const byte numberFont[] = NUMBER_FONT);
@@ -57,6 +60,8 @@ class TM1638 : public TM16XX
 
   protected:
     virtual void sendChar(byte pos, byte data, boolean dot);
+    void setDisplayToDecNumberAt(unsigned long number, byte dots, byte startingPos,
+    	boolean leadingZeros, const byte numberFont[]);
 };
 
 #endif
diff --git a/TM16XXFonts.h b/TM16XXFonts.h
index 92bf7fe..1b1489d 100644
--- a/TM16XXFonts.h
+++ b/TM16XXFonts.h
@@ -50,6 +50,8 @@ const byte NUMBER_FONT[] = {
   0b01110001  // F
 };
 
+const byte MINUS = 0b01000000;
+
 // definition for error
 const byte ERROR_DATA[] = {
   0b01111001, // E