From a4a289c17761a057673d601363439da023a41a57 Mon Sep 17 00:00:00 2001
From: Pavel Krajcevski <pavel@cs.unc.edu>
Date: Tue, 8 Oct 2013 18:37:38 -0400
Subject: [PATCH] Change the pixel channel size to 16 bits so that our
 arithmetic operations don't overflow.

---
 Base/include/Pixel.h | 32 +++++++++++++++++---------------
 Base/src/Pixel.cpp   |  8 ++++----
 2 files changed, 21 insertions(+), 19 deletions(-)

diff --git a/Base/include/Pixel.h b/Base/include/Pixel.h
index 4fa9312..bee3134 100644
--- a/Base/include/Pixel.h
+++ b/Base/include/Pixel.h
@@ -58,17 +58,19 @@
 
 namespace FasTC {
 
-class Pixel : public Vector4<uint8> {
+class Pixel : public Vector4<uint16> {
  private:
+  typedef uint16 ChannelType;
+  typedef Vector4<ChannelType> VectorType;
   uint8 m_BitDepth[4];
 
  public:
-  Pixel() : Vector4<uint8>(0, 0, 0, 0) {
+  Pixel() : VectorType(0, 0, 0, 0) {
     for(int i = 0; i < 4; i++)
       m_BitDepth[i] = 8;
   }
 
-  explicit Pixel(uint32 rgba) : Vector4<uint8>() {
+  explicit Pixel(uint32 rgba) : VectorType() {
     for(int i = 0; i < 4; i++)
       m_BitDepth[i] = 8;
     Unpack(rgba);
@@ -76,7 +78,7 @@ class Pixel : public Vector4<uint8> {
 
   Pixel(const uint8 *bits,
         const uint8 channelDepth[4] = static_cast<uint8 *>(0),
-        uint8 bitOffset = 0) : Vector4<uint8>() {
+        uint8 bitOffset = 0) : VectorType() {
     FromBits(bits, channelDepth, bitOffset);
   }
 
@@ -104,18 +106,18 @@ class Pixel : public Vector4<uint8> {
 
   // Changes the bit depth of a single component. See the comment
   // above for how we do this.
-  static uint8 ChangeBitDepth(uint8 val, uint8 oldDepth, uint8 newDepth);
+  static ChannelType ChangeBitDepth(ChannelType val, uint8 oldDepth, uint8 newDepth);
 
-  const uint8 &A() const { return X(); }
-  uint8 &A() { return X(); }
-  const uint8 &R() const { return Y(); }
-  uint8 &R() { return Y(); }
-  const uint8 &G() const { return Z(); }
-  uint8 &G() { return Z(); }
-  const uint8 &B() const { return W(); }
-  uint8 &B() { return W(); }
-  const uint8 &Component(uint32 idx) const { return vec[idx]; }
-  uint8 &Component(uint32 idx) { return vec[idx]; }
+  const ChannelType &A() const { return X(); }
+  ChannelType &A() { return X(); }
+  const ChannelType &R() const { return Y(); }
+  ChannelType &R() { return Y(); }
+  const ChannelType &G() const { return Z(); }
+  ChannelType &G() { return Z(); }
+  const ChannelType &B() const { return W(); }
+  ChannelType &B() { return W(); }
+  const ChannelType &Component(uint32 idx) const { return vec[idx]; }
+  ChannelType &Component(uint32 idx) { return vec[idx]; }
 
   void GetBitDepth(uint8 (&outDepth)[4]) const {
     for(int i = 0; i < 4; i++) {
diff --git a/Base/src/Pixel.cpp b/Base/src/Pixel.cpp
index 2b047bd..08a5bc4 100644
--- a/Base/src/Pixel.cpp
+++ b/Base/src/Pixel.cpp
@@ -82,7 +82,7 @@ namespace FasTC {
     }
 
     for(int32 i = 0; i < 4; i++) {
-      uint8 &channel = Component(i);
+      ChannelType &channel = Component(i);
       uint32 depth = m_BitDepth[i];
 
       assert(depth <= 8);
@@ -125,7 +125,7 @@ namespace FasTC {
 
     uint8 bitIdx = bitOffset;
     for(int i = 3; i >= 0; i--) {
-      uint8 val = Component(i);
+      ChannelType val = Component(i);
       uint8 depth = m_BitDepth[i];
 
       if(depth + bitIdx > 8) {
@@ -146,7 +146,7 @@ namespace FasTC {
     }
   }
 
-  uint8 Pixel::ChangeBitDepth(uint8 val, uint8 oldDepth, uint8 newDepth) {
+  Pixel::ChannelType Pixel::ChangeBitDepth(Pixel::ChannelType val, uint8 oldDepth, uint8 newDepth) {
     assert(newDepth <= 8);
     assert(oldDepth <= 8);
 
@@ -222,7 +222,7 @@ namespace FasTC {
       ok = ok && m_BitDepth[i] == depths[i];
 
       uint8 mask = (1 << depths[i]) - 1;
-      const uint8 c = other.Component(i) & mask;
+      const ChannelType c = other.Component(i) & mask;
       ok = ok && (c == (Component(i) & mask));
     }
     return ok;