From 244501ad3c23a00a004121ee99ca36eaf6b8abb4 Mon Sep 17 00:00:00 2001
From: Lode <lvandeve@gmail.com>
Date: Thu, 20 Nov 2014 22:04:11 +0100
Subject: small tweaks

---
 lodepng.cpp          | 11 ++++++-----
 lodepng_unittest.cpp |  4 ++++
 2 files changed, 10 insertions(+), 5 deletions(-)

diff --git a/lodepng.cpp b/lodepng.cpp
index 09bb5e6..3179e0a 100644
--- a/lodepng.cpp
+++ b/lodepng.cpp
@@ -3494,7 +3494,7 @@ void lodepng_color_profile_init(LodePNGColorProfile* profile)
 }*/
 
 /*Returns how many bits needed to represent given value (max 8 bit)*/
-unsigned getValueRequiredBits(unsigned char value)
+static unsigned getValueRequiredBits(unsigned char value)
 {
   if(value == 0 || value == 255) return 1;
   /*The scaling of 2-bit and 4-bit values uses multiples of 85 and 17*/
@@ -3531,7 +3531,8 @@ unsigned lodepng_get_color_profile(LodePNGColorProfile* profile,
     for(i = 0; i < numpixels; i++)
     {
       getPixelColorRGBA16(&r, &g, &b, &a, in, i, mode);
-      if(r % 257u != 0 || g % 257u != 0 || b % 257u != 0 || a % 257u != 0) /*first and second byte differ*/
+      if((r & 255u) != ((r >> 8) & 255u) || (g & 255u) != ((g >> 8) & 255u) ||
+         (b & 255u) != ((b >> 8) & 255u) || (a & 255u) != ((a >> 8) & 255u)) /*first and second byte differ*/
       {
         sixteen = 1;
         break;
@@ -3652,9 +3653,9 @@ unsigned lodepng_get_color_profile(LodePNGColorProfile* profile,
     }
 
     /*make the profile's key always 16-bit for consistency - repeat each byte twice*/
-    profile->key_r *= 257;
-    profile->key_g *= 257;
-    profile->key_b *= 257;
+    profile->key_r += (profile->key_r << 8);
+    profile->key_g += (profile->key_g << 8);
+    profile->key_b += (profile->key_b << 8);
   }
 
   color_tree_cleanup(&tree);
diff --git a/lodepng_unittest.cpp b/lodepng_unittest.cpp
index f2b1cf7..e3dbc10 100644
--- a/lodepng_unittest.cpp
+++ b/lodepng_unittest.cpp
@@ -1754,6 +1754,10 @@ void testAutoColorModels()
   std::vector<unsigned char> not16;
   addColor16(not16, 257, 257, 257, 0);
   testAutoColorModel(not16, 16, LCT_PALETTE, 1, false);
+
+  std::vector<unsigned char> alpha16;
+  addColor16(alpha16, 257, 0, 0, 10000);
+  testAutoColorModel(alpha16, 16, LCT_RGBA, 16, false);
 }
 
 void doMain()
-- 
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