Added support for the GL_RGB9_E5 format.
git-svn-id: https://angleproject.googlecode.com/svn/branches/es3proto@2363 736b8ea6-26fd-11df-bfd4-992fa37f6226
diff --git a/src/common/mathutil.cpp b/src/common/mathutil.cpp
new file mode 100644
index 0000000..6a03cb4
--- /dev/null
+++ b/src/common/mathutil.cpp
@@ -0,0 +1,65 @@
+#include "precompiled.h"
+//
+// Copyright (c) 2013 The ANGLE Project Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+//
+
+// mathutil.cpp: Math and bit manipulation functions.
+
+#include "common/mathutil.h"
+
+namespace gl
+{
+
+struct RGB9E5Data
+{
+ unsigned int R : 9;
+ unsigned int G : 9;
+ unsigned int B : 9;
+ unsigned int E : 5;
+};
+
+// B is the exponent bias (15)
+static const int g_sharedexp_bias = 15;
+
+// N is the number of mantissa bits per component (9)
+static const int g_sharedexp_mantissabits = 9;
+
+// Emax is the maximum allowed biased exponent value (31)
+static const int g_sharedexp_maxexponent = 31;
+
+static const float g_sharedexp_max = ((pow(2.0f, g_sharedexp_mantissabits) - 1) /
+ pow(2.0f, g_sharedexp_mantissabits)) *
+ pow(2.0f, g_sharedexp_maxexponent - g_sharedexp_bias);
+
+unsigned int convertRGBFloatsTo999E5(float red, float green, float blue)
+{
+ const float red_c = std::max<float>(0, std::min(g_sharedexp_max, red));
+ const float green_c = std::max<float>(0, std::min(g_sharedexp_max, green));
+ const float blue_c = std::max<float>(0, std::min(g_sharedexp_max, blue));
+
+ const float max_c = std::max<float>(std::max<float>(red_c, green_c), blue_c);
+ const float exp_p = std::max<float>(-g_sharedexp_bias - 1, floor(log(max_c))) + 1 + g_sharedexp_bias;
+ const int max_s = floor((max_c / (pow(2.0f, exp_p - g_sharedexp_bias - g_sharedexp_mantissabits))) + 0.5f);
+ const int exp_s = (max_s < pow(2.0f, g_sharedexp_mantissabits)) ? exp_p : exp_p + 1;
+
+ RGB9E5Data output;
+ output.R = floor((red_c / (pow(2.0f, exp_s - g_sharedexp_bias - g_sharedexp_mantissabits))) + 0.5f);
+ output.G = floor((green_c / (pow(2.0f, exp_s - g_sharedexp_bias - g_sharedexp_mantissabits))) + 0.5f);
+ output.B = floor((blue_c / (pow(2.0f, exp_s - g_sharedexp_bias - g_sharedexp_mantissabits))) + 0.5f);
+ output.E = exp_s;
+
+ return *reinterpret_cast<unsigned int*>(&output);
+}
+
+void convert999E5toRGBFloats(unsigned int input, float *red, float *green, float *blue)
+{
+ const RGB9E5Data *inputData = reinterpret_cast<const RGB9E5Data*>(&input);
+
+ *red = inputData->R * pow(2.0f, (int)inputData->E - g_sharedexp_bias - g_sharedexp_mantissabits);
+ *green = inputData->G * pow(2.0f, (int)inputData->E - g_sharedexp_bias - g_sharedexp_mantissabits);
+ *blue = inputData->B * pow(2.0f, (int)inputData->E - g_sharedexp_bias - g_sharedexp_mantissabits);
+}
+
+}