1 files changed, 83 insertions, 0 deletions
diff --git a/gfx/angle/checkout/src/common/mathutil.cpp b/gfx/angle/checkout/src/common/mathutil.cpp
new file mode 100644
index 0000000000..5cbc6a920a
--- /dev/null
+++ b/gfx/angle/checkout/src/common/mathutil.cpp
@@ -0,0 +1,83 @@
+//
+// Copyright 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"
+
+#include <math.h>
+#include <algorithm>
+
+namespace gl
+{
+
+namespace
+{
+
+struct RGB9E5Data
+{
+    unsigned int R : 9;
+    unsigned int G : 9;
+    unsigned int B : 9;
+    unsigned int E : 5;
+};
+
+// B is the exponent bias (15)
+constexpr int g_sharedexp_bias = 15;
+
+// N is the number of mantissa bits per component (9)
+constexpr int g_sharedexp_mantissabits = 9;
+
+// number of mantissa bits per component pre-biased
+constexpr int g_sharedexp_biased_mantissabits = g_sharedexp_bias + g_sharedexp_mantissabits;
+
+// Emax is the maximum allowed biased exponent value (31)
+constexpr int g_sharedexp_maxexponent = 31;
+
+constexpr float g_sharedexp_max =
+    ((static_cast<float>(1 << g_sharedexp_mantissabits) - 1) /
+     static_cast<float>(1 << g_sharedexp_mantissabits)) *
+    static_cast<float>(1 << (g_sharedexp_maxexponent - g_sharedexp_bias));
+
+}  // anonymous namespace
+
+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 = static_cast<int>(
+        floor((max_c / (pow(2.0f, exp_p - g_sharedexp_biased_mantissabits))) + 0.5f));
+    const int exp_s =
+        static_cast<int>((max_s < pow(2.0f, g_sharedexp_mantissabits)) ? exp_p : exp_p + 1);
+    const float pow2_exp = pow(2.0f, static_cast<float>(exp_s) - g_sharedexp_biased_mantissabits);
+
+    RGB9E5Data output;
+    output.R = static_cast<unsigned int>(floor((red_c / pow2_exp) + 0.5f));
+    output.G = static_cast<unsigned int>(floor((green_c / pow2_exp) + 0.5f));
+    output.B = static_cast<unsigned int>(floor((blue_c / pow2_exp) + 0.5f));
+    output.E = exp_s;
+
+    return bitCast<unsigned int>(output);
+}
+
+void convert999E5toRGBFloats(unsigned int input, float *red, float *green, float *blue)
+{
+    const RGB9E5Data *inputData = reinterpret_cast<const RGB9E5Data *>(&input);
+
+    const float pow2_exp =
+        pow(2.0f, static_cast<float>(inputData->E) - g_sharedexp_biased_mantissabits);
+
+    *red   = inputData->R * pow2_exp;
+    *green = inputData->G * pow2_exp;
+    *blue  = inputData->B * pow2_exp;
+}
+
+}  // namespace gl