blob: 9a2c2ec86bd50d5aa4fa74d14eb31ce8081aa6a0 [file] [log] [blame]
 // // 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 #include 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; // Emax is the maximum allowed biased exponent value (31) constexpr int g_sharedexp_maxexponent = 31; constexpr float g_sharedexp_max = ((static_cast(1 << g_sharedexp_mantissabits) - 1) / static_cast(1 << g_sharedexp_mantissabits)) * static_cast(1 << (g_sharedexp_maxexponent - g_sharedexp_bias)); } // anonymous namespace unsigned int convertRGBFloatsTo999E5(float red, float green, float blue) { const float red_c = std::max(0, std::min(g_sharedexp_max, red)); const float green_c = std::max(0, std::min(g_sharedexp_max, green)); const float blue_c = std::max(0, std::min(g_sharedexp_max, blue)); const float max_c = std::max(std::max(red_c, green_c), blue_c); const float exp_p = std::max(-g_sharedexp_bias - 1, floor(log(max_c))) + 1 + g_sharedexp_bias; const int max_s = static_cast( floor((max_c / (pow(2.0f, exp_p - g_sharedexp_bias - g_sharedexp_mantissabits))) + 0.5f)); const int exp_s = static_cast((max_s < pow(2.0f, g_sharedexp_mantissabits)) ? exp_p : exp_p + 1); RGB9E5Data output; output.R = static_cast( floor((red_c / (pow(2.0f, exp_s - g_sharedexp_bias - g_sharedexp_mantissabits))) + 0.5f)); output.G = static_cast( floor((green_c / (pow(2.0f, exp_s - g_sharedexp_bias - g_sharedexp_mantissabits))) + 0.5f)); output.B = static_cast( floor((blue_c / (pow(2.0f, exp_s - g_sharedexp_bias - g_sharedexp_mantissabits))) + 0.5f)); output.E = exp_s; return bitCast(output); } void convert999E5toRGBFloats(unsigned int input, float *red, float *green, float *blue) { const RGB9E5Data *inputData = reinterpret_cast(&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); } int BitCountPolyfill(uint32_t bits) { int ones = 0; while (bits) { ones += bool(bits & 1); bits >>= 1; } return ones; } } // namespace gl