| /* |
| * Copyright (C) 2011 Marek Olšák <maraeo@gmail.com> |
| * |
| * Permission is hereby granted, free of charge, to any person obtaining a |
| * copy of this software and associated documentation files (the "Software"), |
| * to deal in the Software without restriction, including without limitation |
| * the rights to use, copy, modify, merge, publish, distribute, sublicense, |
| * and/or sell copies of the Software, and to permit persons to whom the |
| * Software is furnished to do so, subject to the following conditions: |
| * |
| * The above copyright notice and this permission notice (including the next |
| * paragraph) shall be included in all copies or substantial portions of the |
| * Software. |
| * |
| * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR |
| * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, |
| * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL |
| * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER |
| * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING |
| * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER |
| * DEALINGS IN THE SOFTWARE. |
| */ |
| |
| /* Based on code from The OpenGL Programming Guide / 7th Edition, Appendix J. |
| * Available here: http://www.opengl-redbook.com/appendices/ |
| * The algorithm in the book contains a bug though, which is fixed in the code |
| * below. |
| */ |
| |
| #include <stdint.h> |
| |
| #define UF11(e, m) ((e << 6) | (m)) |
| #define UF11_EXPONENT_BIAS 15 |
| #define UF11_EXPONENT_BITS 0x1F |
| #define UF11_EXPONENT_SHIFT 6 |
| #define UF11_MANTISSA_BITS 0x3F |
| #define UF11_MANTISSA_SHIFT (23 - UF11_EXPONENT_SHIFT) |
| #define UF11_MAX_EXPONENT (UF11_EXPONENT_BITS << UF11_EXPONENT_SHIFT) |
| |
| #define UF10(e, m) ((e << 5) | (m)) |
| #define UF10_EXPONENT_BIAS 15 |
| #define UF10_EXPONENT_BITS 0x1F |
| #define UF10_EXPONENT_SHIFT 5 |
| #define UF10_MANTISSA_BITS 0x1F |
| #define UF10_MANTISSA_SHIFT (23 - UF10_EXPONENT_SHIFT) |
| #define UF10_MAX_EXPONENT (UF10_EXPONENT_BITS << UF10_EXPONENT_SHIFT) |
| |
| #define F32_INFINITY 0x7f800000 |
| |
| static inline uint32_t f32_to_uf11(float val) |
| { |
| union { |
| float f; |
| uint32_t ui; |
| } f32 = {val}; |
| |
| uint16_t uf11 = 0; |
| |
| /* Decode little-endian 32-bit floating-point value */ |
| int sign = (f32.ui >> 16) & 0x8000; |
| /* Map exponent to the range [-127,128] */ |
| int exponent = ((f32.ui >> 23) & 0xff) - 127; |
| int mantissa = f32.ui & 0x007fffff; |
| |
| if (exponent == 128) { /* Infinity or NaN */ |
| /* From the GL_EXT_packed_float spec: |
| * |
| * "Additionally: negative infinity is converted to zero; positive |
| * infinity is converted to positive infinity; and both positive and |
| * negative NaN are converted to positive NaN." |
| */ |
| uf11 = UF11_MAX_EXPONENT; |
| if (mantissa) { |
| uf11 |= 1; /* NaN */ |
| } else { |
| if (sign) |
| uf11 = 0; /* 0.0 */ |
| } |
| } else if (sign) { |
| return 0; |
| } else if (val > 65024.0f) { |
| /* From the GL_EXT_packed_float spec: |
| * |
| * "Likewise, finite positive values greater than 65024 (the maximum |
| * finite representable unsigned 11-bit floating-point value) are |
| * converted to 65024." |
| */ |
| uf11 = UF11(30, 63); |
| } else if (exponent > -15) { /* Representable value */ |
| exponent += UF11_EXPONENT_BIAS; |
| mantissa >>= UF11_MANTISSA_SHIFT; |
| uf11 = exponent << UF11_EXPONENT_SHIFT | mantissa; |
| } |
| |
| return uf11; |
| } |
| |
| static inline float uf11_to_f32(uint16_t val) |
| { |
| union { |
| float f; |
| uint32_t ui; |
| } f32; |
| |
| int exponent = (val & 0x07c0) >> UF11_EXPONENT_SHIFT; |
| int mantissa = (val & 0x003f); |
| |
| f32.f = 0.0; |
| |
| if (exponent == 0) { |
| if (mantissa != 0) { |
| const float scale = 1.0 / (1 << 20); |
| f32.f = scale * mantissa; |
| } |
| } else if (exponent == 31) { |
| f32.ui = F32_INFINITY | mantissa; |
| } else { |
| float scale, decimal; |
| exponent -= 15; |
| if (exponent < 0) { |
| scale = 1.0f / (1 << -exponent); |
| } else { |
| scale = (float) (1 << exponent); |
| } |
| decimal = 1.0f + (float) mantissa / 64; |
| f32.f = scale * decimal; |
| } |
| |
| return f32.f; |
| } |
| |
| static inline uint32_t f32_to_uf10(float val) |
| { |
| union { |
| float f; |
| uint32_t ui; |
| } f32 = {val}; |
| |
| uint16_t uf10 = 0; |
| |
| /* Decode little-endian 32-bit floating-point value */ |
| int sign = (f32.ui >> 16) & 0x8000; |
| /* Map exponent to the range [-127,128] */ |
| int exponent = ((f32.ui >> 23) & 0xff) - 127; |
| int mantissa = f32.ui & 0x007fffff; |
| |
| if (exponent == 128) { |
| /* From the GL_EXT_packed_float spec: |
| * |
| * "Additionally: negative infinity is converted to zero; positive |
| * infinity is converted to positive infinity; and both positive and |
| * negative NaN are converted to positive NaN." |
| */ |
| uf10 = UF10_MAX_EXPONENT; |
| if (mantissa) { |
| uf10 |= 1; /* NaN */ |
| } else { |
| if (sign) |
| uf10 = 0; /* 0.0 */ |
| } |
| } else if (sign) { |
| return 0; |
| } else if (val > 64512.0f) { |
| /* From the GL_EXT_packed_float spec: |
| * |
| * "Likewise, finite positive values greater than 64512 (the maximum |
| * finite representable unsigned 10-bit floating-point value) are |
| * converted to 64512." |
| */ |
| uf10 = UF10(30, 31); |
| } else if (exponent > -15) { /* Representable value */ |
| exponent += UF10_EXPONENT_BIAS; |
| mantissa >>= UF10_MANTISSA_SHIFT; |
| uf10 = exponent << UF10_EXPONENT_SHIFT | mantissa; |
| } |
| |
| return uf10; |
| } |
| |
| static inline float uf10_to_f32(uint16_t val) |
| { |
| union { |
| float f; |
| uint32_t ui; |
| } f32; |
| |
| int exponent = (val & 0x03e0) >> UF10_EXPONENT_SHIFT; |
| int mantissa = (val & 0x001f); |
| |
| f32.f = 0.0; |
| |
| if (exponent == 0) { |
| if (mantissa != 0) { |
| const float scale = 1.0 / (1 << 19); |
| f32.f = scale * mantissa; |
| } |
| } else if (exponent == 31) { |
| f32.ui = F32_INFINITY | mantissa; |
| } else { |
| float scale, decimal; |
| exponent -= 15; |
| if (exponent < 0) { |
| scale = 1.0f / (1 << -exponent); |
| } |
| else { |
| scale = (float) (1 << exponent); |
| } |
| decimal = 1.0f + (float) mantissa / 32; |
| f32.f = scale * decimal; |
| } |
| |
| return f32.f; |
| } |
| |
| static inline uint32_t float3_to_r11g11b10f(const float rgb[3]) |
| { |
| return ( f32_to_uf11(rgb[0]) & 0x7ff) | |
| ((f32_to_uf11(rgb[1]) & 0x7ff) << 11) | |
| ((f32_to_uf10(rgb[2]) & 0x3ff) << 22); |
| } |
| |
| static inline void r11g11b10f_to_float3(uint32_t rgb, float retval[3]) |
| { |
| retval[0] = uf11_to_f32( rgb & 0x7ff); |
| retval[1] = uf11_to_f32((rgb >> 11) & 0x7ff); |
| retval[2] = uf10_to_f32((rgb >> 22) & 0x3ff); |
| } |