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Diffstat (limited to 'src/mesa/main/rgb9e5.h')
| -rw-r--r-- | src/mesa/main/rgb9e5.h | 173 |
1 files changed, 173 insertions, 0 deletions
diff --git a/src/mesa/main/rgb9e5.h b/src/mesa/main/rgb9e5.h new file mode 100644 index 00000000000..9bb431ffe9c --- /dev/null +++ b/src/mesa/main/rgb9e5.h @@ -0,0 +1,173 @@ +/* + * Copyright (C) 2011 Marek Olšák <[email protected]> + * + * 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. + */ + +/* Copied from EXT_texture_shared_exponent and edited. */ + +#ifndef RGB9E5_H +#define RGB9E5_H + +#include <math.h> +#include <assert.h> + +#define RGB9E5_EXPONENT_BITS 5 +#define RGB9E5_MANTISSA_BITS 9 +#define RGB9E5_EXP_BIAS 15 +#define RGB9E5_MAX_VALID_BIASED_EXP 31 + +#define MAX_RGB9E5_EXP (RGB9E5_MAX_VALID_BIASED_EXP - RGB9E5_EXP_BIAS) +#define RGB9E5_MANTISSA_VALUES (1<<RGB9E5_MANTISSA_BITS) +#define MAX_RGB9E5_MANTISSA (RGB9E5_MANTISSA_VALUES-1) +#define MAX_RGB9E5 (((float)MAX_RGB9E5_MANTISSA)/RGB9E5_MANTISSA_VALUES * (1<<MAX_RGB9E5_EXP)) +#define EPSILON_RGB9E5 ((1.0/RGB9E5_MANTISSA_VALUES) / (1<<RGB9E5_EXP_BIAS)) + +typedef union { + unsigned int raw; + float value; + struct { +#if defined(MESA_BIG_ENDIAN) || defined(PIPE_ARCH_BIG_ENDIAN) + unsigned int negative:1; + unsigned int biasedexponent:8; + unsigned int mantissa:23; +#else + unsigned int mantissa:23; + unsigned int biasedexponent:8; + unsigned int negative:1; +#endif + } field; +} float754; + +typedef union { + unsigned int raw; + struct { +#if defined(MESA_BIG_ENDIAN) || defined(PIPE_ARCH_BIG_ENDIAN) + unsigned int biasedexponent:RGB9E5_EXPONENT_BITS; + unsigned int b:RGB9E5_MANTISSA_BITS; + unsigned int g:RGB9E5_MANTISSA_BITS; + unsigned int r:RGB9E5_MANTISSA_BITS; +#else + unsigned int r:RGB9E5_MANTISSA_BITS; + unsigned int g:RGB9E5_MANTISSA_BITS; + unsigned int b:RGB9E5_MANTISSA_BITS; + unsigned int biasedexponent:RGB9E5_EXPONENT_BITS; +#endif + } field; +} rgb9e5; + +static INLINE float rgb9e5_ClampRange(float x) +{ + if (x > 0.0) { + if (x >= MAX_RGB9E5) { + return MAX_RGB9E5; + } else { + return x; + } + } else { + /* NaN gets here too since comparisons with NaN always fail! */ + return 0.0; + } +} + +static INLINE float rgb9e5_MaxOf3(float x, float y, float z) +{ + if (x > y) { + return MAX2(x, z); + } else { + return MAX2(y, z); + } +} + +/* Ok, FloorLog2 is not correct for the denorm and zero values, but we + are going to do a max of this value with the minimum rgb9e5 exponent + that will hide these problem cases. */ +static INLINE int rgb9e5_FloorLog2(float x) +{ + float754 f; + + f.value = x; + return (f.field.biasedexponent - 127); +} + +static INLINE unsigned float3_to_rgb9e5(const float rgb[3]) +{ + rgb9e5 retval; + float maxrgb; + int rm, gm, bm; + float rc, gc, bc; + int exp_shared, maxm; + double denom; + + rc = rgb9e5_ClampRange(rgb[0]); + gc = rgb9e5_ClampRange(rgb[1]); + bc = rgb9e5_ClampRange(rgb[2]); + + maxrgb = rgb9e5_MaxOf3(rc, gc, bc); + exp_shared = MAX2(-RGB9E5_EXP_BIAS-1, rgb9e5_FloorLog2(maxrgb)) + 1 + RGB9E5_EXP_BIAS; + assert(exp_shared <= RGB9E5_MAX_VALID_BIASED_EXP); + assert(exp_shared >= 0); + /* This pow function could be replaced by a table. */ + denom = pow(2, exp_shared - RGB9E5_EXP_BIAS - RGB9E5_MANTISSA_BITS); + + maxm = (int) floor(maxrgb / denom + 0.5); + if (maxm == MAX_RGB9E5_MANTISSA+1) { + denom *= 2; + exp_shared += 1; + assert(exp_shared <= RGB9E5_MAX_VALID_BIASED_EXP); + } else { + assert(maxm <= MAX_RGB9E5_MANTISSA); + } + + rm = (int) floor(rc / denom + 0.5); + gm = (int) floor(gc / denom + 0.5); + bm = (int) floor(bc / denom + 0.5); + + assert(rm <= MAX_RGB9E5_MANTISSA); + assert(gm <= MAX_RGB9E5_MANTISSA); + assert(bm <= MAX_RGB9E5_MANTISSA); + assert(rm >= 0); + assert(gm >= 0); + assert(bm >= 0); + + retval.field.r = rm; + retval.field.g = gm; + retval.field.b = bm; + retval.field.biasedexponent = exp_shared; + + return retval.raw; +} + +static INLINE void rgb9e5_to_float3(unsigned rgb, float retval[3]) +{ + rgb9e5 v; + int exponent; + float scale; + + v.raw = rgb; + exponent = v.field.biasedexponent - RGB9E5_EXP_BIAS - RGB9E5_MANTISSA_BITS; + scale = (float) pow(2, exponent); + + retval[0] = v.field.r * scale; + retval[1] = v.field.g * scale; + retval[2] = v.field.b * scale; +} + +#endif |