From 9e2b867b3f2e9afc9e9f9178788ae07f6be1f3c0 Mon Sep 17 00:00:00 2001 From: Brian Paul Date: Fri, 22 Aug 2008 15:13:47 -0600 Subject: gallium: new u_math.[ch] files for math functions So far, optimized/low-precision versions of exp(), exp2(), log2(), pow(). --- src/gallium/auxiliary/util/Makefile | 1 + src/gallium/auxiliary/util/SConscript | 1 + src/gallium/auxiliary/util/u_math.c | 60 ++++++++++++++ src/gallium/auxiliary/util/u_math.h | 144 ++++++++++++++++++++++++++++++++++ 4 files changed, 206 insertions(+) create mode 100644 src/gallium/auxiliary/util/u_math.c create mode 100644 src/gallium/auxiliary/util/u_math.h (limited to 'src/gallium/auxiliary/util') diff --git a/src/gallium/auxiliary/util/Makefile b/src/gallium/auxiliary/util/Makefile index db3d810a2e..be1b97b535 100644 --- a/src/gallium/auxiliary/util/Makefile +++ b/src/gallium/auxiliary/util/Makefile @@ -12,6 +12,7 @@ C_SOURCES = \ u_gen_mipmap.c \ u_handle_table.c \ u_hash_table.c \ + u_math.c \ u_mm.c \ u_simple_shaders.c \ u_snprintf.c \ diff --git a/src/gallium/auxiliary/util/SConscript b/src/gallium/auxiliary/util/SConscript index 0309de1ac2..7865307a7a 100644 --- a/src/gallium/auxiliary/util/SConscript +++ b/src/gallium/auxiliary/util/SConscript @@ -13,6 +13,7 @@ util = env.ConvenienceLibrary( 'u_gen_mipmap.c', 'u_handle_table.c', 'u_hash_table.c', + 'u_math.c', 'u_mm.c', 'u_simple_shaders.c', 'u_snprintf.c', diff --git a/src/gallium/auxiliary/util/u_math.c b/src/gallium/auxiliary/util/u_math.c new file mode 100644 index 0000000000..8bf6551b6e --- /dev/null +++ b/src/gallium/auxiliary/util/u_math.c @@ -0,0 +1,60 @@ +/************************************************************************** + * + * Copyright 2008 Tungsten Graphics, Inc., Cedar Park, Texas. + * All Rights Reserved. + * + * 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, sub license, 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 NON-INFRINGEMENT. + * IN NO EVENT SHALL TUNGSTEN GRAPHICS AND/OR ITS SUPPLIERS 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. + * + **************************************************************************/ + + + +#include "util/u_math.h" + + + +float pow2_table[POW2_TABLE_SIZE]; + + +static void +init_pow2_table(void) +{ + int i; + for (i = 0; i < POW2_TABLE_SIZE; i++) { + pow2_table[i] = pow(2.0, i / POW2_TABLE_SCALE); + } +} + + +/** + * One time init for math utilities. + */ +void +util_init_math(void) +{ + static boolean initialized = FALSE; + if (!initialized) { + init_pow2_table(); + initialized = TRUE; + } +} + + diff --git a/src/gallium/auxiliary/util/u_math.h b/src/gallium/auxiliary/util/u_math.h new file mode 100644 index 0000000000..e179ce700f --- /dev/null +++ b/src/gallium/auxiliary/util/u_math.h @@ -0,0 +1,144 @@ +/************************************************************************** + * + * Copyright 2008 Tungsten Graphics, Inc., Cedar Park, Texas. + * All Rights Reserved. + * + * 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, sub license, 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 NON-INFRINGEMENT. + * IN NO EVENT SHALL TUNGSTEN GRAPHICS AND/OR ITS SUPPLIERS 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. + * + **************************************************************************/ + + +/** + * Math utilities and approximations for common math functions. + * Reduced precision is usually acceptable in shaders... + */ + + +#ifndef U_MATH_H +#define U_MATH_H + + +#include "pipe/p_util.h" +#include "util/u_math.h" + + + +#define POW2_TABLE_SIZE 256 +#define POW2_TABLE_SCALE ((float) (POW2_TABLE_SIZE-1)) +extern float pow2_table[POW2_TABLE_SIZE]; + + +extern void +util_init_math(void); + + + + +/** + * Fast approximation to exp(x). + * Compute with base 2 exponents: exp(x) = exp2(log2(e) * x) + * Note: log2(e) is a constant, k = 1.44269 + * So, exp(x) = exp2(k * x); + * Identity: exp2(a + b) = exp2(a) * exp2(b) + * Let ipart = int(k*x) + * Let fpart = k*x - ipart; + * So, exp2(k*x) = exp2(ipart) * exp2(fpart) + * Compute exp2(ipart) with i << ipart + * Compute exp2(fpart) with lookup table. + */ +static INLINE float +util_fast_exp(float x) +{ + if (x >= 0.0f) { + float k = 1.44269f; /* = log2(e) */ + float kx = k * x; + int ipart = (int) kx; + float fpart = kx - (float) ipart; + float y = (float) (1 << ipart) + * pow2_table[(int) (fpart * POW2_TABLE_SCALE)]; + return y; + } + else { + /* exp(-x) = 1.0 / exp(x) */ + float k = -1.44269f; + float kx = k * x; + int ipart = (int) kx; + float fpart = kx - (float) ipart; + float y = (float) (1 << ipart) + * pow2_table[(int) (fpart * POW2_TABLE_SCALE)]; + return 1.0f / y; + } +} + + +/** + * Fast version of 2^x + * XXX the above function could be implemented in terms of this one. + */ +static INLINE float +util_fast_exp2(float x) +{ + if (x >= 0.0f) { + int ipart = (int) x; + float fpart = x - (float) ipart; + float y = (float) (1 << ipart) + * pow2_table[(int) (fpart * POW2_TABLE_SCALE)]; + return y; + } + else { + /* exp(-x) = 1.0 / exp(x) */ + int ipart = (int) -x; + float fpart = -x - (float) ipart; + float y = (float) (1 << ipart) + * pow2_table[(int) (fpart * POW2_TABLE_SCALE)]; + return 1.0f / y; + } +} + + +/** + * Based on code from http://www.flipcode.com/totd/ + */ +static INLINE float +util_fast_log2(float val) +{ + union fi num; + int log_2; + num.f = val; + log_2 = ((num.i >> 23) & 255) - 128; + num.i &= ~(255 << 23); + num.i += 127 << 23; + num.f = ((-1.0f/3) * num.f + 2) * num.f - 2.0f/3; + return num.f + log_2; +} + + +static INLINE float +util_fast_pow(float x, float y) +{ + /* XXX this test may need adjustment */ + if (y >= 3.0 && -0.02f <= x && x <= 0.02f) + return 0.0f; + return util_fast_exp2(util_fast_log2(x) * y); +} + + +#endif /* U_MATH_H */ -- cgit v1.2.3