Campbell Barton
ccf8df66fe
Add utility functions to get the floor/ceiling of a float value to the next power of 10.
118 lines
2.7 KiB
C
118 lines
2.7 KiB
C
/*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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*
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* The Original Code is Copyright (C) 2001-2002 by NaN Holding BV.
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* All rights reserved.
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*
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* The Original Code is: some of this file.
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*
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* */
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/** \file
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* \ingroup bli
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*/
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#include "BLI_math.h"
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#include "BLI_strict_flags.h"
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int pow_i(int base, int exp)
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{
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int result = 1;
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BLI_assert(exp >= 0);
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while (exp) {
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if (exp & 1) {
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result *= base;
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}
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exp >>= 1;
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base *= base;
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}
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return result;
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}
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/* from python 3.1 floatobject.c
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* ndigits must be between 0 and 21 */
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double double_round(double x, int ndigits)
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{
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double pow1, pow2, y, z;
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if (ndigits >= 0) {
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pow1 = pow(10.0, (double)ndigits);
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pow2 = 1.0;
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y = (x * pow1) * pow2;
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/* if y overflows, then rounded value is exactly x */
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if (!isfinite(y)) {
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return x;
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}
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}
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else {
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pow1 = pow(10.0, (double)-ndigits);
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pow2 = 1.0; /* unused; silences a gcc compiler warning */
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y = x / pow1;
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}
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z = round(y);
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if (fabs(y - z) == 0.5) {
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/* halfway between two integers; use round-half-even */
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z = 2.0 * round(y / 2.0);
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}
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if (ndigits >= 0) {
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z = (z / pow2) / pow1;
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}
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else {
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z *= pow1;
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}
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/* if computation resulted in overflow, raise OverflowError */
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return z;
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}
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/**
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* Floor to the nearest power of 10, e.g.:
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* - 15.0 -> 10.0
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* - 0.015 -> 0.01
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* - 1.0 -> 1.0
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*
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* \param f: Value to floor, must be over 0.0.
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* \note If we wanted to support signed values we could if this becomes necessary.
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*/
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float floor_power_of_10(float f)
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{
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BLI_assert(!(f < 0.0f));
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if (f != 0.0f) {
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return 1.0f / (powf(10.0f, ceilf(log10f(1.0f / f))));
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}
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return 0.0f;
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}
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/**
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* Ceiling to the nearest power of 10, e.g.:
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* - 15.0 -> 100.0
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* - 0.015 -> 0.1
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* - 1.0 -> 1.0
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*
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* \param f: Value to ceiling, must be over 0.0.
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* \note If we wanted to support signed values we could if this becomes necessary.
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*/
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float ceil_power_of_10(float f)
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{
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BLI_assert(!(f < 0.0f));
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if (f != 0.0f) {
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return 1.0f / (powf(10.0f, floorf(log10f(1.0f / f))));
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}
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return 0.0f;
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}
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