#### /indra/llcommon/is_approx_equal_fraction.h

C++ Header | 79 lines | 26 code | 9 blank | 44 comment | 3 complexity | 4291aab442aeddf2ca44a40055bad366 MD5 | raw file

1/** 2 * @file is_approx_equal_fraction.h 3 * @author Nat Goodspeed 4 * @date 2009-01-28 5 * @brief lltut.h uses is_approx_equal_fraction(). Moved to this header 6 * file in llcommon so we can use lltut.h for llcommon tests without 7 * making llcommon depend on llmath. 8 * 9 * $LicenseInfo:firstyear=2009&license=viewerlgpl$ 10 * Second Life Viewer Source Code 11 * Copyright (C) 2010, Linden Research, Inc. 12 * 13 * This library is free software; you can redistribute it and/or 14 * modify it under the terms of the GNU Lesser General Public 15 * License as published by the Free Software Foundation; 16 * version 2.1 of the License only. 17 * 18 * This library is distributed in the hope that it will be useful, 19 * but WITHOUT ANY WARRANTY; without even the implied warranty of 20 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 21 * Lesser General Public License for more details. 22 * 23 * You should have received a copy of the GNU Lesser General Public 24 * License along with this library; if not, write to the Free Software 25 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA 26 * 27 * Linden Research, Inc., 945 Battery Street, San Francisco, CA 94111 USA 28 * $/LicenseInfo$ 29 */ 30 31#if ! defined(LL_IS_APPROX_EQUAL_FRACTION_H) 32#define LL_IS_APPROX_EQUAL_FRACTION_H 33 34#include "lldefs.h" 35#include <cmath> 36 37/** 38 * Originally llmath.h contained two complete implementations of 39 * is_approx_equal_fraction(), with signatures as below, bodies identical save 40 * where they specifically mentioned F32/F64. Unifying these into a template 41 * makes sense -- but to preserve the compiler's overload-selection behavior, 42 * we still wrap the template implementation with the specific overloaded 43 * signatures. 44 */ 45template <typename FTYPE> 46inline BOOL is_approx_equal_fraction_impl(FTYPE x, FTYPE y, U32 frac_bits) 47{ 48 BOOL ret = TRUE; 49 FTYPE diff = (FTYPE) fabs(x - y); 50 51 S32 diffInt = (S32) diff; 52 S32 diffFracTolerance = (S32) ((diff - (FTYPE) diffInt) * (1 << frac_bits)); 53 54 // if integer portion is not equal, not enough bits were used for packing 55 // so error out since either the use case is not correct OR there is 56 // an issue with pack/unpack. should fail in either case. 57 // for decimal portion, make sure that the delta is no more than 1 58 // based on the number of bits used for packing decimal portion. 59 if (diffInt != 0 || diffFracTolerance > 1) 60 { 61 ret = FALSE; 62 } 63 64 return ret; 65} 66 67/// F32 flavor 68inline BOOL is_approx_equal_fraction(F32 x, F32 y, U32 frac_bits) 69{ 70 return is_approx_equal_fraction_impl<F32>(x, y, frac_bits); 71} 72 73/// F64 flavor 74inline BOOL is_approx_equal_fraction(F64 x, F64 y, U32 frac_bits) 75{ 76 return is_approx_equal_fraction_impl<F64>(x, y, frac_bits); 77} 78 79#endif /* ! defined(LL_IS_APPROX_EQUAL_FRACTION_H) */