/** * @file is_approx_equal_fraction.h * @author Nat Goodspeed * @date 2009-01-28 * @brief lltut.h uses is_approx_equal_fraction(). Moved to this header * file in llcommon so we can use lltut.h for llcommon tests without * making llcommon depend on llmath. * * $LicenseInfo:firstyear=2009&license=viewerlgpl$ * Second Life Viewer Source Code * Copyright (C) 2010, Linden Research, Inc. * * This library is free software; you can redistribute it and/or * modify it under the terms of the GNU Lesser General Public * License as published by the Free Software Foundation; * version 2.1 of the License only. * * This library is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public * License along with this library; if not, write to the Free Software * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA * * Linden Research, Inc., 945 Battery Street, San Francisco, CA 94111 USA * $/LicenseInfo$ */ #if ! defined(LL_IS_APPROX_EQUAL_FRACTION_H) #define LL_IS_APPROX_EQUAL_FRACTION_H #include "lldefs.h" #include <cmath> /** * Originally llmath.h contained two complete implementations of * is_approx_equal_fraction(), with signatures as below, bodies identical save * where they specifically mentioned F32/F64. Unifying these into a template * makes sense -- but to preserve the compiler's overload-selection behavior, * we still wrap the template implementation with the specific overloaded * signatures. */ template <typename FTYPE> inline BOOL is_approx_equal_fraction_impl(FTYPE x, FTYPE y, U32 frac_bits) { BOOL ret = TRUE; FTYPE diff = (FTYPE) fabs(x - y); S32 diffInt = (S32) diff; S32 diffFracTolerance = (S32) ((diff - (FTYPE) diffInt) * (1 << frac_bits)); // if integer portion is not equal, not enough bits were used for packing // so error out since either the use case is not correct OR there is // an issue with pack/unpack. should fail in either case. // for decimal portion, make sure that the delta is no more than 1 // based on the number of bits used for packing decimal portion. if (diffInt != 0 || diffFracTolerance > 1) { ret = FALSE; } return ret; } /// F32 flavor inline BOOL is_approx_equal_fraction(F32 x, F32 y, U32 frac_bits) { return is_approx_equal_fraction_impl<F32>(x, y, frac_bits); } /// F64 flavor inline BOOL is_approx_equal_fraction(F64 x, F64 y, U32 frac_bits) { return is_approx_equal_fraction_impl<F64>(x, y, frac_bits); } #endif /* ! defined(LL_IS_APPROX_EQUAL_FRACTION_H) */