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/**
* @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.
*
* $LicenseInfo:firstyear=2009&license=viewergpl$
*
* Copyright (c) 2009, Linden Research, Inc.
*
* Second Life Viewer Source Code
* The source code in this file ("Source Code") is provided by Linden Lab
* to you under the terms of the GNU General Public License, version 2.0
* ("GPL"), unless you have obtained a separate licensing agreement
* ("Other License"), formally executed by you and Linden Lab. Terms of
* the GPL can be found in doc/GPL-license.txt in this distribution, or
* online at http://secondlifegrid.net/programs/open_source/licensing/gplv2
*
* There are special exceptions to the terms and conditions of the GPL as
* it is applied to this Source Code. View the full text of the exception
* in the file doc/FLOSS-exception.txt in this software distribution, or
* online at
* http://secondlifegrid.net/programs/open_source/licensing/flossexception
*
* By copying, modifying or distributing this software, you acknowledge
* that you have read and understood your obligations described above,
* and agree to abide by those obligations.
*
* ALL LINDEN LAB SOURCE CODE IS PROVIDED "AS IS." LINDEN LAB MAKES NO
* WARRANTIES, EXPRESS, IMPLIED OR OTHERWISE, REGARDING ITS ACCURACY,
* COMPLETENESS OR PERFORMANCE.
* $/LicenseInfo$
*/
#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) */
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