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diff --git a/indra/llcommon/is_approx_equal_fraction.h b/indra/llcommon/is_approx_equal_fraction.h
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+++ b/indra/llcommon/is_approx_equal_fraction.h
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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.
+ * 
+ * $LicenseInfo:firstyear=2009&license=viewerlgpl$
+ * 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) */