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+------------------------------------------------------------------------------
+-- --
+-- GNAT RUN-TIME COMPONENTS --
+-- --
+-- S Y S T E M . E X N _ L L F --
+-- --
+-- B o d y --
+-- --
+-- Copyright (C) 1992-2012, Free Software Foundation, Inc. --
+-- --
+-- GNAT is free software; you can redistribute it and/or modify it under --
+-- terms of the GNU General Public License as published by the Free Soft- --
+-- ware Foundation; either version 3, or (at your option) any later ver- --
+-- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
+-- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
+-- or FITNESS FOR A PARTICULAR PURPOSE. --
+-- --
+-- As a special exception under Section 7 of GPL version 3, you are granted --
+-- additional permissions described in the GCC Runtime Library Exception, --
+-- version 3.1, as published by the Free Software Foundation. --
+-- --
+-- You should have received a copy of the GNU General Public License and --
+-- a copy of the GCC Runtime Library Exception along with this program; --
+-- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see --
+-- <http://www.gnu.org/licenses/>. --
+-- --
+-- GNAT was originally developed by the GNAT team at New York University. --
+-- Extensive contributions were provided by Ada Core Technologies Inc. --
+-- --
+------------------------------------------------------------------------------
+
+package body System.Exn_LLF is
+
+ -------------------------
+ -- Exn_Long_Long_Float --
+ -------------------------
+
+ function Exn_Long_Long_Float
+ (Left : Long_Long_Float;
+ Right : Integer) return Long_Long_Float
+ is
+ Result : Long_Long_Float := 1.0;
+ Factor : Long_Long_Float := Left;
+ Exp : Integer := Right;
+
+ begin
+ -- We use the standard logarithmic approach, Exp gets shifted right
+ -- testing successive low order bits and Factor is the value of the
+ -- base raised to the next power of 2. If the low order bit or Exp is
+ -- set, multiply the result by this factor. For negative exponents,
+ -- invert result upon return.
+
+ if Exp >= 0 then
+ loop
+ if Exp rem 2 /= 0 then
+ Result := Result * Factor;
+ end if;
+
+ Exp := Exp / 2;
+ exit when Exp = 0;
+ Factor := Factor * Factor;
+ end loop;
+
+ return Result;
+
+ -- Here we have a negative exponent, and we compute the result as:
+
+ -- 1.0 / (Left ** (-Right))
+
+ -- Note that the case of Left being zero is not special, it will
+ -- simply result in a division by zero at the end, yielding a
+ -- correctly signed infinity, or possibly generating an overflow.
+
+ -- Note on overflow: The coding of this routine assumes that the
+ -- target generates infinities with standard IEEE semantics. If this
+ -- is not the case, then the code below may raise Constraint_Error.
+ -- This follows the implementation permission given in RM 4.5.6(12).
+
+ else
+ begin
+ loop
+ if Exp rem 2 /= 0 then
+ Result := Result * Factor;
+ end if;
+
+ Exp := Exp / 2;
+ exit when Exp = 0;
+ Factor := Factor * Factor;
+ end loop;
+
+ return 1.0 / Result;
+ end;
+ end if;
+ end Exn_Long_Long_Float;
+
+end System.Exn_LLF;