impdefg.a

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-- IMPDEFG.A
--
--                             Grant of Unlimited Rights
--
--     Under contracts F33600-87-D-0337, F33600-84-D-0280, MDA903-79-C-0687,
--     F08630-91-C-0015, and DCA100-97-D-0025, the U.S. Government obtained 
--     unlimited rights in the software and documentation contained herein.
--     Unlimited rights are defined in DFAR 252.227-7013(a)(19).  By making 
--     this public release, the Government intends to confer upon all 
--     recipients unlimited rights  equal to those held by the Government.  
--     These rights include rights to use, duplicate, release or disclose the 
--     released technical data and computer software in whole or in part, in 
--     any manner and for any purpose whatsoever, and to have or permit others 
--     to do so.
--
--                                    DISCLAIMER
--
--     ALL MATERIALS OR INFORMATION HEREIN RELEASED, MADE AVAILABLE OR
--     DISCLOSED ARE AS IS.  THE GOVERNMENT MAKES NO EXPRESS OR IMPLIED 
--     WARRANTY AS TO ANY MATTER WHATSOEVER, INCLUDING THE CONDITIONS OF THE
--     SOFTWARE, DOCUMENTATION OR OTHER INFORMATION RELEASED, MADE AVAILABLE 
--     OR DISCLOSED, OR THE OWNERSHIP, MERCHANTABILITY, OR FITNESS FOR A
--     PARTICULAR PURPOSE OF SAID MATERIAL.
--*
--
-- DESCRIPTION:
--     This package provides tailorable entities for a particular
--     implementation.  Each entity may be modified to suit the needs
--     of the implementation.  Default values are provided to act as
--     a guide.
--
--     The entities in this package are those which are used exclusively
--     in tests for Annex G (Numerics).
-- 
-- APPLICABILITY CRITERIA:
--     This package is only required for implementations validating the
--     Numerics Annex.
-- 
-- CHANGE HISTORY:
--     29 Jan 96   SAIC    Initial version for ACVC 2.1.
--
--!
 
package ImpDef.Annex_G is
 
--=====-=====-=====-=====-=====-=====-=====-=====-=====-=====-=====-=====--

   -- This function must return a "negative zero" value for implementations
   -- for which Float'Signed_Zeros is True.

   function Negative_Zero return Float;

--=====-=====-=====-=====-=====-=====-=====-=====-=====-=====-=====-=====--

end ImpDef.Annex_G;


     --==================================================================--

 
package body ImpDef.Annex_G is


--=====-=====-=====-=====-=====-=====-=====-=====-=====-=====-=====-=====--

   --  This function must return a negative zero value for implementations
   --  for which Float'Signed_Zeros is True.
   --  We generate the smallest normalized negative number, and divide by a
   --  few powers of two to obtain a number whose absolute value equals zero
   --  but whose sign is negative.

   function Negative_Zero return Float is
      negz : float := -1.0 *
         float (float'Machine_Radix)
            ** ( Float'Machine_Emin - Float'Machine_Mantissa); 
   begin
      return negz / 8.0;
   end Negative_Zero;

--=====-=====-=====-=====-=====-=====-=====-=====-=====-=====-=====-=====--

end ImpDef.Annex_G;