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------------------------------------------------------------------------------
-- --
-- GNAT COMPILER COMPONENTS --
-- --
-- E V A L _ F A T --
-- --
-- S p e c --
-- --
-- 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. See the GNU General Public License --
-- for more details. You should have received a copy of the GNU General --
-- Public License distributed with GNAT; see file COPYING3. If not, go to --
-- http://www.gnu.org/licenses for a complete copy of the license. --
-- --
-- GNAT was originally developed by the GNAT team at New York University. --
-- Extensive contributions were provided by Ada Core Technologies Inc. --
-- --
------------------------------------------------------------------------------
-- This package provides for compile-time evaluation of static calls to the
-- floating-point attribute functions. It is the compile-time equivalent of
-- the System.Fat_Gen runtime package. The coding is quite similar, as are
-- the subprogram specs, except that the type is passed as an explicit
-- first parameter (and used via ttypes, to obtain the necessary information
-- about the characteristics of the type for computing the results.
with Types; use Types;
with Uintp; use Uintp;
with Urealp; use Urealp;
package Eval_Fat is
subtype UI is Uint;
-- The compile time representation of universal integer
subtype T is Ureal;
-- The compile time representation of floating-point values
subtype R is Entity_Id;
-- The compile time representation of the floating-point root type
-- The following functions perform the operation implied by their name
-- which corresponds to the name of the attribute which they compute.
-- The arguments correspond to the attribute function arguments.
function Adjacent (RT : R; X, Towards : T) return T;
function Ceiling (RT : R; X : T) return T;
function Compose (RT : R; Fraction : T; Exponent : UI) return T;
function Copy_Sign (RT : R; Value, Sign : T) return T;
function Exponent (RT : R; X : T) return UI;
function Floor (RT : R; X : T) return T;
function Fraction (RT : R; X : T) return T;
function Leading_Part (RT : R; X : T; Radix_Digits : UI) return T;
function Model (RT : R; X : T) return T;
function Pred (RT : R; X : T) return T;
function Remainder (RT : R; X, Y : T) return T;
function Rounding (RT : R; X : T) return T;
function Scaling (RT : R; X : T; Adjustment : UI) return T;
function Succ (RT : R; X : T) return T;
function Truncation (RT : R; X : T) return T;
function Unbiased_Rounding (RT : R; X : T) return T;
-- The following global declarations are used by the Machine attribute
type Rounding_Mode is (Floor, Ceiling, Round, Round_Even);
for Rounding_Mode use (0, 1, 2, 3);
-- Used to indicate rounding mode for Machine attribute
-- Note that C code in gigi knows that Round_Even is 3
-- The Machine attribute is special, in that it takes an extra argument
-- indicating the rounding mode, and also an argument Enode that is a
-- node used to post warnings (e.g. if asked to convert a negative zero
-- on a machine for which Signed_Zeros is False).
function Machine
(RT : R;
X : T;
Mode : Rounding_Mode;
Enode : Node_Id) return T;
procedure Decompose_Int
(RT : R;
X : T;
Fraction : out UI;
Exponent : out UI;
Mode : Rounding_Mode);
-- Decomposes a floating-point number into fraction and exponent parts.
-- The Fraction value returned is an integer representing the value
-- Fraction * Scale, where Scale is the value (Machine_Radix_Value (RT) **
-- Machine_Mantissa_Value (RT)). The value is obtained by using biased
-- rounding (halfway cases round away from zero), round to even, a floor
-- operation or a ceiling operation depending on the setting of Mode (see
-- corresponding descriptions in Urealp).
end Eval_Fat;
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