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|
------------------------------------------------------------------------------
-- --
-- GNAT COMPILER COMPONENTS --
-- --
-- S Y S T E M . F A T _ G E N --
-- --
-- S p e c --
-- --
-- Copyright (C) 1992-2003 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 2, 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 COPYING. If not, write --
-- to the Free Software Foundation, 51 Franklin Street, Fifth Floor, --
-- Boston, MA 02110-1301, USA. --
-- --
-- As a special exception, if other files instantiate generics from this --
-- unit, or you link this unit with other files to produce an executable, --
-- this unit does not by itself cause the resulting executable to be --
-- covered by the GNU General Public License. This exception does not --
-- however invalidate any other reasons why the executable file might be --
-- covered by the GNU Public License. --
-- --
-- GNAT was originally developed by the GNAT team at New York University. --
-- Extensive contributions were provided by Ada Core Technologies Inc. --
-- --
------------------------------------------------------------------------------
-- This generic package provides a target independent implementation of the
-- floating-point attributes that denote functions. The implementations here
-- are portable, but very slow. The runtime contains a set of instantiations
-- of this package for all predefined floating-point types, and these should
-- be replaced by efficient assembly language code where possible.
generic
type T is digits <>;
package System.Fat_Gen is
pragma Pure (Fat_Gen);
subtype UI is Integer;
-- The runtime representation of universal integer for the purposes of
-- this package is integer. The expander generates conversions for the
-- actual type used. For functions returning universal integer, there
-- is no problem, since the result always is in range of integer. For
-- input arguments, the expander has to do some special casing to deal
-- with the (very annoying!) cases of out of range values. If we used
-- Long_Long_Integer to represent universal, then there would be no
-- problem, but the resulting inefficiency would be annoying.
function Adjacent (X, Towards : T) return T;
function Ceiling (X : T) return T;
function Compose (Fraction : T; Exponent : UI) return T;
function Copy_Sign (Value, Sign : T) return T;
function Exponent (X : T) return UI;
function Floor (X : T) return T;
function Fraction (X : T) return T;
function Leading_Part (X : T; Radix_Digits : UI) return T;
function Machine (X : T) return T;
function Model (X : T) return T;
function Pred (X : T) return T;
function Remainder (X, Y : T) return T;
function Rounding (X : T) return T;
function Scaling (X : T; Adjustment : UI) return T;
function Succ (X : T) return T;
function Truncation (X : T) return T;
function Unbiased_Rounding (X : T) return T;
function Valid (X : access T) return Boolean;
-- This function checks if the object of type T referenced by X
-- is valid, and returns True/False accordingly. The parameter is
-- passed by reference (access) here, as the object of type T may
-- be an abnormal value that cannot be passed in a floating-point
-- register, and the whole point of 'Valid is to prevent exceptions.
-- Note that the object of type T must have the natural alignment
-- for type T. See Unaligned_Valid for further discussion.
function Unaligned_Valid (A : System.Address) return Boolean;
-- This version of Valid is used if the floating-point value to
-- be checked is not known to be aligned (for example it appears
-- in a packed record). In this case, we cannot call Valid since
-- Valid assumes proper full alignment. Instead Unaligned_Valid
-- performs the same processing for a possibly unaligned float,
-- by first doing a copy and then calling Valid. One might think
-- that the front end could simply do a copy to an aligned temp,
-- but remember that we may have an abnormal value that cannot
-- be copied into a floating-point register, so things are a bit
-- trickier than one might expect.
--
-- Note: Unaligned_Valid is never called for a target which does
-- not require strict alignment (e.g. the ia32/x86), since on a
-- target not requiring strict alignment, it is fine to pass a
-- non-aligned value to the standard Valid routine.
private
pragma Inline (Machine);
pragma Inline (Model);
pragma Inline_Always (Valid);
pragma Inline_Always (Unaligned_Valid);
end System.Fat_Gen;
|
