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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) 1992-2014, 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. --
-- --
------------------------------------------------------------------------------
-- 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;
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 Machine_Rounding (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 : not null 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.
type S is new String (1 .. T'Size / Character'Size);
type P is access all S with Storage_Size => 0;
-- Buffer and access types used to initialize temporaries for validity
-- checks, if the value to be checked has reverse scalar storage order, or
-- is not known to be properly aligned (for example it appears in a packed
-- record). In this case, we cannot call Valid since Valid assumes proper
-- full alignment. Instead, we copy the value to a temporary location using
-- type S (we cannot simply do a copy of a T value, because the value might
-- be invalid, in which case it might not be possible to copy it through a
-- floating point register).
private
pragma Inline (Machine);
pragma Inline (Model);
-- Note: previously the validity checking subprograms (Unaligned_Valid and
-- Valid) were also inlined, but this was changed since there were some
-- problems with this inlining in optimized mode, and in any case it seems
-- better to avoid this inlining (space and robustness considerations).
end System.Fat_Gen;
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