119 lines
6.1 KiB
Ada
119 lines
6.1 KiB
Ada
------------------------------------------------------------------------------
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-- --
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-- GNAT COMPILER COMPONENTS --
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-- --
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-- S Y S T E M . F A T _ G E N --
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-- --
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-- S p e c --
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-- --
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-- Copyright (C) 1992-2014, Free Software Foundation, Inc. --
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-- --
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-- GNAT is free software; you can redistribute it and/or modify it under --
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-- terms of the GNU General Public License as published by the Free Soft- --
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-- ware Foundation; either version 3, or (at your option) any later ver- --
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-- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
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-- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
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-- or FITNESS FOR A PARTICULAR PURPOSE. --
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-- --
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-- As a special exception under Section 7 of GPL version 3, you are granted --
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-- additional permissions described in the GCC Runtime Library Exception, --
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-- version 3.1, as published by the Free Software Foundation. --
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-- --
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-- You should have received a copy of the GNU General Public License and --
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-- a copy of the GCC Runtime Library Exception along with this program; --
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-- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see --
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-- <http://www.gnu.org/licenses/>. --
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-- --
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-- GNAT was originally developed by the GNAT team at New York University. --
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-- Extensive contributions were provided by Ada Core Technologies Inc. --
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-- --
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------------------------------------------------------------------------------
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-- This generic package provides a target independent implementation of the
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-- floating-point attributes that denote functions. The implementations here
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-- are portable, but very slow. The runtime contains a set of instantiations
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-- of this package for all predefined floating-point types, and these should
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-- be replaced by efficient assembly language code where possible.
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generic
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type T is digits <>;
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package System.Fat_Gen is
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pragma Pure;
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subtype UI is Integer;
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-- The runtime representation of universal integer for the purposes of
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-- this package is integer. The expander generates conversions for the
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-- actual type used. For functions returning universal integer, there
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-- is no problem, since the result always is in range of integer. For
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-- input arguments, the expander has to do some special casing to deal
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-- with the (very annoying) cases of out of range values. If we used
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-- Long_Long_Integer to represent universal, then there would be no
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-- problem, but the resulting inefficiency would be annoying.
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function Adjacent (X, Towards : T) return T;
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function Ceiling (X : T) return T;
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function Compose (Fraction : T; Exponent : UI) return T;
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function Copy_Sign (Value, Sign : T) return T;
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function Exponent (X : T) return UI;
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function Floor (X : T) return T;
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function Fraction (X : T) return T;
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function Leading_Part (X : T; Radix_Digits : UI) return T;
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function Machine (X : T) return T;
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function Machine_Rounding (X : T) return T;
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function Model (X : T) return T;
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function Pred (X : T) return T;
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function Remainder (X, Y : T) return T;
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function Rounding (X : T) return T;
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function Scaling (X : T; Adjustment : UI) return T;
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function Succ (X : T) return T;
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function Truncation (X : T) return T;
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function Unbiased_Rounding (X : T) return T;
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function Valid (X : not null access T) return Boolean;
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-- This function checks if the object of type T referenced by X is valid,
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-- and returns True/False accordingly. The parameter is passed by reference
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-- (access) here, as the object of type T may be an abnormal value that
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-- cannot be passed in a floating-point register, and the whole point of
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-- 'Valid is to prevent exceptions. Note that the object of type T must
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-- have the natural alignment for type T.
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type S is new String (1 .. T'Size / Character'Size);
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type P is access all S with Storage_Size => 0;
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-- Buffer and access types used to initialize temporaries for validity
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-- checks, if the value to be checked has reverse scalar storage order, or
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-- is not known to be properly aligned (for example it appears in a packed
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-- record). In this case, we cannot call Valid since Valid assumes proper
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-- full alignment. Instead, we copy the value to a temporary location using
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-- type S (we cannot simply do a copy of a T value, because the value might
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-- be invalid, in which case it might not be possible to copy it through a
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-- floating point register).
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private
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pragma Inline (Machine);
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pragma Inline (Model);
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-- Note: previously the validity checking subprograms (Unaligned_Valid and
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-- Valid) were also inlined, but this was changed since there were some
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-- problems with this inlining in optimized mode, and in any case it seems
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-- better to avoid this inlining (space and robustness considerations).
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end System.Fat_Gen;
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