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------------------------------------------------------------------------------
-- --
-- GNAT COMPILER COMPONENTS --
-- --
-- S Y S T E M . A R I T H _ D O U B L E --
-- --
-- S p e c --
-- --
-- Copyright (C) 1992-2020, 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 package provides software routines for doing arithmetic on "double"
-- signed integer values in cases where either overflow checking is required,
-- or intermediate results are longer than the result type.
generic
type Double_Int is range <>;
type Double_Uns is mod <>;
type Single_Uns is mod <>;
with function Shift_Left (A : Double_Uns; B : Natural) return Double_Uns
is <>;
with function Shift_Right (A : Double_Uns; B : Natural) return Double_Uns
is <>;
with function Shift_Left (A : Single_Uns; B : Natural) return Single_Uns
is <>;
package System.Arith_Double is
pragma Pure;
function Add_With_Ovflo_Check (X, Y : Double_Int) return Double_Int;
-- Raises Constraint_Error if sum of operands overflows Double_Int,
-- otherwise returns the signed integer sum.
function Subtract_With_Ovflo_Check (X, Y : Double_Int) return Double_Int;
-- Raises Constraint_Error if difference of operands overflows Double_Int,
-- otherwise returns the signed integer difference.
function Multiply_With_Ovflo_Check (X, Y : Double_Int) return Double_Int;
pragma Convention (C, Multiply_With_Ovflo_Check);
-- Raises Constraint_Error if product of operands overflows Double_Int,
-- otherwise returns the signed integer product. Gigi may also call this
-- routine directly.
procedure Scaled_Divide
(X, Y, Z : Double_Int;
Q, R : out Double_Int;
Round : Boolean);
-- Performs the division of (X * Y) / Z, storing the quotient in Q
-- and the remainder in R. Constraint_Error is raised if Z is zero,
-- or if the quotient does not fit in Double_Int. Round indicates if
-- the result should be rounded. If Round is False, then Q, R are
-- the normal quotient and remainder from a truncating division.
-- If Round is True, then Q is the rounded quotient. The remainder
-- R is not affected by the setting of the Round flag.
procedure Double_Divide
(X, Y, Z : Double_Int;
Q, R : out Double_Int;
Round : Boolean);
-- Performs the division X / (Y * Z), storing the quotient in Q and
-- the remainder in R. Constraint_Error is raised if Y or Z is zero,
-- or if the quotient does not fit in Double_Int. Round indicates if the
-- result should be rounded. If Round is False, then Q, R are the normal
-- quotient and remainder from a truncating division. If Round is True,
-- then Q is the rounded quotient. The remainder R is not affected by the
-- setting of the Round flag.
end System.Arith_Double;
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