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------------------------------------------------------------------------------
-- --
-- GNAT COMPILER COMPONENTS --
-- --
-- S Y S T E M . A R I T H _ 6 4 --
-- --
-- S p e c --
-- --
-- Copyright (C) 1994,1995,1996 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, 59 Temple Place - Suite 330, Boston, --
-- MA 02111-1307, 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 unit provides software routines for doing arithmetic on 64-bit
-- signed integer values in cases where either overflow checking is
-- required, or intermediate results are longer than 64 bits.
with Interfaces;
package System.Arith_64 is
pragma Pure (Arith_64);
subtype Int64 is Interfaces.Integer_64;
function Add_With_Ovflo_Check (X, Y : Int64) return Int64;
-- Raises Constraint_Error if sum of operands overflows 64 bits,
-- otherwise returns the 64-bit signed integer sum.
function Subtract_With_Ovflo_Check (X, Y : Int64) return Int64;
-- Raises Constraint_Error if difference of operands overflows 64
-- bits, otherwise returns the 64-bit signed integer difference.
function Multiply_With_Ovflo_Check (X, Y : Int64) return Int64;
-- Raises Constraint_Error if product of operands overflows 64
-- bits, otherwise returns the 64-bit signed integer difference.
procedure Scaled_Divide
(X, Y, Z : Int64;
Q, R : out Int64;
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 64-bits. 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 : Int64;
Q, R : out Int64;
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.
-- 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. The
-- result is known to be in range except for the noted possibility of
-- Y or Z being zero, so no other overflow checks are required.
end System.Arith_64;
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