84 lines
4.7 KiB
Ada
84 lines
4.7 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 . A R I T H _ 6 4 --
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-- --
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-- S p e c --
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-- --
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-- --
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-- Copyright (C) 1994,1995,1996 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 2, 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. See the GNU General Public License --
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-- for more details. You should have received a copy of the GNU General --
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-- Public License distributed with GNAT; see file COPYING. If not, write --
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-- to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, --
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-- MA 02111-1307, USA. --
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-- --
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-- As a special exception, if other files instantiate generics from this --
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-- unit, or you link this unit with other files to produce an executable, --
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-- this unit does not by itself cause the resulting executable to be --
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-- covered by the GNU General Public License. This exception does not --
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-- however invalidate any other reasons why the executable file might be --
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-- covered by the GNU Public License. --
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-- --
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-- GNAT was originally developed by the GNAT team at New York University. --
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-- It is now maintained by Ada Core Technologies Inc (http://www.gnat.com). --
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-- --
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------------------------------------------------------------------------------
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-- This unit provides software routines for doing arithmetic on 64-bit
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-- signed integer values in cases where either overflow checking is
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-- required, or intermediate results are longer than 64 bits.
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with Interfaces;
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package System.Arith_64 is
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pragma Pure (Arith_64);
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subtype Int64 is Interfaces.Integer_64;
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function Add_With_Ovflo_Check (X, Y : Int64) return Int64;
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-- Raises Constraint_Error if sum of operands overflows 64 bits,
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-- otherwise returns the 64-bit signed integer sum.
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function Subtract_With_Ovflo_Check (X, Y : Int64) return Int64;
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-- Raises Constraint_Error if difference of operands overflows 64
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-- bits, otherwise returns the 64-bit signed integer difference.
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function Multiply_With_Ovflo_Check (X, Y : Int64) return Int64;
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-- Raises Constraint_Error if product of operands overflows 64
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-- bits, otherwise returns the 64-bit signed integer difference.
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procedure Scaled_Divide
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(X, Y, Z : Int64;
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Q, R : out Int64;
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Round : Boolean);
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-- Performs the division of (X * Y) / Z, storing the quotient in Q
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-- and the remainder in R. Constraint_Error is raised if Z is zero,
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-- or if the quotient does not fit in 64-bits. Round indicates if
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-- the result should be rounded. If Round is False, then Q, R are
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-- the normal quotient and remainder from a truncating division.
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-- If Round is True, then Q is the rounded quotient. the remainder
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-- R is not affected by the setting of the Round flag.
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procedure Double_Divide
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(X, Y, Z : Int64;
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Q, R : out Int64;
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Round : Boolean);
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-- Performs the division X / (Y * Z), storing the quotient in Q and
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-- the remainder in R. Constraint_Error is raised if Y or Z is zero.
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-- Round indicates if the result should be rounded. If Round is False,
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-- then Q, R are the normal quotient and remainder from a truncating
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-- division. If Round is True, then Q is the rounded quotient. The
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-- remainder R is not affected by the setting of the Round flag. The
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-- result is known to be in range except for the noted possibility of
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-- Y or Z being zero, so no other overflow checks are required.
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end System.Arith_64;
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