1------------------------------------------------------------------------------ 2-- -- 3-- GNAT COMPILER COMPONENTS -- 4-- -- 5-- S Y S T E M . A R I T H _ 6 4 -- 6-- -- 7-- S p e c -- 8-- -- 9-- Copyright (C) 1992-2012, Free Software Foundation, Inc. -- 10-- -- 11-- GNAT is free software; you can redistribute it and/or modify it under -- 12-- terms of the GNU General Public License as published by the Free Soft- -- 13-- ware Foundation; either version 3, or (at your option) any later ver- -- 14-- sion. GNAT is distributed in the hope that it will be useful, but WITH- -- 15-- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY -- 16-- or FITNESS FOR A PARTICULAR PURPOSE. -- 17-- -- 18-- As a special exception under Section 7 of GPL version 3, you are granted -- 19-- additional permissions described in the GCC Runtime Library Exception, -- 20-- version 3.1, as published by the Free Software Foundation. -- 21-- -- 22-- You should have received a copy of the GNU General Public License and -- 23-- a copy of the GCC Runtime Library Exception along with this program; -- 24-- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see -- 25-- <http://www.gnu.org/licenses/>. -- 26-- -- 27-- GNAT was originally developed by the GNAT team at New York University. -- 28-- Extensive contributions were provided by Ada Core Technologies Inc. -- 29-- -- 30------------------------------------------------------------------------------ 31 32-- This unit provides software routines for doing arithmetic on 64-bit 33-- signed integer values in cases where either overflow checking is 34-- required, or intermediate results are longer than 64 bits. 35 36pragma Restrictions (No_Elaboration_Code); 37-- Allow direct call from gigi generated code 38 39with Interfaces; 40 41package System.Arith_64 is 42 pragma Pure; 43 44 subtype Int64 is Interfaces.Integer_64; 45 46 function Add_With_Ovflo_Check (X, Y : Int64) return Int64; 47 -- Raises Constraint_Error if sum of operands overflows 64 bits, 48 -- otherwise returns the 64-bit signed integer sum. 49 50 function Subtract_With_Ovflo_Check (X, Y : Int64) return Int64; 51 -- Raises Constraint_Error if difference of operands overflows 64 52 -- bits, otherwise returns the 64-bit signed integer difference. 53 54 function Multiply_With_Ovflo_Check (X, Y : Int64) return Int64; 55 pragma Export (C, Multiply_With_Ovflo_Check, "__gnat_mulv64"); 56 -- Raises Constraint_Error if product of operands overflows 64 57 -- bits, otherwise returns the 64-bit signed integer product. 58 -- GIGI may also call this routine directly. 59 60 procedure Scaled_Divide 61 (X, Y, Z : Int64; 62 Q, R : out Int64; 63 Round : Boolean); 64 -- Performs the division of (X * Y) / Z, storing the quotient in Q 65 -- and the remainder in R. Constraint_Error is raised if Z is zero, 66 -- or if the quotient does not fit in 64-bits. Round indicates if 67 -- the result should be rounded. If Round is False, then Q, R are 68 -- the normal quotient and remainder from a truncating division. 69 -- If Round is True, then Q is the rounded quotient. The remainder 70 -- R is not affected by the setting of the Round flag. 71 72 procedure Double_Divide 73 (X, Y, Z : Int64; 74 Q, R : out Int64; 75 Round : Boolean); 76 -- Performs the division X / (Y * Z), storing the quotient in Q and 77 -- the remainder in R. Constraint_Error is raised if Y or Z is zero, 78 -- or if the quotient does not fit in 64-bits. Round indicates if the 79 -- result should be rounded. If Round is False, then Q, R are the normal 80 -- quotient and remainder from a truncating division. If Round is True, 81 -- then Q is the rounded quotient. The remainder R is not affected by the 82 -- setting of the Round flag. 83 84end System.Arith_64; 85