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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) 1992-2004, 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 2, 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. See the GNU General Public License --
17 -- for more details. You should have received a copy of the GNU General --
18 -- Public License distributed with GNAT; see file COPYING. If not, write --
19 -- to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, --
20 -- MA 02111-1307, USA. --
21 -- --
22 -- As a special exception, if other files instantiate generics from this --
23 -- unit, or you link this unit with other files to produce an executable, --
24 -- this unit does not by itself cause the resulting executable to be --
25 -- covered by the GNU General Public License. This exception does not --
26 -- however invalidate any other reasons why the executable file might be --
27 -- covered by the GNU Public License. --
28 -- --
29 -- GNAT was originally developed by the GNAT team at New York University. --
30 -- Extensive contributions were provided by Ada Core Technologies Inc. --
31 -- --
32 ------------------------------------------------------------------------------
34 -- This unit provides software routines for doing arithmetic on 64-bit
35 -- signed integer values in cases where either overflow checking is
36 -- required, or intermediate results are longer than 64 bits.
38 with Interfaces;
40 package System.Arith_64 is
41 pragma Pure (Arith_64);
43 subtype Int64 is Interfaces.Integer_64;
45 function Add_With_Ovflo_Check (X, Y : Int64) return Int64;
46 -- Raises Constraint_Error if sum of operands overflows 64 bits,
47 -- otherwise returns the 64-bit signed integer sum.
49 function Subtract_With_Ovflo_Check (X, Y : Int64) return Int64;
50 -- Raises Constraint_Error if difference of operands overflows 64
51 -- bits, otherwise returns the 64-bit signed integer difference.
53 function Multiply_With_Ovflo_Check (X, Y : Int64) return Int64;
54 -- Raises Constraint_Error if product of operands overflows 64
55 -- bits, otherwise returns the 64-bit signed integer product.
57 procedure Scaled_Divide
58 (X, Y, Z : Int64;
59 Q, R : out Int64;
60 Round : Boolean);
61 -- Performs the division of (X * Y) / Z, storing the quotient in Q
62 -- and the remainder in R. Constraint_Error is raised if Z is zero,
63 -- or if the quotient does not fit in 64-bits. Round indicates if
64 -- the result should be rounded. If Round is False, then Q, R are
65 -- the normal quotient and remainder from a truncating division.
66 -- If Round is True, then Q is the rounded quotient. the remainder
67 -- R is not affected by the setting of the Round flag.
69 procedure Double_Divide
70 (X, Y, Z : Int64;
71 Q, R : out Int64;
72 Round : Boolean);
73 -- Performs the division X / (Y * Z), storing the quotient in Q and
74 -- the remainder in R. Constraint_Error is raised if Y or Z is zero,
75 -- or if the quotient does not fit in 64-bits. Round indicates if the
76 -- result should be rounded. If Round is False, then Q, R are the normal
77 -- quotient and remainder from a truncating division. If Round is True,
78 -- then Q is the rounded quotient. The remainder R is not affected by the
79 -- setting of the Round flag.
81 end System.Arith_64;