1------------------------------------------------------------------------------
2--                                                                          --
3--                         GNAT COMPILER COMPONENTS                         --
4--                                                                          --
5--                       S Y S T E M . B I G N U M S                        --
6--                                                                          --
7--                                 S p e c                                  --
8--                                                                          --
9--            Copyright (C) 2012-2019, 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 package provides arbitrary precision signed integer arithmetic for
33--  use in computing intermediate values in expressions for the case where
34--  pragma Overflow_Check (Eliminated) is in effect.
35
36--  Note that we cannot use a straight instantiation of System.Generic_Bignums
37--  because the rtsfind mechanism is not ready to handle instantiations.
38
39package System.Bignums is
40   pragma Preelaborate;
41
42   type Bignum is private;
43
44   function Big_Add (X, Y : Bignum) return Bignum;  --  "+"
45   function Big_Sub (X, Y : Bignum) return Bignum;  --  "-"
46   function Big_Mul (X, Y : Bignum) return Bignum;  --  "*"
47   function Big_Div (X, Y : Bignum) return Bignum;  --  "/"
48   function Big_Exp (X, Y : Bignum) return Bignum;  --  "**"
49   function Big_Mod (X, Y : Bignum) return Bignum;  --  "mod"
50   function Big_Rem (X, Y : Bignum) return Bignum;  --  "rem"
51   function Big_Neg (X    : Bignum) return Bignum;  --  "-"
52   function Big_Abs (X    : Bignum) return Bignum;  --  "abs"
53   --  Perform indicated arithmetic operation on bignum values. No exception
54   --  raised except for Div/Mod/Rem by 0 which raises Constraint_Error with
55   --  an appropriate message.
56
57   function Big_EQ  (X, Y : Bignum) return Boolean;  -- "="
58   function Big_NE  (X, Y : Bignum) return Boolean;  -- "/="
59   function Big_GE  (X, Y : Bignum) return Boolean;  -- ">="
60   function Big_LE  (X, Y : Bignum) return Boolean;  -- "<="
61   function Big_GT  (X, Y : Bignum) return Boolean;  --  ">"
62   function Big_LT  (X, Y : Bignum) return Boolean;  --  "<"
63   --  Perform indicated comparison on bignums, returning result as Boolean.
64   --  No exception raised for any input arguments.
65
66   function Bignum_In_LLI_Range (X : Bignum) return Boolean;
67   --  Returns True if the Bignum value is in the range of Long_Long_Integer,
68   --  so that a call to From_Bignum is guaranteed not to raise an exception.
69
70   function To_Bignum (X : Long_Long_Integer) return Bignum;
71   --  Convert Long_Long_Integer to Bignum. No exception can be raised for any
72   --  input argument.
73
74   function From_Bignum (X : Bignum) return Long_Long_Integer;
75   --  Convert Bignum to Long_Long_Integer. Constraint_Error raised with
76   --  appropriate message if value is out of range of Long_Long_Integer.
77
78private
79
80   type Bignum is new System.Address;
81
82   pragma Inline (Big_Add);
83   pragma Inline (Big_Sub);
84   pragma Inline (Big_Mul);
85   pragma Inline (Big_Div);
86   pragma Inline (Big_Exp);
87   pragma Inline (Big_Mod);
88   pragma Inline (Big_Rem);
89   pragma Inline (Big_Neg);
90   pragma Inline (Big_Abs);
91   pragma Inline (Big_EQ);
92   pragma Inline (Big_NE);
93   pragma Inline (Big_GE);
94   pragma Inline (Big_LE);
95   pragma Inline (Big_GT);
96   pragma Inline (Big_LT);
97   pragma Inline (Bignum_In_LLI_Range);
98   pragma Inline (To_Bignum);
99   pragma Inline (From_Bignum);
100
101end System.Bignums;
102