1------------------------------------------------------------------------------ 2-- -- 3-- GNAT COMPILER COMPONENTS -- 4-- -- 5-- S Y S T E M . G E N E R I C _ 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 33-- and can be used either built into the compiler via System.Bignums or to 34-- implement a default version of Ada.Numerics.Big_Numbers.Big_Integers. 35 36-- If Use_Secondary_Stack is True then all Bignum values are allocated on the 37-- secondary stack. If False, the heap is used and the caller is responsible 38-- for memory management. 39 40with Ada.Unchecked_Conversion; 41with Interfaces; 42 43generic 44 Use_Secondary_Stack : Boolean; 45package System.Generic_Bignums is 46 pragma Preelaborate; 47 48 pragma Assert (Long_Long_Integer'Size = 64); 49 -- This package assumes that Long_Long_Integer size is 64 bit (i.e. that it 50 -- has a range of -2**63 to 2**63-1). The front end ensures that the mode 51 -- ELIMINATED is not allowed for overflow checking if this is not the case. 52 53 subtype Length is Natural range 0 .. 2 ** 23 - 1; 54 -- Represent number of words in Digit_Vector 55 56 Base : constant := 2 ** 32; 57 -- Digit vectors use this base 58 59 subtype SD is Interfaces.Unsigned_32; 60 -- Single length digit 61 62 type Digit_Vector is array (Length range <>) of SD; 63 -- Represent digits of a number (most significant digit first) 64 65 type Bignum_Data (Len : Length) is record 66 Neg : Boolean; 67 -- Set if value is negative, never set for zero 68 69 D : Digit_Vector (1 .. Len); 70 -- Digits of number, most significant first, represented in base 71 -- 2**Base. No leading zeroes are stored, and the value of zero is 72 -- represented using an empty vector for D. 73 end record; 74 75 for Bignum_Data use record 76 Len at 0 range 0 .. 23; 77 Neg at 3 range 0 .. 7; 78 end record; 79 80 type Bignum is access all Bignum_Data; 81 -- This is the type that is used externally. Possibly this could be a 82 -- private type, but we leave the structure exposed for now. For one 83 -- thing it helps with debugging. Note that this package never shares 84 -- an allocated Bignum value, so for example for X + 0, a copy of X is 85 -- returned, not X itself. 86 87 function To_Bignum is new Ada.Unchecked_Conversion (System.Address, Bignum); 88 function To_Address is new 89 Ada.Unchecked_Conversion (Bignum, System.Address); 90 91 -- Note: none of the subprograms in this package modify the Bignum_Data 92 -- records referenced by Bignum arguments of mode IN. 93 94 function Big_Add (X, Y : Bignum) return Bignum; -- "+" 95 function Big_Sub (X, Y : Bignum) return Bignum; -- "-" 96 function Big_Mul (X, Y : Bignum) return Bignum; -- "*" 97 function Big_Div (X, Y : Bignum) return Bignum; -- "/" 98 function Big_Exp (X, Y : Bignum) return Bignum; -- "**" 99 function Big_Mod (X, Y : Bignum) return Bignum; -- "mod" 100 function Big_Rem (X, Y : Bignum) return Bignum; -- "rem" 101 function Big_Neg (X : Bignum) return Bignum; -- "-" 102 function Big_Abs (X : Bignum) return Bignum; -- "abs" 103 -- Perform indicated arithmetic operation on bignum values. No exception 104 -- raised except for Div/Mod/Rem by 0 which raises Constraint_Error with 105 -- an appropriate message. 106 107 function Big_EQ (X, Y : Bignum) return Boolean; -- "=" 108 function Big_NE (X, Y : Bignum) return Boolean; -- "/=" 109 function Big_GE (X, Y : Bignum) return Boolean; -- ">=" 110 function Big_LE (X, Y : Bignum) return Boolean; -- "<=" 111 function Big_GT (X, Y : Bignum) return Boolean; -- ">" 112 function Big_LT (X, Y : Bignum) return Boolean; -- "<" 113 -- Perform indicated comparison on bignums, returning result as Boolean. 114 -- No exception raised for any input arguments. 115 116 function Bignum_In_LLI_Range (X : Bignum) return Boolean; 117 -- Returns True if the Bignum value is in the range of Long_Long_Integer, 118 -- so that a call to From_Bignum is guaranteed not to raise an exception. 119 120 function To_Bignum (X : Long_Long_Integer) return Bignum; 121 -- Convert Long_Long_Integer to Bignum. No exception can be raised for any 122 -- input argument. 123 124 function To_Bignum (X : Interfaces.Unsigned_64) return Bignum; 125 -- Convert Unsigned_64 to Bignum. No exception can be raised for any 126 -- input argument. 127 128 function From_Bignum (X : Bignum) return Long_Long_Integer; 129 -- Convert Bignum to Long_Long_Integer. Constraint_Error raised with 130 -- appropriate message if value is out of range of Long_Long_Integer. 131 132 function Is_Zero (X : Bignum) return Boolean; 133 -- Return True if X = 0 134 135end System.Generic_Bignums; 136