| ------------------------------------------------------------------------------ |
| -- -- |
| -- GNAT RUN-TIME COMPONENTS -- |
| -- -- |
| -- S Y S T E M . E X P O N T -- |
| -- -- |
| -- S p e c -- |
| -- -- |
| -- Copyright (C) 1992-2023, Free Software Foundation, Inc. -- |
| -- -- |
| -- GNAT is free software; you can redistribute it and/or modify it under -- |
| -- terms of the GNU General Public License as published by the Free Soft- -- |
| -- ware Foundation; either version 3, or (at your option) any later ver- -- |
| -- sion. GNAT is distributed in the hope that it will be useful, but WITH- -- |
| -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY -- |
| -- or FITNESS FOR A PARTICULAR PURPOSE. -- |
| -- -- |
| -- As a special exception under Section 7 of GPL version 3, you are granted -- |
| -- additional permissions described in the GCC Runtime Library Exception, -- |
| -- version 3.1, as published by the Free Software Foundation. -- |
| -- -- |
| -- You should have received a copy of the GNU General Public License and -- |
| -- a copy of the GCC Runtime Library Exception along with this program; -- |
| -- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see -- |
| -- <http://www.gnu.org/licenses/>. -- |
| -- -- |
| -- GNAT was originally developed by the GNAT team at New York University. -- |
| -- Extensive contributions were provided by Ada Core Technologies Inc. -- |
| -- -- |
| ------------------------------------------------------------------------------ |
| |
| -- Signed integer exponentiation (checks on) |
| |
| with Ada.Numerics.Big_Numbers.Big_Integers_Ghost; |
| |
| generic |
| |
| type Int is range <>; |
| |
| package System.Expont |
| with Pure, SPARK_Mode |
| is |
| -- Preconditions in this unit are meant for analysis only, not for run-time |
| -- checking, so that the expected exceptions are raised. This is enforced |
| -- by setting the corresponding assertion policy to Ignore. Postconditions |
| -- and contract cases should not be executed at runtime as well, in order |
| -- not to slow down the execution of these functions. |
| |
| pragma Assertion_Policy (Pre => Ignore, |
| Post => Ignore, |
| Contract_Cases => Ignore, |
| Ghost => Ignore); |
| |
| package BI_Ghost renames Ada.Numerics.Big_Numbers.Big_Integers_Ghost; |
| subtype Big_Integer is BI_Ghost.Big_Integer with Ghost; |
| use type BI_Ghost.Big_Integer; |
| |
| package Signed_Conversion is new BI_Ghost.Signed_Conversions (Int => Int); |
| |
| function Big (Arg : Int) return Big_Integer is |
| (Signed_Conversion.To_Big_Integer (Arg)) |
| with Ghost; |
| |
| function In_Int_Range (Arg : Big_Integer) return Boolean is |
| (BI_Ghost.In_Range (Arg, Big (Int'First), Big (Int'Last))) |
| with Ghost; |
| |
| function Expon (Left : Int; Right : Natural) return Int |
| with |
| Pre => In_Int_Range (Big (Left) ** Right), |
| Post => Expon'Result = Left ** Right; |
| |
| end System.Expont; |
