| ------------------------------------------------------------------------------ |
| -- -- |
| -- GNAT LIBRARY COMPONENTS -- |
| -- -- |
| -- G N A T . C R C 3 2 -- |
| -- -- |
| -- S p e c -- |
| -- -- |
| -- Copyright (C) 2004-2010, AdaCore -- |
| -- -- |
| -- 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. -- |
| -- -- |
| ------------------------------------------------------------------------------ |
| |
| -- This package provides routines for computing a commonly used checksum |
| -- called CRC-32. This is a checksum based on treating the binary data |
| -- as a polynomial over a binary field, and the exact specifications of |
| -- the CRC-32 algorithm are as follows: |
| |
| -- Name : "CRC-32" |
| -- Width : 32 |
| -- Poly : 04C11DB7 |
| -- Init : FFFFFFFF |
| -- RefIn : True |
| -- RefOut : True |
| -- XorOut : FFFFFFFF |
| -- Check : CBF43926 |
| |
| -- Note that this is the algorithm used by PKZip, Ethernet and FDDI |
| |
| -- For more information about this algorithm see: |
| |
| -- ftp://ftp.rocksoft.com/papers/crc_v3.txt |
| |
| -- "A Painless Guide to CRC Error Detection Algorithms", Ross N. Williams |
| |
| -- "Computation of Cyclic Redundancy Checks via Table Look-Up", Communications |
| -- of the ACM, Vol. 31 No. 8, pp.1008-1013 Aug. 1988. Sarwate, D.V. |
| |
| with Ada.Streams; |
| with Interfaces; |
| with System.CRC32; |
| |
| package GNAT.CRC32 is |
| |
| subtype CRC32 is System.CRC32.CRC32; |
| -- Used to represent CRC32 values, which are 32 bit bit-strings |
| |
| procedure Initialize (C : out CRC32) |
| renames System.CRC32.Initialize; |
| -- Initialize CRC value by assigning the standard Init value (16#FFFF_FFFF) |
| |
| procedure Update |
| (C : in out CRC32; |
| Value : Character) |
| renames System.CRC32.Update; |
| -- Evolve CRC by including the contribution from Character'Pos (Value) |
| |
| procedure Update |
| (C : in out CRC32; |
| Value : String); |
| -- For each character in the Value string call above routine |
| |
| procedure Wide_Update |
| (C : in out CRC32; |
| Value : Wide_Character); |
| -- Evolve CRC by including the contribution from Wide_Character'Pos (Value) |
| -- with the bytes being included in the natural memory order. |
| |
| procedure Wide_Update |
| (C : in out CRC32; |
| Value : Wide_String); |
| -- For each character in the Value string call above routine |
| |
| procedure Update |
| (C : in out CRC32; |
| Value : Ada.Streams.Stream_Element); |
| -- Evolve CRC by including the contribution from Value |
| |
| procedure Update |
| (C : in out CRC32; |
| Value : Ada.Streams.Stream_Element_Array); |
| -- For each element in the Value array call above routine |
| |
| function Get_Value (C : CRC32) return Interfaces.Unsigned_32 |
| renames System.CRC32.Get_Value; |
| -- Get_Value computes the CRC32 value by performing an XOR with the |
| -- standard XorOut value (16#FFFF_FFFF). Note that this does not |
| -- change the value of C, so it may be used to retrieve intermediate |
| -- values of the CRC32 value during a sequence of Update calls. |
| |
| pragma Inline (Update); |
| pragma Inline (Wide_Update); |
| end GNAT.CRC32; |
