/* Part of SWI-Prolog Author: Jan Wielemaker E-mail: J.Wielemaker@vu.nl WWW: http://www.swi-prolog.org Copyright (c) 2011-2013, University of Amsterdam All rights reserved. Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met: 1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer. 2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution. THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */ :- module(base32, [ base32/2, % ?PlainText, ?Encoded base32//1 % ?PlainText ]). /** Base32 encoding and decoding Prolog-based base32 encoding using DCG rules. Encoding according to rfc4648. For example: == 1 ?- base32('Hello World', X). X = 'JBSWY3DPEBLW64TMMQ======' Yes 2 ?- base32(H, 'JBSWY3DPEBLW64TMMQ======'). H = 'Hello World' == @see http://en.wikipedia.org/wiki/Base32 @author Jan Wielemaker */ %! base32(+Plain, -Encoded) is det. %! base32(-Plain, +Encoded) is det. % % Translates between plaintext and base32 encoded atom or string. % See also base32//1. base32(Plain, Encoded) :- nonvar(Plain), !, atom_codes(Plain, PlainCodes), phrase(base32(PlainCodes), EncCodes), atom_codes(Encoded, EncCodes). base32(Plain, Encoded) :- nonvar(Encoded), !, atom_codes(Encoded, EncCodes), phrase(base32(PlainCodes), EncCodes), atom_codes(Plain, PlainCodes). base32(_, _) :- throw(error(instantiation_error, _)). %! base32(+PlainText)// is det. %! base32(-PlainText)// is det. % % Encode/decode list of character codes using _base32_. See also % base32/2. base32(Input) --> { nonvar(Input) }, !, encode(Input). base32(Output) --> decode(Output). /******************************* * ENCODING * *******************************/ encode([I0, I1, I2, I3, I4|Rest]) --> !, [O0, O1, O2, O3, O4, O5, O6, O7], { A is (I0<<32)+(I1<<24)+(I2<<16)+(I3<<8)+I4, O00 is (A>>35) /\ 0x1f, O01 is (A>>30) /\ 0x1f, O02 is (A>>25) /\ 0x1f, O03 is (A>>20) /\ 0x1f, O04 is (A>>15) /\ 0x1f, O05 is (A>>10) /\ 0x1f, O06 is (A>>5) /\ 0x1f, O07 is A /\ 0x1f, base32_char(O00, O0), base32_char(O01, O1), base32_char(O02, O2), base32_char(O03, O3), base32_char(O04, O4), base32_char(O05, O5), base32_char(O06, O6), base32_char(O07, O7) }, encode(Rest). encode([I0, I1, I2, I3]) --> !, [O0, O1, O2, O3, O4, O5, O6, 0'=], { A is (I0<<32)+(I1<<24)+(I2<<16)+(I3<<8), O00 is (A>>35) /\ 0x1f, O01 is (A>>30) /\ 0x1f, O02 is (A>>25) /\ 0x1f, O03 is (A>>20) /\ 0x1f, O04 is (A>>15) /\ 0x1f, O05 is (A>>10) /\ 0x1f, O06 is (A>>5) /\ 0x1f, base32_char(O00, O0), base32_char(O01, O1), base32_char(O02, O2), base32_char(O03, O3), base32_char(O04, O4), base32_char(O05, O5), base32_char(O06, O6) }. encode([I0, I1, I2]) --> !, [O0, O1, O2, O3, O4, 0'=, 0'=, 0'=], { A is (I0<<32)+(I1<<24)+(I2<<16), O00 is (A>>35) /\ 0x1f, O01 is (A>>30) /\ 0x1f, O02 is (A>>25) /\ 0x1f, O03 is (A>>20) /\ 0x1f, O04 is (A>>15) /\ 0x1f, base32_char(O00, O0), base32_char(O01, O1), base32_char(O02, O2), base32_char(O03, O3), base32_char(O04, O4) }. encode([I0, I1]) --> !, [O0, O1, O2, O3, 0'=, 0'=, 0'=, 0'=], { A is (I0<<32)+(I1<<24), O00 is (A>>35) /\ 0x1f, O01 is (A>>30) /\ 0x1f, O02 is (A>>25) /\ 0x1f, O03 is (A>>20) /\ 0x1f, base32_char(O00, O0), base32_char(O01, O1), base32_char(O02, O2), base32_char(O03, O3) }. encode([I0]) --> !, [O0, O1, 0'=, 0'=, 0'=, 0'=, 0'=, 0'=], { A is (I0<<32), O00 is (A>>35) /\ 0x1f, O01 is (A>>30) /\ 0x1f, base32_char(O00, O0), base32_char(O01, O1) }. encode([]) --> []. /******************************* * DECODE * *******************************/ decode(Text) --> [C0, C1, C2, C3, C4, C5, C6, C7], !, { base32_char(B0, C0), base32_char(B1, C1) }, !, { C7 == 0'= -> ( C6 == 0'=, C5 == 0'= -> ( C4 == 0'= -> ( C3 = 0'=, C2 = 0'= -> A is (B0<<35) + (B1<<30), I0 is (A>>32) /\ 0xff, Text = [I0|Rest] ; base32_char(B2, C2), base32_char(B3, C3), base32_char(B4, C4), A is (B0<<35) + (B1<<30) + (B2<<25) + (B3<<20) + (B4<<15), I0 is (A>>32) /\ 0xff, I1 is (A>>24) /\ 0xff, Text = [I0,I1|Rest] ) ; base32_char(B2, C2), base32_char(B3, C3), base32_char(B4, C4), base32_char(B5, C5), A is (B0<<35) + (B1<<30) + (B2<<25) + (B3<<20) + (B4<<15) + (B5<<10), I0 is (A>>32) /\ 0xff, I1 is (A>>24) /\ 0xff, I2 is (A>>16) /\ 0xff, Text = [I0,I1,I2|Rest] ) ; base32_char(B2, C2), base32_char(B3, C3), base32_char(B4, C4), base32_char(B5, C5), base32_char(B6, C6) -> A is (B0<<35) + (B1<<30) + (B2<<25) + (B3<<20) + (B4<<15) + (B5<<10) + (B6<<5), I0 is (A>>32) /\ 0xff, I1 is (A>>24) /\ 0xff, I2 is (A>>16) /\ 0xff, I3 is (A>>8) /\ 0xff, Text = [I0,I1,I2,I3|Rest] ) ; base32_char(B2, C2), base32_char(B3, C3), base32_char(B4, C4), base32_char(B5, C5), base32_char(B6, C6), base32_char(B7, C7) -> A is (B0<<35) + (B1<<30) + (B2<<25) + (B3<<20) + (B4<<15) + (B5<<10) + (B6<<5) + B7, I0 is (A>>32) /\ 0xff, I1 is (A>>24) /\ 0xff, I2 is (A>>16) /\ 0xff, I3 is (A>>8) /\ 0xff, I4 is A /\ 0xff, Text = [I0,I1,I2,I3,I4|Rest] }, decode(Rest). decode([]) --> []. /******************************* * BASIC CHARACTER ENCODING * *******************************/ base32_char(00, 0'A). base32_char(01, 0'B). base32_char(02, 0'C). base32_char(03, 0'D). base32_char(04, 0'E). base32_char(05, 0'F). base32_char(06, 0'G). base32_char(07, 0'H). base32_char(08, 0'I). base32_char(09, 0'J). base32_char(10, 0'K). base32_char(11, 0'L). base32_char(12, 0'M). base32_char(13, 0'N). base32_char(14, 0'O). base32_char(15, 0'P). base32_char(16, 0'Q). base32_char(17, 0'R). base32_char(18, 0'S). base32_char(19, 0'T). base32_char(20, 0'U). base32_char(21, 0'V). base32_char(22, 0'W). base32_char(23, 0'X). base32_char(24, 0'Y). base32_char(25, 0'Z). base32_char(26, 0'2). base32_char(27, 0'3). base32_char(28, 0'4). base32_char(29, 0'5). base32_char(30, 0'6). base32_char(31, 0'7).