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base64.m
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base64.m
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(* ::Package:: *)
(******************************************************************************
Copyright (C) 2010 Dario Malchiodi <[email protected]>
This file is part of base64.
base64 is free software; you can redistribute it and/or modify it under the
terms of the GNU Lesser General Public License as published by the Free
Software Foundation; either version 2.1 of the License, or (at your option)
any later version.
base64 is distributed in the hope that it will be useful, but without any
warranty; without even the implied warranty of merchantability or fitness
for a particular purpose. See the GNU Lesser General Public License for
more details.
You should have received a copy of the GNU Lesser General Public License
along with base64; if not, see <http://www.gnu.org/licenses/>.
******************************************************************************)
(* : Title : base64 *)
(* : Context : base64` *)
(* :
Author : Dario Malchiodi *)
(* :
Summary : base64 encoding and decoding *)
(* :
Package Version : 1.0 *)
(* : Mathematica Version : 5.1 *)
(* :
Keywords : base64 encoding *)
BeginPackage["base64`"]
base64EncodeTable::usage =
"base64EncodeTable[n] returns the ASCII character corresponding to the value n in the base64 encoding";\
base64GroupEncode::usage =
"base64GroupEncode[group] returns the four-character string base64-encoding a group of three bytes";\
base64Encode::usage =
"base64Encode[byt] returns the string base64-encoding the sequence of bytes byt";\
base64DecodeTable::usage =
"base64DecodeTable[c] returns the byte corresponding to the ASCII character c in the base64 encoding";\
base64GroupDecode::usage =
"base64GroupDecode[group] returns the three bytes corresponding to the base64-encoding whose bytes are in the list group";\
base64Decode::usage=
"base64Decode[str] returns the list containing the bytes corresponding to \
the base64-decoded version of the string str";\
Begin["`Private`"]
(*
changes by PB to use it for embedding images in html
0->"A" //not "="
63->"/" //not "-"
replace trailing fillers with "="
now You can do:
raw = BinaryReadList[fn];
base64 = base64Encode[raw];
"<html><head></head><body><img src='data:image/" <> ext <> ";base64,\n" <> base64 <> "'></body></html>";
will show embedded image
specs for changes taken from wikipedia
http://de.wikipedia.org/wiki/Base64
*)
base64EncodeTable[n_] := Which[
n == 0, "A",
n < 26,
FromCharacterCode[ToCharacterCode["A"] + n],
n < 52,
FromCharacterCode[ToCharacterCode["a"] + n - 26],
n < 62,
FromCharacterCode[ToCharacterCode["0"] + n - 52],
n == 62, "+",
n == 63, "/"
]
base64GroupEncode[group_] := Block[{},
f = Partition[Map[IntegerDigits[#, 2, 8] &, group] // Flatten, 6];
base64EncodeTable /@ Map[FromDigits[#, 2] &, f]
]
base64Encode[byt_] := Block[{b,d},
b = byt;
d = Mod[Length[b], 3];
b = Join[b,
Switch[ d,
0, {},
1, {0, 0},
2, {0}
]
];
StringExpression @@ Flatten[{Take[
(base64GroupEncode /@ Partition[b, 3] // Flatten),
{1,-1-d}
],
Table["=",{i,1,d}]}]
]
base64DecodeTable[c_] := Which[
FromCharacterCode[c] == "/", 63,
FromCharacterCode[c] == "+", 62,
ToCharacterCode["0"][[1]] <= c <= ToCharacterCode["9"][[1]],
c - ToCharacterCode["0"][[1]] + 52,
ToCharacterCode["a"][[1]] <= c <= ToCharacterCode["z"][[1]],
c - ToCharacterCode["a"][[1]] + 26,
ToCharacterCode["A"][[1]] <= c <= ToCharacterCode["Z"][[1]],
c - ToCharacterCode["A"][[1]],
FromCharacterCode[c] == "A", 0
]
base64GroupDecode[group_] := Block[{},
FromDigits[#, 2] & /@
Partition[IntegerDigits[#, 2, 6] & /@ group // Flatten, 8]
]
base64Decode[str_] := Block[{s},
s = ToCharacterCode[
StringReplace[str, n : Except["="] ... ~~ {"="} .. -> n]];
(base64GroupDecode /@ Partition[base64DecodeTable/@s,4,4,{1,1},{}]) // Flatten
]
End[]
EndPackage[]