{*******************************************************************}
{ TWebUpdate component                                              }
{ for Delphi & C++Builder                                           }
{ version 1.6                                                       }
{                                                                   }
{ written by                                                        }
{    TMS Software                                                   }
{    copyright © 1998-2004                                          }
{    Email : info@tmssoftware.com                                   }
{    Web   : http://www.tmssoftware.com                             }
{                                                                   }
{ The source code is given as is. The author is not responsible     }
{ for any possible damage done due to the use of this code.         }
{ The component can be freely used in any application. The source   }
{ code remains property of the writer and may not be distributed    }
{ freely as such.                                                   }
{*******************************************************************}

unit WuBase64;

interface

function Base64Encode(const Input: string): string;
function Base64Decode(const Input: string): string;

implementation

var
  EncodeTable: array[0..63] of Char =
    'ABCDEFGHIJKLMNOPQRSTUVWXYZ' +
    'abcdefghijklmnopqrstuvwxyz' +
    '0123456789+/';

  DecodeTable: array[#0..#127] of Integer = (
    Byte('='), 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64,
    64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64,
    64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 62, 64, 64, 64, 63,
    52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 64, 64, 64, 64, 64, 64,
    64,  0,  1,  2,  3,  4,  5,  6,  7,  8,  9, 10, 11, 12, 13, 14,
    15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 64, 64, 64, 64, 64,
    64, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40,
    41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 64, 64, 64, 64, 64);

type
  PPacket = ^TPacket;
  TPacket = packed record
    case Integer of
      0: (b0, b1, b2, b3: Byte);
      1: (i: Integer);
      2: (a: array[0..3] of Byte);
      3: (c: array[0..3] of Char);
  end;

procedure EncodePacket(const Packet: TPacket; NumChars: Integer; OutBuf: PChar);
begin
  OutBuf[0] := EnCodeTable[Packet.a[0] shr 2];
  OutBuf[1] := EnCodeTable[((Packet.a[0] shl 4) or (Packet.a[1] shr 4)) and $0000003f];

  if NumChars < 2 then
    OutBuf[2] := '='
  else
    OutBuf[2] := EnCodeTable[((Packet.a[1] shl 2) or (Packet.a[2] shr 6)) and $0000003f];

  if NumChars < 3 then
    OutBuf[3] := '='
  else
    OutBuf[3] := EnCodeTable[Packet.a[2] and $0000003f];
end;

function Base64Encode(const Input: string): string;
var
  I, K, J: Integer;
  Packet: TPacket;
begin
  Result := '';
  I := (Length(Input) div 3) * 4;
  if Length(Input) mod 3 > 0 then Inc(I, 4);
  SetLength(Result, I);
  J := 1;
  for I := 1 to Length(Input) div 3 do
  begin
    Packet.i := 0;
    Packet.a[0] := Byte(Input[(I - 1) * 3 + 1]);
    Packet.a[1] := Byte(Input[(I - 1) * 3 + 2]);
    Packet.a[2] := Byte(Input[(I - 1) * 3 + 3]);
    EncodePacket(Packet, 3, PChar(@Result[J]));
    Inc(J, 4);
  end;
  K := 0;
  Packet.i := 0;
  for I := Length(Input) - (Length(Input) mod 3) + 1 to Length(Input) do
  begin
    Packet.a[K] := Byte(Input[I]);
    Inc(K);
    if I = Length(Input) then
      EncodePacket(Packet, Length(Input) mod 3, PChar(@Result[J]));
  end;
end;

function DecodePacket(InBuf: PChar; var nChars: Integer): TPacket;
begin
  Result.a[0] := (DecodeTable[InBuf[0]] shl 2) or
    (DecodeTable[InBuf[1]] shr 4);
  NChars := 1;
  if InBuf[2] <> '=' then
  begin
    Inc(NChars);
    Result.a[1] := (DecodeTable[InBuf[1]] shl 4) or (DecodeTable[InBuf[2]] shr 2);
  end;
  if InBuf[3] <> '=' then
  begin
    Inc(NChars);
    Result.a[2] := (DecodeTable[InBuf[2]] shl 6) or DecodeTable[InBuf[3]];
  end;
end;

function Base64Decode(const Input: string): string;
var
  I, J, K: Integer;
  Packet: TPacket;
begin
  Result := '';
  for I := 1 to Length(Input) div 4 do
  begin
    Packet := DecodePacket(PChar(@Input[(I - 1) * 4 + 1]), J);
    K := 0;
    while J > 0 do
    begin
      Result := Result + Packet.c[K];
      Inc(K);
      Dec(J);
    end;
  end;
end;

end.
