使用方法：将缓存中数据转换成字符串并且进行了加密，然后将加密后的字符串通过SOCKET通信传输，接收方收到后，将字符串解密并且还原出数据。

可单独用于结构体的序列也可用于结构体序列+有规则字符串的序列，看似简单，其实万能而通用，有许多游戏都是这么传数据的，无非是改一改加密和解密的算法罢了。

unit EDcode;

//编码/解码函数库

{$WARNINGS OFF}

interface

uses

   Windows, SysUtils, Classes;

const

  BUFFERSIZE=32768;

  DEFBLOCKSIZE=24;

  HEADCHAR = '#';

  TAILCHAR = '!';

const

  CM_TEST = 1000;

  CM_TEST2 = 1001;

const

  SM_TEST = 9000;

  SM_TEST2 = 9001;

type

  TDefaultMessage=packed record  //Size=18

    MsgID: word;

    Param1: Integer;

    Param2: integer;

    Param3: integer;

    Param4: Integer;

  end;

   function EncodeMessage (smsg: TDefaultMessage): AnsiString;

   function DecodeMessage (str: AnsiString): TDefaultMessage;

   function EncodeString (str: AnsiString): AnsiString;

   function DecodeString (str: AnsiString): AnsiString;

   function EncodeBuffer (buf: PAnsiChar; bufsize: integer): AnsiString;

   procedure DecodeBuffer (src: AnsiString; buf: PAnsiChar; bufsize: integer);

   function  MakeDefaultMsg (msgid:word; param1,param2,param3,param4:integer):TDefaultMessage;

var

   CSEncode: TRTLCriticalSection;

implementation

var

   EncBuf, TempBuf: PAnsiChar;

function  MakeDefaultMsg (msgid:word; param1,param2,param3,param4:integer):TDefaultMessage;

begin

    result.MsgID := msgid;

    result.Param1 := param1;

    result.Param2 := param2;

    result.Param3 := param3;

    result.Param4 := param4;

end;

procedure Encode6BitBuf (src, dest: PAnsiChar; srclen, destlen: integer);

var

   i, restcount, destpos: integer;

   made, ch, rest: byte;

begin

  try

   restcount := 0;

   rest    := 0;

   destpos  := 0;

   for i:=0 to srclen - 1 do begin

      if destpos >= destlen then break;

      ch := byte (src[i]);

      made := byte ((rest or (ch shr (2+restcount))) and $3F);

      rest := byte (((ch shl (8 - (2+restcount))) shr 2) and $3F);

      Inc (restcount, 2);

      if restcount < 6 then begin

       dest[destpos] := AnsiChar(made + $3C);

         Inc (destpos);

      end else begin

       if destpos < destlen-1 then begin

            dest[destpos]   := AnsiChar(made + $3C);

            dest[destpos+1] := AnsiChar(rest + $3C);

            Inc (destpos, 2);

         end else begin

            dest[destpos]   := AnsiChar(made + $3C);

            Inc (destpos);

         end;

         restcount := 0;

         rest := 0;

      end;

   end;

   if restcount > 0 then begin

    dest[destpos] := AnsiChar (rest + $3C);

      Inc (destpos);

   end;

   dest[destpos] := #0;

  except

  end;

end;

procedure Decode6BitBuf (source: AnsiString; buf: PAnsiChar; buflen: integer);

const

 Masks: array[2..6] of byte = ($FC, $F8, $F0, $E0, $C0);

var

   i, len, bitpos, madebit, bufpos: integer;

   ch, tmp, _byte: Byte;

begin

try

   len := Length (source);

   bitpos  := 2;

   madebit := 0;

   bufpos  := 0;

   tmp   := 0;

   for i:=1 to len do begin

      if Integer(source[i]) - $3C >= 0 then

     ch := Byte(source[i]) - $3C

      else begin

         bufpos := 0;

       break;

      end;

      if bufpos >= buflen then break;

      if (madebit+6) >= 8 then begin

         _byte := Byte(tmp or ((ch and $3F) shr (6-bitpos)));

         buf[bufpos] := AnsiChar(_byte);

         Inc (bufpos);

         madebit := 0;

         if bitpos < 6 then Inc (bitpos, 2)

         else begin

          bitpos := 2;

            continue;

         end;

      end;

      tmp := Byte (Byte(ch shl bitpos) and Masks[bitpos]);  

      Inc (madebit, 8-bitpos);

   end;

   buf [bufpos] := #0;

except

end;

end;

function DecodeMessage (str: AnsiString): TDefaultMessage;

var

   msg: TDefaultMessage;

begin

   try

      EnterCriticalSection (CSencode);

      Decode6BitBuf (str, EncBuf, 1024);

      Move (EncBuf^, msg, sizeof(TDefaultMessage));

      Result := msg;

   finally

    LeaveCriticalSection (CSencode);

   end;

end;

function DecodeString (str: AnsiString): AnsiString;

begin

   try

      EnterCriticalSection (CSencode);

      Decode6BitBuf (str, EncBuf, BUFFERSIZE);

      Result := StrPas (EncBuf);

   finally

      LeaveCriticalSection (CSencode);

   end;

end;

procedure DecodeBuffer (src: AnsiString; buf: PAnsiChar; bufsize: integer);

begin

   try

      EnterCriticalSection (CSencode);

      Decode6BitBuf (src, EncBuf, BUFFERSIZE);

      Move (EncBuf^, buf^, bufsize);

   finally

    LeaveCriticalSection (CSencode);

   end;

end;

function  EncodeMessage (smsg: TDefaultMessage): AnsiString;

begin

   try

      EnterCriticalSection (CSencode);

      Move (smsg, TempBuf^, sizeof(TDefaultMessage));

      Encode6BitBuf (TempBuf, EncBuf, sizeof(TDefaultMessage), 1024);

      Result := StrPas (EncBuf); 

   finally

    LeaveCriticalSection (CSencode);

   end;

end;

function EncodeString (str: AnsiString): AnsiString;

begin

   try

      EnterCriticalSection (CSencode);

      Encode6BitBuf (PAnsiChar(str), EncBuf, Length(str), BUFFERSIZE);

      Result := StrPas (EncBuf);

   finally

      LeaveCriticalSection (CSencode);

   end;

end;

function  EncodeBuffer (buf: PAnsiChar; bufsize: integer): AnsiString;

begin

   try

      EnterCriticalSection (CSencode);

      if bufsize < BUFFERSIZE then begin

         Move (buf^, TempBuf^, bufsize);

         Encode6BitBuf (TempBuf, EncBuf, bufsize, BUFFERSIZE);

         Result := StrPas (EncBuf);

      end else

         Result := '';

   finally

    LeaveCriticalSection (CSencode);

   end;

end;

initialization

begin

   GetMem (EncBuf, BUFFERSIZE + 100);

   GetMem (TempBuf, 2048);

   InitializeCriticalSection(CSEncode);

end;

finalization

begin

  FreeMem (EncBuf, BUFFERSIZE + 100);

  FreeMem (TempBuf, 2048);

  DeleteCriticalSection(CSEncode);

end;

end.