Delphi BASE64 modification unit EncdDecd

Delphi BASE64 modification unit EncdDecd

EncdDecd.pas two function declaration:

procedure EncodeStream(Input, Output: TStream);
procedure DecodeStream(Input, Output: TStream);

For Output parameter, if it is TMemoryStream, efficiency is really too bad, the test found that encodes a 5M many files, to more than ten seconds!

But if TStringStream, in 0.2 to 0.3 seconds!

WHY?

Because TMemoryStream constantly call the Write method, continue to allocate memory requirements of Windows! Resulting in performance degradation! The TStringStream and TFileStream is not the problem.

How to do?

May be a one-time allocation to TMemoryStream good memory space. Suppose the number of bytes before coding is X, the number of bytes is encoded (X + 2) div 3 * 4

On amending carriage return line feed, locate the following code:

K IF> 75 the then　　　　　
　　　the begin 
　　　　bufptr [0]: = # 0D $; // carriage 
　　　　BufPtr [1]: = # $ 0A; // newline 
　　　　Inc is an (bufptr, 2); 
　　　　K: = 0; 
　　　End;

Every 76 characters, it is mandatory carriage return line feed. Comment it out, because this is actually useless. Means to save the modified EncdDecdEx, use it later on.

Before the encoding / decoding of TMemoryStream Output buffer size parameter is set in advance, to avoid a plurality of times to request memory allocation WINDOWS:

uses
　　encddecdEx; 
　var
　　Input,Output:TMemoryStream;
　begin
　　Input:=TMemoryStream.Create;
　　try
　　　Input.LoadFromFile('c:\aaa.txt');
　　　Output:=TMemoryStream.Create;
　　　try
　　　　Output.Size:=(Input.Size + 2) div 3 * 4;
　　　　EncodeStream(Input,Output);
　　　finally
　　　　Output.Free;
　　　end;
　　finally
　　　Input.Free;
　　end;
　end;