Merlin's Delphi Forge

MIME encoding and decoding is used when transferring binary files over the Internet. Every byte is converted to an ASCII character that can be transfered with no problems. This is the code to encode and decode using Base 64 (MIME). You can TMemo‘s and TRichEdit‘s string text via the Text property. The original code has been written by David Barton davebarton@bigfoot.com but I have optimized it a lot (for size). I have put in all the for loops and case statements.

uses
  SysUtils;
...
const
  B64Table = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/';
...
function Base64Encode(const S: string): string;
var
  InBuf: array[0..2] of Byte;
  OutBuf: array[0..3] of Char;
  iI, iJ: Integer;
begin
  SetLength(Result, ((Length(S) + 2) div 3) * 4);
  for iI := 1 to ((Length(S) + 2) div 3) do begin
    if Length(S) < (iI * 3) then
      Move(S[(iI - 1) * 3 + 1], InBuf, Length(S) - (iI - 1) * 3)
    else
      Move(S[(iI - 1) * 3 + 1], InBuf, 3);
    OutBuf[0] := B64Table[((InBuf[0] and $FC) shr 2) + 1];
    OutBuf[1] := B64Table[(((InBuf[0] and $3) shl 4) or ((InBuf[1] and $F0) shr 4)) + 1];
    OutBuf[2] := B64Table[(((InBuf[1] and $F) shl 2) or ((InBuf[2] and $C0) shr 6)) + 1];
    OutBuf[3] := B64Table[(InBuf[2] and $3F) + 1];
    Move(OutBuf, Result[(iI - 1) * 4 + 1], 4);
  end;
  if Length(S) mod 3 = 1 then begin
    Result[Length(Result) - 1] := '=';
    Result[Length(Result)] := '=';
  end else if Length(S) mod 3 = 2 then
    Result[Length(Result)] := '=';
end;

function Base64Decode(const S: string): string;
var
  OutBuf: array[0..2] of Byte;
  InBuf : array[0..3] of Byte;
  iI, iJ: Integer;
begin
  if Length(S) mod 4 <> 0 then
    raise Exception.Create('Base64: Incorrect string format');
  SetLength(Result, ((Length(S) div 4) - 1) * 3);
  for iI := 1 to (Length(S) div 4) - 1 do begin
    Move(S[(iI - 1) * 4 + 1], InBuf, 4);
    for iJ := 0 to 3 do
      case InBuf[iJ] of
        43: InBuf[iJ] := 62;
        48..57: Inc(InBuf[iJ], 4);
        65..90: Dec(InBuf[iJ], 65);
        97..122: Dec(InBuf[iJ], 71);
      else
        InBuf[iJ] := 63;
      end;
    OutBuf[0] := (InBuf[0] shl 2) or ((InBuf[1] shr 4) and $3);
    OutBuf[1] := (InBuf[1] shl 4) or ((InBuf[2] shr 2) and $F);
    OutBuf[2] := (InBuf[2] shl 6) or (InBuf[3] and $3F);
    Move(OutBuf, Result[(iI - 1) * 3 + 1], 3);
  end;
  if Length(S) <> 0 then begin
    Move(S[Length(S) - 3], InBuf, 4);
    if InBuf[2] = 61 then begin
      for iJ := 0 to 1 do
        case InBuf[iJ] of
          43: InBuf[iJ] := 62;
          48..57: Inc(InBuf[iJ], 4);
          65..90: Dec(InBuf[iJ], 65);
          97..122: Dec(InBuf[iJ], 71);
        else
          InBuf[iJ] := 63;
        end;
      OutBuf[0] := (InBuf[0] shl 2) or ((InBuf[1] shr 4) and $3);
      Result := Result + Char(OutBuf[0]);
    end else if InBuf[3] = 61 then begin
      for iJ := 0 to 2 do
        case InBuf[iJ] of
          43: InBuf[iJ] := 62;
          48..57: Inc(InBuf[iJ], 4);
          65..90: Dec(InBuf[iJ], 65);
          97..122: Dec(InBuf[iJ], 71);
        else
          InBuf[iJ] := 63;
        end;
      OutBuf[0] := (InBuf[0] shl 2) or ((InBuf[1] shr 4) and $3);
      OutBuf[1] := (InBuf[1] shl 4) or ((InBuf[2] shr 2) and $F);
      Result := Result + Char(OutBuf[0]) + Char(OutBuf[1]);
    end else begin
      for iJ := 0 to 3 do
        case InBuf[iJ] of
          43: InBuf[iJ] := 62;
          48..57: Inc(InBuf[iJ], 4);
          65..90: Dec(InBuf[iJ], 65);
          97..122: Dec(InBuf[iJ], 71);
        else
          InBuf[iJ] := 63;
        end;
      OutBuf[0] := (InBuf[0] shl 2) or ((InBuf[1] shr 4) and $3);
      OutBuf[1] := (InBuf[1] shl 4) or ((InBuf[2] shr 2) and $F);
      OutBuf[2] := (InBuf[2] shl 6) or (InBuf[3] and $3F);
      Result := Result + Char(OutBuf[0]) + Char(OutBuf[1]) + Char(OutBuf[2]);
    end;
  end;
end;

The CPUID instruction gives you a lot of information about the CPU. You don’t have to write hundreds of lines of code to find out what CPU is installed as you have to to find out if a 286 or a 386 chip is installed. To get the CPU vendor name use this code. This function uses the CPUID instruction, so use the previous tip to find out if the installed processor supports this.

  {$ifndef ver80} // Because of 32 bit register use
    function GetVendorString: string;
    var
      aVendor: array[0..2] of DWord;
      iI, iJ : Integer;
    begin
      asm
        push  ebx
        xor   eax, eax
        dw    $A20F // CPUID instruction
        mov   DWord ptr aVendor, ebx
        mov   DWord ptr aVendor[+4], edx
        mov   DWord ptr aVendor[+8], ecx
        pop   ebx
      end;
      for iI := 0 to 2 do
        for iJ := 0 to 3 do
          Result := Result + Chr((aVendor[iI] and ($000000FF shl (iJ * 8))) shr (iJ * 8));
    end;
  {$endif}