byte 和 hex 互转

http://topic.csdn.net/u/20100819/10/62a54e6a-2205-4c5c-8551-007321aebb7a.html?668593488

function ByteToHex(Src: Byte): String;
var
  h, l : Byte;
const
  HC : Array [$00..$0F] of char =
     ('0','1','2','3','4','5','6','7','8','9','A','B','C','D','E','F');
begin
  h :=Src shr 4;
  l :=Src shl 4;
  l :=l shr 4;
  Result :=HC[h]+HC[l];
end;

function StrToHex(str : String):String; //字符串转换为2位16进制字符串
var
  i : Integer;
begin
  Result :='';
  for i :=1 to Length(str) do
  begin
    Result :=Result +Right('00'+ByteToHex(Ord(str[i])),2);
  end;
end;
//网上流传的这一段貌似有问题
//begin
//  SetLength(Result, 2);
//  asm
//    MOV         EDI, [Result]
//    MOV         EDI, [EDI]
//    MOV         AL, Src
//    MOV         AH, AL          // Save to AH
//    SHR         AL, 4           // Output High 4 Bits
//    ADD         AL, '0'
//    CMP         AL, '9'
//    JBE         @@OutCharLo
//    ADD         AL, 'A'-'9'-1
//@@OutCharLo:
//    AND         AH, $f
//    ADD         AH, '0'
//    CMP         AH, '9'
//    JBE         @@OutChar
//    ADD         AH, 'A'-'9'-1
//@@OutChar:
//    STOSW
//  end;
//end;