Base24编码以及解码的实现
unit Base24Unt;
{Base24 算法}
interface
uses Windows,Sysutils,Dialogs;
const
EncodeTable: array[0..23] of Char ='BCDFGHJKMPQRTVWXY2346789' ;
DecodeTable: array[#0..#127] of Byte = (
25,25,25,25,25,25,25,25,
25,25,25,25,25,25,25,25,
25,25,25,25,25,25,25,25,
25,25,25,25,25,25,25,25,
25,25,25,25,25,25,25,25,
25,25,25,25,25,25,25,25,
25,25,17,18,19,25,20,21,
22,23,25,25,25,25,25,25,
25,25, 0, 1, 2,25, 3, 4,
5,25, 6, 7,25, 8,25,25,
9,10,11,25,12,25,13,14,
15,16,25,25,25,25,25,25,
25,25,25,25,25,25,25,25,
25,25,25,25,25,25,25,25,
25,25,25,25,25,25,25,25,
25,25,25,25,25,25,25,25);
function ByteToBase24(buf:array of byte):String;
procedure Base24ToByte(sValue:String;var buf:array of byte);
function GetValIndex(tmpchar:String):Integer;
implementation
function GetValIndex(tmpchar:String):Integer;
var
i:Integer;
begin
for i:=0 to 24 do
begin
if tmpchar=EncodeTable[i] then
begin
result:=i;
break;
end;
end;
end;
function ByteToBase24(buf:array of byte):String;
var
i,j:Integer;
K:Longword;
begin
for i := 24 downto 0 do
begin
K := 0;
for j := High(buf) downto Low(buf) do
begin
K := (K shl 8) + buf[j];
buf[j] := K div 24;
K := K mod 24;
end;
Result :=ConCat(EncodeTable[K],Result);
If (i Mod 5 = 0) And (i <> 0) Then
Result := ConCat('-' , Result);
end;
end;
procedure Base24ToByte(sValue:String;var buf:array of byte);
var
i,j,m:Integer;
K:Longword;
tmpchar:string;
TmpBuffer:array[0..24] of Byte;
begin
sValue:=StringReplace(sValue,'-','',[rfReplaceAll, rfIgnoreCase]);
k:=0;
for i:=0 to 24 do
begin
tmpchar:=copy(sValue,i+1,1);
m:=GetValIndex(tmpchar);
k:=m;
for j:=0 to 14 do
begin
k:=(buf[j]*24+k);
buf[j]:=K mod 256;
K:=K div 256;
end;
end;
end;
end.