Kodowanie formatu PDU

Autor programu: [[User:mboniek|mboniek]] Unit ten pozwala na kodowanie lub dekodowanie ze zwyklego tekstu do formatu PDU uzywanego w komorkach do zapisywania SMS: ```delphi unit uSMS;

interface

uses SysUtils;

function GSMLength7Bit(const Value: WideString): integer;
function GSMDecode7Bit(Value: string): WideString;
function GSMEncode7Bit(const Value: WideString): string;

implementation

const
Alphabet7Escape: byte = $1B; // 27
Alphabet7Bit: array[0..127] of word = (
{0 1 2 3 4 5 6 7 8 9 A B C D E F}
{0} 64, 163, 36, 165, 232, 233, 249, 236, 242, 199, 10, 216, 248, 13, 197, 229,
{1} $394, 95,$3A6,$393,$39B,$3A9,$3A0,$3A8,$3A3,$398,$39E, 27, 198, 230, 223, 201,
{2} 32, 33, 34, 35, 164, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47,
{3} 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63,
{4} 161, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79,
{5} 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 196, 214, 209, 220, 167,
{6} 191, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111,
{7} 112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 228, 246, 241, 252, 224);

{ 7BIT helper functions }

function Unpack7Bit(const Value: string): string;
var
i,j: Integer;
x,leftover,octet: byte;
c,septets: string;
begin
Result := '';
j := Round(Length(Value) / 2) - 1;
septets := '';
x := 1;
leftover := 0;
for i := 0 to j do begin
c := copy(Value, (i*2)+1, 2);
if not (c[1] in ['0'..'9','A'..'F']) then // do not localize
break;
if (Length(c) = 2) and not (c[2] in ['0'..'9','A'..'F']) then // do not localize
Delete(c,2,1);
octet := StrToInt('$' + c);
septets := septets + Chr(((octet and ($FF shr x)) shl (x - 1)) or leftover);
leftover := (octet and (not ($FF shr x))) shr (8 - x);
x := x + 1;
if x = 8 then begin
if (i <> j) or (leftover <> 0) then
septets := septets + Chr(leftover);
x := 1;
leftover := 0;
end;
end;
Result := septets;
end;

function Pack7Bit(const Value: string): string;
var
i,j: integer;
x,nextChr: byte;
septets,Octet: string;
begin
Result := '';
septets := Value;
x := 0;
j := length(septets);
for i := 1 to j do begin
if x < 7 then begin
if i = j then
nextChr := 0
else
nextChr := Ord(septets[i+1]);
Octet := IntToHex(((nextChr and (not ($FF shl (x+1)))) shl (7-x)) or (Ord(septets[i]) shr x),2);
Result := Result + Octet;
x := x + 1;
end
else
x := 0;
end;
end;

function AlphabetIndex7Bit(AChar: WideChar): integer;
var
i: integer;
w: word;
begin
Result := -1;
w := Ord(AChar);
for i := 0 to 127 do
if Alphabet7Bit[i] = w then begin
Result := i;
break;
end;
end;

function EscapeIndex7Bit(AChar: WideChar): integer;
begin
case Ord(AChar) of
12,27,91,92,93,94,123,124,125,126,8364:
Result := Ord(AChar);
else
Result := -1;
end;
end;

function Is7Bit(AChar: WideChar): boolean;
begin
Result := (AlphabetIndex7Bit(AChar) <> -1) or (EscapeIndex7Bit(AChar) <> -1);
end;

function Encode7Bit(const Value: WideString): string;
var
item: char;
septets: string;
i,j: integer;
len: integer;
begin
Result := '';
septets := '';
len := Length(Value);
i := 1;
while i <= len do begin
j := AlphabetIndex7Bit(Value[i]);
if j = -1 then begin
{ not in alphabet, so look for escape sequence }
case EscapeIndex7Bit(Value[i]) of
12: item := chr(10); { FORM FEED }
27: item := chr(27); { next escape table }
91: item := chr(60);
92: item := chr(47);
93: item := chr(62);
94: item := chr(20);
123: item := chr(40);
124: item := chr(64);
125: item := chr(41);
126: item := chr(61);
8364: item := chr(101); { Euro sign }
else
item := chr(63);
end;
septets := septets + chr(Alphabet7Escape);
end
else
item := chr(j);
septets := septets + item;
inc(i);
end;
Result := septets;
end;

{ 7BIT }

function GSMLength7Bit(const Value: WideString): integer;
begin
Result := Length(Encode7Bit(Value));
end;

function GSMDecode7Bit(Value: string): WideString;
var
i,j,k,len: integer;
w: word;
begin
Result := '';
Value := Unpack7Bit(Value);
len := Length(Value);
i := 1;
while i <= len do begin
j := Byte(Value[i]);
if j <= 127 then w := Alphabet7Bit[j]
else w := 0; { should error here? }
if j = Alphabet7Escape then begin
inc(i);
if i > len then break;
case Byte(Value[i]) of
10: w := 12; { FORM FEED }
20: w := 94;
27: w := 32;
40: w := 123;
41: w := 125;
47: w := 92;
60: w := 91;
61: w := 126;
62: w := 93;
64: w := 124;
101: w := 8364; { Euro sign }
else begin w := 63;
end;
end; {case}
end
else begin
if (j = 0) and (i < len) and (Byte(Value[i+1]) = 0) then begin
k := i+2;
while (k <= len) and (Byte(Value[k]) = 0) do inc(k); // 0x00 up to the...
if (k > len) or // ...end of (fixed byte length) message -or- FORM FEED
((k < len) and (Byte(Value[k]) = Alphabet7Escape) and ((Byte(Value[k+1]) = 10))) then begin
i := k-1;
w := 0; // NULL unicode char
end;
end;
end;
Result := Result + WideChar(w);
inc(i);
end;
end;

function GSMEncode7Bit(const Value: WideString): string;
begin
Result := Pack7Bit(Encode7Bit(Value));
end;

end.

i teraz tylko :
```delphi
var text,pdu : String;

begin
  text:=GSMDecode7Bit(pdu);
  pdu:=GSMEncode7Bit(text);
end;