[Stamerlan]

Здравствуйте!!!

Помогите пожалуйста перевести код с С на Delphi:

Код:

#define XTEA2_BLOCKSIZE 16

static unsigned __int32 rol(unsigned __int32 base, unsigned __int32 shift)
{
	unsigned __int32 res;
    /* only 5 bits of shift are significant*/
    shift &= 0x1F;
    res = (base << shift) | (base >> (32 - shift));
    return res;
}

void xtea2_decipher(unsigned int num_rounds, unsigned __int32 *v, unsigned __int32 const *k) {
    unsigned int i;
    unsigned long a, b, c, d, t, delta=0x9E3779B9, sum=delta*num_rounds;
    d = v[3];
    c = v[2] ^ k[3];
    b = v[1];
    a = v[0] ^ k[2];
    for (i = 0; i < num_rounds; i++) {
		t = d; d = c; c = b; b = a; a = t;
        c -= ((d << 4) ^ (d >> 5)) + (b ^ sum) + rol(k[(sum >> 11) & 3], d);
        sum -= delta;
        a -= ((b << 4) ^ (b >> 5)) + (d ^ sum) + rol(k[sum & 3], b);
	}
    v[0] = a;
    v[1] = b - k[0];
    v[2] = c;
    v[3] = d - k[1];
}

void XTEA2Decode(BYTE *Addr, DWORD_PTR Size, BYTE *key, DWORD dwEncMode)
{
	int block_length, key_length, blocks_number;
	unsigned __int32 *crypto_block_begin;
	unsigned __int32 *crypto_block_end;
	block_length = 4;
	key_length = 16;
	crypto_block_begin = (unsigned __int32 *)Addr;
	blocks_number = (int)(Size >> 4);
	crypto_block_end = (unsigned __int32 *)(Addr + (blocks_number << 4));

	while (crypto_block_begin < crypto_block_end)
	{
		xtea2_decipher(16, crypto_block_begin, (unsigned __int32 *)key);

		crypto_block_begin += block_length;
	}
}

Вот что у меня получилось:

Код:

unit DecryptXTEA2;

interface

uses HashImpl;

const
  XTEA2_BLOCKSIZE = 16;

type
  TLongWordArray = array [0..3] of LongWord;
  PLongWordArray = ^TLongWordArray;

procedure xtea2_decipher(num_rounds, v, k: PLongWord);
procedure XTEA2Decode(Buffer: PByte; Size: Integer; Key: PByte; Mode: TEncMode);
function rotl(base:LongWord; shift:LongWord): LongWord;

implementation

function rotl(base:LongWord; shift:LongWord): LongWord;
begin
  shift := shift and $1F;
  result := (base shl shift) or (base shr (32-shift));
end;

procedure xtea2_decipher(num_rounds, v, k: PLongWord);
var
  i : LongWord;
  a, b, c, d, t, delta, sum : longword;
begin
  delta := $9E3779B9;
  sum := delta*LongInt(num_rounds);
  d := PLongWordArray(v)[3];
  c := PLongWordArray(v)[2] xor PLongWordArray(k)[3];
  b := PLongWordArray(v)[1];
  a := PLongWordArray(v)[0] xor PLongWordArray(k)[2];
  for i := 0 to LongWord(num_rounds)-1 do
  begin
    t := d; d := c; c := b; b := a; a := t;
    c := c - ((d shl 4) xor (d shr 5)) + (b xor sum) +
      rotl(PLongWordArray(k)[(sum shr 11) and 3], d);
    sum := sum - delta;
    a := a - ((b shl 4) xor (b shr 5)) + (d xor sum) +
      rotl(PLongWordArray(k)[sum and 3], b);
  end;
  PLongWordArray(v)[0] := a;
  PLongWordArray(v)[1] := b - PLongWordArray(k)[0];
  PLongWordArray(v)[2] := c;
  PLongWordArray(v)[3] := d - PLongWordArray(k)[1];
end;

procedure XTEA2Decode(Buffer: PByte; Size: Integer; Key: PByte; Mode: TEncMode);
const
  ENCMODE_BlockSize = XTEA2_BLOCKSIZE;
var
  block_length, key_length, blocks_number : integer;
  crypto_block_begin, crypto_block_end : PLongWord;
begin
  block_length := 4;
  key_length := 16;
  crypto_block_begin := PLongWord(Buffer);
  blocks_number := Size shr 4;
  crypto_block_end := PLongWord(Buffer + (blocks_number shl 4));

  while LongWord(crypto_block_begin) < LongWord(crypto_block_end) do
  begin
    xtea2_decipher(PLongWord(16), PLongWord(crypto_block_begin), PLongWord(Key));
    Inc(crypto_block_begin, block_length);
  end;
end;


end.

Подскажите что я делаю не так? Когда прошелся отладчиком то увидел что на строке:

Код:

c := c - ((d shl 4) xor (d shr 5)) + (b xor sum) +
      rotl(PLongWordArray(k)[(sum shr 11) and 3], d);

переменная c принимает не правильное значение (не такое как в реализации на С)