1 /*

     2 * Copyright (c) 2001-2009 Nokia Corporation and/or its subsidiary(-ies).

     3 * All rights reserved.

     4 * This component and the accompanying materials are made available

     5 * under the terms of the License "Eclipse Public License v1.0"

     6 * which accompanies this distribution, and is available

     7 * at the URL "http://www.eclipse.org/legal/epl-v10.html".

     8 *

     9 * Initial Contributors:

    10 * Nokia Corporation - initial contribution.

    11 *

    12 * Contributors:

    13 *

    14 * Description: 

    15 * Implementation for TASN1EncBase128 class.

    16 *

    17 */

    18 

    19 

    20 #include "base128enc.h"

    21 

    22 

    23 TASN1EncBase128DER::TASN1EncBase128DER(TUint aInt) : iInt(aInt), iLengthDER(0)

    24 	{

    25 	CalculateLengthDER();

    26 	}

    27 

    28 

    29 TUint TASN1EncBase128DER::LengthDER() const

    30 	{

    31 	return iLengthDER;

    32 	}

    33 

    34 

    35 void TASN1EncBase128DER::CalculateLengthDER()

    36 	{

    37 	iLengthDER = 1;

    38 	TUint working = iInt;

    39 	while (working >>= 7)

    40 		{

    41 		++iLengthDER;

    42 		}

    43 	}

    44 

    45 

    46 void TASN1EncBase128DER::WriteDERL(TDes8& aBuf, TUint& aPos) const

    47 	{

    48 	__ASSERT_DEBUG(aBuf.Length() - aPos >= STATIC_CAST(TUint8, iLengthDER), 

    49 		User::Leave(KErrBadDescriptor));

    50 

    51 	TInt last = aPos + iLengthDER - 1;

    52 	TUint working = iInt;

    53 	for (TUint cursor = last; cursor >= aPos; --cursor)

    54 		{

    55 		// Cast takes least significant 8 bits only (actually, we only need 7)

    56 		aBuf[cursor] = STATIC_CAST(TUint8, working);

    57 		aBuf[cursor] |= 0x80; // Top bit always set to 1...

    58 		working >>= 7;

    59 		}

    60 	// ...except top bit on last byte is 0

    61 	aBuf[last] &= 0x7F;

    62 

    63 	aPos += iLengthDER;

    64 	}