/*

* Copyright (c) 2002-2009 Nokia Corporation and/or its subsidiary(-ies).

* All rights reserved.

* This component and the accompanying materials are made available

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

* which accompanies this distribution, and is available

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

*

* Initial Contributors:

* Nokia Corporation - initial contribution.

*

* Contributors:

*

* Description: 

* This file contains the implementation for class encoding bit strings in ASN1 DER.

*

*/

/**

 @file

*/

#include <asn1enc.h>

EXPORT_C CASN1EncBitString* CASN1EncBitString::NewLC(const TDesC8& aBitStr)

	{

	CASN1EncBitString* self = new (ELeave) CASN1EncBitString();

	CleanupStack::PushL(self);

	self->ConstructL(aBitStr);

	return self;

	}

EXPORT_C CASN1EncBitString* CASN1EncBitString::NewL(const TDesC8& aBitStr)

	{

	CASN1EncBitString* self = NewLC(aBitStr);

	CleanupStack::Pop(self);

	return self;

	}

EXPORT_C CASN1EncBitString* CASN1EncBitString::NewLC(const TDesC8& aBitStr, 

													 TUint aLengthBits)

	{

	CASN1EncBitString* self = new (ELeave) CASN1EncBitString();

	CleanupStack::PushL(self);

	self->ConstructL(aBitStr, aLengthBits);

	return self;

	}

EXPORT_C CASN1EncBitString* CASN1EncBitString::NewL(const TDesC8& aBitStr, 

													TUint aLengthBits)

	{

	CASN1EncBitString* self = NewLC(aBitStr, aLengthBits);

	CleanupStack::Pop(self);

	return self;

	}

EXPORT_C CASN1EncBitString* CASN1EncBitString::NewL(const CASN1EncBase& aEncObj)

	{

	CASN1EncBitString* self = NewLC(aEncObj);

	CleanupStack::Pop(self);

	return self;

	}

EXPORT_C CASN1EncBitString* CASN1EncBitString::NewLC(const CASN1EncBase& aEncObj)

	{

	CASN1EncBitString* self = new (ELeave) CASN1EncBitString();

	CleanupStack::PushL(self);

	self->ConstructL(aEncObj);

	return self;

	}

EXPORT_C CASN1EncBitString::~CASN1EncBitString()

	{

	delete iContents;

	}

CASN1EncBitString::CASN1EncBitString()

: CASN1EncPrimitive(EASN1BitString),

  iPadding(0)

	{

	}

void CASN1EncBitString::ConstructL(const TDesC8& aBitStr)

	{

	iContents = aBitStr.AllocL();

	CASN1EncPrimitive::ConstructL();

	}

void CASN1EncBitString::ConstructL(const TDesC8& aBitStr, TUint aLengthBits)

	{

	iContents = aBitStr.AllocL();

	CASN1EncPrimitive::ConstructL();

	TUint totalBits = aBitStr.Length() * 8;

	__ASSERT_ALWAYS(aLengthBits <= totalBits, User::Leave(KErrArgument));

	iPadding = (TUint8)(totalBits - aLengthBits);

	if(iPadding > 7)

		User::Leave(KErrArgument);

	}

/**

 * @internalTechnology

 * Constructs bit string from ASN.1 encoding object.

 * @param aEncObj ASN.1 encoding object to wrap in bit string.

 * @note First produces raw DER encoding from the object, then creates 

 *     a bit string using other construct function.

 */

void CASN1EncBitString::ConstructL(const CASN1EncBase& aEncObj)

	{

	// produce raw DER encoding from the created ASN.1 encoding

	TUint len = aEncObj.LengthDER();

	HBufC8* intDer = HBufC8::NewMaxLC(len);

	TPtr8 ptrDer = intDer->Des();

	TUint pos = 0;

	aEncObj.WriteDERL(ptrDer, pos);

	// wrap the produced DER encoding into a bit string

	ConstructL(*intDer);

	// cleanup

	CleanupStack::PopAndDestroy(intDer);

	}

/** 

 * @internalTechnology 

 * Calculates length of DER-encoded bit string contents. For non empty

 * bit strings this differs from octet string in the extra leading byte 

 * containing the number of unused bits in the last octet.

 */

void CASN1EncBitString::CalculateContentsLengthDER()

	{

	iContentsLengthDER = iContents->Length();

	if (iContentsLengthDER > 0)

		{

		iContentsLengthDER++;

		}

	}

/**

 * @internalTechnology 

 * Writes DER-encoded bit string contents to aBuf. Prepends 

 * the actual bit string octets with extra octet containing 

 * number of unused bits in the last octet. Before writing, 

 * converts contents of the bit string to big-endian form.

 * @param aBuf Buffer to write to; must be long enough; 

 *     see #CalculateContentsLengthDER method.

 */

void CASN1EncBitString::WriteContentsDERL(TDes8& aBuf) const

	{

	if (iContents->Length() > 0)

		{

		aBuf[0] = iPadding;

		TUint len = iContents->Length();

		// We do not need to swap bits, as it is already done.

		aBuf.Replace(1, len, *iContents);		

		}

	else

		{

		// no padding octet for the empty bit string

		aBuf.SetLength(0);

		}

	}