/*

* Copyright (c) 2003, 2004 Nokia Corporation and/or its subsidiary(-ies).

* All rights reserved.

* This component and the accompanying materials are made available

* under the terms of "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:  An internal service class including some utility functions.

*

*/

// INCLUDE FILES

#include "ExifCommon.h"

// ============================ MEMBER FUNCTIONS ===============================

// -----------------------------------------------------------------------------

// TExifCommon::SetUint32

// Puts the given 32-bit unsigned integer to the 4-byte location, whose start 

// point is specified with the given 8-bit unsigned integer pointer. 

// -----------------------------------------------------------------------------

//

TInt TExifCommon::SetUint32( TUint8* aPtr, TUint32 aUint32 )

    {

    if ( !aPtr )

        {

        return KErrGeneral;

        }

    *( aPtr + 3 ) = STATIC_CAST( TUint8, ( aUint32 >> 24 ) & KOneByteMask );

    *( aPtr + 2 ) = STATIC_CAST( TUint8, ( aUint32 >> 16 ) & KOneByteMask );

    *( aPtr + 1 ) = STATIC_CAST( TUint8, ( aUint32 >> 8 ) & KOneByteMask );

    *aPtr = STATIC_CAST( TUint8, aUint32 & KOneByteMask );

    return KErrNone;

    }

// -----------------------------------------------------------------------------

// TExifCommon::SetUint16

// Puts the given 16-bit unsigned integer to the 2-byte location, whose start 

// point is specified with the given 8-bit unsigned integer pointer. 

// -----------------------------------------------------------------------------

//

TInt TExifCommon::SetUint16( TUint8* aPtr, TUint16 aUint16 )

    {

    if ( !aPtr )

        {

        return KErrGeneral;

        }

    *( aPtr + 1 ) = STATIC_CAST( TUint8, ( aUint16 >> 8 ) & KOneByteMask );

    *aPtr = STATIC_CAST( TUint8, aUint16 & KOneByteMask );

    return KErrNone;

    }

// -----------------------------------------------------------------------------

// TExifCommon::Uint32

// Returns a 32-bit unsigned integer from the location, whose start point is 

// specified with the given 8-bit unsigned integer pointer. 

// -----------------------------------------------------------------------------

//

TUint32 TExifCommon::Uint32L( TUint8* aPtr )

    {

    if ( !aPtr )

        {

        User::Leave( KErrGeneral );

        }

    TUint32 ret = 0;

    ret = *( aPtr + 3 );

    ret = ( ret << 8 ) + *( aPtr + 2 );

    ret = ( ret << 8 ) + *( aPtr + 1 );

    ret = ( ret << 8 ) + *aPtr;

    return ret;

    }

// -----------------------------------------------------------------------------

// TExifCommon::Int32

// Returns a 32-bit integer from the location, whose start point is specified  

// with the given 8-bit integer pointer. 

// -----------------------------------------------------------------------------

//

TInt32 TExifCommon::Int32L( TUint8* aPtr )

    {

    if ( !aPtr )

        {

        User::Leave( KErrGeneral );

        }

    TUint32 ret = 0;

    ret = *( aPtr + 3 );

    ret = ( ret << 8 ) + *( aPtr + 2 );

    ret = ( ret << 8 ) + *( aPtr + 1 );

    ret = ( ret << 8 ) + *aPtr;

    return STATIC_CAST( TInt32, ret );

    }

// -----------------------------------------------------------------------------

// TExifCommon::Uint16

// Returns a 16-bit unsigned integer from the location, whose start point is 

// specified with the given 8-bit unsigned integer pointer. 

// -----------------------------------------------------------------------------

//

TUint16 TExifCommon::Uint16L( TUint8* aPtr )

    {

    if ( !aPtr )

        {

        User::Leave( KErrGeneral );

        }

    TUint16 ret = 0;

    ret = *( aPtr + 1 );

    ret = STATIC_CAST( TUint16, ( ret << 8 ) + *aPtr );

    return ret;

    }

// -----------------------------------------------------------------------------

// TExifCommon::IsValidTagId

// Checks if the given 16-bit unsigned integer is one of the defined tag IDs.

// -----------------------------------------------------------------------------

//

TBool TExifCommon::IsValidTagId( TUint16 aTagId )

    {

    TInt i = 0;

    for ( i = 0; i < KNoIfd0Tags; ++i )

        {

        if ( aTagId == ifd0Tags[i].iId )

            {

            return ETrue;

            }

        }

    for ( i = 0; i < KNoIfdExifTags; ++i )

        {

        if ( aTagId == ifdExifTags[i].iId )

            {

            return ETrue;

            }

        }

    for ( i = 0; i < KNoIfd1Tags; ++i )

        {

        if ( aTagId == ifd1Tags[i].iId )

            {

            return ETrue;

            }

        }

    for ( i = 0; i < KNoIfdGpsTags; ++i )

        {

        if ( aTagId == ifdGpsTags[i].iId )

            {

            return ETrue;

            }

        }

    for ( i = 0; i < KNoIfdIntOpTags; ++i )

        {

        if ( aTagId == ifdIntOpTags[i].iId )

            {

            return ETrue;

            }

        }

    LOGTEXT2( _L( "ExifLib: TExifCommon::IsValidTagId() returning EFalse: aTagId=0x%x" ), aTagId );

    return EFalse;

    }

// -----------------------------------------------------------------------------

// TExifCommon::LocateJpegMarkerPtr

// Locates the pointer to the first specified Jpeg Marker from the begining

// inside the given interval.

// -----------------------------------------------------------------------------

//

TUint8* TExifCommon::LocateJpegMarkerPtr( 

    TUint16 aMarker, 

    TUint8* aStartPtr,

    TUint8* aEndPtr)

    {

    if ( ( !aStartPtr ) || ( !aEndPtr ) || ( !aMarker ) )

        {

        return NULL;

        }

    TUint16 revMarker = 

        STATIC_CAST( TUint16, ( aMarker << 8 ) + ( aMarker >> 8 ) );

    --aStartPtr;

    TUint16 atHand = 0;

    TInt error = KErrNone;

    do

        {

        if ( aStartPtr >= aEndPtr )

            {

            return NULL;

            }

        if ( *( ++aStartPtr ) == KMarkerStart )

            {

            TRAP( error, atHand = TExifCommon::Uint16L( aStartPtr ) );

            }

        } 

    while ( (atHand != revMarker ) && ( error == KErrNone) );

    if ( error )

        {

        return NULL;

        }

    return aStartPtr;

    }

// -----------------------------------------------------------------------------

// TExifCommon::LocateJpegMarkerPtrFromEnd

// Locates the pointer to the first specified Jpeg Marker from the end

// inside the given interval.

// -----------------------------------------------------------------------------

//

TUint8* TExifCommon::LocateJpegMarkerPtrFromEnd( 

    TUint16 aMarker, 

    TUint8* aStartPtr,

    TUint8* aEndPtr)

    {

    if ( ( !aStartPtr ) || ( !aEndPtr ) || ( !aMarker ) )

        {

        return NULL;

        }

    TUint16 revMarker = 

        STATIC_CAST( TUint16, ( aMarker << 8 ) + ( aMarker >> 8 ) );

    --aEndPtr;

    TUint16 atHand = 0;

    TInt error = KErrNone;

    do

        {

        if ( aEndPtr <= aStartPtr )

            {

            return NULL;

            }

        if ( *( --aEndPtr ) == KMarkerStart )

            {

            TRAP( error, atHand = TExifCommon::Uint16L( aEndPtr ) );

            }

        } 

    while ( (atHand != revMarker ) && ( error == KErrNone) );

    if ( error )

        {

        return NULL;

        }

    return aEndPtr;

    }