1.1 --- /dev/null	Thu Jan 01 00:00:00 1970 +0000
     1.2 +++ b/os/mm/mmlibs/mmfw/Recogniser/src/id3parser.cpp	Fri Jun 15 03:10:57 2012 +0200
     1.3 @@ -0,0 +1,93 @@
     1.4 +// Copyright (c) 2006-2009 Nokia Corporation and/or its subsidiary(-ies).
     1.5 +// All rights reserved.
     1.6 +// This component and the accompanying materials are made available
     1.7 +// under the terms of "Eclipse Public License v1.0"
     1.8 +// which accompanies this distribution, and is available
     1.9 +// at the URL "http://www.eclipse.org/legal/epl-v10.html".
    1.10 +//
    1.11 +// Initial Contributors:
    1.12 +// Nokia Corporation - initial contribution.
    1.13 +//
    1.14 +// Contributors:
    1.15 +//
    1.16 +// Description:
    1.17 +//
    1.18 +
    1.19 +#include "parsers.h"
    1.20 +
    1.21 +// The ID3 tag has a 10 byte header.
    1.22 +static const TInt KID3HeaderSize = 10;
    1.23 +
    1.24 +
    1.25 +//
    1.26 +// Checks if an ID3 header is present at the current
    1.27 +// reader position, and skips over it if it is.
    1.28 +// Returns ETrue if a header was found, EFalse otherwise.
    1.29 +//
    1.30 +TBool TID3Parser::ReadAndSkipID3L(CReader& aReader)
    1.31 +	{
    1.32 +	TBuf8<KID3HeaderSize> header;
    1.33 +	TUint8 a;
    1.34 +	TUint8 b;
    1.35 +	TUint8 c;
    1.36 +	TUint8 d;
    1.37 +	
    1.38 +	header.SetLength(KID3HeaderSize);
    1.39 +	aReader.ReadBytesL(header);
    1.40 +	
    1.41 +	do
    1.42 +		{
    1.43 +		// Look for the ID3 header.
    1.44 +		if ((header[0] != 'I') || (header[1] != 'D') || (header[2] != '3'))
    1.45 +			{
    1.46 +			break;
    1.47 +			}
    1.48 +			
    1.49 +		// The last 4 bits of byte[5] should be zero.
    1.50 +		if ((header[5] & 0x0f))	// [00001111]
    1.51 +			{
    1.52 +			break;
    1.53 +			}
    1.54 +			
    1.55 +		// Read the tag size. It's stored in a sync-safe manner
    1.56 +		// (the highest bit is never set so it won't be confused
    1.57 +		// with a frame-sync). If the highest bit is set, it's invalid.
    1.58 +		a = header[6];
    1.59 +		b = header[7];
    1.60 +		c = header[8];
    1.61 +		d = header[9];
    1.62 +		
    1.63 +		// OR the values together and check that the highest bit of
    1.64 +		// the result isn't set. Saves on doing four individual checks.
    1.65 +		if ((a | b | c | d) & 0x80) // [10000000]
    1.66 +			{
    1.67 +			break;
    1.68 +			}
    1.69 +		
    1.70 +		// Convert from sync-safe format to normal format.
    1.71 +		// [0aaaaaaa][0bbbbbbb][0ccccccc][0ddddddd] is changed to
    1.72 +		// [0000aaaa][aaabbbbb][bbcccccc][cddddddd]
    1.73 +		//
    1.74 +		// Copy bit[0] of c into bit[7] of d.
    1.75 +		d |= ((c & 0x01) << 7);
    1.76 +		c >>= 1;
    1.77 +		
    1.78 +		// Copy bit[1,0] of b into bit[7,6] of c.
    1.79 +		c |= ((b & 0x03) << 6);
    1.80 +		b >>= 2;
    1.81 +		
    1.82 +		// Copy bit[2,1,0] of a into bit[7,6,5] of b.
    1.83 +		b |= ((a & 0x07) << 5);
    1.84 +		a >>= 3;
    1.85 +		
    1.86 +		TInt length = MAKE_INT32(a, b, c, d);
    1.87 +		aReader.SeekL(length);
    1.88 +		return ETrue;
    1.89 +		}
    1.90 +	while (EFalse);
    1.91 +	
    1.92 +	// It's not an ID3 header.
    1.93 +	// Undo the header read.
    1.94 +	aReader.SeekL(-KID3HeaderSize);
    1.95 +	return EFalse;
    1.96 +	}