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// The authors have released ID3Lib as Public Domain (PD) and claim no copyright,
// patent or other intellectual property protection in this work. This means that
// it may be modified, redistributed and used in commercial and non-commercial
// software and hardware without restrictions. ID3Lib is distributed on an "AS IS"
// basis, WITHOUT WARRANTY OF ANY KIND, either express or implied.
//
// The ID3Lib authors encourage improvements and optimisations to be sent to the
// ID3Lib coordinator, currently Dirk Mahoney (dirk@id3.org). Approved
// submissions may be altered, and will be included and released under these terms.
//
// Mon Nov 23 18:34:01 1998
#include "id3_tag.h"
// To be used when reading an ID3v2-tag
// Transforms all FF 00 sequences into FF
luint ID3_Tag::ReSync ( uchar *binarySourceData, luint sourceSize )
{
uchar *source, *dest;
uchar temp;
luint destinationSize;
source = binarySourceData;
destinationSize = sourceSize;
while ( source < binarySourceData + sourceSize )
{
temp = *source++;
if ( temp == 0xFF )
{
if ( ( temp = *source++ ) == 0x00 )
destinationSize--;
}
}
dest = source = binarySourceData;
while ( ( source < binarySourceData + sourceSize ) && ( dest < binarySourceData + sourceSize ) )
{
*dest++ = temp = *source++;
if ( temp == 0xFF )
{
if ( ( temp = *source++ ) != 0x00 )
*dest++ = temp;
}
}
return destinationSize;
}
// How big will the tag be after we unsync?
luint ID3_Tag::GetUnSyncSize ( uchar *buffer, luint size )
{
luint extraSize = 0;
uchar *source = buffer;
uchar temp;
// Determine the size needed for the destination data
while ( source < buffer + size )
{
temp = *source++;
if ( temp == 0xFF )
{
// last byte?
if ( source == ( buffer + size ) )
extraSize++;
else
{
temp = *source;
if ( ( ( temp & 0xE0 ) == 0xE0 ) || ( temp == 0 ) )
extraSize++;
}
}
}
return extraSize + size;
}
// To be used when writing an ID3v2-tag
// Transforms:
// 11111111 111xxxxx -> 11111111 00000000 111xxxxx
// 11111111 00000000 -> 11111111 00000000 00000000
// 11111111 <EOF> -> 11111111 00000000 <EOF>
void ID3_Tag::UnSync ( uchar *destData, luint destSize, uchar *sourceData, luint sourceSize )
{
uchar temp;
uchar *source = sourceData;
uchar *dest = destData;
// Now do the real transformation
while ( source < sourceData + sourceSize )
{
*dest++ = temp = *source++;
if ( temp == 0xFF )
{
// last byte?
if ( source == ( sourceData + sourceSize ) )
*dest++ = 0;
else
{
temp = *source;
if ( ( ( temp & 0xE0 ) == 0xE0 ) || ( temp == 0 ) )
*dest++ = 0;
}
}
}
return;
}
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