69 lines
1.7 KiB
Java
69 lines
1.7 KiB
Java
/**
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* cache for a single square
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*
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* @author ab
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*/
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package btools.mapaccess;
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import java.io.*;
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import btools.util.Crc32;
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final class PhysicalFile
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{
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RandomAccessFile ra = null;
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long[] fileIndex = new long[25];
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int[] fileHeaderCrcs;
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private int fileIndexCrc;
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public long creationTime;
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String fileName;
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public PhysicalFile( File f, byte[] iobuffer, int lookupVersion ) throws Exception
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{
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fileName = f.getName();
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ra = new RandomAccessFile( f, "r" );
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ra.readFully( iobuffer, 0, 200 );
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fileIndexCrc = Crc32.crc( iobuffer, 0, 200 );
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ByteDataReader dis = new ByteDataReader( iobuffer );
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for( int i=0; i<25; i++ )
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{
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long lv = dis.readLong();
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short readVersion = (short)(lv >> 48);
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if ( readVersion != lookupVersion )
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{
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throw new IllegalArgumentException( "lookup version mismatch (old rd5?) lookups.dat="
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+ lookupVersion + " " + f. getAbsolutePath() + "=" + readVersion );
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}
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fileIndex[i] = lv & 0xffffffffffffL;
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}
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// read some extra info from the end of the file, if present
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long len = ra.length();
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long pos = fileIndex[24];
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int extraLen = 8 + 26*4;
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if ( len == pos ) return; // old format o.k.
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if ( len < pos+extraLen ) // > is o.k. for future extensions!
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{
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throw new IOException( "file of size " + len + " + too short, should be " + (pos+extraLen) );
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}
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ra.seek( pos );
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ra.readFully( iobuffer, 0, extraLen );
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dis = new ByteDataReader( iobuffer );
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creationTime = dis.readLong();
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if ( dis.readInt() != fileIndexCrc )
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{
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throw new IOException( "top index checksum error" );
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}
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fileHeaderCrcs = new int[25];
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for( int i=0; i<25; i++ )
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{
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fileHeaderCrcs[i] = dis.readInt();
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}
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}
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}
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