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package uk.ac.bristol.star.cdf.record;
import java.io.IOException;
import java.lang.reflect.Array;
import uk.ac.bristol.star.cdf.CdfFormatException;
import uk.ac.bristol.star.cdf.DataType;
/**
* Reads items with a given data type from a buffer into an array.
*
* @author Mark Taylor
* @since 20 Jun 2013
*/
public class DataReader {
private final DataType dataType_;
private final int nelPerItem_;
private final int nItem_;
/**
* Constructor.
*
* @param dataType data type
* @param nelPerItem number of dataType elements per read item;
* usually 1 except for character data
* @param nItem number of items of given data type in the array,
* for scalar records it will be 1
*/
public DataReader( DataType dataType, int nelPerItem, int nItem ) {
dataType_ = dataType;
nelPerItem_ = nelPerItem;
nItem_ = nItem;
}
/**
* Creates a workspace array which can contain a value read for one record.
* The return value will be an array of a primitive type or String.
*
* @return workspace array for this reader
*/
public Object createValueArray() {
return Array.newInstance( dataType_.getArrayElementClass(),
nItem_ * dataType_.getGroupSize() );
}
/**
* Reads a value from a data buffer into a workspace array.
*
* @param buf data buffer
* @param offset byte offset into buf of data start
* @param valueArray object created by <code>createValueArray</code>
* into which results will be read
*/
public void readValue( Buf buf, long offset, Object valueArray )
throws IOException {
dataType_.readValues( buf, offset, nelPerItem_, valueArray, nItem_ );
}
/**
* Returns the size in bytes of one record as stored in the data buffer.
*
* @return record size in bytes
*/
public int getRecordSize() {
return dataType_.getByteCount() * nelPerItem_ * nItem_;
}
}
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