ucar.nc2.iosp.Layout Maven / Gradle / Ivy
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/*
* Copyright (c) 1998-2018 John Caron and University Corporation for Atmospheric Research/Unidata
* See LICENSE for license information.
*/
package ucar.nc2.iosp;
import java.io.IOException;
/**
* Iterator to read/write subsets of a multidimensional array, finding the contiguous chunks.
* The iteration is monotonic in both src and dest positions.
*
* Example for Integers:
*
int[] read( Layout index, int[] src) {
int[] dest = new int[index.getTotalNelems()];
while (index.hasNext()) {
Layout.Chunk chunk = index.next();
System.arraycopy(src, chunk.getSrcElem(), dest, chunk.getDestElem(), chunk.getNelems());
}
return dest;
}
int[] read( Layout index, RandomAccessFile raf) {
int[] dest = new int[index.getTotalNelems()];
while (index.hasNext()) {
Layout.Chunk chunk = index.next();
raf.seek( chunk.getSrcPos());
raf.readInt(dest, chunk.getDestElem(), chunk.getNelems());
}
return dest;
}
// note src and dest misnamed
void write( Layout index, int[] src, RandomAccessFile raf) {
while (index.hasNext()) {
Layout.Chunk chunk = index.next();
raf.seek ( chunk.getSrcPos());
for (int k=0; k
*
* @author caron
* @since Jan 2, 2008
*/
public interface Layout {
/**
* Get total number of elements in the wanted subset.
*
* @return total number of elements in the wanted subset.
*/
public long getTotalNelems();
/**
* Get size of each element in bytes.
*
* @return size of each element in bytes.
*/
public int getElemSize();
/**
* Is there more to do
*
* @return true if theres more to do
*/
public boolean hasNext();
/**
* Get the next chunk
*
* @return next chunk, or null if !hasNext()
* @throws java.io.IOException on i/o error
*/
public Chunk next() throws IOException;
/**
* A chunk of data that is contiguous in both the source and destination.
* Read nelems from src at filePos, store in destination at startElem.
* (or) Write nelems to file at filePos, from array at startElem.
*/
public interface Chunk {
/**
* Get the position in source where to read or write: "file position"
* @return position as a byte count into the source, eg a file
*/
public long getSrcPos();
/**
* Get number of elements to transfer contiguously (Note: elements, not bytes)
* @return number of elements to transfer
*/
public int getNelems();
/**
* Get starting element position as a 1D element index into the destination, eg the requested array with shape "wantSection".
* @return starting element in the array (Note: elements, not bytes)
*/
public long getDestElem();
}
}