water.fvec.CUDChunk Maven / Gradle / Ivy

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package water.fvec;

import water.AutoBuffer;
import water.MemoryManager;
import water.util.UnsafeUtils;

import java.util.HashMap;
import java.util.Map;

/**
 * The "few unique doubles"-compression function
 */
public class CUDChunk extends Chunk {
  public static int MAX_UNIQUES=256;
  public static int computeByteSize(int uniques, int len) {
    return 4 + 4 // _len + numUniques
            + (uniques << 3) //unique double values
            + (len << 1); //mapping of row -> unique value index (0...255)
  }
  int numUniques;
  CUDChunk() {}
  CUDChunk(byte[] bs, HashMap hs, int len) {
    _start = -1;
    numUniques = hs.size();
    set_len(len);
    _mem = MemoryManager.malloc1(computeByteSize(numUniques, _len), false);
    UnsafeUtils.set4(_mem, 0, _len);
    UnsafeUtils.set4(_mem, 4, numUniques);
    int j=0;
    //create the mapping and also store the unique values (as longs)
    for (Map.Entry e : hs.entrySet()) {
      e.setValue(new Byte((byte)(j-128))); //j is in 0...256  -> byte value needs to be in -128...127 for storage
      UnsafeUtils.set8(_mem, 8 + (j << 3), e.getKey());
      j++;
    }
    // store the mapping
    for (int i=0; i