private static void CopyBits(MyOpenBitSet compressedSet, int val, int offset, int length)
{
long[] bits = compressedSet.Bits;
int index = (int)((uint)offset) >> 6;
int skip = offset & 0x3f;
val &= (int)(((uint)0xffffffff) >> (32 - length));
bits[index] |= (((long)val) << skip);
if (64 - skip < length)
{
bits[index + 1] |= (long)(((ulong)val) >> (64 - skip));
}
}
///<summary>Alternate implementation for compress
/// * </summary>
/// * <param name="input"> </param>
/// * <returns> compressed bitset </returns>
/// * <exception cref="ArgumentException"> </exception>
public virtual OpenBitSet Compress(int[] input)
{
if (_base == INVALID || _b == INVALID)
{
throw new ArgumentException(" Codec not initialized correctly ");
}
int BATCH_MAX = 1 << (_b - 1);
// int validCount = (_batchSize - _exceptionCount)*_b +SIZE_MASK+BASE_MASK;
// Compression mumbo jumbo
// Set Size -b+base+compressedSet+exception*BASE_MASK
MyOpenBitSet compressedSet = new MyOpenBitSet((_batchSize) * _b
+ HEADER_MASK + _exceptionCount * (BASE_MASK));
// System.out.println("Compressed Set Size : " + compressedSet.capacity());
// Load the b
CopyBits(compressedSet, _b, 0, BYTE_MASK);
// copy the base value to BASE_MASK offset
// copyBits(compressedSet, _base, BYTE_MASK, BASE_MASK);
// Offset is the offset of the next location to place the value
int offset = HEADER_MASK;
int exceptionOffset = _exceptionOffset;
int exceptionIndex = 0;
// 1. Walk the list
// TODO : Optimize this process.
for (int i = 0; i < _batchSize; i++)
{
// else copy in the end
if (input[i] < BATCH_MAX)
{
CopyBits(compressedSet, input[i] << 1, offset, _b);
}
else
{
// Copy the value to the exception location
// Add a bit marker to place
CopyBits(compressedSet, ((exceptionIndex << 1) | 0x1), offset, _b);
// System.out.println("Adding Exception
// Marker:"+(BATCH_MAX|(exceptionIndex-1)) + " at offset:"+offset);
// Copy the patch value to patch offset location
CopyBits(compressedSet, input[i], exceptionOffset, BASE_MASK);
// reset exceptionDelta
exceptionOffset += BASE_MASK;
exceptionIndex++;
}
offset += _b;
}
return compressedSet;
}