public unsafe override bool write(laszip_point item)
{
enc.encodeSymbol(m_packet_index, item.wave_packet[0]);
fixed(byte *pItem = item.wave_packet)
{
LASwavepacket13 *wave = (LASwavepacket13 *)(pItem + 1);
// calculate the difference between the two offsets
long curr_diff_64 = (long)(wave->offset - last_item.offset);
int curr_diff_32 = (int)curr_diff_64;
// if the current difference can be represented with 32 bits
if (curr_diff_64 == (long)(curr_diff_32))
{
if (curr_diff_32 == 0) // current difference is zero
{
enc.encodeSymbol(m_offset_diff[sym_last_offset_diff], 0);
sym_last_offset_diff = 0;
}
else if (curr_diff_32 == (int)last_item.packet_size) // current difference is size of last packet
{
enc.encodeSymbol(m_offset_diff[sym_last_offset_diff], 1);
sym_last_offset_diff = 1;
}
else //
{
enc.encodeSymbol(m_offset_diff[sym_last_offset_diff], 2);
sym_last_offset_diff = 2;
ic_offset_diff.compress(last_diff_32, curr_diff_32);
last_diff_32 = curr_diff_32;
}
}
else
{
enc.encodeSymbol(m_offset_diff[sym_last_offset_diff], 3);
sym_last_offset_diff = 3;
enc.writeInt64(wave->offset);
}
ic_packet_size.compress((int)last_item.packet_size, (int)wave->packet_size);
ic_return_point.compress(last_item.return_point.i32, wave->return_point.i32);
ic_xyz.compress(last_item.x.i32, wave->x.i32, 0);
ic_xyz.compress(last_item.y.i32, wave->y.i32, 1);
ic_xyz.compress(last_item.z.i32, wave->z.i32, 2);
last_item = *wave;
}
return(true);
}
public unsafe override void read(laszip_point item)
{
item.wave_packet[0] = (byte)(dec.decodeSymbol(m_packet_index));
fixed(byte *pItem = item.wave_packet)
{
LASwavepacket13 *wave = (LASwavepacket13 *)(pItem + 1);
sym_last_offset_diff = dec.decodeSymbol(m_offset_diff[sym_last_offset_diff]);
if (sym_last_offset_diff == 0)
{
wave->offset = last_item.offset;
}
else if (sym_last_offset_diff == 1)
{
wave->offset = last_item.offset + last_item.packet_size;
}
else if (sym_last_offset_diff == 2)
{
last_diff_32 = ic_offset_diff.decompress(last_diff_32);
wave->offset = (ulong)((long)last_item.offset + last_diff_32);
}
else
{
wave->offset = dec.readInt64();
}
wave->packet_size = (uint)ic_packet_size.decompress((int)last_item.packet_size);
wave->return_point.i32 = ic_return_point.decompress(last_item.return_point.i32);
wave->x.i32 = ic_xyz.decompress(last_item.x.i32, 0);
wave->y.i32 = ic_xyz.decompress(last_item.y.i32, 1);
wave->z.i32 = ic_xyz.decompress(last_item.z.i32, 2);
last_item = *wave;
}
}