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the game where you go into mines and start crafting! but for consoles (forked directly from smartcmd's github)
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at master
123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384#pragma once#include <stdint.h>
// 4J added - Storage for block & sky light data. Lighting data is normally stored as 4-bits per tile, in a DataLayer class of 16384 bytes ( 128 x 16 x 16 x 0.5 )// This class provides more economical storage for such data by taking into consideration that it is quite common for large parts of the lighting data in a level to// be very compressible (large amounts of 0 for block lights, 0 and 15 for sky lights).// We are aiming here to balance performance (lighting data is accessed very frequently) against size.
// Details of storage method:
// 1. Lighting is split into horizontal planes, of which there are 128, and each taking up 128 bytes (16 x 16 x 0.5)// 2. Each of these layers has a permanently allocated index in this class (planeIndices).// 3. Data for allocatedPlaneCount planes worth of data is allocated in the data array ( allocatedPlaneCount * 128 bytes )// 4. If a plane index for a layer is < 128, then the data for that layer is at data[ index * 128 ]// 5. If a plane index for a layer is 128, then all values for that plane are 0// 6. If a plane index for a layer is 129, then all values for that plane are 15
// This class needs to be thread safe as there are times where chunk (and light) data are shared between server & main threads. Light values are queried// very regularly so this needs to be as light-weight as possible.
// To meet these requirements, this class is now implemented using a lock-free system, implemented using a read-copy-update (RCU) type algorithm. Some details...
// (1) The storage details for the class are now packed into a single __int64, which contains both a pointer to the data that is required and a count of how many planes worth// of storage are allocated. This allows the full storage to be updated atomically using compare and exchange operations (implemented with InterlockedCompareExchangeRelease64).// (2) The data pointer referenced in this __int64 points to an area of memory which is 128 + 128 * plane_count bytes long, where the first 128 bytes stoere the plane indices, and// the rest of the data is variable in size to accomodate however many planes are required to be stored// (3) The RCU bit of the algorithm means that any read operations don't need to do any checks or locks at all. When the data needs to be updated, a copy of it is made and updated,// then an attempt is made to swap the new data in - if this succeeds then the old data pointer is deleted later at some point where we know nothing will be reading from it anymore.// This is achieved by putting the delete request in a queue which means it won't actually get deleted until 2 game ticks after the last time its reference existed, which should give// us a large margin of safety. If the attempt to swap the new data in fails, then the whole write operation has to be attempted again - this is the only time there is really a// high cost for this algorithm and such write collisions should be rare.
//#define LIGHT_COMPRESSION_STATS
class SparseLightStorage_SPU{private:// unsigned char planeIndices[128]; unsigned char* m_pData;
// unsigned char *data;// unsigned int allocatedPlaneCount;
static const int ALL_0_INDEX = 128; static const int ALL_15_INDEX = 129;public: SparseLightStorage_SPU(unsigned char* data) : m_pData(data) {}
unsigned char* getDataPtr() { return m_pData; }
inline int get(int x, int y, int z) // Get an individual lighting value { unsigned char *planeIndices, *data; getPlaneIndicesAndData(&planeIndices, &data);
if( planeIndices[y] == ALL_0_INDEX ) { return 0; } else if ( planeIndices[y] == ALL_15_INDEX ) { return 15; } else { int planeIndex = x * 16 + z; // Index within this xz plane int byteIndex = planeIndex / 2; // Byte index within the plane (2 tiles stored per byte) int shift = ( planeIndex & 1 ) * 4; // Bit shift within the byte int retval = ( data[ planeIndices[y] * 128 + byteIndex ] >> shift ) & 15;
return retval; } }
inline void getPlaneIndicesAndData(unsigned char **planeIndices, unsigned char **data) { *planeIndices = m_pData; *data = m_pData + 128; }
};