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Revert "New, safer method of packing which makes careful use of casting to avoid problems with e.g. signed integer sign extension."

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This reverts commit fd451be2dd7b65671274791105e76bd6a31a0f79.
This commit is contained in:
David Williams 2015-03-21 14:40:11 +01:00
parent fd451be2dd
commit f574563672
2 changed files with 6 additions and 44 deletions
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25
include/PolyVox/PagedVolume.h
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@ -285,36 +285,17 @@ namespace PolyVox
ChunkKey posToChunkKey(int32_t iXPos, int32_t iYPos, int32_t iZPos) const ChunkKey posToChunkKey(int32_t iXPos, int32_t iYPos, int32_t iZPos) const
{ {
int32_t iBlockX = iXPos >> m_uChunkSideLengthPower;
int32_t iBlockY = iYPos >> m_uChunkSideLengthPower;
int32_t iBlockZ = iZPos >> m_uChunkSideLengthPower;
int16_t iBlockXAsInt16 = static_cast<int16_t>(iBlockX);
int16_t iBlockYAsInt16 = static_cast<int16_t>(iBlockY);
int16_t iBlockZAsInt16 = static_cast<int16_t>(iBlockZ);
uint16_t uBlockXAsUint16 = reinterpret_cast<uint16_t&>(iBlockXAsInt16);
uint16_t uBlockYAsUint16 = reinterpret_cast<uint16_t&>(iBlockYAsInt16);
uint16_t uBlockZAsUint16 = reinterpret_cast<uint16_t&>(iBlockZAsInt16);
uint64_t uBlockXAsUint64 = static_cast<uint64_t>(uBlockXAsUint16);
uint64_t uBlockYAsUint64 = static_cast<uint64_t>(uBlockYAsUint16);
uint64_t uBlockZAsUint64 = static_cast<uint64_t>(uBlockZAsUint16);
uBlockXAsUint64 = uBlockXAsUint64 << 32;
uBlockYAsUint64 = uBlockYAsUint64 << 16;
// Bit-shifting of signed integer values has various issues with undefined or implementation-defined behaviour. // Bit-shifting of signed integer values has various issues with undefined or implementation-defined behaviour.
// Therefore we cast to unsigned to avoid these (we only care about the bit pattern anyway, not the actual value). // Therefore we cast to unsigned to avoid these (we only care about the bit pattern anyway, not the actual value).
/*const ChunkKey uXPos = static_cast<ChunkKey>(iXPos); const ChunkKey uXPos = static_cast<ChunkKey>(iXPos);
const ChunkKey uYPos = static_cast<ChunkKey>(iYPos); const ChunkKey uYPos = static_cast<ChunkKey>(iYPos);
const ChunkKey uZPos = static_cast<ChunkKey>(iZPos); const ChunkKey uZPos = static_cast<ChunkKey>(iZPos);
const ChunkKey xKey = ((uXPos >> m_uChunkSideLengthPower) & 0x3FF) << 20; const ChunkKey xKey = ((uXPos >> m_uChunkSideLengthPower) & 0x3FF) << 20;
const ChunkKey yKey = ((uYPos >> m_uChunkSideLengthPower) & 0x3FF) << 10; const ChunkKey yKey = ((uYPos >> m_uChunkSideLengthPower) & 0x3FF) << 10;
const ChunkKey zKey = ((uZPos >> m_uChunkSideLengthPower) & 0x3FF);*/ const ChunkKey zKey = ((uZPos >> m_uChunkSideLengthPower) & 0x3FF);
const ChunkKey key = 0xFFFF000000000000 | uBlockXAsUint64 | uBlockYAsUint64 | uBlockZAsUint64; const ChunkKey key = 0x80000000 | xKey | yKey | zKey;
return key; return key;
} }

25
include/PolyVox/PagedVolume.inl
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@ -293,33 +293,14 @@ namespace PolyVox
// If we still haven't found the chunk then it's time to create a new one and page it in from disk. // If we still haven't found the chunk then it's time to create a new one and page it in from disk.
if (!pChunk) if (!pChunk)
{ {
uint64_t uBlockXAsUint64 = iKeyAsInt32; const int32_t uChunkX = (iKeyAsInt32 >> 20) & 0x3FF;
uint64_t uBlockYAsUint64 = iKeyAsInt32;
uint64_t uBlockZAsUint64 = iKeyAsInt32;
uBlockXAsUint64 = uBlockXAsUint64 >> 32;
uBlockYAsUint64 = uBlockYAsUint64 >> 16;
uBlockXAsUint64 = uBlockXAsUint64 & 0xFFFF;
uBlockYAsUint64 = uBlockYAsUint64 & 0xFFFF;
uBlockZAsUint64 = uBlockZAsUint64 & 0xFFFF;
uint16_t uBlockXAsUint16 = static_cast<uint16_t>(uBlockXAsUint64);
uint16_t uBlockYAsUint16 = static_cast<uint16_t>(uBlockYAsUint64);
uint16_t uBlockZAsUint16 = static_cast<uint16_t>(uBlockZAsUint64);
int16_t uBlockXAsInt16 = reinterpret_cast<int16_t&>(uBlockXAsUint16);
int16_t uBlockYAsInt16 = reinterpret_cast<int16_t&>(uBlockYAsUint16);
int16_t uBlockZAsInt16 = reinterpret_cast<int16_t&>(uBlockZAsUint16);
/*const int32_t uChunkX = (iKeyAsInt32 >> 20) & 0x3FF;
const int32_t uChunkY = (iKeyAsInt32 >> 10) & 0x3FF; const int32_t uChunkY = (iKeyAsInt32 >> 10) & 0x3FF;
const int32_t uChunkZ = (iKeyAsInt32) & 0x3FF;*/ const int32_t uChunkZ = (iKeyAsInt32) & 0x3FF;
// The chunk was not found so we will create a new one. // The chunk was not found so we will create a new one.
/*ChunkKeyConverter converter; /*ChunkKeyConverter converter;
converter.i = key;*/ converter.i = key;*/
//ChunkKey realKey = force_cast<ChunkKey>(iKeyAsInt32); //ChunkKey realKey = force_cast<ChunkKey>(iKeyAsInt32);
Vector3DInt32 v3dChunkPos(uBlockXAsInt16, uBlockYAsInt16, uBlockZAsInt16); Vector3DInt32 v3dChunkPos(uChunkX, uChunkY, uChunkZ);
pChunk = new PagedVolume<VoxelType>::Chunk(v3dChunkPos, m_uChunkSideLength, m_pPager); pChunk = new PagedVolume<VoxelType>::Chunk(v3dChunkPos, m_uChunkSideLength, m_pPager);
pChunk->m_uChunkLastAccessed = ++m_uTimestamper; // Important, as we may soon delete the oldest chunk pChunk->m_uChunkLastAccessed = ++m_uTimestamper; // Important, as we may soon delete the oldest chunk
m_mapChunks.insert(std::make_pair(iKeyAsInt32, std::unique_ptr<Chunk>(pChunk))); m_mapChunks.insert(std::make_pair(iKeyAsInt32, std::unique_ptr<Chunk>(pChunk)));