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-rw-r--r--src/database.cpp39
-rw-r--r--src/database.h2
2 files changed, 31 insertions, 10 deletions
diff --git a/src/database.cpp b/src/database.cpp
index 15579a7f0..26f6992fc 100644
--- a/src/database.cpp
+++ b/src/database.cpp
@@ -20,6 +20,14 @@ with this program; if not, write to the Free Software Foundation, Inc.,
#include "database.h"
#include "irrlichttypes.h"
+
+/****************
+ * Black magic! *
+ ****************
+ * The position hashing is very messed up.
+ * It's a lot more complicated than it looks.
+ */
+
static inline s16 unsigned_to_signed(u16 i, u16 max_positive)
{
if (i < max_positive) {
@@ -30,19 +38,32 @@ static inline s16 unsigned_to_signed(u16 i, u16 max_positive)
}
+// Modulo of a negative number does not work consistently in C
+static inline s64 pythonmodulo(s64 i, s16 mod)
+{
+ if (i >= 0) {
+ return i % mod;
+ }
+ return mod - ((-i) % mod);
+}
+
+
s64 Database::getBlockAsInteger(const v3s16 pos) const
{
- return (((u64) pos.Z) << 24) +
- (((u64) pos.Y) << 12) +
- ((u64) pos.X);
+ return (u64) pos.Z * 0x1000000 +
+ (u64) pos.Y * 0x1000 +
+ (u64) pos.X;
}
-v3s16 Database::getIntegerAsBlock(const s64 i) const
+
+v3s16 Database::getIntegerAsBlock(s64 i) const
{
- v3s16 pos;
- pos.Z = unsigned_to_signed((i >> 24) & 0xFFF, 0x1000 / 2);
- pos.Y = unsigned_to_signed((i >> 12) & 0xFFF, 0x1000 / 2);
- pos.X = unsigned_to_signed((i ) & 0xFFF, 0x1000 / 2);
- return pos;
+ v3s16 pos;
+ pos.X = unsigned_to_signed(pythonmodulo(i, 4096), 2048);
+ i = (i - pos.X) / 4096;
+ pos.Y = unsigned_to_signed(pythonmodulo(i, 4096), 2048);
+ i = (i - pos.Y) / 4096;
+ pos.Z = unsigned_to_signed(pythonmodulo(i, 4096), 2048);
+ return pos;
}
diff --git a/src/database.h b/src/database.h
index a86861379..f009877d2 100644
--- a/src/database.h
+++ b/src/database.h
@@ -35,7 +35,7 @@ public:
virtual void saveBlock(MapBlock *block)=0;
virtual MapBlock* loadBlock(v3s16 blockpos)=0;
s64 getBlockAsInteger(const v3s16 pos) const;
- v3s16 getIntegerAsBlock(const s64 i) const;
+ v3s16 getIntegerAsBlock(s64 i) const;
virtual void listAllLoadableBlocks(std::list<v3s16> &dst)=0;
virtual int Initialized(void)=0;
virtual ~Database() {};