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-rw-r--r--src/util/numeric.cpp44
1 files changed, 44 insertions, 0 deletions
diff --git a/src/util/numeric.cpp b/src/util/numeric.cpp
index 67df4ffba..0426656a5 100644
--- a/src/util/numeric.cpp
+++ b/src/util/numeric.cpp
@@ -22,6 +22,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
#include "../log.h"
#include "../constants.h" // BS, MAP_BLOCKSIZE
+#include <string.h>
#include <iostream>
// Calculate the borders of a "d-radius" cube
@@ -139,6 +140,49 @@ int myrand_range(int min, int max)
return (myrand()%(max-min+1))+min;
}
+// 64-bit unaligned version of MurmurHash
+u64 murmur_hash_64_ua(const void *key, int len, unsigned int seed)
+{
+ const u64 m = 0xc6a4a7935bd1e995;
+ const int r = 47;
+ u64 h = seed ^ (len * m);
+
+ const u64 *data = (const u64 *)key;
+ const u64 *end = data + (len / 8);
+
+ while (data != end) {
+ u64 k;
+ memcpy(&k, data, sizeof(u64));
+ data++;
+
+ k *= m;
+ k ^= k >> r;
+ k *= m;
+
+ h ^= k;
+ h *= m;
+ }
+
+ const unsigned char *data2 = (const unsigned char *)data;
+ switch (len & 7) {
+ case 7: h ^= (u64)data2[6] << 48;
+ case 6: h ^= (u64)data2[5] << 40;
+ case 5: h ^= (u64)data2[4] << 32;
+ case 4: h ^= (u64)data2[3] << 24;
+ case 3: h ^= (u64)data2[2] << 16;
+ case 2: h ^= (u64)data2[1] << 8;
+ case 1: h ^= (u64)data2[0];
+ h *= m;
+ }
+
+ h ^= h >> r;
+ h *= m;
+ h ^= h >> r;
+
+ return h;
+}
+
+
/*
blockpos: position of block in block coordinates
camera_pos: position of camera in nodes