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authorkumquat-ir <66188216+kumquat-ir@users.noreply.github.com>2022-07-18 14:05:23 -0400
committerkumquat-ir <66188216+kumquat-ir@users.noreply.github.com>2022-07-18 14:05:23 -0400
commit20b1723e78149c1f2ac4072cbd46997e9c5160fa (patch)
tree7d97c8bc2edfe5cb41b91e6d04ba36da8aa163e6 /libraries/murmur2/src
parentbe78afeee54a19cd0115e1d2ec63f3a3201a3940 (diff)
parentdec81c4f274dd8388d442062cf9fa18600aa850d (diff)
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Signed-off-by: kumquat-ir <66188216+kumquat-ir@users.noreply.github.com>
Diffstat (limited to 'libraries/murmur2/src')
-rw-r--r--libraries/murmur2/src/MurmurHash2.cpp86
-rw-r--r--libraries/murmur2/src/MurmurHash2.h30
2 files changed, 116 insertions, 0 deletions
diff --git a/libraries/murmur2/src/MurmurHash2.cpp b/libraries/murmur2/src/MurmurHash2.cpp
new file mode 100644
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+++ b/libraries/murmur2/src/MurmurHash2.cpp
@@ -0,0 +1,86 @@
+//-----------------------------------------------------------------------------
+// MurmurHash2 was written by Austin Appleby, and is placed in the public
+// domain. The author hereby disclaims copyright to this source code.
+
+// Note - This code makes a few assumptions about how your machine behaves -
+
+// 1. We can read a 4-byte value from any address without crashing
+// 2. sizeof(int) == 4
+
+// And it has a few limitations -
+
+// 1. It will not work incrementally.
+// 2. It will not produce the same results on little-endian and big-endian
+// machines.
+
+#include "MurmurHash2.h"
+
+//-----------------------------------------------------------------------------
+// Platform-specific functions and macros
+
+// Microsoft Visual Studio
+
+#if defined(_MSC_VER)
+
+#define BIG_CONSTANT(x) (x)
+
+// Other compilers
+
+#else // defined(_MSC_VER)
+
+#define BIG_CONSTANT(x) (x##LLU)
+
+#endif // !defined(_MSC_VER)
+
+//-----------------------------------------------------------------------------
+
+uint64_t MurmurHash2 ( const void* key, int len, uint32_t seed )
+{
+ // 'm' and 'r' are mixing constants generated offline.
+ // They're not really 'magic', they just happen to work well.
+
+ const uint32_t m = 0x5bd1e995;
+ const int r = 24;
+
+ // Initialize the hash to a 'random' value
+
+ uint32_t h = seed ^ len;
+
+ // Mix 4 bytes at a time into the hash
+ const auto* data = (const unsigned char*) key;
+ while(len >= 4)
+ {
+ uint32_t k = *(uint32_t*)data;
+
+ k *= m;
+ k ^= k >> r;
+ k *= m;
+
+ h *= m;
+ h ^= k;
+
+ data += 4*sizeof(char);
+ len -= 4;
+ }
+
+ // Handle the last few bytes of the input array
+
+ switch(len)
+ {
+ case 3: h ^= data[2] << 16;
+ case 2: h ^= data[1] << 8;
+ case 1: h ^= data[0];
+ h *= m;
+ };
+
+ // Do a few final mixes of the hash to ensure the last few
+ // bytes are well-incorporated.
+
+ h ^= h >> 13;
+ h *= m;
+ h ^= h >> 15;
+
+ return h;
+}
+
+//-----------------------------------------------------------------------------
diff --git a/libraries/murmur2/src/MurmurHash2.h b/libraries/murmur2/src/MurmurHash2.h
new file mode 100644
index 00000000..c7b83bca
--- /dev/null
+++ b/libraries/murmur2/src/MurmurHash2.h
@@ -0,0 +1,30 @@
+//-----------------------------------------------------------------------------
+// MurmurHash2 was written by Austin Appleby, and is placed in the public
+// domain. The author hereby disclaims copyright to this source code.
+
+#pragma once
+
+//-----------------------------------------------------------------------------
+// Platform-specific functions and macros
+
+// Microsoft Visual Studio
+
+#if defined(_MSC_VER) && (_MSC_VER < 1600)
+
+typedef unsigned char uint8_t;
+typedef unsigned int uint32_t;
+typedef unsigned __int64 uint64_t;
+
+// Other compilers
+
+#else // defined(_MSC_VER)
+
+#include <stdint.h>
+
+#endif // !defined(_MSC_VER)
+
+//-----------------------------------------------------------------------------
+
+uint64_t MurmurHash2 ( const void* key, int len, uint32_t seed = 1 );
+
+//-----------------------------------------------------------------------------