64c0c13e6e
Murmur2a is a very fast hashing function generation int32 hashes. It also features a very good distribution of generated hashes. However, it is not endianness-agnostic, meaning it will usually generate different hashes for a same key on big- and little-endian architectures. Consequently, **it shall not be used to generate persistent hashes** (never store them in .blend file e.g.). This implementation supports incremental hashing, and is a direct adaptation of reference implementation (in c++): https://smhasher.googlecode.com/svn-history/r130/trunk/MurmurHash2.cpp That cpp code was also used to generate reference values in gtests file. Reviewers: sergey, campbellbarton Reviewed By: campbellbarton Projects: #bf_blender Differential Revision: https://developer.blender.org/D892
76 lines
1.9 KiB
C++
76 lines
1.9 KiB
C++
/* Apache License, Version 2.0 */
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#include "testing/testing.h"
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extern "C" {
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#include "BLI_hash_mm2a.h"
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}
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/* Note: Reference results are taken from reference implementation (cpp code, CMurmurHash2A variant):
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* https://smhasher.googlecode.com/svn-history/r130/trunk/MurmurHash2.cpp
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*/
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TEST(hash_mm2a, MM2ABasic)
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{
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BLI_HashMurmur2A mm2;
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const char *data = "Blender";
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BLI_hash_mm2a_init(&mm2, 0);
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BLI_hash_mm2a_add(&mm2, (const unsigned char *)data, strlen(data));
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#ifdef __LITTLE_ENDIAN__
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EXPECT_EQ(1633988145, BLI_hash_mm2a_end(&mm2));
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#else
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EXPECT_EQ(959283772, BLI_hash_mm2a_end(&mm2));
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#endif
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}
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TEST(hash_mm2a, MM2AConcatenateStrings)
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{
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BLI_HashMurmur2A mm2;
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uint32_t hash;
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const char *data1 = "Blender";
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const char *data2 = " is ";
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const char *data3 = "FaNtAsTiC";
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const char *data123 = "Blender is FaNtAsTiC";
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BLI_hash_mm2a_init(&mm2, 0);
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BLI_hash_mm2a_add(&mm2, (const unsigned char *)data1, strlen(data1));
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BLI_hash_mm2a_add(&mm2, (const unsigned char *)data2, strlen(data2));
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BLI_hash_mm2a_add(&mm2, (const unsigned char *)data3, strlen(data3));
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hash = BLI_hash_mm2a_end(&mm2);
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BLI_hash_mm2a_init(&mm2, 0);
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BLI_hash_mm2a_add(&mm2, (const unsigned char *)data123, strlen(data123));
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#ifdef __LITTLE_ENDIAN__
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EXPECT_EQ(1545105348, hash);
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#else
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EXPECT_EQ(2604964730, hash);
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#endif
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EXPECT_EQ(hash, BLI_hash_mm2a_end(&mm2));
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}
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TEST(hash_mm2a, MM2AIntegers)
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{
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BLI_HashMurmur2A mm2;
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uint32_t hash;
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const int ints[4] = {1, 2, 3, 4};
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BLI_hash_mm2a_init(&mm2, 0);
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BLI_hash_mm2a_add_int(&mm2, ints[0]);
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BLI_hash_mm2a_add_int(&mm2, ints[1]);
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BLI_hash_mm2a_add_int(&mm2, ints[2]);
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BLI_hash_mm2a_add_int(&mm2, ints[3]);
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hash = BLI_hash_mm2a_end(&mm2);
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BLI_hash_mm2a_init(&mm2, 0);
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BLI_hash_mm2a_add(&mm2, (const unsigned char *)ints, sizeof(ints));
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/* Yes, same hash here on little and big endian. */
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#ifdef __LITTLE_ENDIAN__
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EXPECT_EQ(405493096, hash);
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#else
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EXPECT_EQ(405493096, hash);
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#endif
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EXPECT_EQ(hash, BLI_hash_mm2a_end(&mm2));
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}
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