1 /*
2 * Copyright 2012 Google Inc.
3 *
4 * Use of this source code is governed by a BSD-style license that can be
5 * found in the LICENSE file.
6 */
7
8 #include "SkChecksum.h"
9 #include "SkRandom.h"
10 #include "Test.h"
11
12
13 // Murmur3 has an optional third seed argument, so we wrap it to fit a uniform type.
murmur_noseed(const uint32_t * d,size_t l)14 static uint32_t murmur_noseed(const uint32_t* d, size_t l) { return SkChecksum::Murmur3(d, l); }
15
16 #define ASSERT(x) REPORTER_ASSERT(r, x)
17
DEF_TEST(Checksum,r)18 DEF_TEST(Checksum, r) {
19 // Algorithms to test. They're currently all uint32_t(const uint32_t*, size_t).
20 typedef uint32_t(*algorithmProc)(const uint32_t*, size_t);
21 const algorithmProc kAlgorithms[] = { &murmur_noseed };
22
23 // Put 128 random bytes into two identical buffers. Any multiple of 4 will do.
24 const size_t kBytes = SkAlign4(128);
25 SkRandom rand;
26 uint32_t data[kBytes/4], tweaked[kBytes/4];
27 for (size_t i = 0; i < SK_ARRAY_COUNT(tweaked); ++i) {
28 data[i] = tweaked[i] = rand.nextU();
29 }
30
31 // Test each algorithm.
32 for (size_t i = 0; i < SK_ARRAY_COUNT(kAlgorithms); ++i) {
33 const algorithmProc algorithm = kAlgorithms[i];
34
35 // Hash of nullptr is always 0.
36 ASSERT(algorithm(nullptr, 0) == 0);
37
38 const uint32_t hash = algorithm(data, kBytes);
39 // Should be deterministic.
40 ASSERT(hash == algorithm(data, kBytes));
41
42 // Changing any single element should change the hash.
43 for (size_t j = 0; j < SK_ARRAY_COUNT(tweaked); ++j) {
44 const uint32_t saved = tweaked[j];
45 tweaked[j] = rand.nextU();
46 const uint32_t tweakedHash = algorithm(tweaked, kBytes);
47 ASSERT(tweakedHash != hash);
48 ASSERT(tweakedHash == algorithm(tweaked, kBytes));
49 tweaked[j] = saved;
50 }
51 }
52 }
53
DEF_TEST(GoodHash,r)54 DEF_TEST(GoodHash, r) {
55 ASSERT(SkGoodHash()(( int32_t)4) == 614249093); // 4 bytes. Hits SkChecksum::Mix fast path.
56 ASSERT(SkGoodHash()((uint32_t)4) == 614249093); // (Ditto)
57
58 // None of these are 4 byte sized, so they use SkChecksum::Murmur3, not SkChecksum::Mix.
59 ASSERT(SkGoodHash()((uint64_t)4) == 3491892518);
60 ASSERT(SkGoodHash()((uint16_t)4) == 899251846);
61 ASSERT(SkGoodHash()( (uint8_t)4) == 962700458);
62
63 // Tests SkString is correctly specialized.
64 ASSERT(SkGoodHash()(SkString("Hi")) == 55667557);
65 }
66