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 "include/core/SkString.h"
9 #include "include/core/SkTypes.h"
10 #include "include/private/SkChecksum.h"
11 #include "include/private/base/SkAlign.h"
12 #include "src/base/SkRandom.h"
13 #include "src/core/SkOpts.h"
14 #include "tests/Test.h"
15
16 #include <cstddef>
17 #include <cstdint>
18 #include <string>
19 #include <string_view>
20
DEF_TEST(Checksum,r)21 DEF_TEST(Checksum, r) {
22 // Put 128 random bytes into two identical buffers. Any multiple of 4 will do.
23 const size_t kBytes = SkAlign4(128);
24 SkRandom rand;
25 uint32_t data[kBytes/4], tweaked[kBytes/4];
26 for (size_t i = 0; i < std::size(tweaked); ++i) {
27 data[i] = tweaked[i] = rand.nextU();
28 }
29
30 // Hash of nullptr is always 0.
31 REPORTER_ASSERT(r, SkOpts::hash(nullptr, 0) == 0);
32
33 const uint32_t hash = SkOpts::hash(data, kBytes);
34 // Should be deterministic.
35 REPORTER_ASSERT(r, hash == SkOpts::hash(data, kBytes));
36
37 // Changing any single element should change the hash.
38 for (size_t j = 0; j < std::size(tweaked); ++j) {
39 const uint32_t saved = tweaked[j];
40 tweaked[j] = rand.nextU();
41 const uint32_t tweakedHash = SkOpts::hash(tweaked, kBytes);
42 REPORTER_ASSERT(r, tweakedHash != hash);
43 REPORTER_ASSERT(r, tweakedHash == SkOpts::hash(tweaked, kBytes));
44 tweaked[j] = saved;
45 }
46 }
47
DEF_TEST(GoodHash,r)48 DEF_TEST(GoodHash, r) {
49 // 4 bytes --> hits SkChecksum::Mix fast path.
50 REPORTER_ASSERT(r, SkGoodHash()(( int32_t)4) == 614249093);
51 REPORTER_ASSERT(r, SkGoodHash()((uint32_t)4) == 614249093);
52 }
53
DEF_TEST(ChecksumCollisions,r)54 DEF_TEST(ChecksumCollisions, r) {
55 // We noticed a few workloads that would cause hash collisions due to the way
56 // our optimized hashes split into three concurrent hashes and merge those hashes together.
57 //
58 // One of these two workloads ought to cause an unintentional hash collision on very similar
59 // data in those old algorithms, the float version on 32-bit x86 and double elsewhere.
60 {
61 float a[9] = { 0, 1, 2,
62 3, 4, 5,
63 6, 7, 8, };
64 float b[9] = { 1, 2, 0,
65 4, 5, 3,
66 7, 8, 6, };
67
68 REPORTER_ASSERT(r, SkOpts::hash(a, sizeof(a)) != SkOpts::hash(b, sizeof(b)));
69 }
70 {
71 double a[9] = { 0, 1, 2,
72 3, 4, 5,
73 6, 7, 8, };
74 double b[9] = { 1, 2, 0,
75 4, 5, 3,
76 7, 8, 6, };
77
78 REPORTER_ASSERT(r, SkOpts::hash(a, sizeof(a)) != SkOpts::hash(b, sizeof(b)));
79 }
80 }
81
DEF_TEST(ChecksumConsistent,r)82 DEF_TEST(ChecksumConsistent, r) {
83 // We've decided to make SkOpts::hash() always return consistent results, so spot check a few:
84 uint8_t bytes[256];
85 for (int i = 0; i < 256; i++) {
86 bytes[i] = i;
87 }
88 REPORTER_ASSERT(r, SkOpts::hash(bytes, 0) == 0x00000000, "%08x", SkOpts::hash(bytes, 0));
89 REPORTER_ASSERT(r, SkOpts::hash(bytes, 1) == 0x00000000, "%08x", SkOpts::hash(bytes, 1));
90 REPORTER_ASSERT(r, SkOpts::hash(bytes, 2) == 0xf26b8303, "%08x", SkOpts::hash(bytes, 2));
91 REPORTER_ASSERT(r, SkOpts::hash(bytes, 7) == 0x18678721, "%08x", SkOpts::hash(bytes, 7));
92 REPORTER_ASSERT(r, SkOpts::hash(bytes, 32) == 0x9d1ef96b, "%08x", SkOpts::hash(bytes, 32));
93 REPORTER_ASSERT(r, SkOpts::hash(bytes, 63) == 0xc4b07d3a, "%08x", SkOpts::hash(bytes, 63));
94 REPORTER_ASSERT(r, SkOpts::hash(bytes, 64) == 0x3535a461, "%08x", SkOpts::hash(bytes, 64));
95 REPORTER_ASSERT(r, SkOpts::hash(bytes, 99) == 0x3f98a130, "%08x", SkOpts::hash(bytes, 99));
96 REPORTER_ASSERT(r, SkOpts::hash(bytes,255) == 0x3b9ceab2, "%08x", SkOpts::hash(bytes,255));
97 }
98
DEF_TEST(ChecksumStrings,r)99 DEF_TEST(ChecksumStrings, r) {
100 constexpr char kMessage[] = "Checksums are supported for SkString, string, and string_view.";
101 const uint32_t expectedHash = SkOpts::hash(kMessage, strlen(kMessage));
102
103 REPORTER_ASSERT(r, expectedHash == SkGoodHash()(SkString(kMessage)));
104 REPORTER_ASSERT(r, expectedHash == SkGoodHash()(std::string(kMessage)));
105 REPORTER_ASSERT(r, expectedHash == SkGoodHash()(std::string_view(kMessage)));
106 }
107