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 "SkOpts.h"
10 #include "SkRandom.h"
11 #include "Test.h"
12 
13 DEF_TEST(Checksum, r) {
14     // Put 128 random bytes into two identical buffers.  Any multiple of 4 will do.
15     const size_t kBytes = SkAlign4(128);
16     SkRandom rand;
17     uint32_t data[kBytes/4], tweaked[kBytes/4];
18     for (size_t i = 0; i < SK_ARRAY_COUNT(tweaked); ++i) {
19         data[i] = tweaked[i] = rand.nextU();
20     }
21 
22     // Hash of nullptr is always 0.
23     REPORTER_ASSERT(r, SkOpts::hash(nullptr, 0) == 0);
24 
25     const uint32_t hash = SkOpts::hash(data, kBytes);
26     // Should be deterministic.
27     REPORTER_ASSERT(r, hash == SkOpts::hash(data, kBytes));
28 
29     // Changing any single element should change the hash.
30     for (size_t j = 0; j < SK_ARRAY_COUNT(tweaked); ++j) {
31         const uint32_t saved = tweaked[j];
32         tweaked[j] = rand.nextU();
33         const uint32_t tweakedHash = SkOpts::hash(tweaked, kBytes);
34         REPORTER_ASSERT(r, tweakedHash != hash);
35         REPORTER_ASSERT(r, tweakedHash == SkOpts::hash(tweaked, kBytes));
36         tweaked[j] = saved;
37     }
38 }
39 
40 DEF_TEST(GoodHash, r) {
41     // 4 bytes --> hits SkChecksum::Mix fast path.
42     REPORTER_ASSERT(r, SkGoodHash()(( int32_t)4) ==  614249093);
43     REPORTER_ASSERT(r, SkGoodHash()((uint32_t)4) ==  614249093);
44 }
45