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- /*
- * Copyright 2012 Google Inc.
- *
- * Use of this source code is governed by a BSD-style license that can be
- * found in the LICENSE file.
- */
- #include "include/core/SkTypes.h"
- #include "include/private/SkChecksum.h"
- #include "include/utils/SkRandom.h"
- #include "src/core/SkOpts.h"
- #include "tests/Test.h"
- DEF_TEST(Checksum, r) {
- // Put 128 random bytes into two identical buffers. Any multiple of 4 will do.
- const size_t kBytes = SkAlign4(128);
- SkRandom rand;
- uint32_t data[kBytes/4], tweaked[kBytes/4];
- for (size_t i = 0; i < SK_ARRAY_COUNT(tweaked); ++i) {
- data[i] = tweaked[i] = rand.nextU();
- }
- // Hash of nullptr is always 0.
- REPORTER_ASSERT(r, SkOpts::hash(nullptr, 0) == 0);
- const uint32_t hash = SkOpts::hash(data, kBytes);
- // Should be deterministic.
- REPORTER_ASSERT(r, hash == SkOpts::hash(data, kBytes));
- // Changing any single element should change the hash.
- for (size_t j = 0; j < SK_ARRAY_COUNT(tweaked); ++j) {
- const uint32_t saved = tweaked[j];
- tweaked[j] = rand.nextU();
- const uint32_t tweakedHash = SkOpts::hash(tweaked, kBytes);
- REPORTER_ASSERT(r, tweakedHash != hash);
- REPORTER_ASSERT(r, tweakedHash == SkOpts::hash(tweaked, kBytes));
- tweaked[j] = saved;
- }
- }
- DEF_TEST(GoodHash, r) {
- // 4 bytes --> hits SkChecksum::Mix fast path.
- REPORTER_ASSERT(r, SkGoodHash()(( int32_t)4) == 614249093);
- REPORTER_ASSERT(r, SkGoodHash()((uint32_t)4) == 614249093);
- }
- DEF_TEST(ChecksumCollisions, r) {
- // We noticed a few workloads that would cause hash collisions due to the way
- // our optimized hashes split into three concurrent hashes and merge those hashes together.
- //
- // One of these two workloads ought to cause an unintentional hash collision on very similar
- // data in those old algorithms, the float version on 32-bit x86 and double elsewhere.
- {
- float a[9] = { 0, 1, 2,
- 3, 4, 5,
- 6, 7, 8, };
- float b[9] = { 1, 2, 0,
- 4, 5, 3,
- 7, 8, 6, };
- REPORTER_ASSERT(r, SkOpts::hash(a, sizeof(a)) != SkOpts::hash(b, sizeof(b)));
- }
- {
- double a[9] = { 0, 1, 2,
- 3, 4, 5,
- 6, 7, 8, };
- double b[9] = { 1, 2, 0,
- 4, 5, 3,
- 7, 8, 6, };
- REPORTER_ASSERT(r, SkOpts::hash(a, sizeof(a)) != SkOpts::hash(b, sizeof(b)));
- }
- }
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