| /* |
| * 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/SkString.h" |
| #include "include/core/SkTypes.h" |
| #include "include/private/base/SkAlign.h" |
| #include "src/base/SkRandom.h" |
| #include "src/core/SkChecksum.h" |
| #include "tests/Test.h" |
| |
| #include <cstddef> |
| #include <cstdint> |
| #include <cstring> |
| #include <string> |
| #include <string_view> |
| |
| 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 < std::size(tweaked); ++i) { |
| data[i] = tweaked[i] = rand.nextU(); |
| } |
| |
| const uint32_t hash = SkChecksum::Hash32(data, kBytes); |
| // Should be deterministic. |
| REPORTER_ASSERT(r, hash == SkChecksum::Hash32(data, kBytes)); |
| |
| // Changing any single element should change the hash. |
| for (size_t j = 0; j < std::size(tweaked); ++j) { |
| const uint32_t saved = tweaked[j]; |
| tweaked[j] = rand.nextU(); |
| const uint32_t tweakedHash = SkChecksum::Hash32(tweaked, kBytes); |
| REPORTER_ASSERT(r, tweakedHash != hash); |
| REPORTER_ASSERT(r, tweakedHash == SkChecksum::Hash32(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 old optimized hashes split into three concurrent hashes and merged 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, SkChecksum::Hash32(a, sizeof(a)) != SkChecksum::Hash32(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, SkChecksum::Hash32(a, sizeof(a)) != SkChecksum::Hash32(b, sizeof(b))); |
| } |
| } |
| |
| DEF_TEST(ChecksumConsistent, r) { |
| // We don't guarantee that SkChecksum::Hash32 will return consistent results, but it does today. |
| // Spot check a few: |
| uint8_t bytes[256]; |
| for (int i = 0; i < 256; i++) { |
| bytes[i] = i; |
| } |
| auto hash_bytes = [&](int n) { return SkChecksum::Hash32(bytes, n); }; |
| REPORTER_ASSERT(r, hash_bytes( 0) == 0xe2bde459, "%08x", hash_bytes( 0)); |
| REPORTER_ASSERT(r, hash_bytes( 1) == 0xe5f8bd85, "%08x", hash_bytes( 1)); |
| REPORTER_ASSERT(r, hash_bytes( 2) == 0x77acd42a, "%08x", hash_bytes( 2)); |
| REPORTER_ASSERT(r, hash_bytes( 7) == 0x78d0861f, "%08x", hash_bytes( 7)); |
| REPORTER_ASSERT(r, hash_bytes( 32) == 0x4e73df6d, "%08x", hash_bytes( 32)); |
| REPORTER_ASSERT(r, hash_bytes( 63) == 0x5e66a3f4, "%08x", hash_bytes( 63)); |
| REPORTER_ASSERT(r, hash_bytes( 64) == 0x962d6746, "%08x", hash_bytes( 64)); |
| REPORTER_ASSERT(r, hash_bytes( 99) == 0x79e09416, "%08x", hash_bytes( 99)); |
| REPORTER_ASSERT(r, hash_bytes(255) == 0x85f837f0, "%08x", hash_bytes(255)); |
| } |
| |
| DEF_TEST(ChecksumStrings, r) { |
| constexpr char kMessage[] = "Checksums are supported for SkString, string, and string_view."; |
| const uint32_t expectedHash = SkChecksum::Hash32(kMessage, strlen(kMessage)); |
| |
| REPORTER_ASSERT(r, expectedHash == SkGoodHash()(SkString(kMessage))); |
| REPORTER_ASSERT(r, expectedHash == SkGoodHash()(std::string(kMessage))); |
| REPORTER_ASSERT(r, expectedHash == SkGoodHash()(std::string_view(kMessage))); |
| } |