blob: c1e71c5a94b433fdc6a9a13e2354102994218790 [file] [log] [blame]
/*
* 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)));
}