| |
| /* |
| * 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 "Test.h" |
| #include "SkChecksum.h" |
| #include "SkCityHash.h" |
| |
| // Word size that is large enough to hold results of any checksum type. |
| typedef uint64_t checksum_result; |
| |
| namespace skiatest { |
| class ChecksumTestClass : public Test { |
| public: |
| static Test* Factory(void*) {return SkNEW(ChecksumTestClass); } |
| protected: |
| virtual void onGetName(SkString* name) { name->set("Checksum"); } |
| virtual void onRun(Reporter* reporter) { |
| this->fReporter = reporter; |
| RunTest(); |
| } |
| private: |
| enum Algorithm { |
| kSkChecksum, |
| kSkCityHash32, |
| kSkCityHash64 |
| }; |
| |
| // Call Compute(data, size) on the appropriate checksum algorithm, |
| // depending on this->fWhichAlgorithm. |
| checksum_result ComputeChecksum(const char *data, size_t size) { |
| switch(fWhichAlgorithm) { |
| case kSkChecksum: |
| REPORTER_ASSERT_MESSAGE(fReporter, |
| reinterpret_cast<uintptr_t>(data) % 4 == 0, |
| "test data pointer is not 32-bit aligned"); |
| REPORTER_ASSERT_MESSAGE(fReporter, SkIsAlign4(size), |
| "test data size is not 32-bit aligned"); |
| return SkChecksum::Compute(reinterpret_cast<const uint32_t *>(data), size); |
| case kSkCityHash32: |
| return SkCityHash::Compute32(data, size); |
| case kSkCityHash64: |
| return SkCityHash::Compute64(data, size); |
| default: |
| SkString message("fWhichAlgorithm has unknown value "); |
| message.appendf("%d", fWhichAlgorithm); |
| fReporter->reportFailed(message); |
| } |
| // we never get here |
| return 0; |
| } |
| |
| // Confirm that the checksum algorithm (specified by fWhichAlgorithm) |
| // generates the same results if called twice over the same data. |
| void TestChecksumSelfConsistency(size_t buf_size) { |
| SkAutoMalloc storage(buf_size); |
| char* ptr = reinterpret_cast<char *>(storage.get()); |
| |
| REPORTER_ASSERT(fReporter, |
| GetTestDataChecksum(8, 0) == |
| GetTestDataChecksum(8, 0)); |
| REPORTER_ASSERT(fReporter, |
| GetTestDataChecksum(8, 0) != |
| GetTestDataChecksum(8, 1)); |
| |
| sk_bzero(ptr, buf_size); |
| checksum_result prev = 0; |
| |
| // assert that as we change values (from 0 to non-zero) in |
| // our buffer, we get a different value |
| for (size_t i = 0; i < buf_size; ++i) { |
| ptr[i] = (i & 0x7f) + 1; // need some non-zero value here |
| |
| // Try checksums of different-sized chunks, but always |
| // 32-bit aligned and big enough to contain all the |
| // nonzero bytes. (Remaining bytes will still be zero |
| // from the initial sk_bzero() call.) |
| size_t checksum_size = (((i/4)+1)*4); |
| REPORTER_ASSERT(fReporter, checksum_size <= buf_size); |
| |
| checksum_result curr = ComputeChecksum(ptr, checksum_size); |
| REPORTER_ASSERT(fReporter, prev != curr); |
| checksum_result again = ComputeChecksum(ptr, checksum_size); |
| REPORTER_ASSERT(fReporter, again == curr); |
| prev = curr; |
| } |
| } |
| |
| // Return the checksum of a buffer of bytes 'len' long. |
| // The pattern of values within the buffer will be consistent |
| // for every call, based on 'seed'. |
| checksum_result GetTestDataChecksum(size_t len, char seed=0) { |
| SkAutoMalloc storage(len); |
| char* start = reinterpret_cast<char *>(storage.get()); |
| char* ptr = start; |
| for (size_t i = 0; i < len; ++i) { |
| *ptr++ = ((seed+i) & 0x7f); |
| } |
| checksum_result result = ComputeChecksum(start, len); |
| return result; |
| } |
| |
| void RunTest() { |
| // Test self-consistency of checksum algorithms. |
| fWhichAlgorithm = kSkChecksum; |
| TestChecksumSelfConsistency(128); |
| fWhichAlgorithm = kSkCityHash32; |
| TestChecksumSelfConsistency(128); |
| fWhichAlgorithm = kSkCityHash64; |
| TestChecksumSelfConsistency(128); |
| |
| // Test checksum results that should be consistent across |
| // versions and platforms. |
| fWhichAlgorithm = kSkChecksum; |
| REPORTER_ASSERT(fReporter, ComputeChecksum(NULL, 0) == 0); |
| fWhichAlgorithm = kSkCityHash32; |
| REPORTER_ASSERT(fReporter, ComputeChecksum(NULL, 0) == 0xdc56d17a); |
| REPORTER_ASSERT(fReporter, GetTestDataChecksum(4) == 0x616e1132); |
| REPORTER_ASSERT(fReporter, GetTestDataChecksum(8) == 0xeb0fd2d6); |
| REPORTER_ASSERT(fReporter, GetTestDataChecksum(128) == 0x5321e430); |
| REPORTER_ASSERT(fReporter, GetTestDataChecksum(132) == 0x924a10e4); |
| REPORTER_ASSERT(fReporter, GetTestDataChecksum(256) == 0xd4de9dc9); |
| REPORTER_ASSERT(fReporter, GetTestDataChecksum(260) == 0xecf0325d); |
| fWhichAlgorithm = kSkCityHash64; |
| REPORTER_ASSERT(fReporter, ComputeChecksum(NULL, 0) == 0x9ae16a3b2f90404f); |
| REPORTER_ASSERT(fReporter, GetTestDataChecksum(4) == 0x82bffd898958e540); |
| REPORTER_ASSERT(fReporter, GetTestDataChecksum(8) == 0xad5a13e1e8e93b98); |
| REPORTER_ASSERT(fReporter, GetTestDataChecksum(128) == 0x10b153630af1f395); |
| REPORTER_ASSERT(fReporter, GetTestDataChecksum(132) == 0x7db71dc4adcc6647); |
| REPORTER_ASSERT(fReporter, GetTestDataChecksum(256) == 0xeee763519b91b010); |
| REPORTER_ASSERT(fReporter, GetTestDataChecksum(260) == 0x2fe19e0b2239bc23); |
| |
| // TODO: note the weakness exposed by these collisions... |
| // We need to improve the SkChecksum algorithm. |
| // We would prefer that these asserts FAIL! |
| // Filed as https://code.google.com/p/skia/issues/detail?id=981 |
| // ('SkChecksum algorithm allows for way too many collisions') |
| fWhichAlgorithm = kSkChecksum; |
| REPORTER_ASSERT(fReporter, |
| GetTestDataChecksum(128) == GetTestDataChecksum(256)); |
| REPORTER_ASSERT(fReporter, |
| GetTestDataChecksum(132) == GetTestDataChecksum(260)); |
| } |
| |
| Reporter* fReporter; |
| Algorithm fWhichAlgorithm; |
| }; |
| |
| static TestRegistry gReg(ChecksumTestClass::Factory); |
| } |