-
/*
* 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"
-
-// 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,
- kMurmur3,
- };
-
- // 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 kMurmur3:
- 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::Murmur3(reinterpret_cast<const uint32_t *>(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() {
- const Algorithm algorithms[] = { kSkChecksum, kMurmur3 };
- for (size_t i = 0; i < SK_ARRAY_COUNT(algorithms); i++) {
- fWhichAlgorithm = algorithms[i];
-
- // Test self-consistency of checksum algorithms.
- TestChecksumSelfConsistency(128);
-
- // Test checksum results that should be consistent across
- // versions and platforms.
- REPORTER_ASSERT(fReporter, ComputeChecksum(NULL, 0) == 0);
-
- const bool colision1 = GetTestDataChecksum(128) == GetTestDataChecksum(256);
- const bool colision2 = GetTestDataChecksum(132) == GetTestDataChecksum(260);
- if (fWhichAlgorithm == kSkChecksum) {
- // 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')
- REPORTER_ASSERT(fReporter, colision1);
- REPORTER_ASSERT(fReporter, colision2);
- } else {
- REPORTER_ASSERT(fReporter, !colision1);
- REPORTER_ASSERT(fReporter, !colision2);
- }
- }
+#include "SkRandom.h"
+#include "Test.h"
+#include "TestClassDef.h"
+
+
+// Murmur3 has an optional third seed argument, so we wrap it to fit a uniform type.
+static uint32_t murmur_noseed(const uint32_t* d, size_t l) { return SkChecksum::Murmur3(d, l); }
+
+#define ASSERT(x) REPORTER_ASSERT(r, x)
+
+DEF_TEST(Checksum, r) {
+ // Algorithms to test. They're currently all uint32_t(const uint32_t*, size_t).
+ typedef uint32_t(*algorithmProc)(const uint32_t*, size_t);
+ const algorithmProc kAlgorithms[] = { &SkChecksum::Compute, &murmur_noseed };
+
+ // 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();
+ }
+
+ // Test each algorithm.
+ for (size_t i = 0; i < SK_ARRAY_COUNT(kAlgorithms); ++i) {
+ const algorithmProc algorithm = kAlgorithms[i];
+
+ // Hash of NULL is always 0.
+ ASSERT(algorithm(NULL, 0) == 0);
+
+ const uint32_t hash = algorithm(data, kBytes);
+ // Should be deterministic.
+ ASSERT(hash == algorithm(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 = algorithm(tweaked, kBytes);
+ ASSERT(tweakedHash != hash);
+ ASSERT(tweakedHash == algorithm(tweaked, kBytes));
+ tweaked[j] = saved;
}
-
- Reporter* fReporter;
- Algorithm fWhichAlgorithm;
- };
-
- static TestRegistry gReg(ChecksumTestClass::Factory);
+ }
}
projects / platform / upstream / libSkiaSharp.git / commitdiff