1 /* 2 * Copyright 2012 Google Inc. 3 * 4 * Use of this source code is governed by a BSD-style license that can be 5 * found in the LICENSE file. 6 */ 7 8 #include "SkChecksum.h" 9 #include "SkRandom.h" 10 #include "Test.h" 11 12 13 // Murmur3 has an optional third seed argument, so we wrap it to fit a uniform type. 14 static uint32_t murmur_noseed(const uint32_t* d, size_t l) { return SkChecksum::Murmur3(d, l); } 15 16 #define ASSERT(x) REPORTER_ASSERT(r, x) 17 18 DEF_TEST(Checksum, r) { 19 // Algorithms to test. They're currently all uint32_t(const uint32_t*, size_t). 20 typedef uint32_t(*algorithmProc)(const uint32_t*, size_t); 21 const algorithmProc kAlgorithms[] = { &SkChecksum::Compute, &murmur_noseed }; 22 23 // Put 128 random bytes into two identical buffers. Any multiple of 4 will do. 24 const size_t kBytes = SkAlign4(128); 25 SkRandom rand; 26 uint32_t data[kBytes/4], tweaked[kBytes/4]; 27 for (size_t i = 0; i < SK_ARRAY_COUNT(tweaked); ++i) { 28 data[i] = tweaked[i] = rand.nextU(); 29 } 30 31 // Test each algorithm. 32 for (size_t i = 0; i < SK_ARRAY_COUNT(kAlgorithms); ++i) { 33 const algorithmProc algorithm = kAlgorithms[i]; 34 35 // Hash of NULL is always 0. 36 ASSERT(algorithm(NULL, 0) == 0); 37 38 const uint32_t hash = algorithm(data, kBytes); 39 // Should be deterministic. 40 ASSERT(hash == algorithm(data, kBytes)); 41 42 // Changing any single element should change the hash. 43 for (size_t j = 0; j < SK_ARRAY_COUNT(tweaked); ++j) { 44 const uint32_t saved = tweaked[j]; 45 tweaked[j] = rand.nextU(); 46 const uint32_t tweakedHash = algorithm(tweaked, kBytes); 47 ASSERT(tweakedHash != hash); 48 ASSERT(tweakedHash == algorithm(tweaked, kBytes)); 49 tweaked[j] = saved; 50 } 51 } 52 } 53
