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/*
* 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 "SkChecksum.h"
#include "SkRandom.h"
#include "Test.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;
}
}
}
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