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// Copyright 2021 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "src/base/vlq.h"
#include <cmath>
#include <limits>
#include "src/base/memory.h"
#include "test/unittests/test-utils.h"
#include "testing/gtest-support.h"
namespace v8 {
namespace base {
int ExpectedBytesUsed(int64_t value, bool is_signed) {
uint64_t bits = value;
if (is_signed) {
bits = (value < 0 ? -value : value) << 1;
}
int num_bits = 0;
while (bits != 0) {
num_bits++;
bits >>= 1;
}
return std::max(1, static_cast<int>(ceil(static_cast<float>(num_bits) / 7)));
}
void TestVLQUnsignedEquals(uint32_t value) {
std::vector<byte> buffer;
VLQEncodeUnsigned(&buffer, value);
byte* data_start = buffer.data();
int index = 0;
int expected_bytes_used = ExpectedBytesUsed(value, false);
EXPECT_EQ(buffer.size(), static_cast<size_t>(expected_bytes_used));
EXPECT_EQ(value, VLQDecodeUnsigned(data_start, &index));
EXPECT_EQ(index, expected_bytes_used);
}
void TestVLQEquals(int32_t value) {
std::vector<byte> buffer;
VLQEncode(&buffer, value);
byte* data_start = buffer.data();
int index = 0;
int expected_bytes_used = ExpectedBytesUsed(value, true);
EXPECT_EQ(buffer.size(), static_cast<size_t>(expected_bytes_used));
EXPECT_EQ(value, VLQDecode(data_start, &index));
EXPECT_EQ(index, expected_bytes_used);
}
TEST(VLQ, Unsigned) {
TestVLQUnsignedEquals(0);
TestVLQUnsignedEquals(1);
TestVLQUnsignedEquals(63);
TestVLQUnsignedEquals(64);
TestVLQUnsignedEquals(127);
TestVLQUnsignedEquals(255);
TestVLQUnsignedEquals(256);
}
TEST(VLQ, Positive) {
TestVLQEquals(0);
TestVLQEquals(1);
TestVLQEquals(63);
TestVLQEquals(64);
TestVLQEquals(127);
TestVLQEquals(255);
TestVLQEquals(256);
}
TEST(VLQ, Negative) {
TestVLQEquals(-1);
TestVLQEquals(-63);
TestVLQEquals(-64);
TestVLQEquals(-127);
TestVLQEquals(-255);
TestVLQEquals(-256);
}
TEST(VLQ, LimitsUnsigned) {
TestVLQEquals(std::numeric_limits<uint8_t>::max());
TestVLQEquals(std::numeric_limits<uint8_t>::max() - 1);
TestVLQEquals(std::numeric_limits<uint8_t>::max() + 1);
TestVLQEquals(std::numeric_limits<uint16_t>::max());
TestVLQEquals(std::numeric_limits<uint16_t>::max() - 1);
TestVLQEquals(std::numeric_limits<uint16_t>::max() + 1);
TestVLQEquals(std::numeric_limits<uint32_t>::max());
TestVLQEquals(std::numeric_limits<uint32_t>::max() - 1);
}
TEST(VLQ, LimitsSigned) {
TestVLQEquals(std::numeric_limits<int8_t>::max());
TestVLQEquals(std::numeric_limits<int8_t>::max() - 1);
TestVLQEquals(std::numeric_limits<int8_t>::max() + 1);
TestVLQEquals(std::numeric_limits<int16_t>::max());
TestVLQEquals(std::numeric_limits<int16_t>::max() - 1);
TestVLQEquals(std::numeric_limits<int16_t>::max() + 1);
TestVLQEquals(std::numeric_limits<int32_t>::max());
TestVLQEquals(std::numeric_limits<int32_t>::max() - 1);
TestVLQEquals(std::numeric_limits<int8_t>::min());
TestVLQEquals(std::numeric_limits<int8_t>::min() - 1);
TestVLQEquals(std::numeric_limits<int8_t>::min() + 1);
TestVLQEquals(std::numeric_limits<int16_t>::min());
TestVLQEquals(std::numeric_limits<int16_t>::min() - 1);
TestVLQEquals(std::numeric_limits<int16_t>::min() + 1);
// int32_t::min() is not supported.
TestVLQEquals(std::numeric_limits<int32_t>::min() + 1);
}
TEST(VLQ, Random) {
static constexpr int RANDOM_RUNS = 50;
base::RandomNumberGenerator rng(::testing::FLAGS_gtest_random_seed);
for (int i = 0; i < RANDOM_RUNS; ++i) {
TestVLQUnsignedEquals(rng.NextInt(std::numeric_limits<int32_t>::max()));
}
for (int i = 0; i < RANDOM_RUNS; ++i) {
TestVLQEquals(rng.NextInt());
}
}
} // namespace base
} // namespace v8
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