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/*
* Copyright (C) 2017 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "bit_string.h"
#include "gtest/gtest.h"
#include "android-base/logging.h"
namespace art {
constexpr size_t BitString::kBitSizeAtPosition[BitString::kCapacity];
constexpr size_t BitString::kCapacity;
}; // namespace art
using namespace art; // NOLINT [build/namespaces] [5]
// These helper functions are only used by the test,
// so they are not in the main BitString class.
std::string Stringify(BitString bit_string) {
std::stringstream ss;
ss << bit_string;
return ss.str();
}
BitStringChar MakeBitStringChar(size_t idx, size_t val) {
return BitStringChar(val, BitString::MaybeGetBitLengthAtPosition(idx));
}
BitStringChar MakeBitStringChar(size_t val) {
return BitStringChar(val, MinimumBitsToStore(val));
}
BitString MakeBitString(std::initializer_list<size_t> values = {}) {
CHECK_GE(BitString::kCapacity, values.size());
BitString bs{};
size_t i = 0;
for (size_t val : values) {
bs.SetAt(i, MakeBitStringChar(i, val));
++i;
}
return bs;
}
template <typename T>
size_t AsUint(const T& value) {
size_t uint_value = 0;
memcpy(&uint_value, &value, sizeof(value));
return uint_value;
}
// Make max bitstring, e.g. BitString[4095,15,2047] for {12,4,11}
template <size_t kCount = BitString::kCapacity>
BitString MakeBitStringMax() {
BitString bs{};
for (size_t i = 0; i < kCount; ++i) {
bs.SetAt(i,
MakeBitStringChar(i, MaxInt<BitStringChar::StorageType>(BitString::kBitSizeAtPosition[i])));
}
return bs;
}
BitString SetBitStringCharAt(BitString bit_string, size_t i, size_t val) {
BitString bs = bit_string;
bs.SetAt(i, MakeBitStringChar(i, val));
return bs;
}
#define EXPECT_BITSTRING_STR(expected_str, actual_value) \
EXPECT_STREQ((expected_str), Stringify((actual_value)).c_str())
// TODO: Consider removing this test, it's kind of replicating the logic in GetLsbForPosition().
TEST(InstanceOfBitString, GetLsbForPosition) {
ASSERT_LE(3u, BitString::kCapacity);
// Test will fail if kCapacity is not at least 3. Update it.
EXPECT_EQ(0u, BitString::GetLsbForPosition(0u));
EXPECT_EQ(BitString::kBitSizeAtPosition[0u], BitString::GetLsbForPosition(1u));
EXPECT_EQ(BitString::kBitSizeAtPosition[0u] + BitString::kBitSizeAtPosition[1u],
BitString::GetLsbForPosition(2u));
}
TEST(InstanceOfBitString, ToString) {
EXPECT_BITSTRING_STR("BitString[]", MakeBitString({0}));
EXPECT_BITSTRING_STR("BitString[1]", MakeBitString({1}));
EXPECT_BITSTRING_STR("BitString[1,2,3]", MakeBitString({1, 2, 3}));
}
TEST(InstanceOfBitString, ReadWrite) {
BitString bs = MakeBitString();
// Update tests if changing the capacity.
ASSERT_EQ(BitString::kCapacity, 3u);
EXPECT_BITSTRING_STR("BitString[]", bs);
bs = SetBitStringCharAt(bs, /*i=*/0, /*val=*/1u);
EXPECT_BITSTRING_STR("BitString[1]", bs);
bs = SetBitStringCharAt(bs, /*i=*/1, /*val=*/2u);
EXPECT_BITSTRING_STR("BitString[1,2]", bs);
bs = SetBitStringCharAt(bs, /*i=*/2, /*val=*/3u);
EXPECT_BITSTRING_STR("BitString[1,2,3]", bs);
// There should be at least "kCapacity" # of checks here, 1 for each unique position.
EXPECT_EQ(MakeBitStringChar(/*idx=*/0, /*val=*/1u), bs[0]);
EXPECT_EQ(MakeBitStringChar(/*idx=*/1, /*val=*/2u), bs[1]);
EXPECT_EQ(MakeBitStringChar(/*idx=*/2, /*val=*/3u), bs[2]);
// Each maximal value should be tested here for each position.
uint32_t max_bitstring_ints[] = {
MaxInt<uint32_t>(12),
MaxInt<uint32_t>(4),
MaxInt<uint32_t>(11),
};
// Update tests if changing the tuning values above.
for (size_t i = 0; i < arraysize(max_bitstring_ints); ++i) {
ASSERT_EQ(MinimumBitsToStore(max_bitstring_ints[i]), BitString::kBitSizeAtPosition[i]) << i;
}
BitString bs_max = MakeBitStringMax();
for (size_t i = 0; i < arraysize(max_bitstring_ints); ++i) {
ASSERT_EQ(max_bitstring_ints[i], static_cast<uint32_t>(bs_max[i])) << i;
}
EXPECT_EQ(MaskLeastSignificant(BitString::GetBitLengthTotalAtPosition(BitString::kCapacity)),
AsUint(MakeBitStringMax()));
}
template <size_t kPos>
constexpr auto MaxForPos() {
return MaxInt<BitString::StorageType>(BitString::kBitSizeAtPosition[kPos]);
}
TEST(InstanceOfBitString, MemoryRepresentation) {
// Verify that the lower positions are stored in less significant bits.
BitString bs = MakeBitString({MaxForPos<0>(), MaxForPos<1>()});
BitString::StorageType as_int = static_cast<BitString::StorageType>(bs);
// Below tests assumes the capacity is at least 3.
ASSERT_LE(3u, BitString::kCapacity);
EXPECT_EQ((MaxForPos<0>() << 0) | (MaxForPos<1>() << BitString::kBitSizeAtPosition[0]),
as_int);
}
TEST(InstanceOfBitString, Truncate) {
EXPECT_BITSTRING_STR("BitString[]", MakeBitString({1, 2, 3}).Truncate(0));
EXPECT_BITSTRING_STR("BitString[1]", MakeBitString({1, 2, 3}).Truncate(1));
EXPECT_BITSTRING_STR("BitString[1,2]", MakeBitString({1, 2, 3}).Truncate(2));
EXPECT_BITSTRING_STR("BitString[1,2,3]", MakeBitString({1, 2, 3}).Truncate(3));
}
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