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// Copyright 2020 The Pigweed Authors
//
// 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
//
// https://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 "pw_hdlc/encoder.h"
#include <algorithm>
#include <array>
#include <cstddef>
#include "gtest/gtest.h"
#include "pw_bytes/array.h"
#include "pw_hdlc/internal/encoder.h"
#include "pw_hdlc/internal/protocol.h"
#include "pw_stream/memory_stream.h"
using std::byte;
namespace pw::hdlc {
namespace {
constexpr uint8_t kAddress = 0x7B; // 123
constexpr uint8_t kEncodedAddress = (kAddress << 1) | 1;
#define EXPECT_ENCODER_WROTE(...) \
do { \
constexpr auto expected_data = (__VA_ARGS__); \
EXPECT_EQ(writer_.bytes_written(), expected_data.size()); \
EXPECT_EQ( \
std::memcmp( \
writer_.data(), expected_data.data(), writer_.bytes_written()), \
0); \
} while (0)
class WriteUnnumberedFrame : public ::testing::Test {
protected:
WriteUnnumberedFrame() : writer_(buffer_) {}
stream::MemoryWriter writer_;
std::array<byte, 32> buffer_;
};
constexpr byte kUnnumberedControl = byte{0x3};
TEST_F(WriteUnnumberedFrame, EmptyPayload) {
ASSERT_EQ(OkStatus(), WriteUIFrame(kAddress, std::span<byte>(), writer_));
EXPECT_ENCODER_WROTE(bytes::Concat(
kFlag, kEncodedAddress, kUnnumberedControl, uint32_t{0x832d343f}, kFlag));
}
TEST_F(WriteUnnumberedFrame, OneBytePayload) {
ASSERT_EQ(OkStatus(), WriteUIFrame(kAddress, bytes::String("A"), writer_));
EXPECT_ENCODER_WROTE(bytes::Concat(kFlag,
kEncodedAddress,
kUnnumberedControl,
'A',
uint32_t{0x653c9e82},
kFlag));
}
TEST_F(WriteUnnumberedFrame, OneBytePayload_Escape0x7d) {
ASSERT_EQ(OkStatus(), WriteUIFrame(kAddress, bytes::Array<0x7d>(), writer_));
EXPECT_ENCODER_WROTE(bytes::Concat(kFlag,
kEncodedAddress,
kUnnumberedControl,
kEscape,
byte{0x7d} ^ byte{0x20},
uint32_t{0x4a53e205},
kFlag));
}
TEST_F(WriteUnnumberedFrame, OneBytePayload_Escape0x7E) {
ASSERT_EQ(OkStatus(), WriteUIFrame(kAddress, bytes::Array<0x7e>(), writer_));
EXPECT_ENCODER_WROTE(bytes::Concat(kFlag,
kEncodedAddress,
kUnnumberedControl,
kEscape,
byte{0x7e} ^ byte{0x20},
uint32_t{0xd35ab3bf},
kFlag));
}
TEST_F(WriteUnnumberedFrame, AddressNeedsEscaping) {
// Becomes 0x7d when encoded.
constexpr uint8_t kEscapeRequiredAddress = 0x7d >> 1;
ASSERT_EQ(OkStatus(),
WriteUIFrame(kEscapeRequiredAddress, bytes::String("A"), writer_));
EXPECT_ENCODER_WROTE(bytes::Concat(kFlag,
kEscape,
byte{0x5d},
kUnnumberedControl,
'A',
uint32_t{0x899E00D4},
kFlag));
}
TEST_F(WriteUnnumberedFrame, Crc32NeedsEscaping) {
ASSERT_EQ(OkStatus(), WriteUIFrame(kAddress, bytes::String("aa"), writer_));
// The CRC-32 of {kEncodedAddress, kUnnumberedControl, "aa"} is 0x7ee04473, so
// the 0x7e must be escaped.
constexpr auto expected_crc32 = bytes::Array<0x73, 0x44, 0xe0, 0x7d, 0x5e>();
EXPECT_ENCODER_WROTE(bytes::Concat(kFlag,
kEncodedAddress,
kUnnumberedControl,
bytes::String("aa"),
expected_crc32,
kFlag));
}
TEST_F(WriteUnnumberedFrame, MultiplePayloads) {
ASSERT_EQ(OkStatus(), WriteUIFrame(kAddress, bytes::String("ABC"), writer_));
ASSERT_EQ(OkStatus(), WriteUIFrame(kAddress, bytes::String("DEF"), writer_));
EXPECT_ENCODER_WROTE(bytes::Concat(kFlag,
kEncodedAddress,
kUnnumberedControl,
bytes::String("ABC"),
uint32_t{0x72410ee4},
kFlag,
kFlag,
kEncodedAddress,
kUnnumberedControl,
bytes::String("DEF"),
uint32_t{0x4ba1ae47},
kFlag));
}
TEST_F(WriteUnnumberedFrame, PayloadWithNoEscapes) {
ASSERT_EQ(
OkStatus(),
WriteUIFrame(kAddress, bytes::String("1995 toyota corolla"), writer_));
EXPECT_ENCODER_WROTE(bytes::Concat(kFlag,
kEncodedAddress,
kUnnumberedControl,
bytes::String("1995 toyota corolla"),
uint32_t{0x53ee911c},
kFlag));
}
TEST_F(WriteUnnumberedFrame, MultibyteAddress) {
ASSERT_EQ(OkStatus(), WriteUIFrame(0x3fff, bytes::String("abc"), writer_));
EXPECT_ENCODER_WROTE(bytes::Concat(kFlag,
bytes::String("\xfe\xff"),
kUnnumberedControl,
bytes::String("abc"),
uint32_t{0x8cee2978},
kFlag));
}
TEST_F(WriteUnnumberedFrame, PayloadWithMultipleEscapes) {
ASSERT_EQ(
OkStatus(),
WriteUIFrame(kAddress,
bytes::Array<0x7E, 0x7B, 0x61, 0x62, 0x63, 0x7D, 0x7E>(),
writer_));
EXPECT_ENCODER_WROTE(bytes::Concat(
kFlag,
kEncodedAddress,
kUnnumberedControl,
bytes::
Array<0x7D, 0x5E, 0x7B, 0x61, 0x62, 0x63, 0x7D, 0x5D, 0x7D, 0x5E>(),
uint32_t{0x1563a4e6},
kFlag));
}
TEST_F(WriteUnnumberedFrame, PayloadTooLarge_WritesNothing) {
constexpr auto data = bytes::Initialized<sizeof(buffer_)>(0x7e);
EXPECT_EQ(Status::ResourceExhausted(), WriteUIFrame(kAddress, data, writer_));
EXPECT_EQ(0u, writer_.bytes_written());
}
class ErrorWriter : public stream::Writer {
private:
Status DoWrite(ConstByteSpan) override { return Status::Unimplemented(); }
};
TEST(WriteUnnumberedFrame, WriterError) {
ErrorWriter writer;
EXPECT_EQ(Status::Unimplemented(),
WriteUIFrame(kAddress, bytes::Array<0x01>(), writer));
}
} // namespace
namespace internal {
namespace {
constexpr uint8_t kEscapeAddress = 0x7d;
TEST(Encoder, MaxEncodedSize_EmptyPayload) {
EXPECT_EQ(11u, Encoder::MaxEncodedSize(kAddress, {}));
EXPECT_EQ(11u, Encoder::MaxEncodedSize(kEscapeAddress, {}));
}
TEST(Encoder, MaxEncodedSize_PayloadWithoutEscapes) {
constexpr auto data = bytes::Array<0x00, 0x01, 0x02, 0x03>();
EXPECT_EQ(15u, Encoder::MaxEncodedSize(kAddress, data));
EXPECT_EQ(15u, Encoder::MaxEncodedSize(kEscapeAddress, data));
}
TEST(Encoder, MaxEncodedSize_PayloadWithOneEscape) {
constexpr auto data = bytes::Array<0x00, 0x01, 0x7e, 0x03>();
EXPECT_EQ(16u, Encoder::MaxEncodedSize(kAddress, data));
EXPECT_EQ(16u, Encoder::MaxEncodedSize(kEscapeAddress, data));
}
TEST(Encoder, MaxEncodedSize_PayloadWithAllEscapes) {
constexpr auto data = bytes::Initialized<8>(0x7e);
EXPECT_EQ(27u, Encoder::MaxEncodedSize(kAddress, data));
EXPECT_EQ(27u, Encoder::MaxEncodedSize(kEscapeAddress, data));
}
} // namespace
} // namespace internal
} // namespace pw::hdlc
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