1 // Copyright 2020 The Pigweed Authors
3 // Licensed under the Apache License, Version 2.0 (the "License"); you may not
4 // use this file except in compliance with the License. You may obtain a copy of
7 // https://www.apache.org/licenses/LICENSE-2.0
9 // Unless required by applicable law or agreed to in writing, software
10 // distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
11 // WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
12 // License for the specific language governing permissions and limitations under
15 #include "pw_checksum/crc16_ccitt.h"
17 #include <string_view>
19 #include "gtest/gtest.h"
21 namespace pw::checksum {
24 // The expected CRC16 values were calculated using
26 // http://www.sunshine2k.de/coding/javascript/crc/crc_js.html
28 // with polynomial 0x1021, initial value 0xFFFF.
29 constexpr uint8_t kBytes[] = {1, 2, 3, 4, 5, 6, 7, 8, 9};
30 constexpr uint16_t kBufferCrc = 0x3B0A;
32 constexpr std::string_view kString =
33 "In the beginning the Universe was created. This has made a lot of "
34 "people very angry and been widely regarded as a bad move.";
35 constexpr uint16_t kStringCrc = 0xC184;
38 EXPECT_EQ(Crc16Ccitt::Calculate(std::span<std::byte>()),
39 Crc16Ccitt::kInitialValue);
42 TEST(Crc16, ByteByByte) {
43 uint16_t crc = Crc16Ccitt::kInitialValue;
44 for (size_t i = 0; i < sizeof(kBytes); i++) {
45 crc = Crc16Ccitt::Calculate(std::byte{kBytes[i]}, crc);
47 EXPECT_EQ(crc, kBufferCrc);
51 EXPECT_EQ(Crc16Ccitt::Calculate(std::as_bytes(std::span(kBytes))),
56 EXPECT_EQ(Crc16Ccitt::Calculate(std::as_bytes(std::span(kString))),
60 TEST(Crc16Class, Buffer) {
62 crc16.Update(std::as_bytes(std::span(kBytes)));
63 EXPECT_EQ(crc16.value(), kBufferCrc);
66 TEST(Crc16Class, String) {
68 crc16.Update(std::as_bytes(std::span(kString)));
69 EXPECT_EQ(crc16.value(), kStringCrc);
72 extern "C" uint16_t CallChecksumCrc16Ccitt(const void* data, size_t size_bytes);
74 TEST(Crc16FromC, Buffer) {
75 EXPECT_EQ(CallChecksumCrc16Ccitt(kBytes, sizeof(kBytes)), kBufferCrc);
78 TEST(Crc16FromC, String) {
79 EXPECT_EQ(CallChecksumCrc16Ccitt(kString.data(), kString.size()), kStringCrc);
83 } // namespace pw::checksum