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◆ main openmsx / src / unittest / CRC16_test.cc
3.4 KiB · C++ · last changed chore(): initial commit 1 month ago source blame history raw
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#include "catch.hpp"
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#include "CRC16.hh"
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#include "narrow.hh"
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#include "xrange.hh"
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#include <array>
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#include <bit>
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using namespace openmsx;
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TEST_CASE("CRC16")
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{
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	CRC16 crc;
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	REQUIRE(crc.getValue() == 0xFFFF);
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	// Test a simple sequence
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	SECTION("'3 x A1' in a loop") {
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		repeat(3, [&] { crc.update(0xA1); });
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		CHECK(crc.getValue() == 0xCDB4);
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	}
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	SECTION("'3 x A1' in one chunk") {
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		static constexpr std::array<uint8_t, 3> buf = { 0xA1, 0xA1, 0xA1 };
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		crc.update(buf);
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		CHECK(crc.getValue() == 0xCDB4);
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	}
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	SECTION("'3 x A1' via init") {
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		crc.init({0xA1, 0xA1, 0xA1});
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		CHECK(crc.getValue() == 0xCDB4);
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	}
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	// Internally the block-update method works on chunks of 8 bytes,
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	// so also try a few bigger examples
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	//   not (an integer) multiple of 8
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	SECTION("'123456789' in a loop") {
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		for (char c : {'1', '2', '3', '4', '5', '6', '7', '8', '9'}) crc.update(c);
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		CHECK(crc.getValue() == 0x29B1);
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	}
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	SECTION("'123456789' in one chunk") {
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		static constexpr const char* const digits = "123456789";
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		crc.update(std::span{std::bit_cast<const uint8_t*>(digits), 9});
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		CHECK(crc.getValue() == 0x29B1);
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	}
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	// same as disk sector size
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	SECTION("512 bytes") {
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		std::array<uint8_t, 512> buf;
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		for (auto i : xrange(512)) buf[i] = narrow_cast<uint8_t>(i & 255);
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		SECTION("in a loop") {
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			for (char c : buf) crc.update(c);
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			CHECK(crc.getValue() == 0x56EE);
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		}
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		SECTION("in one chunk") {
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			crc.update(buf);
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			CHECK(crc.getValue() == 0x56EE);
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		}
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	}
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	// Tests for init<..>()
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	// It's possible to pass up-to 4 parameters. Verify that this gives
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	// the same result as the other 2 CRC calculation methods.
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	SECTION("'11' in a loop") {
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		for (uint8_t c : {uint8_t(0x11)}) crc.update(c);
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		CHECK(crc.getValue() == 0xE3E0);
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	}
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	SECTION("'11' in one chunk") {
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		static constexpr std::array<uint8_t, 1> buf = {0x11};
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		crc.update(buf);
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		CHECK(crc.getValue() == 0xE3E0);
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	}
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	SECTION("'11' via init") {
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		crc.init({0x11});
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		CHECK(crc.getValue() == 0xE3E0);
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	}
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	SECTION("'11 22' in a loop") {
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		for (uint8_t c : {uint8_t(0x11), uint8_t(0x22)}) crc.update(c);
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		CHECK(crc.getValue() == 0x296D);
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	}
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	SECTION("'11 22' in one chunk") {
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		static constexpr std::array<uint8_t, 2> buf = {0x11, 0x22};
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		crc.update(buf);
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		CHECK(crc.getValue() == 0x296D);
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	}
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	SECTION("'11 22' via init") {
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		crc.init({0x11, 0x22});
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		CHECK(crc.getValue() == 0x296D);
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	}
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	SECTION("'11 22 33' in a loop") {
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		for (uint8_t c : {uint8_t(0x11), uint8_t(0x22), uint8_t(0x33)}) crc.update(c);
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		CHECK(crc.getValue() == 0xDE7B);
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	}
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	SECTION("'11 22 33' in one chunk") {
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		static constexpr std::array<uint8_t, 3> buf = {0x11, 0x22, 0x33};
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		crc.update(buf);
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		CHECK(crc.getValue() == 0xDE7B);
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	}
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	SECTION("'11 22 33' via init") {
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		crc.init({0x11, 0x22, 0x33});
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		CHECK(crc.getValue() == 0xDE7B);
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	}
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	SECTION("'11 22 33 44' in a loop") {
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		for (uint8_t c : {uint8_t(0x11), uint8_t(0x22), uint8_t(0x33), uint8_t(0x44)}) crc.update(c);
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		CHECK(crc.getValue() == 0x59F3);
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	}
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	SECTION("'11 22 33 44' in one chunk") {
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		static constexpr std::array<uint8_t, 4> buf = {0x11, 0x22, 0x33, 0x44};
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		crc.update(buf);
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		CHECK(crc.getValue() == 0x59F3);
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	}
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	SECTION("'11 22 33 44' via init") {
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		crc.init({0x11, 0x22, 0x33, 0x44});
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		CHECK(crc.getValue() == 0x59F3);
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	}
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}
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#if 0
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// Functions to inspect the quality of the generated code
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uint16_t test_init()
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{
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	// I verified that gcc is capable of optimizing this to 'return 0xcdb4'.
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	CRC16 crc;
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	crc.init({0xA1, 0xA1, 0xA1});
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	return crc.getValue();
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}
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#endif