[math] Add BCD conversion algorithms

Author: rasmuskleist

src/modm/math/utils.hpp

@@ -22,5 +22,6 @@
 #include "utils/operator.hpp"
 #include "utils/endianness.hpp"
 #include "utils/crc.hpp"
+#include "utils/bcd.hpp"
 
 #endif // MODM_MATH_UTILS_HPP

src/modm/math/utils/bcd.hpp

@@ -0,0 +1,50 @@
+/*
+ * Copyright (c) 2023, Rasmus Kleist Hørlyck Sørensen
+ *
+ * This file is part of the modm project.
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+// ----------------------------------------------------------------------------
+
+#pragma once
+
+#include <stdint.h>
+#include <cstdlib>
+
+namespace modm
+{
+
+/// @ingroup modm_math_utils
+/// @{
+
+constexpr uint32_t
+fromBcd(uint32_t bcd)
+{
+	uint32_t decimal = 0;
+	for (uint16_t multiplier = 1; bcd; multiplier *= 10)
+	{
+		decimal += (bcd & 0b1111) * multiplier;
+		bcd >>= 4;
+	}
+	return decimal;
+}
+
+constexpr uint32_t
+toBcd(uint32_t decimal)
+{
+	uint32_t bcd = 0;
+	for (uint16_t shift = 0; decimal; shift += 4)
+	{
+		const auto dv = std::div(decimal, 10l);
+		bcd |= dv.rem << shift;
+		decimal = dv.quot;
+	}
+	return bcd;
+}
+
+/// @}
+
+} // namespace modm

test/modm/math/utils/bcd_test.cpp

@@ -0,0 +1,42 @@
+/*
+ * Copyright (c) 2023, Rasmus Kleist Hørlyck Sørensen
+ *
+ * This file is part of the modm project.
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+// ----------------------------------------------------------------------------
+
+#include <modm/math/utils/bcd.hpp>
+
+#include "bcd_test.hpp"
+
+void
+BcdTest::testFromBcd()
+{
+	TEST_ASSERT_EQUALS(modm::fromBcd(0x01), 0x01U);
+	TEST_ASSERT_EQUALS(modm::fromBcd(0x02), 0x02U);
+	TEST_ASSERT_EQUALS(modm::fromBcd(0x03), 0x03U);
+	TEST_ASSERT_EQUALS(modm::fromBcd(0x04), 0x04U);
+	TEST_ASSERT_EQUALS(modm::fromBcd(0x05), 0x05U);
+	TEST_ASSERT_EQUALS(modm::fromBcd(0x06), 0x06U);
+	TEST_ASSERT_EQUALS(modm::fromBcd(0x07), 0x07U);
+	TEST_ASSERT_EQUALS(modm::fromBcd(0x08), 0x08U);
+	TEST_ASSERT_EQUALS(modm::fromBcd(0x09), 0x09U);
+}
+
+void
+BcdTest::testToBcd()
+{
+	TEST_ASSERT_EQUALS(modm::toBcd(0x01), 0x01U);
+	TEST_ASSERT_EQUALS(modm::toBcd(0x02), 0x02U);
+	TEST_ASSERT_EQUALS(modm::toBcd(0x03), 0x03U);
+	TEST_ASSERT_EQUALS(modm::toBcd(0x04), 0x04U);
+	TEST_ASSERT_EQUALS(modm::toBcd(0x05), 0x05U);
+	TEST_ASSERT_EQUALS(modm::toBcd(0x06), 0x06U);
+	TEST_ASSERT_EQUALS(modm::toBcd(0x07), 0x07U);
+	TEST_ASSERT_EQUALS(modm::toBcd(0x08), 0x08U);
+	TEST_ASSERT_EQUALS(modm::toBcd(0x09), 0x09U);
+}

test/modm/math/utils/bcd_test.hpp

@@ -0,0 +1,23 @@
+/*
+ * Copyright (c) 2023, Rasmus Kleist Hørlyck Sørensen
+ *
+ * This file is part of the modm project.
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+// ----------------------------------------------------------------------------
+
+#include <unittest/testsuite.hpp>
+
+/// @ingroup modm_test_test_math
+class BcdTest : public unittest::TestSuite
+{
+public:
+	void
+	testFromBcd();
+
+	void
+	testToBcd();
+};