Closes #16

core/signal_layout.h

@@ -0,0 +1,19 @@
+// SPDX-License-Identifier: MIT
+#ifndef SIGNAL_LAYOUT_H
+#define SIGNAL_LAYOUT_H
+
+#include <cstdint>
+
+/** Linear coordinate in the signal's bit order, widened before arithmetic. */
+inline std::uint64_t SignalStartCoordinate(std::uint32_t startBit, bool littleEndian) {
+    return littleEndian ? std::uint64_t(startBit)
+                        : std::uint64_t(startBit / 8U) * 8U + 7U - startBit % 8U;
+}
+
+inline bool IsValidSignalLayout(std::uint32_t startBit, std::uint32_t length,
+                                bool littleEndian, std::uint8_t dlc) {
+    return length >= 1U && length <= 64U &&
+           SignalStartCoordinate(startBit, littleEndian) + length <= std::uint64_t(dlc) * 8U;
+}
+
+#endif