SHM Alignment Checker

Calculate the memory footprint and padding of C-structs passed over Shared Memory (SHM) to the PLC to avoid unaligned access faults on real-time cores.

Number of 64-bit Doubles

Number of 32-bit Integers

Number of Booleans / 8-bit Chars

Struct Layout (8-Byte Boundary)

Raw Payload Size
Padding Inserted by Compiler

Total Aligned Size (sizeof)

Bytes

For deterministic performance across the SHM bridge, we enforce strict 8-byte alignment for all structs shared between the C++ motion kernel and the IEC 61131-3 PLC environment.

JavaScript Required

Raw = (Doubles × 8) + (Ints × 4) + (Chars × 1)

Aligned = CEIL(Raw / 8) × 8

Padding = Aligned - Raw