#if AR_USE_64_BIT typedef UINT64 ULONG; #else typedef UINT32 ULONG; #endif
The ULONG type is a configuration-dependent data type designed to represent the widest unsigned integer supported by the current system build. It resolves to a 64-bit unsigned integer (UINT64) when 64-bit support is enabled via the AR_USE_64_BIT constant; otherwise, it defaults to a 32-bit unsigned integer (UINT32).