Mapping and Address Conversion

The essential mechanism for address conversion from a persistent pointer to its corresponding reference pointer is a mapping of a region of a storage file in main memory. When a region of a file is mapped in a region in main memory, the offset from the beginning of the file can easily be converted to the address in the region in main memory by a simple calculation described below.

$\parbox{1\linewidth}{ \begin{center} $ A_m = S_m + (A_f - S_f) $\end{... ...y \item [$ S_f $] : Starting offset of the region in the file\end{description}}$

This formula is valid on condition that the offset in the file is within the region.