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\newpage
\section{Library Design}


\subsection{Design considerations}

The \product{dyncall} library encapsulates function call invocation semantics
that depend on the compiler, operating system and architecture.
The core library is driven by a function call invocation engine, 
named \emph{CallVM}, that encapsulates a call stack to foreign functions 
and manages the following three phases that constitute a truly dynamic function
call:

\begin{enumerate}
\item Specify the calling convention. Some run-time platforms, such as
Microsoft Windows on a 32-bit X86 architecture, even support multiple calling
conventions.
\item Specify the function call arguments in a specific order. The 
interface design dictates a \emph{left to right} order for C and C++ function 
calls in which the arguments are bound.
\item Specify the target function address, expected return value and 
invoke the function call.
\end{enumerate}

The calling convention mode entirely depends on the way the foreign function
has been compiled and specifies the low-level details on how a function
actually expects input parameters (in memory, in registers or both) and how to
return its result(s).