\fcolorbox{black}{white}{%
	\setlength{\tabcolsep}{.2em}%
	\begin{tabular}{lcccccccc}
		\multicolumn{7}{c}{\textbf{Function Calls}}\\\hline
		Arguments:    & rcx & rdx & r8 & r9\\
									& A0  & A1  & A2 & scr\\
		\hline
		Result:       & rax \\
									& B0 \\
		\hline
		Callee-saved: & rbx & rbp & rdi & rsi & r12 & r13 & r14 & r15 \\
									& B1  & scr & hp  & asp & B4  & B5  & B6  & free \\
	\end{tabular}%
}%