edits from Jay

book.tex

@@ -4307,9 +4307,9 @@ succeed.
    static void cheney(int64_t** rootstack_ptr);
 \end{lstlisting}
   The parameter \code{rootstack\_ptr} is a pointer to the top of the
-  rootstack (which is array of pointers).  The \code{cheney} function
+  rootstack (which is an array of pointers).  The \code{cheney} function
   also communicates with \code{collect} through several global
-  variables, the \code{framespace\_begin} and \code{framespace\_end}
+  variables, the \code{fromspace\_begin} and \code{fromspace\_end}
   mentioned in Figure~\ref{fig:gc-header} as well as the pointers for
   the ToSpace:
 \begin{lstlisting}