\end_inset
-
+
+\newline
+
+\layout Standard
+
+In accordance with ISO/IEC 9899 bits and bitfields without an explicit signed
+ modifier are implemented as unsigned.
+\layout Standard
+
+
\begin_inset Foot
collapsed false
\emph default
is where the chip designers decided to put it.
Needless to say that they didn't agree on a common name either.
- As pdata addressing is used in the startup code for the initialization
- of xdata variables a separate startup code should be used as described
- in section
+ So that the startup code can correctly initialize xdata variables, you
+ should define an sfr with the name _XPAGE at the appropriate location if
+ the default, port P2, is not used for this.
+ Some examples are:
+\layout Verse
+
+
+\family typewriter
+sfr at 0x92 _XPAGE; /* Cypress EZ-USB family */
+\layout Verse
+
+
+\family typewriter
+sfr at 0xaf _XPAGE; /* some Silicon Labs (Cygnal) chips */
+\layout Verse
+
+
+\family typewriter
+sfr at 0xaa _XPAGE; /* some Silicon Labs (Cygnal) chips */
+\layout Standard
+
+For more exotic implementations further customizations may be needed.
+ See section
\begin_inset LatexCommand \ref{sub:Startup-Code}
\end_inset
-.
+ for other possibilities.
\layout Subsection
Other Features available by SFR