view docs/manual/x46.html @ 416:b4d0eafc5bfe

Fix code generation error in gcc6809 It turned out that under some circumstances, the gcc optimizer would select an instruction sequence that had the sense of a branch inverted. It seems this was due to a particular instruction pattern included in the machine description not being quite right with respect to how the condition codes were tracked. Removing that instruction pattern seems to fix things (subtraction with the arguments reversed). gcc seems to be smart enough to figure out how to reorganize code to work without this reversed sense subtraction and then do the right thing.
author William Astle <lost@l-w.ca>
date Thu, 24 Mar 2016 20:07:20 -0600
parents b30091890d62
children
line wrap: on
line source

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN""http://www.w3.org/TR/html4/loose.dtd">
<HTML
><HEAD
><TITLE
>OS9 Modules</TITLE
><META
NAME="GENERATOR"
CONTENT="Modular DocBook HTML Stylesheet Version 1.79"><LINK
REL="HOME"
TITLE="LW Tool Chain"
HREF="index.html"><LINK
REL="UP"
TITLE="Output Formats"
HREF="c21.html"><LINK
REL="PREVIOUS"
TITLE="Intel Hex"
HREF="x41.html"><LINK
REL="NEXT"
TITLE="Object Files"
HREF="x54.html"></HEAD
><BODY
CLASS="SECTION"
BGCOLOR="#FFFFFF"
TEXT="#000000"
LINK="#0000FF"
VLINK="#840084"
ALINK="#0000FF"
><DIV
CLASS="NAVHEADER"
><TABLE
SUMMARY="Header navigation table"
WIDTH="100%"
BORDER="0"
CELLPADDING="0"
CELLSPACING="0"
><TR
><TH
COLSPAN="3"
ALIGN="center"
>LW Tool Chain</TH
></TR
><TR
><TD
WIDTH="10%"
ALIGN="left"
VALIGN="bottom"
><A
HREF="x41.html"
ACCESSKEY="P"
>Prev</A
></TD
><TD
WIDTH="80%"
ALIGN="center"
VALIGN="bottom"
>Chapter 2. Output Formats</TD
><TD
WIDTH="10%"
ALIGN="right"
VALIGN="bottom"
><A
HREF="x54.html"
ACCESSKEY="N"
>Next</A
></TD
></TR
></TABLE
><HR
ALIGN="LEFT"
WIDTH="100%"></DIV
><DIV
CLASS="SECTION"
><H1
CLASS="SECTION"
><A
NAME="AEN46"
>2.6. OS9 Modules</A
></H1
><P
>&#13;Since version 2.5, LWASM is able to generate OS9 modules. The syntax is
basically the same as for other assemblers.  A module starts with the MOD
directive and ends with the EMOD directive.  The OS9 directive is provided
as a shortcut for writing system calls.&#13;</P
><P
>&#13;LWASM does NOT provide an OS9Defs file. You must provide your own. Also note
that the common practice of using "ifp1" around the inclusion of the OS9Defs
file is discouraged as it is pointless and can lead to unintentional
problems and phasing errors.  Because LWASM reads each file exactly once,
there is no benefit to restricting the inclusion to the first assembly pass.&#13;</P
><P
>&#13;As of version 4.5, LWASM also implements the standard data/code address
streams for OS9 modules.  That means that between MOD and EMOD, any RMB,
RMD, RMQ, or equivalent directives will move the data address ahead and
leave the code address unmodified.  Outside of an actual module, both the
code and data addresses are moved ahead equally.  That last bit is critical
to understand because it means any directives that follow an EMOD directive
may have different results than other assemblers.&#13;</P
><P
>&#13;Additionally, within a module body, the ORG directive sets only the data
address, not the code address. However, outside a module body, ORG sets both
addresses.&#13;</P
><P
>Both code and data addresses are reset to 0 by the MOD directive.</P
><P
>&#13;As of version 4.5, LWLINK also supports creation of OS9 modules.&#13;</P
></DIV
><DIV
CLASS="NAVFOOTER"
><HR
ALIGN="LEFT"
WIDTH="100%"><TABLE
SUMMARY="Footer navigation table"
WIDTH="100%"
BORDER="0"
CELLPADDING="0"
CELLSPACING="0"
><TR
><TD
WIDTH="33%"
ALIGN="left"
VALIGN="top"
><A
HREF="x41.html"
ACCESSKEY="P"
>Prev</A
></TD
><TD
WIDTH="34%"
ALIGN="center"
VALIGN="top"
><A
HREF="index.html"
ACCESSKEY="H"
>Home</A
></TD
><TD
WIDTH="33%"
ALIGN="right"
VALIGN="top"
><A
HREF="x54.html"
ACCESSKEY="N"
>Next</A
></TD
></TR
><TR
><TD
WIDTH="33%"
ALIGN="left"
VALIGN="top"
>Intel Hex</TD
><TD
WIDTH="34%"
ALIGN="center"
VALIGN="top"
><A
HREF="c21.html"
ACCESSKEY="U"
>Up</A
></TD
><TD
WIDTH="33%"
ALIGN="right"
VALIGN="top"
>Object Files</TD
></TR
></TABLE
></DIV
></BODY
></HTML
>