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<!-- Copyright (C) 2003 Red Hat, Inc. --> <!-- This material may be distributed only subject to the terms --> <!-- and conditions set forth in the Open Publication License, v1.0 --> <!-- or later (the latest version is presently available at --> <!-- http://www.opencontent.org/openpub/). --> <!-- Distribution of the work or derivative of the work in any --> <!-- standard (paper) book form is prohibited unless prior --> <!-- permission is obtained from the copyright holder. --> <HTML ><HEAD ><TITLE >Programming With eCos</TITLE ><meta name="MSSmartTagsPreventParsing" content="TRUE"> <META NAME="GENERATOR" CONTENT="Modular DocBook HTML Stylesheet Version 1.76b+ "><LINK REL="HOME" TITLE="eCos User Guide" HREF="ecos-user-guide.html"><LINK REL="UP" TITLE="Programming With eCos" HREF="user-guide-programming.html"><LINK REL="PREVIOUS" TITLE="Programming With eCos" HREF="user-guide-programming.html"><LINK REL="NEXT" TITLE="Configuring and Building eCos from Source" HREF="configuring-and-building-ecos-from-source.html"></HEAD ><BODY CLASS="CHAPTER" 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" >eCos User Guide</TH ></TR ><TR ><TD WIDTH="10%" ALIGN="left" VALIGN="bottom" ><A HREF="user-guide-programming.html" ACCESSKEY="P" >Prev</A ></TD ><TD WIDTH="80%" ALIGN="center" VALIGN="bottom" ></TD ><TD WIDTH="10%" ALIGN="right" VALIGN="bottom" ><A HREF="configuring-and-building-ecos-from-source.html" ACCESSKEY="N" >Next</A ></TD ></TR ></TABLE ><HR ALIGN="LEFT" WIDTH="100%"></DIV ><DIV CLASS="CHAPTER" ><H1 ><A NAME="PROGRAMMING-WITH-ECOS">Chapter 10. Programming With <SPAN CLASS="PRODUCTNAME" >eCos</SPAN ></H1 ><P >The following chapters of this manual comprise a simple tutorial for configuring and building <SPAN CLASS="PRODUCTNAME" >eCos</SPAN >, building and running <SPAN CLASS="PRODUCTNAME" >eCos</SPAN > tests, and finally building three stand-alone example programs which use the <SPAN CLASS="PRODUCTNAME" >eCos</SPAN > API to perform some simple tasks.</P ><P >You will need a properly installed <SPAN CLASS="PRODUCTNAME" >eCos</SPAN > system, with the correct versions of the GNU toolchain. On Windows you will be using the bash command line interpreter that comes with Cygwin, with the environment variables set as described in the toolchain documentation.</P ><DIV CLASS="SECT1" ><H1 CLASS="SECT1" ><A NAME="DEVELOPMENT-PROCESS">The Development Process</H1 ><P >Most development projects using <SPAN CLASS="PRODUCTNAME" >eCos</SPAN > would contain some (or most) of the following:</P ><DIV CLASS="SECT2" ><H2 CLASS="SECT2" ><A NAME="AEN471"><SPAN CLASS="PRODUCTNAME" >eCos</SPAN > Configuration</H2 ><P ><SPAN CLASS="PRODUCTNAME" >eCos</SPAN > is configured to provide the desired API (the inclusion of libc, uitron, and the disabling of certain undesired funtions, etc.), and semantics (selecting scheduler, mutex behavior, etc.). See <A HREF="configuring-and-building-ecos-from-source.html" >Chapter 11</A >.</P ><P >It would normally make sense to enable <SPAN CLASS="PRODUCTNAME" >eCos</SPAN > assertion checking at this time as well, to catch as many programming errors during the development phase as possible.</P ><P >Note that it should not be necessary to spend much time on <SPAN CLASS="PRODUCTNAME" >eCos</SPAN > configuration initially. It may be important to perform fine tuning to reduce the memory footprint and to improve performance later when the product reaches a testable state.</P ></DIV ><DIV CLASS="SECT2" ><H2 CLASS="SECT2" ><A NAME="AEN481">Integrity check of the <SPAN CLASS="PRODUCTNAME" >eCos</SPAN > configuration</H2 ><P >While we strive to thoroughly test <SPAN CLASS="PRODUCTNAME" >eCos</SPAN >, the vast number of configuration permutations mean that the particular configuration parameters used for your project may not have been tested. Therefore, we advise running the <SPAN CLASS="PRODUCTNAME" >eCos</SPAN > tests after the project's <SPAN CLASS="PRODUCTNAME" >eCos</SPAN > configuration has been determined. See <A HREF="running-an-ecos-test-case.html" >Chapter 12</A >.</P ><P >Obviously, this should be repeated if the configuration changes later on in the development process.</P ></DIV ><DIV CLASS="SECT2" ><H2 CLASS="SECT2" ><A NAME="AEN490">Application Development - Target Neutral Part</H2 ><P >While your project is probably targeting a specific architecture and platform, possibly custom hardware, it may be possible to perform part of the application development using simulated or synthetic targets.</P ><P >There are three good reasons for doing this:</P ><P ></P ><UL ><LI ><P >It may be possible by this means to perform application development in parallel with the design/implementation of the target hardware, thus providing more time for developing and testing functionality, and reducing time-to-market.</P ></LI ><LI ><P >The build-run-debug-cycle may be faster when the application does not have to be downloaded to a target via a serial interface. Debugging is also likely to be more responsive when you do not have to to communicate with the remote GDB stubs in RedBoot via serial. It also removes the need for manually or automatically resetting the target hardware.</P ></LI ><LI ><P >New hardware can often be buggy. Comparing the behaviour of the program on the hardware and in the simulator or synthetic target may allow you to identify where the problems lie.</P ></LI ></UL ><P >This approach is possible because all targets (including simulators and synthetic ones) provide the same basic API: that is, kernel, libc, libm, uitron, infra, and to some extent, HAL and IO.</P ><P >Synthetic targets are especially suitable as they allow you to construct simulations of elaborate devices by interaction with the host system, where an IO device API can hide the details from the application. When switching to hardware later in the development cycle, the IO driver is properly implemented.</P ><P >Simulators can also do this, but it all depends on the design and capabilities of the simulator you use. Some, like <A HREF="http://sources.redhat.com/sid" TARGET="_top" >SID</A > or <A HREF="http://bochs.sourceforge.net/" TARGET="_top" >Bochs</A > provide complete hardware emulation, while others just support enough of the instruction set to run compiled code.</P ><P >Therefore, select a simulator or synthetic target and use it for as long as possible for application development. That is, configure for the selected target, build <SPAN CLASS="PRODUCTNAME" >eCos</SPAN >, build the application and link with <SPAN CLASS="PRODUCTNAME" >eCos</SPAN >, run and debug. Repeat the latter two steps until you are happy with it.</P ><P >Obviously, at some time you will have to switch to the intended target hardware, for example when adding target specific feature support, for memory footprint/performance characterization, and for final tuning of <SPAN CLASS="PRODUCTNAME" >eCos</SPAN > and the application.</P ></DIV ><DIV CLASS="SECT2" ><H2 CLASS="SECT2" ><A NAME="AEN511">Application Development - Target Specific Part</H2 ><P >Repeat the build-run-debug-cycle while performing final tuning and debugging of application. Remember to disable <SPAN CLASS="PRODUCTNAME" >eCos</SPAN > assertion checking if you are testing any performance-related aspects, it can make a big difference.</P ><P >It may be useful to switch between this and the previous step repeatedly through the development process; use the simulator/synthetic target for actual development, and use the target hardware to continually check memory footprint and performance. There should be little cost in switching between the two targets when using two separate build trees. </P ></DIV ></DIV ></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="user-guide-programming.html" ACCESSKEY="P" >Prev</A ></TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="ecos-user-guide.html" ACCESSKEY="H" >Home</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" ><A HREF="configuring-and-building-ecos-from-source.html" ACCESSKEY="N" >Next</A ></TD ></TR ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" >Programming With <SPAN CLASS="PRODUCTNAME" >eCos</SPAN ></TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="user-guide-programming.html" ACCESSKEY="U" >Up</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" >Configuring and Building <SPAN CLASS="PRODUCTNAME" >eCos</SPAN > from Source</TD ></TR ></TABLE ></DIV ></BODY ></HTML >