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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 >Diagnostic Support</TITLE ><meta name="MSSmartTagsPreventParsing" content="TRUE"> <META NAME="GENERATOR" CONTENT="Modular DocBook HTML Stylesheet Version 1.76b+ "><LINK REL="HOME" TITLE="eCos Reference Manual" HREF="ecos-ref.html"><LINK REL="UP" TITLE="HAL Interfaces" HREF="hal-interfaces.html"><LINK REL="PREVIOUS" TITLE="Linker Scripts" HREF="hal-linker-scripts.html"><LINK REL="NEXT" TITLE="SMP Support" HREF="hal-smp-support.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" >eCos Reference Manual</TH ></TR ><TR ><TD WIDTH="10%" ALIGN="left" VALIGN="bottom" ><A HREF="hal-linker-scripts.html" ACCESSKEY="P" >Prev</A ></TD ><TD WIDTH="80%" ALIGN="center" VALIGN="bottom" >Chapter 9. HAL Interfaces</TD ><TD WIDTH="10%" ALIGN="right" VALIGN="bottom" ><A HREF="hal-smp-support.html" ACCESSKEY="N" >Next</A ></TD ></TR ></TABLE ><HR ALIGN="LEFT" WIDTH="100%"></DIV ><DIV CLASS="SECTION" ><H1 CLASS="SECTION" ><A NAME="HAL-DIAGNOSTIC-SUPPORT">Diagnostic Support</H1 ><P >The HAL provides support for low level diagnostic IO. This is particularly useful during early development as an aid to bringing up a new platform. Usually this diagnostic channel is a UART or some other serial IO device, but it may equally be a a memory buffer, a simulator supported output channel, a ROM emulator virtual UART, and LCD panel, a memory mapped video buffer or any other output device.</P ><P ><TT CLASS="FUNCTION" >HAL_DIAG_INIT()</TT > performs any initialization required on the device being used to generate diagnostic output. This may include, for a UART, setting baud rate, and stop, parity and character bits. For other devices it may include initializing a controller or establishing contact with a remote device.</P ><P ><TT CLASS="FUNCTION" >HAL_DIAG_WRITE_CHAR(c)</TT > writes the character supplied to the diagnostic output device.</P ><P ><TT CLASS="FUNCTION" >HAL_DIAG_READ_CHAR(c)</TT > reads a character from the diagnostic device into the supplied variable. This is not supported for all diagnostic devices.</P ><P >These macros are defined in the header file <TT CLASS="FILENAME" >cyg/hal/hal_diag.h</TT >. This file is usually supplied by the variant or platform HAL, depending on where the IO device being used is located. For example for on-chip UARTs it would be in the variant HAL, but for a board-level LCD panel it would be in the platform HAL.</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="hal-linker-scripts.html" ACCESSKEY="P" >Prev</A ></TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="ecos-ref.html" ACCESSKEY="H" >Home</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" ><A HREF="hal-smp-support.html" ACCESSKEY="N" >Next</A ></TD ></TR ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" >Linker Scripts</TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="hal-interfaces.html" ACCESSKEY="U" >Up</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" >SMP Support</TD ></TR ></TABLE ></DIV ></BODY ></HTML >
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