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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 >User API</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="I/O Package (Device Drivers)" HREF="io.html"><LINK REL="PREVIOUS" TITLE="Introduction" HREF="io-package-intro.html"><LINK REL="NEXT" TITLE="Serial driver details" HREF="io-serial-driver-details.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 Reference Manual</TH ></TR ><TR ><TD WIDTH="10%" ALIGN="left" VALIGN="bottom" ><A HREF="io-package-intro.html" ACCESSKEY="P" >Prev</A ></TD ><TD WIDTH="80%" ALIGN="center" VALIGN="bottom" ></TD ><TD WIDTH="10%" ALIGN="right" VALIGN="bottom" ><A HREF="io-serial-driver-details.html" ACCESSKEY="N" >Next</A ></TD ></TR ></TABLE ><HR ALIGN="LEFT" WIDTH="100%"></DIV ><DIV CLASS="CHAPTER" ><H1 ><A NAME="IO-USER-API">Chapter 15. User API</H1 ><P >All functions, except <TT CLASS="FUNCTION" >cyg_io_lookup()</TT > require an I/O “handle”.</P ><P >All functions return a value of the type <SPAN CLASS="TYPE" >Cyg_ErrNo</SPAN >. If an error condition is detected, this value will be negative and the absolute value indicates the actual error, as specified in <TT CLASS="FILENAME" >cyg/error/codes.h</TT >. The only other legal return value will be <TT CLASS="VARNAME" >ENOERR</TT >. All other function arguments are pointers (references). This allows the drivers to pass information efficiently, both into and out of the driver. The most striking example of this is the “length” value passed to the read and write functions. This parameter contains the desired length of data on input to the function and the actual transferred length on return.</P ><TABLE BORDER="5" BGCOLOR="#E0E0F0" WIDTH="70%" ><TR ><TD ><PRE CLASS="PROGRAMLISTING" >// Lookup a device and return its handle Cyg_ErrNo <TT CLASS="FUNCTION" >cyg_io_lookup</TT >( const char <TT CLASS="PARAMETER" ><I >*name</I ></TT >, cyg_io_handle_t <TT CLASS="PARAMETER" ><I >*handle</I ></TT > )</PRE ></TD ></TR ></TABLE ><P >This function maps a device name onto an appropriate handle. If the named device is not in the system, then the error <TT CLASS="VARNAME" >-ENOENT</TT > is returned. If the device is found, then the handle for the device is returned by way of the handle pointer <TT CLASS="PARAMETER" ><I >*handle</I ></TT >.</P ><TABLE BORDER="5" BGCOLOR="#E0E0F0" WIDTH="70%" ><TR ><TD ><PRE CLASS="PROGRAMLISTING" >// Write data to a device Cyg_ErrNo <TT CLASS="FUNCTION" >cyg_io_write</TT >( cyg_io_handle_t <TT CLASS="PARAMETER" ><I >handle</I ></TT >, const void <TT CLASS="PARAMETER" ><I >*buf</I ></TT >, cyg_uint32 <TT CLASS="PARAMETER" ><I >*len</I ></TT > )</PRE ></TD ></TR ></TABLE ><P >This function sends data to a device. The size of data to send is contained in <TT CLASS="PARAMETER" ><I >*len</I ></TT > and the actual size sent will be returned in the same place.</P ><TABLE BORDER="5" BGCOLOR="#E0E0F0" WIDTH="70%" ><TR ><TD ><PRE CLASS="PROGRAMLISTING" >// Read data from a device Cyg_ErrNo <TT CLASS="FUNCTION" >cyg_io_read</TT >( cyg_io_handle_t <TT CLASS="PARAMETER" ><I >handle</I ></TT >, void <TT CLASS="PARAMETER" ><I >*buf</I ></TT >, cyg_uint32 <TT CLASS="PARAMETER" ><I >*len</I ></TT > )</PRE ></TD ></TR ></TABLE ><P >This function receives data from a device. The desired size of data to receive is contained in <TT CLASS="PARAMETER" ><I >*len</I ></TT > and the actual size obtained will be returned in the same place.</P ><TABLE BORDER="5" BGCOLOR="#E0E0F0" WIDTH="70%" ><TR ><TD ><PRE CLASS="PROGRAMLISTING" >// Get the configuration of a device Cyg_ErrNo <TT CLASS="FUNCTION" >cyg_io_get_config</TT >( cyg_io_handle_t <TT CLASS="PARAMETER" ><I >handle</I ></TT >, cyg_uint32 <TT CLASS="PARAMETER" ><I >key</I ></TT >, void *<TT CLASS="PARAMETER" ><I >buf</I ></TT >, cyg_uint32 *<TT CLASS="PARAMETER" ><I >len</I ></TT > )</PRE ></TD ></TR ></TABLE ><P >This function is used to obtain run-time configuration about a device. The type of information retrieved is specified by the <TT CLASS="PARAMETER" ><I >key</I ></TT >. The data will be returned in the given buffer. The value of <TT CLASS="PARAMETER" ><I >*len</I ></TT > should contain the amount of data requested, which must be at least as large as the size appropriate to the selected key. The actual size of data retrieved is placed in <TT CLASS="PARAMETER" ><I > *len</I ></TT >. The appropriate key values differ for each driver and are all listed in the file <TT CLASS="FILENAME" ><cyg/io/config_keys.h></TT >.</P ><TABLE BORDER="5" BGCOLOR="#E0E0F0" WIDTH="70%" ><TR ><TD ><PRE CLASS="PROGRAMLISTING" >// Change the configuration of a device Cyg_ErrNo <TT CLASS="FUNCTION" >cyg_io_set_config</TT >( cyg_io_handle_t <TT CLASS="PARAMETER" ><I >handle</I ></TT >, cyg_uint32 <TT CLASS="PARAMETER" ><I >key</I ></TT >, const void <TT CLASS="PARAMETER" ><I >*buf</I ></TT >, cyg_uint32 <TT CLASS="PARAMETER" ><I >*len</I ></TT > )</PRE ></TD ></TR ></TABLE ><P >This function is used to manipulate or change the run-time configuration of a device. The type of information is specified by the <TT CLASS="PARAMETER" ><I >key</I ></TT >. The data will be obtained from the given buffer. The value of <TT CLASS="PARAMETER" ><I >*len</I ></TT > should contain the amount of data provided, which must match the size appropriate to the selected key. The appropriate key values differ for each driver and are all listed in the file <TT CLASS="FILENAME" ><cyg/io/config_keys.h></TT >.</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="io-package-intro.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="io-serial-driver-details.html" ACCESSKEY="N" >Next</A ></TD ></TR ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" >Introduction</TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="io.html" ACCESSKEY="U" >Up</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" >Serial driver details</TD ></TR ></TABLE ></DIV ></BODY ></HTML >
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