io-user-api.html

来自「有关ecos2。0介绍了实时嵌入式的结构以及线程调度的实现和内存的管理等」· HTML 代码 · 共 435 行

HTML
435 行
字号 
<!-- 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"><METANAME="GENERATOR"CONTENT="Modular DocBook HTML Stylesheet Version 1.76b+"><LINKREL="HOME"TITLE="eCos Reference Manual"HREF="ecos-ref.html"><LINKREL="UP"TITLE="I/O Package (Device Drivers)"HREF="io.html"><LINKREL="PREVIOUS"TITLE="Introduction"HREF="io-package-intro.html"><LINKREL="NEXT"TITLE="Serial driver details"HREF="io-serial-driver-details.html"></HEAD><BODYCLASS="CHAPTER"BGCOLOR="#FFFFFF"TEXT="#000000"LINK="#0000FF"VLINK="#840084"ALINK="#0000FF"><DIVCLASS="NAVHEADER"><TABLESUMMARY="Header navigation table"WIDTH="100%"BORDER="0"CELLPADDING="0"CELLSPACING="0"><TR><THCOLSPAN="3"ALIGN="center">eCos Reference Manual</TH></TR><TR><TDWIDTH="10%"ALIGN="left"VALIGN="bottom"><AHREF="io-package-intro.html"ACCESSKEY="P">Prev</A></TD><TDWIDTH="80%"ALIGN="center"VALIGN="bottom"></TD><TDWIDTH="10%"ALIGN="right"VALIGN="bottom"><AHREF="io-serial-driver-details.html"ACCESSKEY="N">Next</A></TD></TR></TABLE><HRALIGN="LEFT"WIDTH="100%"></DIV><DIVCLASS="CHAPTER"><H1><ANAME="IO-USER-API">Chapter 15. User API</H1><P>All functions, except <TTCLASS="FUNCTION">cyg_io_lookup()</TT>require an I/O &#8220;handle&#8221;.</P><P>All functions return a value of the type <SPANCLASS="TYPE">Cyg_ErrNo</SPAN>. If anerror condition is detected, this value will be negative and theabsolute value indicates the actual error, as specified in<TTCLASS="FILENAME">cyg/error/codes.h</TT>. The only other legal returnvalue will be <TTCLASS="VARNAME">ENOERR</TT>. All other function argumentsare pointers (references). This allows the drivers to pass informationefficiently, both into and out of the driver. The most strikingexample of this is the &#8220;length&#8221; value passed to the readand write functions. This parameter contains the desired length ofdata on input to the function and the actual transferred length onreturn.</P><TABLEBORDER="5"BGCOLOR="#E0E0F0"WIDTH="70%"><TR><TD><PRECLASS="PROGRAMLISTING">// Lookup a device and return its handle   Cyg_ErrNo <TTCLASS="FUNCTION">cyg_io_lookup</TT>(     const char <TTCLASS="PARAMETER"><I>*name</I></TT>,    cyg_io_handle_t <TTCLASS="PARAMETER"><I>*handle</I></TT> )</PRE></TD></TR></TABLE><P>This function maps a device name onto an appropriate handle. If thenamed device is not in the system, then the error<TTCLASS="VARNAME">-ENOENT</TT> is returned. If the device is found, thenthe handle for the device is returned by way of the handle pointer<TTCLASS="PARAMETER"><I>*handle</I></TT>.</P><TABLEBORDER="5"BGCOLOR="#E0E0F0"WIDTH="70%"><TR><TD><PRECLASS="PROGRAMLISTING">// Write data to a device Cyg_ErrNo <TTCLASS="FUNCTION">cyg_io_write</TT>(     cyg_io_handle_t <TTCLASS="PARAMETER"><I>handle</I></TT>,    const void <TTCLASS="PARAMETER"><I>*buf</I></TT>,    cyg_uint32 <TTCLASS="PARAMETER"><I>*len</I></TT> )</PRE></TD></TR></TABLE><P>This function sends data to a device. The size of data to send iscontained in <TTCLASS="PARAMETER"><I>*len</I></TT> and the actual size sent willbe returned in the same place.</P><TABLEBORDER="5"BGCOLOR="#E0E0F0"WIDTH="70%"><TR><TD><PRECLASS="PROGRAMLISTING">// Read data from a device Cyg_ErrNo <TTCLASS="FUNCTION">cyg_io_read</TT>(     cyg_io_handle_t <TTCLASS="PARAMETER"><I>handle</I></TT>,    void <TTCLASS="PARAMETER"><I>*buf</I></TT>,    cyg_uint32 <TTCLASS="PARAMETER"><I>*len</I></TT> )</PRE></TD></TR></TABLE><P>This function receives data from a device. The desired size of data toreceive is contained in <TTCLASS="PARAMETER"><I>*len</I></TT> and the actualsize obtained will be returned in the same place.</P><TABLEBORDER="5"BGCOLOR="#E0E0F0"WIDTH="70%"><TR><TD><PRECLASS="PROGRAMLISTING">// Get the configuration of a device Cyg_ErrNo <TTCLASS="FUNCTION">cyg_io_get_config</TT>(     cyg_io_handle_t <TTCLASS="PARAMETER"><I>handle</I></TT>,    cyg_uint32 <TTCLASS="PARAMETER"><I>key</I></TT>,    void *<TTCLASS="PARAMETER"><I>buf</I></TT>,    cyg_uint32 *<TTCLASS="PARAMETER"><I>len</I></TT> )</PRE></TD></TR></TABLE><P>This function is used to obtain run-time configuration about adevice. The type of information retrieved is specified by the<TTCLASS="PARAMETER"><I>key</I></TT>. The data will be returned in the givenbuffer. The value of <TTCLASS="PARAMETER"><I>*len</I></TT> should contain theamount of data requested, which must be at least as large as the sizeappropriate to the selected key. The actual size of data retrieved isplaced in <TTCLASS="PARAMETER"><I> *len</I></TT>. The appropriate key valuesdiffer for each driver and are all listed in the file<TTCLASS="FILENAME">&lt;cyg/io/config_keys.h&gt;</TT>.</P><TABLEBORDER="5"BGCOLOR="#E0E0F0"WIDTH="70%"><TR><TD><PRECLASS="PROGRAMLISTING">// Change the configuration of a device Cyg_ErrNo <TTCLASS="FUNCTION">cyg_io_set_config</TT>(     cyg_io_handle_t <TTCLASS="PARAMETER"><I>handle</I></TT>,    cyg_uint32 <TTCLASS="PARAMETER"><I>key</I></TT>,    const void <TTCLASS="PARAMETER"><I>*buf</I></TT>,    cyg_uint32 <TTCLASS="PARAMETER"><I>*len</I></TT> )</PRE></TD></TR></TABLE><P>This function is used to manipulate or change the run-timeconfiguration of a device. The type of information is specified by the<TTCLASS="PARAMETER"><I>key</I></TT>. The data will be obtained from the givenbuffer. The value of <TTCLASS="PARAMETER"><I>*len</I></TT> should contain theamount of data provided, which must match the size appropriate to theselected key.  The appropriate key values differ for each driver andare all listed in the file<TTCLASS="FILENAME">&lt;cyg/io/config_keys.h&gt;</TT>.</P></DIV><DIVCLASS="NAVFOOTER"><HRALIGN="LEFT"WIDTH="100%"><TABLESUMMARY="Footer navigation table"WIDTH="100%"BORDER="0"CELLPADDING="0"CELLSPACING="0"><TR><TDWIDTH="33%"ALIGN="left"VALIGN="top"><AHREF="io-package-intro.html"ACCESSKEY="P">Prev</A></TD><TDWIDTH="34%"ALIGN="center"VALIGN="top"><AHREF="ecos-ref.html"ACCESSKEY="H">Home</A></TD><TDWIDTH="33%"ALIGN="right"VALIGN="top"><AHREF="io-serial-driver-details.html"ACCESSKEY="N">Next</A></TD></TR><TR><TDWIDTH="33%"ALIGN="left"VALIGN="top">Introduction</TD><TDWIDTH="34%"ALIGN="center"VALIGN="top"><AHREF="io.html"ACCESSKEY="U">Up</A></TD><TDWIDTH="33%"ALIGN="right"VALIGN="top">Serial driver details</TD></TR></TABLE></DIV></BODY></HTML>

io-user-api.html - 源码说明

本页面展示了「有关ecos2。0介绍了实时嵌入式的结构以及线程调度的实现和内存的管理等」中的 io-user-api.html 源码文件，采用 HTML 编程语言编写，共 435 行代码。您可以在线阅读完整代码内容，也可以返回资源详情页下载完整源码包进行本地学习和开发。

虫虫下载站收录了大量与ecos2相关的技术资源，包括源代码、技术文档、电路图等，是电子工程师和嵌入式开发者的专业学习平台。

⌨️ 快捷键说明

复制代码Ctrl + C
搜索代码Ctrl + F
全屏模式F11
增大字号Ctrl + =
减小字号Ctrl + -
显示快捷键?