📄 hal-general-principles.html
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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>General principles</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="The eCos Hardware Abstraction Layer (HAL)"HREF="the-ecos-hardware-abstraction-layer.html"><LINKREL="PREVIOUS"TITLE="Architecture, Variant and Platform"HREF="hal-architecture-variant-and-platform.html"><LINKREL="NEXT"TITLE="HAL Interfaces"HREF="hal-interfaces.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="hal-architecture-variant-and-platform.html"ACCESSKEY="P">Prev</A></TD><TDWIDTH="80%"ALIGN="center"VALIGN="bottom"></TD><TDWIDTH="10%"ALIGN="right"VALIGN="bottom"><AHREF="hal-interfaces.html"ACCESSKEY="N">Next</A></TD></TR></TABLE><HRALIGN="LEFT"WIDTH="100%"></DIV><DIVCLASS="CHAPTER"><H1><ANAME="HAL-GENERAL-PRINCIPLES">Chapter 8. General principles</H1><P>The HAL has been implemented according to the following generalprinciples:</P><P></P><OLTYPE="1"><LI><P> The HAL is implemented in C and assembler, although the eCos kernel is largely implemented in C++. This is to permit the HAL the widest possible applicability.</P></LI><LI><P>All interfaces to the HAL are implemented by CPP macros. This allows them to be implemented as inline C code, inline assembler or function calls to external C or assembler code. This allows the most efficient implementation to be selected without affecting the interface. It also allows them to be redefined if the platform or variant HAL needs to replace or enhance a definition from the architecture HAL.</P></LI><LI><P>The HAL provides simple, portable mechanisms for dealingwith the hardware of a wide range of architectures and platforms.It is always possible to bypass the HAL and program the hardwaredirectly, but this may lead to a loss of portability. </P></LI></OL></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="hal-architecture-variant-and-platform.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="hal-interfaces.html"ACCESSKEY="N">Next</A></TD></TR><TR><TDWIDTH="33%"ALIGN="left"VALIGN="top">Architecture, Variant and Platform</TD><TDWIDTH="34%"ALIGN="center"VALIGN="top"><AHREF="the-ecos-hardware-abstraction-layer.html"ACCESSKEY="U">Up</A></TD><TDWIDTH="33%"ALIGN="right"VALIGN="top">HAL Interfaces</TD></TR></TABLE></DIV></BODY></HTML>⌨️ 快捷键说明
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