uc/os源码 uc/os源码

              size=2>会根据你在开始创建工程时选择的工程模板来自动地设置子系统的选项； </FONT>
              <LI><B><FONT size=2>子系统 </FONT><FONT 
              face="Arial, Helvetica, sans-serif" size=2>ID/</FONT><FONT 
              size=2>用户 </FONT><FONT face="Arial, Helvetica, sans-serif" 
              size=2>ID(Subsystem ID/UserID):</B> </FONT><FONT 
              size=2>和子系统项一样，这个选项也是由 </FONT><FONT 
              face="Arial, Helvetica, sans-serif" size=2>CodeWarrior 
              </FONT><FONT size=2>自动设置的。具体系统对应的 </FONT><FONT 
              face="Arial, Helvetica, sans-serif" size=2>ID </FONT><FONT 
              size=2>为：</FONT><FONT face="Arial, Helvetica, sans-serif" 
              size=2>Windows 3.1</FONT><FONT size=2>，</FONT><FONT 
              face="Arial, Helvetica, sans-serif" size=2>Windows 95 </FONT><FONT 
              size=2>和 </FONT><FONT face="Arial, Helvetica, sans-serif" 
              size=2>Windows NT 3.5 </FONT><FONT size=2>的 </FONT><FONT 
              face="Arial, Helvetica, sans-serif" size=2>ID </FONT><FONT 
              size=2>为 </FONT><FONT face="Arial, Helvetica, sans-serif" 
              size=2>3.10</FONT><FONT size=2>，</FONT><FONT 
              face="Arial, Helvetica, sans-serif" size=2>Windows NT 4 
              </FONT><FONT size=2>的 </FONT><FONT 
              face="Arial, Helvetica, sans-serif" size=2>ID </FONT><FONT 
              size=2>为 </FONT><FONT face="Arial, Helvetica, sans-serif" 
              size=2>4.00</FONT><FONT size=2>；</FONT> 
              <LI><B><FONT size=2>生成连接映射</FONT><FONT 
              face="Arial, Helvetica, sans-serif" size=2>(Generate Link 
              Map):</B> </FONT><FONT 
              size=2>这个选项允许你生成一个文本文件，其中包含了程序中使用到的所有的类和函数的详细信息。当需要通过匹配变量或函数名的地址来调试代码时，这个选项就非常有用了；</FONT> 

              <LI><B><FONT size=2>生成 </FONT><FONT 
              face="Arial, Helvetica, sans-serif" size=2>SYM </FONT><FONT 
              size=2>文件</FONT><FONT face="Arial, Helvetica, sans-serif" 
              size=2>(Generate SYM File):</B> </FONT><FONT 
              size=2>这个选项允许你在连接过程中生成一个符号文件。大多数的调试器在进行调试时需要一个符号文件来逐步调试你的源代码。我们将在第五课中详细讨论这个内容。此外，你还可以通过选中生成 
              </FONT><FONT face="Arial, Helvetica, sans-serif" size=2>CV 
              </FONT><FONT size=2>信息项</FONT><FONT 
              face="Arial, Helvetica, sans-serif" size=2>(Generate CV Info 
              item)</FONT><FONT size=2>来生成一个可用于 </FONT><FONT 
              face="Arial, Helvetica, sans-serif" size=2>CodeView </FONT><FONT 
              size=2>的符号文件。</FONT><FONT face="Arial, Helvetica, sans-serif" 
              size=2>CodeView </FONT><FONT size=2>是一个流行的 </FONT><FONT 
              face="Arial, Helvetica, sans-serif" size=2>Windows </FONT><FONT 
              size=2>调试工具；</FONT> 
              <LI><STRONG><FONT size=2>生成 </FONT><FONT 
              face="Arial, Helvetica, sans-serif" size=2>CV </FONT><FONT 
              size=2>信息</STRONG><B><FONT 
              face="Arial, Helvetica, sans-serif">(</FONT></FONT><FONT 
              face="Arial, Helvetica, sans-serif" size=2>Generate CV Info):</B> 
              </FONT><FONT size=2>生成一个可用于 </FONT><FONT 
              face="Arial, Helvetica, sans-serif" size=2>CodeView </FONT><FONT 
              size=2>的符号文件。</FONT><FONT face="Arial, Helvetica, sans-serif" 
              size=2>CodeView </FONT><FONT size=2>是一个流行的 </FONT><FONT 
              face="Arial, Helvetica, sans-serif" size=2>Windows </FONT><FONT 
              size=2>调试工具；</FONT> 
              <LI><B><FONT size=2>命令文件</FONT><FONT 
              face="Arial, Helvetica, sans-serif" size=2>(Command File):</B> 
              </FONT><FONT 
              size=2>这个选项要你选择一个用于指示复杂的连接选项设置的文本文件。该文件称为连接器命令文件。它被使用来指定要导入和导出哪些符号。除非你正在编写一个特殊目的的代码，你才不需要一个连接器文件。</FONT> 
              </LI></UL>
            <P><FONT face="Arial, Helvetica, sans-serif" 
            size=2>&nbsp;&nbsp;&nbsp; </FONT><FONT 
            size=2>正如你所知的，连接器的设置过程是非常复杂的。但是，在多数情况下，你不需要修改连接器的默认设置。</FONT><FONT 
            face="Arial, Helvetica, sans-serif" size=2>Metrowerks </FONT><FONT 
            size=2>公司的开发人员已经帮助你很好地解决了这个问题。</FONT></P>
            <HR>

            <P>附原文：</P>
            <P><FONT face="Arial, Helvetica, sans-serif" color=#000000 
            size=3><B><B>Step Two: Link your Program's 
            Components</B></B><BR></FONT><BR></P><FONT 
            face="Arial, Helvetica, sans-serif" size=2>
            <P>After the compiler compiles your code, the linker links together 
            the files that make up your program.</P>
            <P>The linker is responsible for combining your compiled code, which 
            may be located in various files after they are compiled, and 
            connecting the files together, along with any libraries the program 
            requires. Linking makes sure each piece of code knows how to find 
            the other elements of your program. For example, the linker modifies 
            the machine code so that your call to printf() gets correctly routed 
            to the MSL library function printf(), which does the all of the 
            magic necessary to implement console I/O.</P>
            <P>When you write a program, you split your code into functions that 
            are stored in different files and are compiled to a single output 
            file. In the case of the Hello World program I've been using as an 
            example, this output file is an application. In some cases, 
            functions used in a program may not even be stored in the same 
            output file. When would this happen? When you write an application, 
            for example, that contains a lot of code that is reused in several 
            parts of your program, you might compile all of that reusable code 
            into a single shared DLL. When you do this, the application can 
            still access the code, but it needs to know where and how to find it 
            when it needs it, hence the need for linking.</P>
            <P><B><FONT size=+1>Types of Linking</FONT></B></P>
            <P>In programming, a link is a pointer, either to an object, such as 
            a compiled function, or to data, such as a variable or an array. 
            There are two ways to link: hard linking and soft linking. </P>
            <P>Hard linking occurs when all of the code is accounted for at link 
            time. That is, if a function is used, the linker knows exactly where 
            it is at link time and can create a direct link to it.</P>
            <P>Soft linking (also known as weak linking) is when some of the 
            code may not be accounted for at link time, but you know that it is 
            in a DLL that will be accessible at runtime. In this case, the 
            linker can tell your application to search for the DLL when it is 
            needed.</P>
            <P>Soft linking is the method used by many elements of your 
            computer's operating system. Next, we'll take a look at some of the 
            options that the linker provides.</FONT></P>
            <P><FONT face="Arial, Helvetica, sans-serif" color=#000000 
            size=3><B><B>A Detailed Look at 
            Linking</B></B><BR></FONT><BR></P><FONT 
            face="Arial, Helvetica, sans-serif" size=2>
            <P>To further appreciate the functionality of the CodeWarrior linker 
            for the Windows platform, you need to understand how you can 
            configure the CodeWarrior linker to accomplish what you need.</P>
            <P><B><FONT size=+1>Configure the Linker to Suit your 
            Needs</FONT></B></P>
            <P>The choices in this lesson appear in the x86 version of the 
            CodeWarrior linker panel (Figure 4-1). But many of the terms used in 
            the x86 linker are applicable to other linkers.</P>
            <TABLE cellSpacing=0 cellPadding=0 border=0>
              <TBODY>
              <TR>
                <TD><IMG height=421 
                  alt="Figure. 4-1 The x86 linker settings window." 
                  src="第四课    连  接.files/icwwL4_fig1.gif" width=627 align=left> 
                </TD></TR>
              <TR>
                <TD align=middle><FONT size=1><I>Figure. 4-1 The x86 linker 
                  settings window.</I></FONT> </TD></TR></TBODY></TABLE>
            <P>Open the Settings window by choosing "Project Name" Settings from 
            the Edit menu. (Project_Name is the currently active project -- in 
            this case, Hello World x86.) Click on the x86 Linker (or similar) 
            tab in the Settings window.</P>
            <P>Let's take a look at some of the linker options:
            <UL>
              <LI><B>Entry Point Usage:</B> Under the Windows OS architecture, 
              each code module has a number of entry points that may or may not 
              be optional, depending on the type of code you are building. The 
              nature of these entry points depends upon the type of output file 
              you're making (application, library, or DLL) and other factors. 
              The host OS uses this entry point information to properly call a 
              DLL's initialization functions when an application demands its 
              services. Most often, you will leave this set to Default as shown 
              in Figure 4-1. This lets CodeWarrior automatically set up the 
              proper entry points for the output file, based upon your choice of 
              target in the x86 Target panel. 
              <LI><B>Subsystem: </B>There are several settings here. Of interest 
              to you are the Native, Windows CUI, and Windows GUI selections. 
              The Native setting is for building drivers and other exotic system 
              modules. The Windows CUI setting is for those applications 
              sporting a console-style user interface (hence the name CUI). The 
              Windows GUI choice supports applications that rely on the Windows 
              graphic user interface (GUI). You'll notice that our simple, 
              console-based Windows application uses the CUI subsystem, as 
              expected. Normally, CodeWarrior sets the subsystem for you 
              automatically when you choose a CodeWarrior project template to 
              construct the project file. 
              <LI><B>Subsystem ID/UserID:</B> Like the subsystem item, this item 
              is typically set for you automatically. For the curious: Windows 
              3.1, Windows 95, and Windows NT 3.5 have an ID of 3.10, while 
              Windows NT 4 has an ID of 4.00. 
              <LI><B>Generate Link Map:</B> This option allows you to generate a 
              text file that contains detailed information on the classes and 
              functions used throughout your program. This can be extremely 
              helpful when debugging code by matching addresses to variable or 
              function names. 
              <LI><B>Generate SYM File:</B> This option allows you to generate a 
              symbol file during the link process. Most debuggers require a 
              symbol file in order to step through your source code when 
              debugging. This is discussed in more detail in Lesson 5. You can 
              also generate a symbol file for CodeView, a popular Windows 
              debugging tool, by checking the Generate CV Info item. 
              <LI><B>Generate CV Info:</B> Generates a symbol file for CodeView, 
              a popular Windows debugging tool. 
              <LI><B>Command File:</B> This item lets you pick the name of an 
              optional text file that directs sophisticated linking options. 
              Called the linker command file, you use it to specify which 
              symbols to import and export, and other advanced linking 
              operations. Unless you're writing special-purpose code, you won't 
              normally need a linker command file. </LI></UL>
            <P>As you can see, the linker can be a relatively complex piece of 
            software machinery. Luckily, in many cases, the default settings 
            will suffice. Very rarely will you have to tweak the linker settings 
            to get your programs to work. The folks at Metrowerks have done an 
            excellent job of managing this thankless job for you. Yay, 
            CodeWarrior!</FONT></P>
            <P>　</P></TD></TR></TBODY></TABLE></CENTER></DIV></TD></TR>
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