📄 vax-opts.html

📁 gcc手册
💻 HTML
字号:
<html lang="en">

<head>

<title>Using as</title>

<meta http-equiv="Content-Type" content="text/html">

<meta name="description" content="Using as">

<meta name="generator" content="makeinfo 4.3">

<link href="http://www.gnu.org/software/texinfo/" rel="generator-home">

</head>

<body>

<div class="node">

<p>

Node:<a name="VAX-Opts">VAX-Opts</a>,

Next:<a rel="next" accesskey="n" href="VAX-float.html#VAX-float">VAX-float</a>,

Up:<a rel="up" accesskey="u" href="Vax-Dependent.html#Vax-Dependent">Vax-Dependent</a>

<hr><br>

</div>



<h4 class="section">VAX Command-Line Options</h4>



   <p>The Vax version of <code>as</code> accepts any of the following options,

gives a warning message that the option was ignored and proceeds. 

These options are for compatibility with scripts designed for other

people's assemblers.



     <dl>

<dt><code>-D (Debug)</code>

     <dd><dt><code>-S (Symbol Table)</code>

     <dd><dt><code>-T (Token Trace)</code>

     <dd>These are obsolete options used to debug old assemblers.



     <br><dt><code>-d (Displacement size for JUMPs)</code>

     <dd>This option expects a number following the <code>-d</code>.  Like options

that expect filenames, the number may immediately follow the

<code>-d</code> (old standard) or constitute the whole of the command line

argument that follows <code>-d</code> (<small>GNU</small> standard).



     <br><dt><code>-V (Virtualize Interpass Temporary File)</code>

     <dd>Some other assemblers use a temporary file.  This option

commanded them to keep the information in active memory rather

than in a disk file.  <code>as</code> always does this, so this

option is redundant.



     <br><dt><code>-J (JUMPify Longer Branches)</code>

     <dd>Many 32-bit computers permit a variety of branch instructions

to do the same job.  Some of these instructions are short (and

fast) but have a limited range; others are long (and slow) but

can branch anywhere in virtual memory.  Often there are 3

flavors of branch: short, medium and long.  Some other

assemblers would emit short and medium branches, unless told by

this option to emit short and long branches.



     <br><dt><code>-t (Temporary File Directory)</code>

     <dd>Some other assemblers may use a temporary file, and this option

takes a filename being the directory to site the temporary

file.  Since <code>as</code> does not use a temporary disk file, this

option makes no difference.  <code>-t</code> needs exactly one

filename. 

</dl>



   <p>The Vax version of the assembler accepts additional options when

compiled for VMS:



     <dl>

<dt><code>-h </code><var>n</var><code></code>

     <dd>External symbol or section (used for global variables) names are not

case sensitive on VAX/VMS and always mapped to upper case.  This is

contrary to the C language definition which explicitly distinguishes

upper and lower case.  To implement a standard conforming C compiler,

names must be changed (mapped) to preserve the case information.  The

default mapping is to convert all lower case characters to uppercase and

adding an underscore followed by a 6 digit hex value, representing a 24

digit binary value.  The one digits in the binary value represent which

characters are uppercase in the original symbol name.



     <p>The <code>-h </code><var>n</var><code></code> option determines how we map names.  This takes

several values.  No <code>-h</code> switch at all allows case hacking as

described above.  A value of zero (<code>-h0</code>) implies names should be

upper case, and inhibits the case hack.  A value of 2 (<code>-h2</code>)

implies names should be all lower case, with no case hack.  A value of 3

(<code>-h3</code>) implies that case should be preserved.  The value 1 is

unused.  The <code>-H</code> option directs <code>as</code> to display

every mapped symbol during assembly.



     <p>Symbols whose names include a dollar sign <code>$</code> are exceptions to the

general name mapping.  These symbols are normally only used to reference

VMS library names.  Such symbols are always mapped to upper case.



     <br><dt><code>-+</code>

     <dd>The <code>-+</code> option causes <code>as</code> to truncate any symbol

name larger than 31 characters.  The <code>-+</code> option also prevents some

code following the <code>_main</code> symbol normally added to make the object

file compatible with Vax-11 "C".



     <br><dt><code>-1</code>

     <dd>This option is ignored for backward compatibility with <code>as</code>

version 1.x.



     <br><dt><code>-H</code>

     <dd>The <code>-H</code> option causes <code>as</code> to print every symbol

which was changed by case mapping. 

</dl>



   </body></html>
⌨️ 快捷键说明

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