| <html lang="en"> |
| <head> |
| <title>MMIX-Symbols - Using as</title> |
| <meta http-equiv="Content-Type" content="text/html"> |
| <meta name="description" content="Using as"> |
| <meta name="generator" content="makeinfo 4.13"> |
| <link title="Top" rel="start" href="index.html#Top"> |
| <link rel="up" href="MMIX_002dSyntax.html#MMIX_002dSyntax" title="MMIX-Syntax"> |
| <link rel="prev" href="MMIX_002dChars.html#MMIX_002dChars" title="MMIX-Chars"> |
| <link rel="next" href="MMIX_002dRegs.html#MMIX_002dRegs" title="MMIX-Regs"> |
| <link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage"> |
| <!-- |
| This file documents the GNU Assembler "as". |
| |
| Copyright (C) 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, |
| 2000, 2001, 2002, 2006, 2007, 2008, 2009, 2010 Free Software Foundation, Inc. |
| |
| Permission is granted to copy, distribute and/or modify this document |
| under the terms of the GNU Free Documentation License, Version 1.3 |
| or any later version published by the Free Software Foundation; |
| with no Invariant Sections, with no Front-Cover Texts, and with no |
| Back-Cover Texts. A copy of the license is included in the |
| section entitled ``GNU Free Documentation License''. |
| |
| --> |
| <meta http-equiv="Content-Style-Type" content="text/css"> |
| <style type="text/css"><!-- |
| pre.display { font-family:inherit } |
| pre.format { font-family:inherit } |
| pre.smalldisplay { font-family:inherit; font-size:smaller } |
| pre.smallformat { font-family:inherit; font-size:smaller } |
| pre.smallexample { font-size:smaller } |
| pre.smalllisp { font-size:smaller } |
| span.sc { font-variant:small-caps } |
| span.roman { font-family:serif; font-weight:normal; } |
| span.sansserif { font-family:sans-serif; font-weight:normal; } |
| --></style> |
| <link rel="stylesheet" type="text/css" href="../cs.css"> |
| </head> |
| <body> |
| <div class="node"> |
| <a name="MMIX-Symbols"></a> |
| <a name="MMIX_002dSymbols"></a> |
| <p> |
| Next: <a rel="next" accesskey="n" href="MMIX_002dRegs.html#MMIX_002dRegs">MMIX-Regs</a>, |
| Previous: <a rel="previous" accesskey="p" href="MMIX_002dChars.html#MMIX_002dChars">MMIX-Chars</a>, |
| Up: <a rel="up" accesskey="u" href="MMIX_002dSyntax.html#MMIX_002dSyntax">MMIX-Syntax</a> |
| <hr> |
| </div> |
| |
| <h5 class="subsubsection">9.25.3.2 Symbols</h5> |
| |
| <p>The character ‘<samp><span class="samp">:</span></samp>’ is permitted in identifiers. There are two |
| exceptions to it being treated as any other symbol character: if a symbol |
| begins with ‘<samp><span class="samp">:</span></samp>’, it means that the symbol is in the global namespace |
| and that the current prefix should not be prepended to that symbol |
| (see <a href="MMIX_002dprefix.html#MMIX_002dprefix">MMIX-prefix</a>). The ‘<samp><span class="samp">:</span></samp>’ is then not considered part of the |
| symbol. For a symbol in the label position (first on a line), a ‘<samp><span class="samp">:</span></samp>’ |
| at the end of a symbol is silently stripped off. A label is permitted, |
| but not required, to be followed by a ‘<samp><span class="samp">:</span></samp>’, as with many other |
| assembly formats. |
| |
| <p>The character ‘<samp><span class="samp">@</span></samp>’ in an expression, is a synonym for ‘<samp><span class="samp">.</span></samp>’, the |
| current location. |
| |
| <p>In addition to the common forward and backward local symbol formats |
| (see <a href="Symbol-Names.html#Symbol-Names">Symbol Names</a>), they can be specified with upper-case ‘<samp><span class="samp">B</span></samp>’ and |
| ‘<samp><span class="samp">F</span></samp>’, as in ‘<samp><span class="samp">8B</span></samp>’ and ‘<samp><span class="samp">9F</span></samp>’. A local label defined for the |
| current position is written with a ‘<samp><span class="samp">H</span></samp>’ appended to the number: |
| <pre class="smallexample"> 3H LDB $0,$1,2 |
| </pre> |
| <p>This and traditional local-label formats cannot be mixed: a label must be |
| defined and referred to using the same format. |
| |
| <p>There's a minor caveat: just as for the ordinary local symbols, the local |
| symbols are translated into ordinary symbols using control characters are |
| to hide the ordinal number of the symbol. Unfortunately, these symbols |
| are not translated back in error messages. Thus you may see confusing |
| error messages when local symbols are used. Control characters |
| ‘<samp><span class="samp">\003</span></samp>’ (control-C) and ‘<samp><span class="samp">\004</span></samp>’ (control-D) are used for the |
| MMIX-specific local-symbol syntax. |
| |
| <p>The symbol ‘<samp><span class="samp">Main</span></samp>’ is handled specially; it is always global. |
| |
| <p>By defining the symbols ‘<samp><span class="samp">__.MMIX.start..text</span></samp>’ and |
| ‘<samp><span class="samp">__.MMIX.start..data</span></samp>’, the address of respectively the ‘<samp><span class="samp">.text</span></samp>’ |
| and ‘<samp><span class="samp">.data</span></samp>’ segments of the final program can be defined, though when |
| linking more than one object file, the code or data in the object file |
| containing the symbol is not guaranteed to be start at that position; just |
| the final executable. See <a href="MMIX_002dloc.html#MMIX_002dloc">MMIX-loc</a>. |
| |
| </body></html> |
| |