<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <!-- This file documents the GNU Assembler "as". Copyright (C) 1991-2019 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". --> <!-- Created by GNU Texinfo 6.4, http://www.gnu.org/software/texinfo/ --> <head> <title>Literal Position Directive (Using as)</title> <meta name="description" content="Literal Position Directive (Using as)"> <meta name="keywords" content="Literal Position Directive (Using as)"> <meta name="resource-type" content="document"> <meta name="distribution" content="global"> <meta name="Generator" content="makeinfo"> <meta http-equiv="Content-Type" content="text/html; charset=utf-8"> <link href="index.html#Top" rel="start" title="Top"> <link href="AS-Index.html#AS-Index" rel="index" title="AS Index"> <link href="index.html#SEC_Contents" rel="contents" title="Table of Contents"> <link href="Xtensa-Directives.html#Xtensa-Directives" rel="up" title="Xtensa Directives"> <link href="Literal-Prefix-Directive.html#Literal-Prefix-Directive" rel="next" title="Literal Prefix Directive"> <link href="Literal-Directive.html#Literal-Directive" rel="prev" title="Literal Directive"> <style type="text/css"> <!-- a.summary-letter {text-decoration: none} blockquote.indentedblock {margin-right: 0em} blockquote.smallindentedblock {margin-right: 0em; font-size: smaller} blockquote.smallquotation {font-size: smaller} div.display {margin-left: 3.2em} div.example {margin-left: 3.2em} div.lisp {margin-left: 3.2em} div.smalldisplay {margin-left: 3.2em} div.smallexample {margin-left: 3.2em} div.smalllisp {margin-left: 3.2em} kbd {font-style: oblique} pre.display {font-family: inherit} pre.format {font-family: inherit} pre.menu-comment {font-family: serif} pre.menu-preformatted {font-family: serif} pre.smalldisplay {font-family: inherit; font-size: smaller} pre.smallexample {font-size: smaller} pre.smallformat {font-family: inherit; font-size: smaller} pre.smalllisp {font-size: smaller} span.nolinebreak {white-space: nowrap} span.roman {font-family: initial; font-weight: normal} span.sansserif {font-family: sans-serif; font-weight: normal} ul.no-bullet {list-style: none} --> </style> </head> <body lang="en"> <a name="Literal-Position-Directive"></a> <div class="header"> <p> Next: <a href="Literal-Prefix-Directive.html#Literal-Prefix-Directive" accesskey="n" rel="next">Literal Prefix Directive</a>, Previous: <a href="Literal-Directive.html#Literal-Directive" accesskey="p" rel="prev">Literal Directive</a>, Up: <a href="Xtensa-Directives.html#Xtensa-Directives" accesskey="u" rel="up">Xtensa Directives</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="AS-Index.html#AS-Index" title="Index" rel="index">Index</a>]</p> </div> <hr> <a name="literal_005fposition"></a> <h4 class="subsubsection">9.54.5.5 literal_position</h4> <a name="index-literal_005fposition-directive"></a> <p>When using ‘<samp>--text-section-literals</samp>’ to place literals inline in the section being assembled, the <code>.literal_position</code> directive can be used to mark a potential location for a literal pool. </p> <div class="smallexample"> <pre class="smallexample"> .literal_position </pre></div> <p>The <code>.literal_position</code> directive is ignored when the ‘<samp>--text-section-literals</samp>’ option is not used or when <code>L32R</code> instructions use the absolute addressing mode. </p> <p>The assembler will automatically place text section literal pools before <code>ENTRY</code> instructions, so the <code>.literal_position</code> directive is only needed to specify some other location for a literal pool. You may need to add an explicit jump instruction to skip over an inline literal pool. </p> <p>For example, an interrupt vector does not begin with an <code>ENTRY</code> instruction so the assembler will be unable to automatically find a good place to put a literal pool. Moreover, the code for the interrupt vector must be at a specific starting address, so the literal pool cannot come before the start of the code. The literal pool for the vector must be explicitly positioned in the middle of the vector (before any uses of the literals, due to the negative offsets used by PC-relative <code>L32R</code> instructions). The <code>.literal_position</code> directive can be used to do this. In the following code, the literal for ‘<samp>M</samp>’ will automatically be aligned correctly and is placed after the unconditional jump. </p> <div class="smallexample"> <pre class="smallexample"> .global M code_start: </pre><pre class="smallexample"> j continue .literal_position .align 4 </pre><pre class="smallexample">continue: movi a4, M </pre></div> </body> </html>