ePenguin-Software-Framework/toolchains/riscv/share/doc/gcc/Epiphany-Function-Attribute...

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<!-- Copyright (C) 1988-2018 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 the
Invariant Sections being "Funding Free Software", the Front-Cover
Texts being (a) (see below), and with the Back-Cover Texts being (b)
(see below).  A copy of the license is included in the section entitled
"GNU Free Documentation License".

(a) The FSF's Front-Cover Text is:

A GNU Manual

(b) The FSF's Back-Cover Text is:

You have freedom to copy and modify this GNU Manual, like GNU
     software.  Copies published by the Free Software Foundation raise
     funds for GNU development. -->
<!-- Created by GNU Texinfo 6.4, http://www.gnu.org/software/texinfo/ -->
<head>
<title>Epiphany Function Attributes (Using the GNU Compiler Collection (GCC))</title>

<meta name="description" content="Epiphany Function Attributes (Using the GNU Compiler Collection (GCC))">
<meta name="keywords" content="Epiphany Function Attributes (Using the GNU Compiler Collection (GCC))">
<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="Option-Index.html#Option-Index" rel="index" title="Option Index">
<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
<link href="Function-Attributes.html#Function-Attributes" rel="up" title="Function Attributes">
<link href="H8_002f300-Function-Attributes.html#H8_002f300-Function-Attributes" rel="next" title="H8/300 Function Attributes">
<link href="CR16-Function-Attributes.html#CR16-Function-Attributes" rel="prev" title="CR16 Function Attributes">
<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="Epiphany-Function-Attributes"></a>
<div class="header">
<p>
Next: <a href="H8_002f300-Function-Attributes.html#H8_002f300-Function-Attributes" accesskey="n" rel="next">H8/300 Function Attributes</a>, Previous: <a href="CR16-Function-Attributes.html#CR16-Function-Attributes" accesskey="p" rel="prev">CR16 Function Attributes</a>, Up: <a href="Function-Attributes.html#Function-Attributes" accesskey="u" rel="up">Function Attributes</a> &nbsp; [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Option-Index.html#Option-Index" title="Index" rel="index">Index</a>]</p>
</div>
<hr>
<a name="Epiphany-Function-Attributes-1"></a>
<h4 class="subsection">6.31.8 Epiphany Function Attributes</h4>

<p>These function attributes are supported by the Epiphany back end:
</p>
<dl compact="compact">
<dt><code>disinterrupt</code></dt>
<dd><a name="index-disinterrupt-function-attribute_002c-Epiphany"></a>
<p>This attribute causes the compiler to emit
instructions to disable interrupts for the duration of the given
function.
</p>
</dd>
<dt><code>forwarder_section</code></dt>
<dd><a name="index-forwarder_005fsection-function-attribute_002c-Epiphany"></a>
<p>This attribute modifies the behavior of an interrupt handler.
The interrupt handler may be in external memory which cannot be
reached by a branch instruction, so generate a local memory trampoline
to transfer control.  The single parameter identifies the section where
the trampoline is placed.
</p>
</dd>
<dt><code>interrupt</code></dt>
<dd><a name="index-interrupt-function-attribute_002c-Epiphany"></a>
<p>Use this attribute to indicate
that the specified function is an interrupt handler.  The compiler generates
function entry and exit sequences suitable for use in an interrupt handler
when this attribute is present.  It may also generate
a special section with code to initialize the interrupt vector table.
</p>
<p>On Epiphany targets one or more optional parameters can be added like this:
</p>
<div class="smallexample">
<pre class="smallexample">void __attribute__ ((interrupt (&quot;dma0, dma1&quot;))) universal_dma_handler ();
</pre></div>

<p>Permissible values for these parameters are: <code>reset</code><!-- /@w -->,
<code><span class="nolinebreak">software_exception</span></code><!-- /@w -->, <code><span class="nolinebreak">page_miss</span></code><!-- /@w -->,
<code>timer0</code><!-- /@w -->, <code>timer1</code><!-- /@w -->, <code>message</code><!-- /@w -->,
<code>dma0</code><!-- /@w -->, <code>dma1</code><!-- /@w -->, <code>wand</code><!-- /@w --> and <code>swi</code><!-- /@w -->.
Multiple parameters indicate that multiple entries in the interrupt
vector table should be initialized for this function, i.e. for each
parameter <var>name</var><!-- /@w -->, a jump to the function is emitted in
the section <span class="nolinebreak">ivt_entry_</span><var>name</var><!-- /@w -->.  The parameter(s) may be omitted
entirely, in which case no interrupt vector table entry is provided.
</p>
<p>Note that interrupts are enabled inside the function
unless the <code>disinterrupt</code> attribute is also specified.
</p>
<p>The following examples are all valid uses of these attributes on
Epiphany targets:
</p><div class="smallexample">
<pre class="smallexample">void __attribute__ ((interrupt)) universal_handler ();
void __attribute__ ((interrupt (&quot;dma1&quot;))) dma1_handler ();
void __attribute__ ((interrupt (&quot;dma0, dma1&quot;)))
  universal_dma_handler ();
void __attribute__ ((interrupt (&quot;timer0&quot;), disinterrupt))
  fast_timer_handler ();
void __attribute__ ((interrupt (&quot;dma0, dma1&quot;),
                     forwarder_section (&quot;tramp&quot;)))
  external_dma_handler ();
</pre></div>

</dd>
<dt><code>long_call</code></dt>
<dt><code>short_call</code></dt>
<dd><a name="index-long_005fcall-function-attribute_002c-Epiphany"></a>
<a name="index-short_005fcall-function-attribute_002c-Epiphany"></a>
<a name="index-indirect-calls_002c-Epiphany"></a>
<p>These attributes specify how a particular function is called.
These attributes override the
<samp>-mlong-calls</samp> (see <a href="Adapteva-Epiphany-Options.html#Adapteva-Epiphany-Options">Adapteva Epiphany Options</a>)
command-line switch and <code>#pragma long_calls</code> settings.
</p></dd>
</dl>


<hr>
<div class="header">
<p>
Next: <a href="H8_002f300-Function-Attributes.html#H8_002f300-Function-Attributes" accesskey="n" rel="next">H8/300 Function Attributes</a>, Previous: <a href="CR16-Function-Attributes.html#CR16-Function-Attributes" accesskey="p" rel="prev">CR16 Function Attributes</a>, Up: <a href="Function-Attributes.html#Function-Attributes" accesskey="u" rel="up">Function Attributes</a> &nbsp; [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Option-Index.html#Option-Index" title="Index" rel="index">Index</a>]</p>
</div>


</body>
</html>