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<!DOCTYPE html><html lang="en"><head><meta charset="utf-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><meta name="generator" content="rustdoc"><meta name="description" content="API documentation for the Rust `exception` macro in crate `cortex_m_rt`."><meta name="keywords" content="rust, rustlang, rust-lang, exception"><title>cortex_m_rt::exception - Rust</title><link rel="stylesheet" type="text/css" href="../normalize.css"><link rel="stylesheet" type="text/css" href="../rustdoc.css" id="mainThemeStyle"><link rel="stylesheet" type="text/css" href="../dark.css"><link rel="stylesheet" type="text/css" href="../light.css" id="themeStyle"><script src="../storage.js"></script></head><body class="rustdoc macro"><!--[if lte IE 8]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><nav class="sidebar"><div class="sidebar-menu">&#9776;</div><div class="sidebar-elems"><p class='location'><a href='index.html'>cortex_m_rt</a></p><script>window.sidebarCurrent = {name: 'exception', ty: 'macro', relpath: ''};</script><script defer src="sidebar-items.js"></script></div></nav><div class="theme-picker"><button id="theme-picker" aria-label="Pick another theme!"><img src="../brush.svg" width="18" alt="Pick another theme!"></button><div id="theme-choices"></div></div><script src="../theme.js"></script><nav class="sub"><form class="search-form js-only"><div class="search-container"><input class="search-input" name="search" autocomplete="off" placeholder="Click or press S to search, ? for more options…" type="search"><a id="settings-menu" href="../settings.html"><img src="../wheel.svg" width="18" alt="Change settings"></a></div></form></nav><section id="main" class="content"><h1 class='fqn'><span class='out-of-band'><span id='render-detail'><a id="toggle-all-docs" href="javascript:void(0)" title="collapse all docs">[<span class='inner'>&#x2212;</span>]</a></span><a class='srclink' href='../src/cortex_m_rt/lib.rs.html#832-894' title='goto source code'>[src]</a></span><span class='in-band'>Macro <a href='index.html'>cortex_m_rt</a>::<wbr><a class="macro" href=''>exception</a></span></h1><div class="docblock type-decl"><pre class="rust macro">
<span class="macro">macro_rules</span><span class="macro">!</span> <span class="ident">exception</span> {
(<span class="op">*</span> , <span class="macro-nonterminal">$</span><span class="macro-nonterminal">handler</span>:<span class="ident">expr</span>) <span class="op">=&gt;</span> { ... };
(<span class="ident">HardFault</span>, <span class="macro-nonterminal">$</span><span class="macro-nonterminal">handler</span>:<span class="ident">expr</span>) <span class="op">=&gt;</span> { ... };
(<span class="macro-nonterminal">$</span><span class="macro-nonterminal">Name</span>:<span class="ident">ident</span>, <span class="macro-nonterminal">$</span><span class="macro-nonterminal">handler</span>:<span class="ident">expr</span>,<span class="ident">state</span>: <span class="macro-nonterminal">$</span><span class="macro-nonterminal">State</span>:<span class="ident">ty</span> <span class="op">=</span> <span class="macro-nonterminal">$</span><span class="macro-nonterminal">initial_state</span>:<span class="ident">expr</span>) <span class="op">=&gt;</span> { ... };
(<span class="macro-nonterminal">$</span><span class="macro-nonterminal">Name</span>:<span class="ident">ident</span>, <span class="macro-nonterminal">$</span><span class="macro-nonterminal">handler</span>:<span class="ident">expr</span>) <span class="op">=&gt;</span> { ... };
}</pre>
</div><div class='docblock'><p>Macro to set or override a processor core exception handler</p>
<p><strong>NOTE</strong> This macro must be invoked from an accessible module, ideally from the root of the
crate.</p>
<h1 id="syntax" class="section-header"><a href="#syntax">Syntax</a></h1>
<div class='information'><div class='tooltip ignore'><span class='tooltiptext'>This example is not tested</span></div></div><pre class="rust rust-example-rendered ignore">
<span class="macro">exception</span><span class="macro">!</span>(
<span class="comment">// Name of the exception</span>
<span class="macro-nonterminal">$</span><span class="macro-nonterminal">Name</span>:<span class="ident">ident</span>,
<span class="comment">// Path to the exception handler (a function)</span>
<span class="macro-nonterminal">$</span><span class="macro-nonterminal">handler</span>:<span class="ident">expr</span>,
<span class="comment">// Optional, state preserved across invocations of the handler</span>
<span class="ident">state</span>: <span class="macro-nonterminal">$</span><span class="macro-nonterminal">State</span>:<span class="ident">ty</span> <span class="op">=</span> <span class="macro-nonterminal">$</span><span class="macro-nonterminal">initial_state</span>:<span class="ident">expr</span>,
);</pre>
<p>where <code>$Name</code> can be one of:</p>
<ul>
<li><code>*</code></li>
<li><code>NonMaskableInt</code></li>
<li><code>HardFault</code></li>
<li><code>MemoryManagement</code> (a)</li>
<li><code>BusFault</code> (a)</li>
<li><code>UsageFault</code> (a)</li>
<li><code>SecureFault</code> (b)</li>
<li><code>SVCall</code></li>
<li><code>DebugMonitor</code> (a)</li>
<li><code>PendSV</code></li>
<li><code>SysTick</code></li>
</ul>
<p>(a) Not available on Cortex-M0 variants (<code>thumbv6m-none-eabi</code>)</p>
<p>(b) Only available on ARMv8-M</p>
<h1 id="usage" class="section-header"><a href="#usage">Usage</a></h1>
<p><code>exception!(HardFault, ..)</code> sets the hard fault handler. The handler must have signature
<code>fn(&amp;ExceptionFrame) -&gt; !</code>. This handler is not allowed to return as that can cause undefined
behavior. It's mandatory to set the <code>HardFault</code> handler somewhere in the dependency graph of an
application.</p>
<p><code>exception!(*, ..)</code> sets the <em>default</em> handler. All exceptions which have not been assigned a
handler will be serviced by this handler. This handler must have signature <code>fn(irqn: i16)</code>.
<code>irqn</code> is the IRQ number (cf. CMSIS); <code>irqn</code> will be a negative number when the handler is
servicing a core exception; <code>irqn</code> will be a positive number when the handler is servicing a
device specific exception (interrupt). It's mandatory to set the default handler somewhere
in the dependency graph of an application.</p>
<p><code>exception!($Exception, ..)</code> overrides the default handler for <code>$Exception</code>. All exceptions,
except for <code>HardFault</code>, can be assigned some <code>$State</code>.</p>
<h1 id="examples" class="section-header"><a href="#examples">Examples</a></h1>
<ul>
<li>Setting the <code>HardFault</code> handler</li>
</ul>
<pre class="rust rust-example-rendered">
<span class="attribute">#[<span class="ident">macro_use</span>(<span class="ident">exception</span>)]</span>
<span class="kw">extern</span> <span class="kw">crate</span> <span class="ident">cortex_m_rt</span> <span class="kw">as</span> <span class="ident">rt</span>;
<span class="kw">use</span> <span class="ident">rt</span>::<span class="ident">ExceptionFrame</span>;
<span class="macro">exception</span><span class="macro">!</span>(<span class="ident">HardFault</span>, <span class="ident">hard_fault</span>);
<span class="kw">fn</span> <span class="ident">hard_fault</span>(<span class="ident">ef</span>: <span class="kw-2">&amp;</span><span class="ident">ExceptionFrame</span>) <span class="op">-&gt;</span> <span class="op">!</span> {
<span class="comment">// prints the exception frame as a panic message</span>
<span class="macro">panic</span><span class="macro">!</span>(<span class="string">&quot;{:#?}&quot;</span>, <span class="ident">ef</span>);
}
</pre>
<ul>
<li>Setting the default handler</li>
</ul>
<pre class="rust rust-example-rendered">
<span class="attribute">#[<span class="ident">macro_use</span>(<span class="ident">exception</span>)]</span>
<span class="kw">extern</span> <span class="kw">crate</span> <span class="ident">cortex_m_rt</span> <span class="kw">as</span> <span class="ident">rt</span>;
<span class="macro">exception</span><span class="macro">!</span>(<span class="kw-2">*</span>, <span class="ident">default_handler</span>);
<span class="kw">fn</span> <span class="ident">default_handler</span>(<span class="ident">irqn</span>: <span class="ident">i16</span>) {
<span class="macro">println</span><span class="macro">!</span>(<span class="string">&quot;IRQn = {}&quot;</span>, <span class="ident">irqn</span>);
}
</pre>
<ul>
<li>Overriding the <code>SysTick</code> handler</li>
</ul>
<pre class="rust rust-example-rendered">
<span class="attribute">#[<span class="ident">macro_use</span>(<span class="ident">exception</span>)]</span>
<span class="kw">extern</span> <span class="kw">crate</span> <span class="ident">cortex_m_rt</span> <span class="kw">as</span> <span class="ident">rt</span>;
<span class="macro">exception</span><span class="macro">!</span>(<span class="ident">SysTick</span>, <span class="ident">sys_tick</span>, <span class="ident">state</span>: <span class="ident">u32</span> <span class="op">=</span> <span class="number">0</span>);
<span class="kw">fn</span> <span class="ident">sys_tick</span>(<span class="ident">count</span>: <span class="kw-2">&amp;</span><span class="kw-2">mut</span> <span class="ident">u32</span>) {
<span class="macro">println</span><span class="macro">!</span>(<span class="string">&quot;count = {}&quot;</span>, <span class="kw-2">*</span><span class="ident">count</span>);
<span class="kw-2">*</span><span class="ident">count</span> <span class="op">+=</span> <span class="number">1</span>;
}
</pre>
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