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<header id="title-block-header">
<h1 class="title">README</h1>
</header>
<h1 id="stack-analysis-for-avr">Stack analysis for AVR</h1>
<p>This crate provides helper functions for stack analysis on AVR
microcontrollers.</p>
<ul>
<li><strong>Stack Usage Estimation:</strong> Estimate the amount of
unused stack space.</li>
</ul>
<h2 id="usage">Usage</h2>
<p>This crate provides two main items:</p>
<ul>
<li><code>init_stack_pattern!()</code>: A macro to initialize the stack
with a known pattern. This must be called once in your application’s
main crate.</li>
<li><code>estimate_unused_stack_space()</code>: A function that returns
an estimate of the number of unused bytes on the stack.</li>
</ul>
<h3 id="example-cargo.toml">Example <code>Cargo.toml</code></h3>
<div class="sourceCode" id="cb1"><pre
class="sourceCode toml"><code class="sourceCode toml"><span id="cb1-1"><a href="#cb1-1" aria-hidden="true" tabindex="-1"></a><span class="kw">[dependencies]</span></span>
<span id="cb1-2"><a href="#cb1-2" aria-hidden="true" tabindex="-1"></a><span class="dt">avr_stack</span> <span class="op">=</span> <span class="st">"1"</span></span>
<span id="cb1-3"><a href="#cb1-3" aria-hidden="true" tabindex="-1"></a><span class="dt">avr_device</span> <span class="op">=</span> <span class="op">{ </span><span class="dt">version</span><span class="op"> =</span> <span class="st">"0.8"</span><span class="op">, </span><span class="dt">features</span><span class="op"> =</span> <span class="op">[</span> <span class="st">"atmega328p"</span><span class="op">,</span> <span class="st">"rt"</span><span class="op">,</span> <span class="st">"critical-section"</span> <span class="op">] }</span></span></code></pre></div>
<h3 id="example-code">Example code</h3>
<div class="sourceCode" id="cb2"><pre
class="sourceCode rust"><code class="sourceCode rust"><span id="cb2-1"><a href="#cb2-1" aria-hidden="true" tabindex="-1"></a><span class="at">#[</span><span class="pp">avr_device::</span>entry<span class="at">]</span></span>
<span id="cb2-2"><a href="#cb2-2" aria-hidden="true" tabindex="-1"></a><span class="kw">fn</span> main() <span class="op">-></span> <span class="op">!</span> <span class="op">{</span></span>
<span id="cb2-3"><a href="#cb2-3" aria-hidden="true" tabindex="-1"></a> <span class="cf">loop</span> <span class="op">{</span></span>
<span id="cb2-4"><a href="#cb2-4" aria-hidden="true" tabindex="-1"></a> <span class="co">// ...</span></span>
<span id="cb2-5"><a href="#cb2-5" aria-hidden="true" tabindex="-1"></a> <span class="kw">let</span> nr_unused_stack_bytes <span class="op">=</span> <span class="pp">avr_stack::</span>estimate_unused_stack_space()<span class="op">;</span></span>
<span id="cb2-6"><a href="#cb2-6" aria-hidden="true" tabindex="-1"></a> <span class="co">// ...</span></span>
<span id="cb2-7"><a href="#cb2-7" aria-hidden="true" tabindex="-1"></a> <span class="op">}</span></span>
<span id="cb2-8"><a href="#cb2-8" aria-hidden="true" tabindex="-1"></a><span class="op">}</span></span>
<span id="cb2-9"><a href="#cb2-9" aria-hidden="true" tabindex="-1"></a></span>
<span id="cb2-10"><a href="#cb2-10" aria-hidden="true" tabindex="-1"></a><span class="pp">avr_stack::init_stack_pattern!</span>()<span class="op">;</span></span></code></pre></div>
<h2 id="details-stack-usage-estimation">Details: Stack Usage
Estimation</h2>
<p>The <code>init_stack_pattern!</code> macro defines a function that
runs in the <code>.init4</code> section of the AVR’s program memory.
This function executes before <code>main</code> and fills the entire
stack with a pattern.</p>
<p>The <code>estimate_unused_stack_space()</code> function then walks
the stack from its end towards its beginning, counting the number of
bytes that still contain the initialization pattern. This provides an
estimate of how much stack space has never been touched.</p>
<h2 id="license">License</h2>
<p>This project is licensed under either:</p>
<ul>
<li>Apache License, Version 2.0 (<a
href="LICENSE-APACHE">LICENSE-APACHE</a> or
http://www.apache.org/licenses/LICENSE-2.0)</li>
<li>MIT License (<a href="LICENSE-MIT">LICENSE-MIT</a> or
http://opensource.org/licenses/MIT)</li>
</ul>
<p>at your option.</p>
<p>Copyright (C) 2025 - 2026 Michael Büsch <a href="mailto:m@bues.ch"
class="email">m@bues.ch</a></p>
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