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<a href='https://github.com/akkartik/mu/blob/master/310copy-bytes.subx'>https://github.com/akkartik/mu/blob/master/310copy-bytes.subx</a>
<pre id='vimCodeElement'>
<span id="L1" class="LineNr"> 1 </span><span class="subxComment"># Fill a region of memory with zeroes.</span>
<span id="L2" class="LineNr"> 2 </span>
<span id="L3" class="LineNr"> 3 </span>== code
<span id="L4" class="LineNr"> 4 </span>
<span id="L5" class="LineNr"> 5 </span><span class="subxFunction">copy-bytes</span>:  <span class="subxComment"># src: (addr byte), dest: (addr byte), size: int</span>
<span id="L6" class="LineNr"> 6 </span>    <span class="subxComment"># pseudocode:</span>
<span id="L7" class="LineNr"> 7 </span>    <span class="subxComment">#   curr-src/esi = src</span>
<span id="L8" class="LineNr"> 8 </span>    <span class="subxComment">#   curr-dest/edi = dest</span>
<span id="L9" class="LineNr"> 9 </span>    <span class="subxComment">#   i/ecx = 0</span>
<span id="L10" class="LineNr">10 </span>    <span class="subxComment">#   while true</span>
<span id="L11" class="LineNr">11 </span>    <span class="subxComment">#     if (i &gt;= size) break</span>
<span id="L12" class="LineNr">12 </span>    <span class="subxComment">#     *curr-dest = *curr-src</span>
<span id="L13" class="LineNr">13 </span>    <span class="subxComment">#     ++curr-src</span>
<span id="L14" class="LineNr">14 </span>    <span class="subxComment">#     ++curr-dest</span>
<span id="L15" class="LineNr">15 </span>    <span class="subxComment">#     ++i</span>
<span id="L16" class="LineNr">16 </span>    <span class="subxComment">#</span>
<span id="L17" class="LineNr">17 </span>    <span class="subxS1Comment"># . prologue</span>
<span id="L18" class="LineNr">18 </span>    55/push-ebp
<span id="L19" class="LineNr">19 </span>    89/&lt;- %ebp 4/r32/esp
<span id="L20" class="LineNr">20 </span>    <span class="subxS1Comment"># . save registers</span>
<span id="L21" class="LineNr">21 </span>    50/push-eax
<span id="L22" class="LineNr">22 </span>    51/push-ecx
<span id="L23" class="LineNr">23 </span>    52/push-edx
<span id="L24" class="LineNr">24 </span>    56/push-esi
<span id="L25" class="LineNr">25 </span>    57/push-edi
<span id="L26" class="LineNr">26 </span>    <span class="subxComment"># curr-src/esi = src</span>
<span id="L27" class="LineNr">27 </span>    8b/-&gt; *(ebp+8) 6/r32/esi
<span id="L28" class="LineNr">28 </span>    <span class="subxComment"># curr-dest/edi = dest</span>
<span id="L29" class="LineNr">29 </span>    8b/-&gt; *(ebp+0xc) 7/r32/edi
<span id="L30" class="LineNr">30 </span>    <span class="subxComment"># var i/ecx: int = 0</span>
<span id="L31" class="LineNr">31 </span>    b9/copy-to-ecx 0/imm32
<span id="L32" class="LineNr">32 </span>    <span class="subxComment"># edx = size</span>
<span id="L33" class="LineNr">33 </span>    8b/-&gt; *(ebp+0x10) 2/r32/edx
<span id="L34" class="LineNr">34 </span>    {
<span id="L35" class="LineNr">35 </span>      <span class="subxComment"># if (i &gt;= size) break</span>
<span id="L36" class="LineNr">36 </span>      39/compare %ecx 2/r32/edx
<span id="L37" class="LineNr">37 </span>      7d/jump-if-&gt;=  <span class="Constant">break</span>/disp8
<span id="L38" class="LineNr">38 </span>      <span class="subxComment"># *curr-dest = *curr-src</span>
<span id="L39" class="LineNr">39 </span>      8a/byte-&gt; *esi 0/r32/AL
<span id="L40" class="LineNr">40 </span>      88/byte&lt;- *edi 0/r32/AL
<span id="L41" class="LineNr">41 </span>      <span class="subxComment"># update</span>
<span id="L42" class="LineNr">42 </span>      46/increment-esi
<span id="L43" class="LineNr">43 </span>      47/increment-edi
<span id="L44" class="LineNr">44 </span>      41/increment-ecx
<span id="L45" class="LineNr">45 </span>      eb/jump <span class="Constant">loop</span>/disp8
<span id="L46" class="LineNr">46 </span>    }
<span id="L47" class="LineNr">47 </span><span class="Constant">$copy-bytes:end</span>:
<span id="L48" class="LineNr">48 </span>    <span class="subxS1Comment"># . restore registers</span>
<span id="L49" class="LineNr">49 </span>    5f/pop-to-edi
<span id="L50" class="LineNr">50 </span>    5e/pop-to-esi
<span id="L51" class="LineNr">51 </span>    5a/pop-to-edx
<span id="L52" class="LineNr">52 </span>    59/pop-to-ecx
<span id="L53" class="LineNr">53 </span>    58/pop-to-eax
<span id="L54" class="LineNr">54 </span>    <span class="subxS1Comment"># . epilogue</span>
<span id="L55" class="LineNr">55 </span>    89/&lt;- %esp 5/r32/ebp
<span id="L56" class="LineNr">56 </span>    5d/pop-to-ebp
<span id="L57" class="LineNr">57 </span>    c3/return
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