html/linux/bootstrap/021div.cc.html


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<a href='https://github.com/akkartik/mu/blob/main/linux/bootstrap/021div.cc'>https://github.com/akkartik/mu/blob/main/linux/bootstrap/021div.cc</a>
<pre id='vimCodeElement'>
<span id="L1" class="LineNr"> 1 </span><span class="Comment">//: helper for division operations: sign-extend EAX into EDX</span>
<span id="L2" class="LineNr"> 2 </span>
<span id="L3" class="LineNr"> 3 </span><span class="Delimiter">:(before &quot;End Initialize Op Names&quot;)</span>
<span id="L4" class="LineNr"> 4 </span><a href='001help.cc.html#L237'>put_new</a><span class="Delimiter">(</span><a href='010vm.cc.html#L355'>Name</a><span class="Delimiter">,</span> <span class="Constant">&quot;99&quot;</span><span class="Delimiter">,</span> <span class="Constant">&quot;sign-extend <a href='010vm.cc.html#L10'>EAX</a> into <a href='010vm.cc.html#L12'>EDX</a> (cdq)&quot;</span><span class="Delimiter">);</span>
<span id="L5" class="LineNr"> 5 </span>
<span id="L6" class="LineNr"> 6 </span><span class="Delimiter">:(code)</span>
<span id="L7" class="LineNr"> 7 </span><span class="Normal">void</span> <a href='021div.cc.html#L7'>test_cdq</a><span class="Delimiter">()</span> <span class="Delimiter">{</span>
<span id="L8" class="LineNr"> 8 </span>  Reg[EAX]<span class="Delimiter">.</span>i = <span class="Constant">10</span><span class="Delimiter">;</span>
<span id="L9" class="LineNr"> 9 </span>  <a href='011run.cc.html#L82'>run</a><span class="Delimiter">(</span>
<span id="L10" class="LineNr">10 </span>      <span class="Constant">&quot;== code 0x1</span><span class="cSpecial">\n</span><span class="Constant">&quot;</span>
<span id="L11" class="LineNr">11 </span>      <span class="Constant">&quot;99</span><span class="cSpecial">\n</span><span class="Constant">&quot;</span>
<span id="L12" class="LineNr">12 </span>  <span class="Delimiter">);</span>
<span id="L13" class="LineNr">13 </span>  <a href='003trace.cc.html#L290'>CHECK_TRACE_CONTENTS</a><span class="Delimiter">(</span>
<span id="L14" class="LineNr">14 </span>      <span class="Constant">&quot;run: sign-extend <a href='010vm.cc.html#L10'>EAX</a> into <a href='010vm.cc.html#L12'>EDX</a></span><span class="cSpecial">\n</span><span class="Constant">&quot;</span>
<span id="L15" class="LineNr">15 </span>      <span class="Constant">&quot;run: <a href='010vm.cc.html#L12'>EDX</a> is now 0x00000000</span><span class="cSpecial">\n</span><span class="Constant">&quot;</span>
<span id="L16" class="LineNr">16 </span>  <span class="Delimiter">);</span>
<span id="L17" class="LineNr">17 </span><span class="Delimiter">}</span>
<span id="L18" class="LineNr">18 </span>
<span id="L19" class="LineNr">19 </span><span class="Delimiter">:(before &quot;End Single-Byte Opcodes&quot;)</span>
<span id="L20" class="LineNr">20 </span><span class="Normal">case</span> <span class="Constant">0x99</span>: <span class="Delimiter">{</span>  <span class="Comment">// sign-extend EAX into EDX</span>
<span id="L21" class="LineNr">21 </span>  <a href='003trace.cc.html#L96'>trace</a><span class="Delimiter">(</span>Callstack_depth+<span class="Constant">1</span><span class="Delimiter">,</span> <span class="Constant">&quot;run&quot;</span><span class="Delimiter">)</span> &lt;&lt; <span class="Constant">&quot;sign-extend <a href='010vm.cc.html#L10'>EAX</a> into EDX&quot;</span> &lt;&lt; end<span class="Delimiter">();</span>
<span id="L22" class="LineNr">22 </span>  Reg[EDX]<span class="Delimiter">.</span>i = <span class="Delimiter">(</span>Reg[EAX]<span class="Delimiter">.</span>i &lt; <span class="Constant">0</span><span class="Delimiter">)</span> ? -<span class="Constant">1</span> : <span class="Constant">0</span><span class="Delimiter">;</span>
<span id="L23" class="LineNr">23 </span>  <a href='003trace.cc.html#L96'>trace</a><span class="Delimiter">(</span>Callstack_depth+<span class="Constant">1</span><span class="Delimiter">,</span> <span class="Constant">&quot;run&quot;</span><span class="Delimiter">)</span> &lt;&lt; <span class="Constant">&quot;EDX is now 0x&quot;</span> &lt;&lt; <a href='010vm.cc.html#L408'>HEXWORD</a> &lt;&lt; Reg[EDX]<span class="Delimiter">.</span>u &lt;&lt; end<span class="Delimiter">();</span>
<span id="L24" class="LineNr">24 </span>  <span class="Identifier">break</span><span class="Delimiter">;</span>
<span id="L25" class="LineNr">25 </span><span class="Delimiter">}</span>
<span id="L26" class="LineNr">26 </span>
<span id="L27" class="LineNr">27 </span><span class="Delimiter">:(code)</span>
<span id="L28" class="LineNr">28 </span><span class="Normal">void</span> <a href='021div.cc.html#L28'>test_cdq_negative</a><span class="Delimiter">()</span> <span class="Delimiter">{</span>
<span id="L29" class="LineNr">29 </span>  Reg[EAX]<span class="Delimiter">.</span>i = -<span class="Constant">10</span><span class="Delimiter">;</span>
<span id="L30" class="LineNr">30 </span>  <a href='011run.cc.html#L82'>run</a><span class="Delimiter">(</span>
<span id="L31" class="LineNr">31 </span>      <span class="Constant">&quot;== code 0x1</span><span class="cSpecial">\n</span><span class="Constant">&quot;</span>
<span id="L32" class="LineNr">32 </span>      <span class="Constant">&quot;99</span><span class="cSpecial">\n</span><span class="Constant">&quot;</span>
<span id="L33" class="LineNr">33 </span>  <span class="Delimiter">);</span>
<span id="L34" class="LineNr">34 </span>  <a href='003trace.cc.html#L290'>CHECK_TRACE_CONTENTS</a><span class="Delimiter">(</span>
<span id="L35" class="LineNr">35 </span>      <span class="Constant">&quot;run: sign-extend <a href='010vm.cc.html#L10'>EAX</a> into <a href='010vm.cc.html#L12'>EDX</a></span><span class="cSpecial">\n</span><span class="Constant">&quot;</span>
<span id="L36" class="LineNr">36 </span>      <span class="Constant">&quot;run: <a href='010vm.cc.html#L12'>EDX</a> is now 0xffffffff</span><span class="cSpecial">\n</span><span class="Constant">&quot;</span>
<span id="L37" class="LineNr">37 </span>  <span class="Delimiter">);</span>
<span id="L38" class="LineNr">38 </span><span class="Delimiter">}</span>
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