html/303kernel-string.subx.html


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<a href='https://github.com/akkartik/mu/blob/main/303kernel-string.subx'>https://github.com/akkartik/mu/blob/main/303kernel-string.subx</a>
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<span id="L1" class="LineNr"> 1 </span><span class="subxComment"># We can't really do much with null-terminated kernel strings, and we don't</span>
<span id="L2" class="LineNr"> 2 </span><span class="subxComment"># want to. Let's turn them into regular length-prefixed strings at the first</span>
<span id="L3" class="LineNr"> 3 </span><span class="subxComment"># opportunity.</span>
<span id="L4" class="LineNr"> 4 </span>
<span id="L5" class="LineNr"> 5 </span>== code
<span id="L6" class="LineNr"> 6 </span>
<span id="L7" class="LineNr"> 7 </span><span class="subxFunction">kernel-string-to-string</span>:  <span class="subxComment"># ad: (addr allocation-descriptor), in: (addr kernel-string), out: (addr handle array byte)</span>
<span id="L8" class="LineNr"> 8 </span>    <span class="subxS1Comment"># . prologue</span>
<span id="L9" class="LineNr"> 9 </span>    55/push-ebp
<span id="L10" class="LineNr">10 </span>    89/&lt;- %ebp 4/r32/esp
<span id="L11" class="LineNr">11 </span>    <span class="subxS1Comment"># . save registers</span>
<span id="L12" class="LineNr">12 </span>    51/push-ecx
<span id="L13" class="LineNr">13 </span>    52/push-edx
<span id="L14" class="LineNr">14 </span>    53/push-ebx
<span id="L15" class="LineNr">15 </span>    56/push-esi
<span id="L16" class="LineNr">16 </span>    57/push-edi
<span id="L17" class="LineNr">17 </span>    <span class="subxComment"># var len/ecx: int = length(in)</span>
<span id="L18" class="LineNr">18 </span>    (<a href='303kernel-string.subx.html#L57'>kernel-string-length</a> *(ebp+0xc))
<span id="L19" class="LineNr">19 </span>    89/&lt;- %ecx 0/r32/eax
<span id="L20" class="LineNr">20 </span>    <span class="subxComment"># result = allocate-array(ad, len)</span>
<span id="L21" class="LineNr">21 </span>    (<a href='120allocate.subx.html#L576'>allocate-array</a> *(ebp+8) %ecx *(ebp+0x10))
<span id="L22" class="LineNr">22 </span>    <span class="subxComment"># var c/edx: byte = 0</span>
<span id="L23" class="LineNr">23 </span>    ba/copy-to-edx 0/imm32
<span id="L24" class="LineNr">24 </span>    <span class="subxComment"># var src/esi: (addr byte) = in</span>
<span id="L25" class="LineNr">25 </span>    8b/-&gt; *(ebp+0xc) 6/r32/esi
<span id="L26" class="LineNr">26 </span>    <span class="subxComment"># var dest/edi: (addr byte) = result-&gt;data</span>
<span id="L27" class="LineNr">27 </span>    8b/-&gt; *(ebp+0x10) 7/r32/edi
<span id="L28" class="LineNr">28 </span>    (<a href='120allocate.subx.html#L256'>lookup</a> *edi *(edi+4))  <span class="subxComment"># =&gt; eax</span>
<span id="L29" class="LineNr">29 </span>    8d/copy-address *(eax+4) 7/r32/edi
<span id="L30" class="LineNr">30 </span>    {
<span id="L31" class="LineNr">31 </span><span class="Constant">$kernel-string-to-string:loop</span>:
<span id="L32" class="LineNr">32 </span>      <span class="subxComment"># c = *src</span>
<span id="L33" class="LineNr">33 </span>      8a/byte-&gt; *esi 2/r32/dl
<span id="L34" class="LineNr">34 </span>      <span class="subxComment"># if (c == 0) break</span>
<span id="L35" class="LineNr">35 </span>      81 7/subop/compare %edx 0/imm32
<span id="L36" class="LineNr">36 </span>      74/jump-if-= <span class="Constant">break</span>/disp8
<span id="L37" class="LineNr">37 </span>      <span class="subxComment"># *dest = c</span>
<span id="L38" class="LineNr">38 </span>      88/byte&lt;- *edi 2/r32/dl
<span id="L39" class="LineNr">39 </span>      <span class="subxComment"># ++src</span>
<span id="L40" class="LineNr">40 </span>      46/increment-esi
<span id="L41" class="LineNr">41 </span>      <span class="subxComment"># ++dest</span>
<span id="L42" class="LineNr">42 </span>      47/increment-edi
<span id="L43" class="LineNr">43 </span>      eb/jump <span class="Constant">loop</span>/disp8
<span id="L44" class="LineNr">44 </span>    }
<span id="L45" class="LineNr">45 </span><span class="Constant">$kernel-string-to-string:end</span>:
<span id="L46" class="LineNr">46 </span>    <span class="subxS1Comment"># . restore registers</span>
<span id="L47" class="LineNr">47 </span>    5f/pop-to-edi
<span id="L48" class="LineNr">48 </span>    5e/pop-to-esi
<span id="L49" class="LineNr">49 </span>    5b/pop-to-ebx
<span id="L50" class="LineNr">50 </span>    5a/pop-to-edx
<span id="L51" class="LineNr">51 </span>    59/pop-to-ecx
<span id="L52" class="LineNr">52 </span>    <span class="subxS1Comment"># . epilogue</span>
<span id="L53" class="LineNr">53 </span>    89/&lt;- %esp 5/r32/ebp
<span id="L54" class="LineNr">54 </span>    5d/pop-to-ebp
<span id="L55" class="LineNr">55 </span>    c3/return
<span id="L56" class="LineNr">56 </span>
<span id="L57" class="LineNr">57 </span><span class="subxFunction">kernel-string-length</span>:  <span class="subxComment"># in: (addr kernel-string) -&gt; result/eax: int</span>
<span id="L58" class="LineNr">58 </span>    <span class="subxS1Comment"># . prologue</span>
<span id="L59" class="LineNr">59 </span>    55/push-ebp
<span id="L60" class="LineNr">60 </span>    89/&lt;- %ebp 4/r32/esp
<span id="L61" class="LineNr">61 </span>    <span class="subxS1Comment"># . save registers</span>
<span id="L62" class="LineNr">62 </span>    51/push-ecx
<span id="L63" class="LineNr">63 </span>    52/push-edx
<span id="L64" class="LineNr">64 </span>    <span class="subxComment"># result = 0</span>
<span id="L65" class="LineNr">65 </span>    b8/copy-to-eax 0/imm32
<span id="L66" class="LineNr">66 </span>    <span class="subxComment"># var c/ecx: byte = 0</span>
<span id="L67" class="LineNr">67 </span>    b9/copy-to-ecx 0/imm32
<span id="L68" class="LineNr">68 </span>    <span class="subxComment"># var curr/edx: (addr byte) = in</span>
<span id="L69" class="LineNr">69 </span>    8b/-&gt; *(ebp+8) 2/r32/edx
<span id="L70" class="LineNr">70 </span>    {
<span id="L71" class="LineNr">71 </span><span class="Constant">$kernel-string-length:loop</span>:
<span id="L72" class="LineNr">72 </span>      <span class="subxComment"># c = *curr</span>
<span id="L73" class="LineNr">73 </span>      8a/byte-&gt; *edx 1/r32/ecx
<span id="L74" class="LineNr">74 </span>      <span class="subxComment"># if (c == 0) break</span>
<span id="L75" class="LineNr">75 </span>      81 7/subop/compare %ecx 0/imm32
<span id="L76" class="LineNr">76 </span>      74/jump-if-= <span class="Constant">break</span>/disp8
<span id="L77" class="LineNr">77 </span>      <span class="subxComment"># ++curr</span>
<span id="L78" class="LineNr">78 </span>      42/increment-edx
<span id="L79" class="LineNr">79 </span>      <span class="subxComment"># ++result</span>
<span id="L80" class="LineNr">80 </span>      40/increment-eax
<span id="L81" class="LineNr">81 </span>      <span class="subxComment">#</span>
<span id="L82" class="LineNr">82 </span>      eb/jump <span class="Constant">loop</span>/disp8
<span id="L83" class="LineNr">83 </span>    }
<span id="L84" class="LineNr">84 </span><span class="Constant">$kernel-string-length:end</span>:
<span id="L85" class="LineNr">85 </span>    <span class="subxS1Comment"># . restore registers</span>
<span id="L86" class="LineNr">86 </span>    5a/pop-to-edx
<span id="L87" class="LineNr">87 </span>    59/pop-to-ecx
<span id="L88" class="LineNr">88 </span>    <span class="subxS1Comment"># . epilogue</span>
<span id="L89" class="LineNr">89 </span>    89/&lt;- %esp 5/r32/ebp
<span id="L90" class="LineNr">90 </span>    5d/pop-to-ebp
<span id="L91" class="LineNr">91 </span>    c3/return
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