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<a href='https://github.com/akkartik/mu/blob/master/subx/055stream.subx'>https://github.com/akkartik/mu/blob/master/subx/055stream.subx</a>
<pre id='vimCodeElement'>
<span id="L1" class="LineNr"> 1 </span><span class="subxComment"># streams: data structure for operating on arrays in a stateful manner</span>
<span id="L2" class="LineNr"> 2 </span><span class="subxComment">#</span>
<span id="L3" class="LineNr"> 3 </span><span class="subxComment"># A stream looks like this:</span>
<span id="L4" class="LineNr"> 4 </span><span class="subxComment">#   write : int  # index at which writes go</span>
<span id="L5" class="LineNr"> 5 </span><span class="subxComment">#   read : int  # index that we've read until</span>
<span id="L6" class="LineNr"> 6 </span><span class="subxComment">#   data : (array byte)  # prefixed by length as usual</span>
<span id="L7" class="LineNr"> 7 </span><span class="subxComment">#</span>
<span id="L8" class="LineNr"> 8 </span><span class="subxComment"># some primitives for operating on streams:</span>
<span id="L9" class="LineNr"> 9 </span><span class="subxComment">#   - clear-stream (clears everything but the data length)</span>
<span id="L10" class="LineNr">10 </span><span class="subxComment">#   - rewind-stream (resets read pointer)</span>
<span id="L11" class="LineNr">11 </span>
<span id="L12" class="LineNr">12 </span>== code
<span id="L13" class="LineNr">13 </span><span class="subxComment">#   instruction                     effective address                                                   register    displacement    immediate</span>
<span id="L14" class="LineNr">14 </span><span class="subxS1Comment"># . op          subop               mod             rm32          base        index         scale       r32</span>
<span id="L15" class="LineNr">15 </span><span class="subxS1Comment"># . 1-3 bytes   3 bits              2 bits          3 bits        3 bits      3 bits        2 bits      2 bits      0/1/2/4 bytes   0/1/2/4 bytes</span>
<span id="L16" class="LineNr">16 </span>
<span id="L17" class="LineNr">17 </span><span class="subxFunction">clear-stream</span>:  <span class="subxComment"># f : (address stream) -&gt; &lt;void&gt;</span>
<span id="L18" class="LineNr">18 </span>    <span class="subxS1Comment"># . prolog</span>
<span id="L19" class="LineNr">19 </span>    55/push-EBP
<span id="L20" class="LineNr">20 </span>    89/copy                         3/mod/direct    5/rm32/EBP   <span class="Normal"> . </span>         <span class="Normal"> . </span>           <span class="Normal"> . </span>          4/r32/ESP  <span class="Normal"> . </span>             <span class="Normal"> . </span>                <span class="subxComment"># copy ESP to EBP</span>
<span id="L21" class="LineNr">21 </span>    <span class="subxS1Comment"># . save registers</span>
<span id="L22" class="LineNr">22 </span>    50/push-EAX
<span id="L23" class="LineNr">23 </span>    51/push-ECX
<span id="L24" class="LineNr">24 </span>    <span class="subxComment"># EAX = f</span>
<span id="L25" class="LineNr">25 </span>    8b/copy                         1/mod/*+disp8   5/rm32/EBP   <span class="Normal"> . </span>         <span class="Normal"> . </span>                        0/r32/EAX   8/disp8        <span class="Normal"> . </span>                <span class="subxComment"># copy *(EBP+8) to EAX</span>
<span id="L26" class="LineNr">26 </span>    <span class="subxComment"># ECX = f-&gt;length</span>
<span id="L27" class="LineNr">27 </span>    8b/copy                         1/mod/*+disp8   0/rm32/EAX   <span class="Normal"> . </span>         <span class="Normal"> . </span>           <span class="Normal"> . </span>          1/r32/ECX   8/disp8        <span class="Normal"> . </span>                <span class="subxComment"># copy *(EAX+8) to ECX</span>
<span id="L28" class="LineNr">28 </span>    <span class="subxComment"># ECX = &amp;f-&gt;data[f-&gt;length]</span>
<span id="L29" class="LineNr">29 </span>    8d/copy-address                 1/mod/*+disp8   4/rm32/sib    0/base/EAX  1/index/ECX  <span class="Normal"> . </span>          1/r32/ECX   0xc/disp8      <span class="Normal"> . </span>                <span class="subxComment"># copy EAX+ECX+12 to ECX</span>
<span id="L30" class="LineNr">30 </span>    <span class="subxComment"># f-&gt;write = 0</span>
<span id="L31" class="LineNr">31 </span>    c7          0/subop/copy        0/mod/direct    0/rm32/EAX   <span class="Normal"> . </span>         <span class="Normal"> . </span>           <span class="Normal"> . </span>         <span class="Normal"> . </span>         <span class="Normal"> . </span>              0/imm32           <span class="subxComment"># copy to *EAX</span>
<span id="L32" class="LineNr">32 </span>    <span class="subxComment"># f-&gt;read = 0</span>
<span id="L33" class="LineNr">33 </span>    c7          0/subop/copy        1/mod/*+disp8   0/rm32/EAX   <span class="Normal"> . </span>         <span class="Normal"> . </span>           <span class="Normal"> . </span>         <span class="Normal"> . </span>          4/disp8         0/imm32           <span class="subxComment"># copy to *(EAX+4)</span>
<span id="L34" class="LineNr">34 </span>    <span class="subxComment"># EAX = f-&gt;data</span>
<span id="L35" class="LineNr">35 </span>    81          0/subop/add         3/mod/direct    0/rm32/EAX   <span class="Normal"> . </span>         <span class="Normal"> . </span>           <span class="Normal"> . </span>         <span class="Normal"> . </span>         <span class="Normal"> . </span>              0xc/imm32         <span class="subxComment"># add to EAX</span>
<span id="L36" class="LineNr">36 </span>    <span class="subxComment"># while (true)</span>
<span id="L37" class="LineNr">37 </span><span class="Constant">$clear-stream:loop</span>:
<span id="L38" class="LineNr">38 </span>    <span class="subxComment"># if (EAX &gt;= ECX) break</span>
<span id="L39" class="LineNr">39 </span>    39/compare                      3/mod/direct    0/rm32/EAX   <span class="Normal"> . </span>         <span class="Normal"> . </span>           <span class="Normal"> . </span>          1/r32/ECX  <span class="Normal"> . </span>             <span class="Normal"> . </span>                <span class="subxComment"># compare EAX with ECX</span>
<span id="L40" class="LineNr">40 </span>    73/jump-if-greater-or-equal-unsigned  $clear-stream:end/disp8
<span id="L41" class="LineNr">41 </span>    <span class="subxComment"># *EAX = 0</span>
<span id="L42" class="LineNr">42 </span>    c6          0/subop/copy        0/mod/direct    0/rm32/EAX   <span class="Normal"> . </span>         <span class="Normal"> . </span>           <span class="Normal"> . </span>         <span class="Normal"> . </span>         <span class="Normal"> . </span>              0/imm8            <span class="subxComment"># copy byte to *EAX</span>
<span id="L43" class="LineNr">43 </span>    <span class="subxComment"># ++EAX</span>
<span id="L44" class="LineNr">44 </span>    40/increment-EAX
<span id="L45" class="LineNr">45 </span>    eb/jump  $clear-stream:loop/disp8
<span id="L46" class="LineNr">46 </span><span class="Constant">$clear-stream:end</span>:
<span id="L47" class="LineNr">47 </span>    <span class="subxS1Comment"># . restore registers</span>
<span id="L48" class="LineNr">48 </span>    59/pop-to-ECX
<span id="L49" class="LineNr">49 </span>    58/pop-to-EAX
<span id="L50" class="LineNr">50 </span>    <span class="subxS1Comment"># . epilog</span>
<span id="L51" class="LineNr">51 </span>    89/copy                         3/mod/direct    4/rm32/ESP   <span class="Normal"> . </span>         <span class="Normal"> . </span>           <span class="Normal"> . </span>          5/r32/EBP  <span class="Normal"> . </span>             <span class="Normal"> . </span>                <span class="subxComment"># copy EBP to ESP</span>
<span id="L52" class="LineNr">52 </span>    5d/pop-to-EBP
<span id="L53" class="LineNr">53 </span>    c3/return
<span id="L54" class="LineNr">54 </span>
<span id="L55" class="LineNr">55 </span><span class="subxFunction">rewind-stream</span>:  <span class="subxComment"># f : (address stream) -&gt; &lt;void&gt;</span>
<span id="L56" class="LineNr">56 </span>    <span class="subxS1Comment"># . prolog</span>
<span id="L57" class="LineNr">57 </span>    55/push-EBP
<span id="L58" class="LineNr">58 </span>    89/copy                         3/mod/direct    5/rm32/EBP   <span class="Normal"> . </span>         <span class="Normal"> . </span>           <span class="Normal"> . </span>          4/r32/ESP  <span class="Normal"> . </span>             <span class="Normal"> . </span>                <span class="subxComment"># copy ESP to EBP</span>
<span id="L59" class="LineNr">59 </span>    <span class="subxS1Comment"># . save registers</span>
<span id="L60" class="LineNr">60 </span>    50/push-EAX
<span id="L61" class="LineNr">61 </span>    <span class="subxComment"># EAX = f</span>
<span id="L62" class="LineNr">62 </span>    8b/copy                         1/mod/*+disp8   5/rm32/EBP   <span class="Normal"> . </span>         <span class="Normal"> . </span>                        0/r32/EAX   8/disp8        <span class="Normal"> . </span>                <span class="subxComment"># copy *(EBP+8) to EAX</span>
<span id="L63" class="LineNr">63 </span>    <span class="subxComment"># f-&gt;read = 0</span>
<span id="L64" class="LineNr">64 </span>    c7          0/subop/copy        1/mod/*+disp8   0/rm32/EAX   <span class="Normal"> . </span>         <span class="Normal"> . </span>           <span class="Normal"> . </span>         <span class="Normal"> . </span>          4/disp8         0/imm32           <span class="subxComment"># copy to *(EAX+4)</span>
<span id="L65" class="LineNr">65 </span><span class="Constant">$rewind-stream:end</span>:
<span id="L66" class="LineNr">66 </span>    <span class="subxS1Comment"># . restore registers</span>
<span id="L67" class="LineNr">67 </span>    58/pop-to-EAX
<span id="L68" class="LineNr">68 </span>    <span class="subxS1Comment"># . epilog</span>
<span id="L69" class="LineNr">69 </span>    89/copy                         3/mod/direct    4/rm32/ESP   <span class="Normal"> . </span>         <span class="Normal"> . </span>           <span class="Normal"> . </span>          5/r32/EBP  <span class="Normal"> . </span>             <span class="Normal"> . </span>                <span class="subxComment"># copy EBP to ESP</span>
<span id="L70" class="LineNr">70 </span>    5d/pop-to-EBP
<span id="L71" class="LineNr">71 </span>    c3/return
<span id="L72" class="LineNr">72 </span>
<span id="L73" class="LineNr">73 </span><span class="subxS2Comment"># . . vim&#0058;nowrap:textwidth=0</span>
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