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<a href='https://github.com/akkartik/mu/blob/main/linux/106stream.subx'>https://github.com/akkartik/mu/blob/main/linux/106stream.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 size 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 size)</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: (addr stream byte)</span>
<span id="L18" class="LineNr">18 </span> <span class="subxS1Comment"># . prologue</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"># var count/ecx: int = f->size</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"># var max/ecx: (addr byte) = &f->data[f->size]</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->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->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="subxH1Comment"># - clear all stream data</span>
<span id="L35" class="LineNr">35 </span> <span class="subxH1Comment"># - this isn't strictly necessary, and it can slow things down *a lot*, but better safe than sorry.</span>
<span id="L36" class="LineNr">36 </span> <span class="subxComment"># var curr/eax: (addr byte) = f->data</span>
<span id="L37" class="LineNr">37 </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="L38" class="LineNr">38 </span><span class="Constant">$clear-stream:loop</span>:
<span id="L39" class="LineNr">39 </span> <span class="subxComment"># if (curr >= max) break</span>
<span id="L40" class="LineNr">40 </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="L41" class="LineNr">41 </span> 73/jump-if-addr>= $clear-stream:end/disp8
<span id="L42" class="LineNr">42 </span> <span class="subxComment"># *curr = 0</span>
<span id="L43" class="LineNr">43 </span> c6 0/subop/copy-byte 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="L44" class="LineNr">44 </span> <span class="subxComment"># ++curr</span>
<span id="L45" class="LineNr">45 </span> 40/increment-eax
<span id="L46" class="LineNr">46 </span> eb/jump $clear-stream:<span class="Constant">loop</span>/disp8
<span id="L47" class="LineNr">47 </span><span class="Constant">$clear-stream:end</span>:
<span id="L48" class="LineNr">48 </span> <span class="subxS1Comment"># . restore registers</span>
<span id="L49" class="LineNr">49 </span> 59/pop-to-ecx
<span id="L50" class="LineNr">50 </span> 58/pop-to-eax
<span id="L51" class="LineNr">51 </span> <span class="subxS1Comment"># . epilogue</span>
<span id="L52" class="LineNr">52 </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="L53" class="LineNr">53 </span> 5d/pop-to-ebp
<span id="L54" class="LineNr">54 </span> c3/return
<span id="L55" class="LineNr">55 </span>
<span id="L56" class="LineNr">56 </span><span class="subxFunction">rewind-stream</span>: <span class="subxComment"># f: (addr stream byte)</span>
<span id="L57" class="LineNr">57 </span> <span class="subxS1Comment"># . prologue</span>
<span id="L58" class="LineNr">58 </span> 55/push-ebp
<span id="L59" class="LineNr">59 </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="L60" class="LineNr">60 </span> <span class="subxS1Comment"># . save registers</span>
<span id="L61" class="LineNr">61 </span> 50/push-eax
<span id="L62" class="LineNr">62 </span> <span class="subxComment"># eax = f</span>
<span id="L63" class="LineNr">63 </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="L64" class="LineNr">64 </span> <span class="subxComment"># f->read = 0</span>
<span id="L65" class="LineNr">65 </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="L66" class="LineNr">66 </span><span class="Constant">$rewind-stream:end</span>:
<span id="L67" class="LineNr">67 </span> <span class="subxS1Comment"># . restore registers</span>
<span id="L68" class="LineNr">68 </span> 58/pop-to-eax
<span id="L69" class="LineNr">69 </span> <span class="subxS1Comment"># . epilogue</span>
<span id="L70" class="LineNr">70 </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="L71" class="LineNr">71 </span> 5d/pop-to-ebp
<span id="L72" class="LineNr">72 </span> c3/return
<span id="L73" class="LineNr">73 </span>
<span id="L74" class="LineNr">74 </span><span class="subxS2Comment"># . . vim:nowrap:textwidth=0</span>
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