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<a href='https://github.com/akkartik/mu/blob/main/linux/202write-int.subx'>https://github.com/akkartik/mu/blob/main/linux/202write-int.subx</a>
<pre id='vimCodeElement'>
<span id="L1" class="LineNr">  1 </span><span class="subxComment"># write-int: add (the binary representation of) a single int to a stream</span>
<span id="L2" class="LineNr">  2 </span>
<span id="L3" class="LineNr">  3 </span>== code
<span id="L4" class="LineNr">  4 </span><span class="subxComment">#   instruction                     effective address                                                   register    displacement    immediate</span>
<span id="L5" class="LineNr">  5 </span><span class="subxS1Comment"># . op          subop               mod             rm32          base        index         scale       r32</span>
<span id="L6" class="LineNr">  6 </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="L7" class="LineNr">  7 </span>
<span id="L8" class="LineNr">  8 </span><span class="subxFunction">write-int</span>:  <span class="subxComment"># out: (addr stream byte), n: int</span>
<span id="L9" class="LineNr">  9 </span>    <span class="subxS1Comment"># . prologue</span>
<span id="L10" class="LineNr"> 10 </span>    55/push-ebp
<span id="L11" class="LineNr"> 11 </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="L12" class="LineNr"> 12 </span>    <span class="subxS1Comment"># . save registers</span>
<span id="L13" class="LineNr"> 13 </span>    50/push-eax
<span id="L14" class="LineNr"> 14 </span>    51/push-ecx
<span id="L15" class="LineNr"> 15 </span>    57/push-edi
<span id="L16" class="LineNr"> 16 </span>    <span class="subxComment"># edi = out</span>
<span id="L17" class="LineNr"> 17 </span>    8b/copy                         1/mod/*+disp8   5/rm32/ebp   <span class="Normal"> . </span>         <span class="Normal"> . </span>           <span class="Normal"> . </span>          7/r32/edi   8/disp8        <span class="Normal"> . </span>                <span class="subxComment"># copy *(ebp+8) to edi</span>
<span id="L18" class="LineNr"> 18 </span>    <span class="subxComment"># ecx = out-&gt;write</span>
<span id="L19" class="LineNr"> 19 </span>    8b/copy                         0/mod/indirect  7/rm32/edi   <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"># copy *edi to ecx</span>
<span id="L20" class="LineNr"> 20 </span>    <span class="subxComment"># if (out-&gt;write &gt;= out-&gt;size) abort</span>
<span id="L21" class="LineNr"> 21 </span>    3b/compare                      1/mod/*+disp8   7/rm32/edi   <span class="Normal"> . </span>         <span class="Normal"> . </span>           <span class="Normal"> . </span>          1/r32/ecx   8/disp8        <span class="Normal"> . </span>                <span class="subxComment"># compare ecx with *(edi+8)</span>
<span id="L22" class="LineNr"> 22 </span>    7d/jump-if-&gt;=  $write-int:abort/disp8
<span id="L23" class="LineNr"> 23 </span><span class="Constant">$write-int:to-stream</span>:
<span id="L24" class="LineNr"> 24 </span>    <span class="subxComment"># out-&gt;data[out-&gt;write] = n</span>
<span id="L25" class="LineNr"> 25 </span>    8b/copy                         1/mod/*+disp8   5/rm32/ebp   <span class="Normal"> . </span>         <span class="Normal"> . </span>           <span class="Normal"> . </span>          0/r32/eax   0xc/disp8      <span class="Normal"> . </span>                <span class="subxComment"># copy *(ebp+12) to eax</span>
<span id="L26" class="LineNr"> 26 </span>    89/copy                         1/mod/*+disp8   4/rm32/sib    7/base/edi  1/index/ecx  <span class="Normal"> . </span>          0/r32/eax   0xc/disp8      <span class="Normal"> . </span>                <span class="subxComment"># copy eax to *(edi+ecx+12)</span>
<span id="L27" class="LineNr"> 27 </span>    <span class="subxComment"># out-&gt;write += 4</span>
<span id="L28" class="LineNr"> 28 </span>    81          0/subop/add         0/mod/indirect  7/rm32/edi   <span class="Normal"> . </span>         <span class="Normal"> . </span>           <span class="Normal"> . </span>         <span class="Normal"> . </span>         <span class="Normal"> . </span>              4/imm32           <span class="subxComment"># add to *edi</span>
<span id="L29" class="LineNr"> 29 </span><span class="Constant">$write-int:end</span>:
<span id="L30" class="LineNr"> 30 </span>    <span class="subxS1Comment"># . restore registers</span>
<span id="L31" class="LineNr"> 31 </span>    5f/pop-to-edi
<span id="L32" class="LineNr"> 32 </span>    59/pop-to-ecx
<span id="L33" class="LineNr"> 33 </span>    58/pop-to-eax
<span id="L34" class="LineNr"> 34 </span>    <span class="subxS1Comment"># . epilogue</span>
<span id="L35" class="LineNr"> 35 </span>    89/copy                         3/mod/direct    4/rm32/esp   <span class="Normal"> . </span>         <span class="Normal"> . </span>           <span class="Normal"> . </span>          5/r32/ebp  <span class="Normal"> . </span>             <span class="Normal"> . </span>                <span class="subxComment"># copy ebp to esp</span>
<span id="L36" class="LineNr"> 36 </span>    5d/pop-to-ebp
<span id="L37" class="LineNr"> 37 </span>    c3/return
<span id="L38" class="LineNr"> 38 </span>
<span id="L39" class="LineNr"> 39 </span><span class="Constant">$write-int:abort</span>:
<span id="L40" class="LineNr"> 40 </span>    <span class="subxS1Comment"># . _write(2/stderr, error)</span>
<span id="L41" class="LineNr"> 41 </span>    <span class="subxS2Comment"># . . push args</span>
<span id="L42" class="LineNr"> 42 </span>    68/push  <span class="Constant">&quot;write-int: out of space\n&quot;</span>/imm32
<span id="L43" class="LineNr"> 43 </span>    68/push  2/imm32/stderr
<span id="L44" class="LineNr"> 44 </span>    <span class="subxS2Comment"># . . call</span>
<span id="L45" class="LineNr"> 45 </span>    e8/call  <a href='101_write.subx.html#L12'>_write</a>/disp32
<span id="L46" class="LineNr"> 46 </span>    <span class="subxS2Comment"># . . discard args</span>
<span id="L47" class="LineNr"> 47 </span>    81          0/subop/add         3/mod/direct    4/rm32/esp   <span class="Normal"> . </span>         <span class="Normal"> . </span>           <span class="Normal"> . </span>         <span class="Normal"> . </span>         <span class="Normal"> . </span>              8/imm32           <span class="subxComment"># add to esp</span>
<span id="L48" class="LineNr"> 48 </span>    <span class="subxS1Comment"># . syscall(exit, 1)</span>
<span id="L49" class="LineNr"> 49 </span>    bb/copy-to-ebx  1/imm32
<span id="L50" class="LineNr"> 50 </span>    e8/call  <a href='000init.subx.html#L18'>syscall_exit</a>/disp32
<span id="L51" class="LineNr"> 51 </span>    <span class="subxComment"># never gets here</span>
<span id="L52" class="LineNr"> 52 </span>
<span id="L53" class="LineNr"> 53 </span><span class="subxTest">test-write-int-single</span>:
<span id="L54" class="LineNr"> 54 </span>    <span class="subxH1Comment"># - check that write-int writes to first int of 'stream'</span>
<span id="L55" class="LineNr"> 55 </span>    <span class="subxComment"># setup</span>
<span id="L56" class="LineNr"> 56 </span>    <span class="subxS1Comment"># . clear-stream(_test-stream)</span>
<span id="L57" class="LineNr"> 57 </span>    <span class="subxS2Comment"># . . push args</span>
<span id="L58" class="LineNr"> 58 </span>    68/push  <a href='108write.subx.html#L151'>_test-stream</a>/imm32
<span id="L59" class="LineNr"> 59 </span>    <span class="subxS2Comment"># . . call</span>
<span id="L60" class="LineNr"> 60 </span>    e8/call  <a href='106stream.subx.html#L17'>clear-stream</a>/disp32
<span id="L61" class="LineNr"> 61 </span>    <span class="subxS2Comment"># . . discard args</span>
<span id="L62" class="LineNr"> 62 </span>    81          0/subop/add         3/mod/direct    4/rm32/esp   <span class="Normal"> . </span>         <span class="Normal"> . </span>           <span class="Normal"> . </span>         <span class="Normal"> . </span>         <span class="Normal"> . </span>              4/imm32           <span class="subxComment"># add to esp</span>
<span id="L63" class="LineNr"> 63 </span>    <span class="subxComment"># write-int(_test-stream, &quot;abcd&quot;)</span>
<span id="L64" class="LineNr"> 64 </span>    <span class="subxS2Comment"># . . push args</span>
<span id="L65" class="LineNr"> 65 </span>    68/push  0x64636261/imm32
<span id="L66" class="LineNr"> 66 </span>    68/push  <a href='108write.subx.html#L151'>_test-stream</a>/imm32
<span id="L67" class="LineNr"> 67 </span>    <span class="subxS2Comment"># . . call</span>
<span id="L68" class="LineNr"> 68 </span>    e8/call  <a href='202write-int.subx.html#L8'>write-int</a>/disp32
<span id="L69" class="LineNr"> 69 </span>    <span class="subxS2Comment"># . . discard args</span>
<span id="L70" class="LineNr"> 70 </span>    81          0/subop/add         3/mod/direct    4/rm32/esp   <span class="Normal"> . </span>         <span class="Normal"> . </span>           <span class="Normal"> . </span>         <span class="Normal"> . </span>         <span class="Normal"> . </span>              8/imm32           <span class="subxComment"># add to esp</span>
<span id="L71" class="LineNr"> 71 </span>    <span class="subxComment"># check-stream-equal(_test-stream, &quot;abcd&quot;, msg)</span>
<span id="L72" class="LineNr"> 72 </span>    <span class="subxS2Comment"># . . push args</span>
<span id="L73" class="LineNr"> 73 </span>    68/push  <span class="Constant">&quot;F - test-write-int-single&quot;</span>/imm32
<span id="L74" class="LineNr"> 74 </span>    68/push  <span class="Constant">&quot;abcd&quot;</span>/imm32
<span id="L75" class="LineNr"> 75 </span>    68/push  <a href='108write.subx.html#L151'>_test-stream</a>/imm32
<span id="L76" class="LineNr"> 76 </span>    <span class="subxS2Comment"># . . call</span>
<span id="L77" class="LineNr"> 77 </span>    e8/call  <a href='109stream-equal.subx.html#L194'>check-stream-equal</a>/disp32
<span id="L78" class="LineNr"> 78 </span>    <span class="subxS2Comment"># . . discard args</span>
<span id="L79" class="LineNr"> 79 </span>    81          0/subop/add         3/mod/direct    4/rm32/esp   <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 esp</span>
<span id="L80" class="LineNr"> 80 </span>    <span class="subxS1Comment"># . end</span>
<span id="L81" class="LineNr"> 81 </span>    c3/return
<span id="L82" class="LineNr"> 82 </span>
<span id="L83" class="LineNr"> 83 </span><span class="subxTest">test-write-byte-buffered-multiple</span>:
<span id="L84" class="LineNr"> 84 </span>    <span class="subxH1Comment"># - check that write-int correctly appends multiple writes</span>
<span id="L85" class="LineNr"> 85 </span>    <span class="subxComment"># setup</span>
<span id="L86" class="LineNr"> 86 </span>    <span class="subxS1Comment"># . clear-stream(_test-stream)</span>
<span id="L87" class="LineNr"> 87 </span>    <span class="subxS2Comment"># . . push args</span>
<span id="L88" class="LineNr"> 88 </span>    68/push  <a href='108write.subx.html#L151'>_test-stream</a>/imm32
<span id="L89" class="LineNr"> 89 </span>    <span class="subxS2Comment"># . . call</span>
<span id="L90" class="LineNr"> 90 </span>    e8/call  <a href='106stream.subx.html#L17'>clear-stream</a>/disp32
<span id="L91" class="LineNr"> 91 </span>    <span class="subxS2Comment"># . . discard args</span>
<span id="L92" class="LineNr"> 92 </span>    81          0/subop/add         3/mod/direct    4/rm32/esp   <span class="Normal"> . </span>         <span class="Normal"> . </span>           <span class="Normal"> . </span>         <span class="Normal"> . </span>         <span class="Normal"> . </span>              4/imm32           <span class="subxComment"># add to esp</span>
<span id="L93" class="LineNr"> 93 </span>    <span class="subxComment"># write-int(_test-stream, &quot;abcd&quot;)</span>
<span id="L94" class="LineNr"> 94 </span>    <span class="subxS2Comment"># . . push args</span>
<span id="L95" class="LineNr"> 95 </span>    68/push  0x64636261/imm32
<span id="L96" class="LineNr"> 96 </span>    68/push  <a href='108write.subx.html#L151'>_test-stream</a>/imm32
<span id="L97" class="LineNr"> 97 </span>    <span class="subxS2Comment"># . . call</span>
<span id="L98" class="LineNr"> 98 </span>    e8/call  <a href='202write-int.subx.html#L8'>write-int</a>/disp32
<span id="L99" class="LineNr"> 99 </span>    <span class="subxS2Comment"># . . discard args</span>
<span id="L100" class="LineNr">100 </span>    81          0/subop/add         3/mod/direct    4/rm32/esp   <span class="Normal"> . </span>         <span class="Normal"> . </span>           <span class="Normal"> . </span>         <span class="Normal"> . </span>         <span class="Normal"> . </span>              8/imm32           <span class="subxComment"># add to esp</span>
<span id="L101" class="LineNr">101 </span>    <span class="subxComment"># write-int(_test-stream, &quot;efgh&quot;)</span>
<span id="L102" class="LineNr">102 </span>    <span class="subxS2Comment"># . . push args</span>
<span id="L103" class="LineNr">103 </span>    68/push  0x68676665/imm32
<span id="L104" class="LineNr">104 </span>    68/push  <a href='108write.subx.html#L151'>_test-stream</a>/imm32
<span id="L105" class="LineNr">105 </span>    <span class="subxS2Comment"># . . call</span>
<span id="L106" class="LineNr">106 </span>    e8/call  <a href='202write-int.subx.html#L8'>write-int</a>/disp32
<span id="L107" class="LineNr">107 </span>    <span class="subxS2Comment"># . . discard args</span>
<span id="L108" class="LineNr">108 </span>    81          0/subop/add         3/mod/direct    4/rm32/esp   <span class="Normal"> . </span>         <span class="Normal"> . </span>           <span class="Normal"> . </span>         <span class="Normal"> . </span>         <span class="Normal"> . </span>              8/imm32           <span class="subxComment"># add to esp</span>
<span id="L109" class="LineNr">109 </span>    <span class="subxComment"># check-stream-equal(_test-stream, &quot;abcdefgh&quot;, msg)</span>
<span id="L110" class="LineNr">110 </span>    <span class="subxS2Comment"># . . push args</span>
<span id="L111" class="LineNr">111 </span>    68/push  <span class="Constant">&quot;F - test-write-byte-buffered-multiple&quot;</span>/imm32
<span id="L112" class="LineNr">112 </span>    68/push  <span class="Constant">&quot;abcdefgh&quot;</span>/imm32
<span id="L113" class="LineNr">113 </span>    68/push  <a href='108write.subx.html#L151'>_test-stream</a>/imm32
<span id="L114" class="LineNr">114 </span>    <span class="subxS2Comment"># . . call</span>
<span id="L115" class="LineNr">115 </span>    e8/call  <a href='109stream-equal.subx.html#L194'>check-stream-equal</a>/disp32
<span id="L116" class="LineNr">116 </span>    <span class="subxS2Comment"># . . discard args</span>
<span id="L117" class="LineNr">117 </span>    81          0/subop/add         3/mod/direct    4/rm32/esp   <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 esp</span>
<span id="L118" class="LineNr">118 </span>    <span class="subxS1Comment"># . end</span>
<span id="L119" class="LineNr">119 </span>    c3/return
<span id="L120" class="LineNr">120 </span>
<span id="L121" class="LineNr">121 </span><span class="subxS2Comment"># . . vim&#0058;nowrap:textwidth=0</span>
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