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<a href='https://github.com/akkartik/mu/blob/main/baremetal/108write.subx'>https://github.com/akkartik/mu/blob/main/baremetal/108write.subx</a>
<pre id='vimCodeElement'>
<span id="L1" class="LineNr"> 1 </span><span class="subxComment"># instruction effective address register displacement immediate</span>
<span id="L2" class="LineNr"> 2 </span><span class="subxS1Comment"># . op subop mod rm32 base index scale r32</span>
<span id="L3" class="LineNr"> 3 </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="L4" class="LineNr"> 4 </span>
<span id="L5" class="LineNr"> 5 </span><span class="subxFunction">write</span>: <span class="subxComment"># f: (addr stream byte), s: (addr array byte)</span>
<span id="L6" class="LineNr"> 6 </span> <span class="subxS1Comment"># . prologue</span>
<span id="L7" class="LineNr"> 7 </span> 55/push-ebp
<span id="L8" class="LineNr"> 8 </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="L9" class="LineNr"> 9 </span> <span class="subxComment"># if (s == 0) return</span>
<span id="L10" class="LineNr"> 10 </span> 81 7/subop/compare 1/mod/*+disp8 5/rm32/ebp <span class="Normal"> . </span> <span class="Normal"> . </span> <span class="Normal"> . </span> <span class="Normal"> . </span> 0xc/disp8 0/imm32 <span class="subxComment"># compare *(ebp+12)</span>
<span id="L11" class="LineNr"> 11 </span> 74/jump-if-= $write:end/disp8
<span id="L12" class="LineNr"> 12 </span> <span class="subxComment"># TODO: write to file</span>
<span id="L13" class="LineNr"> 13 </span> <span class="subxComment"># otherwise, treat 'f' as a stream to append to</span>
<span id="L14" class="LineNr"> 14 </span> <span class="subxS1Comment"># . save registers</span>
<span id="L15" class="LineNr"> 15 </span> 50/push-eax
<span id="L16" class="LineNr"> 16 </span> 51/push-ecx
<span id="L17" class="LineNr"> 17 </span> 52/push-edx
<span id="L18" class="LineNr"> 18 </span> 53/push-ebx
<span id="L19" class="LineNr"> 19 </span> <span class="subxComment"># ecx = f</span>
<span id="L20" class="LineNr"> 20 </span> 8b/copy 1/mod/*+disp8 5/rm32/ebp <span class="Normal"> . </span> <span class="Normal"> . </span> 1/r32/ecx 8/disp8 <span class="Normal"> . </span> <span class="subxComment"># copy *(ebp+8) to ecx</span>
<span id="L21" class="LineNr"> 21 </span> <span class="subxComment"># edx = f->write</span>
<span id="L22" class="LineNr"> 22 </span> 8b/copy 0/mod/indirect 1/rm32/ecx <span class="Normal"> . </span> <span class="Normal"> . </span> <span class="Normal"> . </span> 2/r32/edx <span class="Normal"> . </span> <span class="Normal"> . </span> <span class="subxComment"># copy *ecx to edx</span>
<span id="L23" class="LineNr"> 23 </span> <span class="subxComment"># ebx = f->size</span>
<span id="L24" class="LineNr"> 24 </span> 8b/copy 1/mod/*+disp8 1/rm32/ecx <span class="Normal"> . </span> <span class="Normal"> . </span> <span class="Normal"> . </span> 3/r32/ebx 8/disp8 <span class="Normal"> . </span> <span class="subxComment"># copy *(ecx+8) to ebx</span>
<span id="L25" class="LineNr"> 25 </span> <span class="subxComment"># eax = _append-3(&f->data[f->write], &f->data[f->size], s)</span>
<span id="L26" class="LineNr"> 26 </span> <span class="subxS2Comment"># . . push s</span>
<span id="L27" class="LineNr"> 27 </span> ff 6/subop/push 1/mod/*+disp8 5/rm32/ebp <span class="Normal"> . </span> <span class="Normal"> . </span> <span class="Normal"> . </span> <span class="Normal"> . </span> 0xc/disp8 <span class="Normal"> . </span> <span class="subxComment"># push *(ebp+12)</span>
<span id="L28" class="LineNr"> 28 </span> <span class="subxS2Comment"># . . push &f->data[f->size]</span>
<span id="L29" class="LineNr"> 29 </span> 8d/copy-address 1/mod/*+disp8 4/rm32/sib 1/base/ecx 3/index/ebx <span class="Normal"> . </span> 3/r32/ebx 0xc/disp8 <span class="Normal"> . </span> <span class="subxComment"># copy ecx+ebx+12 to ebx</span>
<span id="L30" class="LineNr"> 30 </span> 53/push-ebx
<span id="L31" class="LineNr"> 31 </span> <span class="subxS2Comment"># . . push &f->data[f->write]</span>
<span id="L32" class="LineNr"> 32 </span> 8d/copy-address 1/mod/*+disp8 4/rm32/sib 1/base/ecx 2/index/edx <span class="Normal"> . </span> 3/r32/ebx 0xc/disp8 <span class="Normal"> . </span> <span class="subxComment"># copy ecx+edx+12 to ebx</span>
<span id="L33" class="LineNr"> 33 </span> 53/push-ebx
<span id="L34" class="LineNr"> 34 </span> <span class="subxS2Comment"># . . call</span>
<span id="L35" class="LineNr"> 35 </span> e8/call <a href='108write.subx.html#L54'>_append-3</a>/disp32
<span id="L36" class="LineNr"> 36 </span> <span class="subxS2Comment"># . . discard args</span>
<span id="L37" class="LineNr"> 37 </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="L38" class="LineNr"> 38 </span> <span class="subxComment"># f->write += eax</span>
<span id="L39" class="LineNr"> 39 </span> 01/add 0/mod/indirect 1/rm32/ecx <span class="Normal"> . </span> <span class="Normal"> . </span> <span class="Normal"> . </span> 0/r32/eax <span class="Normal"> . </span> <span class="Normal"> . </span> <span class="subxComment"># add eax to *ecx</span>
<span id="L40" class="LineNr"> 40 </span> <span class="subxS1Comment"># . restore registers</span>
<span id="L41" class="LineNr"> 41 </span> 5b/pop-to-ebx
<span id="L42" class="LineNr"> 42 </span> 5a/pop-to-edx
<span id="L43" class="LineNr"> 43 </span> 59/pop-to-ecx
<span id="L44" class="LineNr"> 44 </span> 58/pop-to-eax
<span id="L45" class="LineNr"> 45 </span><span class="Constant">$write:end</span>:
<span id="L46" class="LineNr"> 46 </span> <span class="subxS1Comment"># . epilogue</span>
<span id="L47" class="LineNr"> 47 </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="L48" class="LineNr"> 48 </span> 5d/pop-to-ebp
<span id="L49" class="LineNr"> 49 </span> c3/return
<span id="L50" class="LineNr"> 50 </span>
<span id="L51" class="LineNr"> 51 </span><span class="subxComment"># TODO: bring in tests once we have check-ints-equal</span>
<span id="L52" class="LineNr"> 52 </span>
<span id="L53" class="LineNr"> 53 </span><span class="subxComment"># 3-argument variant of _append</span>
<span id="L54" class="LineNr"> 54 </span><span class="subxMinorFunction">_append-3</span>: <span class="subxComment"># out: (addr byte), outend: (addr byte), s: (addr array byte) -> num_bytes_appended/eax</span>
<span id="L55" class="LineNr"> 55 </span> <span class="subxS1Comment"># . prologue</span>
<span id="L56" class="LineNr"> 56 </span> 55/push-ebp
<span id="L57" class="LineNr"> 57 </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="L58" class="LineNr"> 58 </span> <span class="subxS1Comment"># . save registers</span>
<span id="L59" class="LineNr"> 59 </span> 51/push-ecx
<span id="L60" class="LineNr"> 60 </span> <span class="subxComment"># eax = _append-4(out, outend, &s->data[0], &s->data[s->size])</span>
<span id="L61" class="LineNr"> 61 </span> <span class="subxS2Comment"># . . push &s->data[s->size]</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 0x10/disp8 <span class="Normal"> . </span> <span class="subxComment"># copy *(ebp+16) to eax</span>
<span id="L63" class="LineNr"> 63 </span> 8b/copy 0/mod/indirect 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"># copy *eax to ecx</span>
<span id="L64" class="LineNr"> 64 </span> 8d/copy-address 1/mod/*+disp8 4/rm32/sib 0/base/eax 1/index/ecx <span class="Normal"> . </span> 1/r32/ecx 4/disp8 <span class="Normal"> . </span> <span class="subxComment"># copy eax+ecx+4 to ecx</span>
<span id="L65" class="LineNr"> 65 </span> 51/push-ecx
<span id="L66" class="LineNr"> 66 </span> <span class="subxS2Comment"># . . push &s->data[0]</span>
<span id="L67" class="LineNr"> 67 </span> 8d/copy-address 1/mod/*+disp8 0/rm32/eax <span class="Normal"> . </span> <span class="Normal"> . </span> <span class="Normal"> . </span> 1/r32/ecx 4/disp8 <span class="Normal"> . </span> <span class="subxComment"># copy eax+4 to ecx</span>
<span id="L68" class="LineNr"> 68 </span> 51/push-ecx
<span id="L69" class="LineNr"> 69 </span> <span class="subxS2Comment"># . . push outend</span>
<span id="L70" class="LineNr"> 70 </span> ff 6/subop/push 1/mod/*+disp8 5/rm32/ebp <span class="Normal"> . </span> <span class="Normal"> . </span> <span class="Normal"> . </span> <span class="Normal"> . </span> 0xc/disp8 <span class="Normal"> . </span> <span class="subxComment"># push *(ebp+12)</span>
<span id="L71" class="LineNr"> 71 </span> <span class="subxS2Comment"># . . push out</span>
<span id="L72" class="LineNr"> 72 </span> ff 6/subop/push 1/mod/*+disp8 5/rm32/ebp <span class="Normal"> . </span> <span class="Normal"> . </span> <span class="Normal"> . </span> <span class="Normal"> . </span> 8/disp8 <span class="Normal"> . </span> <span class="subxComment"># push *(ebp+8)</span>
<span id="L73" class="LineNr"> 73 </span> <span class="subxS2Comment"># . . call</span>
<span id="L74" class="LineNr"> 74 </span> e8/call <a href='108write.subx.html#L86'>_append-4</a>/disp32
<span id="L75" class="LineNr"> 75 </span> <span class="subxS2Comment"># . . discard args</span>
<span id="L76" class="LineNr"> 76 </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> 0x10/imm32 <span class="subxComment"># add to esp</span>
<span id="L77" class="LineNr"> 77 </span><span class="Constant">$_append-3:end</span>:
<span id="L78" class="LineNr"> 78 </span> <span class="subxS1Comment"># . restore registers</span>
<span id="L79" class="LineNr"> 79 </span> 59/pop-to-ecx
<span id="L80" class="LineNr"> 80 </span> <span class="subxS1Comment"># . epilogue</span>
<span id="L81" class="LineNr"> 81 </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="L82" class="LineNr"> 82 </span> 5d/pop-to-ebp
<span id="L83" class="LineNr"> 83 </span> c3/return
<span id="L84" class="LineNr"> 84 </span>
<span id="L85" class="LineNr"> 85 </span><span class="subxComment"># 4-argument variant of _append</span>
<span id="L86" class="LineNr"> 86 </span><span class="subxMinorFunction">_append-4</span>: <span class="subxComment"># out: (addr byte), outend: (addr byte), in: (addr byte), inend: (addr byte) -> num_bytes_appended/eax: int</span>
<span id="L87" class="LineNr"> 87 </span> <span class="subxS1Comment"># . prologue</span>
<span id="L88" class="LineNr"> 88 </span> 55/push-ebp
<span id="L89" class="LineNr"> 89 </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="L90" class="LineNr"> 90 </span> <span class="subxS1Comment"># . save registers</span>
<span id="L91" class="LineNr"> 91 </span> 51/push-ecx
<span id="L92" class="LineNr"> 92 </span> 52/push-edx
<span id="L93" class="LineNr"> 93 </span> 53/push-ebx
<span id="L94" class="LineNr"> 94 </span> 56/push-esi
<span id="L95" class="LineNr"> 95 </span> 57/push-edi
<span id="L96" class="LineNr"> 96 </span> <span class="subxComment"># num_bytes_appended = 0</span>
<span id="L97" class="LineNr"> 97 </span> b8/copy-to-eax 0/imm32
<span id="L98" class="LineNr"> 98 </span> <span class="subxComment"># edi = out</span>
<span id="L99" class="LineNr"> 99 </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="L100" class="LineNr">100 </span> <span class="subxComment"># edx = outend</span>
<span id="L101" class="LineNr">101 </span> 8b/copy 1/mod/*+disp8 5/rm32/ebp <span class="Normal"> . </span> <span class="Normal"> . </span> <span class="Normal"> . </span> 2/r32/edx 0xc/disp8 <span class="Normal"> . </span> <span class="subxComment"># copy *(ebp+12) to edx</span>
<span id="L102" class="LineNr">102 </span> <span class="subxComment"># esi = in</span>
<span id="L103" class="LineNr">103 </span> 8b/copy 1/mod/*+disp8 5/rm32/ebp <span class="Normal"> . </span> <span class="Normal"> . </span> <span class="Normal"> . </span> 6/r32/esi 0x10/disp8 <span class="Normal"> . </span> <span class="subxComment"># copy *(ebp+16) to esi</span>
<span id="L104" class="LineNr">104 </span> <span class="subxComment"># ecx = inend</span>
<span id="L105" class="LineNr">105 </span> 8b/copy 1/mod/*+disp8 5/rm32/ebp <span class="Normal"> . </span> <span class="Normal"> . </span> <span class="Normal"> . </span> 1/r32/ecx 0x14/disp8 <span class="Normal"> . </span> <span class="subxComment"># copy *(ebp+20) to ecx</span>
<span id="L106" class="LineNr">106 </span><span class="Constant">$_append-4:loop</span>:
<span id="L107" class="LineNr">107 </span> <span class="subxComment"># if (in >= inend) break</span>
<span id="L108" class="LineNr">108 </span> 39/compare 3/mod/direct 6/rm32/esi <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 esi with ecx</span>
<span id="L109" class="LineNr">109 </span> 73/jump-if-addr>= $_append-4:end/disp8
<span id="L110" class="LineNr">110 </span> <span class="subxComment"># if (out >= outend) abort # just to catch test failures fast</span>
<span id="L111" class="LineNr">111 </span> 39/compare 3/mod/direct 7/rm32/edi <span class="Normal"> . </span> <span class="Normal"> . </span> <span class="Normal"> . </span> 2/r32/edx <span class="Normal"> . </span> <span class="Normal"> . </span> <span class="subxComment"># compare edi with edx</span>
<span id="L112" class="LineNr">112 </span> 73/jump-if-addr>= $_append-4:end/disp8 <span class="subxComment"># TODO: abort</span>
<span id="L113" class="LineNr">113 </span> <span class="subxComment"># *out = *in</span>
<span id="L114" class="LineNr">114 </span> 8a/copy-byte 0/mod/indirect 6/rm32/esi <span class="Normal"> . </span> <span class="Normal"> . </span> <span class="Normal"> . </span> 3/r32/BL <span class="Normal"> . </span> <span class="Normal"> . </span> <span class="subxComment"># copy byte at *esi to BL</span>
<span id="L115" class="LineNr">115 </span> 88/copy-byte 0/mod/indirect 7/rm32/edi <span class="Normal"> . </span> <span class="Normal"> . </span> <span class="Normal"> . </span> 3/r32/BL <span class="Normal"> . </span> <span class="Normal"> . </span> <span class="subxComment"># copy byte at BL to *edi</span>
<span id="L116" class="LineNr">116 </span> <span class="subxComment"># ++num_bytes_appended</span>
<span id="L117" class="LineNr">117 </span> 40/increment-eax
<span id="L118" class="LineNr">118 </span> <span class="subxComment"># ++in</span>
<span id="L119" class="LineNr">119 </span> 46/increment-esi
<span id="L120" class="LineNr">120 </span> <span class="subxComment"># ++out</span>
<span id="L121" class="LineNr">121 </span> 47/increment-edi
<span id="L122" class="LineNr">122 </span> eb/jump $_append-4:<span class="Constant">loop</span>/disp8
<span id="L123" class="LineNr">123 </span><span class="Constant">$_append-4:end</span>:
<span id="L124" class="LineNr">124 </span> <span class="subxS1Comment"># . restore registers</span>
<span id="L125" class="LineNr">125 </span> 5f/pop-to-edi
<span id="L126" class="LineNr">126 </span> 5e/pop-to-esi
<span id="L127" class="LineNr">127 </span> 5b/pop-to-ebx
<span id="L128" class="LineNr">128 </span> 5a/pop-to-edx
<span id="L129" class="LineNr">129 </span> 59/pop-to-ecx
<span id="L130" class="LineNr">130 </span> <span class="subxS1Comment"># . epilogue</span>
<span id="L131" class="LineNr">131 </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="L132" class="LineNr">132 </span> 5d/pop-to-ebp
<span id="L133" class="LineNr">133 </span> c3/return
<span id="L134" class="LineNr">134 </span>
<span id="L135" class="LineNr">135 </span><span class="subxS2Comment"># . . vim:nowrap:textwidth=0</span>
</pre>
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