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<a href='https://github.com/akkartik/mu/blob/main/linux/111read.subx'>https://github.com/akkartik/mu/blob/main/linux/111read.subx</a>
<pre id='vimCodeElement'>
<span id="L1" class="LineNr"> 1 </span><span class="subxComment"># read: analogously to write, support reading from in-memory streams in</span>
<span id="L2" class="LineNr"> 2 </span><span class="subxComment"># addition to file descriptors.</span>
<span id="L3" class="LineNr"> 3 </span><span class="subxComment">#</span>
<span id="L4" class="LineNr"> 4 </span><span class="subxComment"># We can pass it either a file descriptor or an address to a stream. If a</span>
<span id="L5" class="LineNr"> 5 </span><span class="subxComment"># file descriptor is passed in, we _read from it using the right syscall. If a</span>
<span id="L6" class="LineNr"> 6 </span><span class="subxComment"># stream is passed in (a fake file descriptor), we read from it instead. This</span>
<span id="L7" class="LineNr"> 7 </span><span class="subxComment"># lets us initialize input for tests.</span>
<span id="L8" class="LineNr"> 8 </span><span class="subxComment">#</span>
<span id="L9" class="LineNr"> 9 </span><span class="subxComment"># A little counter-intuitively, the output of 'read' ends up in.. a stream. So</span>
<span id="L10" class="LineNr"> 10 </span><span class="subxComment"># tests end up doing a redundant copy. Why? Well, consider the alternatives:</span>
<span id="L11" class="LineNr"> 11 </span><span class="subxComment">#</span>
<span id="L12" class="LineNr"> 12 </span><span class="subxComment"># a) Reading into a string, and returning a pointer to the end of the read</span>
<span id="L13" class="LineNr"> 13 </span><span class="subxComment"># region, or a count of bytes written. Now this count or end pointer must be</span>
<span id="L14" class="LineNr"> 14 </span><span class="subxComment"># managed separately by the caller, which can be error-prone.</span>
<span id="L15" class="LineNr"> 15 </span><span class="subxComment">#</span>
<span id="L16" class="LineNr"> 16 </span><span class="subxComment"># b) Having 'read' return a buffer that it allocates. But there's no way to</span>
<span id="L17" class="LineNr"> 17 </span><span class="subxComment"># know in advance how large to make the buffer. If you read less than the</span>
<span id="L18" class="LineNr"> 18 </span><span class="subxComment"># size of the buffer you again end up needing to manage initialized vs</span>
<span id="L19" class="LineNr"> 19 </span><span class="subxComment"># uninitialized memory.</span>
<span id="L20" class="LineNr"> 20 </span><span class="subxComment">#</span>
<span id="L21" class="LineNr"> 21 </span><span class="subxComment"># c) Creating more helpful variants like 'read-byte' or 'read-until' which</span>
<span id="L22" class="LineNr"> 22 </span><span class="subxComment"># also can take a file descriptor or stream, just like 'write'. But such</span>
<span id="L23" class="LineNr"> 23 </span><span class="subxComment"># primitives don't exist in the Linux kernel, so we'd be implementing them</span>
<span id="L24" class="LineNr"> 24 </span><span class="subxComment"># somehow, either with more internal buffering or by making multiple</span>
<span id="L25" class="LineNr"> 25 </span><span class="subxComment"># syscalls.</span>
<span id="L26" class="LineNr"> 26 </span><span class="subxComment">#</span>
<span id="L27" class="LineNr"> 27 </span><span class="subxComment"># Reading into a stream avoids these problems. The buffer is externally</span>
<span id="L28" class="LineNr"> 28 </span><span class="subxComment"># provided and the caller has control over where it's allocated, its lifetime,</span>
<span id="L29" class="LineNr"> 29 </span><span class="subxComment"># and so on. The buffer's read and write pointers are internal to it so it's</span>
<span id="L30" class="LineNr"> 30 </span><span class="subxComment"># easier to keep in a consistent state. And it can now be passed directly to</span>
<span id="L31" class="LineNr"> 31 </span><span class="subxComment"># helpers like 'read-byte' or 'read-until' that only need to support streams,</span>
<span id="L32" class="LineNr"> 32 </span><span class="subxComment"># never file descriptors.</span>
<span id="L33" class="LineNr"> 33 </span><span class="subxComment">#</span>
<span id="L34" class="LineNr"> 34 </span><span class="subxComment"># Like with 'write', we assume our data segment will never begin at an address</span>
<span id="L35" class="LineNr"> 35 </span><span class="subxComment"># shorter than 0x08000000, so any smaller arguments are assumed to be real</span>
<span id="L36" class="LineNr"> 36 </span><span class="subxComment"># file descriptors.</span>
<span id="L37" class="LineNr"> 37 </span><span class="subxComment">#</span>
<span id="L38" class="LineNr"> 38 </span><span class="subxComment"># As a reminder, a stream looks like this:</span>
<span id="L39" class="LineNr"> 39 </span><span class="subxComment"># write: int # index at which to write to next</span>
<span id="L40" class="LineNr"> 40 </span><span class="subxComment"># read: int # index at which to read next</span>
<span id="L41" class="LineNr"> 41 </span><span class="subxComment"># data: (array byte) # prefixed by size as usual</span>
<span id="L42" class="LineNr"> 42 </span>
<span id="L43" class="LineNr"> 43 </span>== code
<span id="L44" class="LineNr"> 44 </span><span class="subxComment"># instruction effective address register displacement immediate</span>
<span id="L45" class="LineNr"> 45 </span><span class="subxS1Comment"># . op subop mod rm32 base index scale r32</span>
<span id="L46" class="LineNr"> 46 </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="L47" class="LineNr"> 47 </span>
<span id="L48" class="LineNr"> 48 </span><span class="subxFunction">read</span>: <span class="subxComment"># f: fd or (addr stream byte), s: (addr stream byte) -> num-bytes-read/eax: int</span>
<span id="L49" class="LineNr"> 49 </span> <span class="subxS1Comment"># . prologue</span>
<span id="L50" class="LineNr"> 50 </span> 55/push-ebp
<span id="L51" class="LineNr"> 51 </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="L52" class="LineNr"> 52 </span> <span class="subxComment"># if (f < 0x08000000) return _read(f, s) # f can't be a user-mode address, so treat it as a kernel file descriptor</span>
<span id="L53" class="LineNr"> 53 </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> 8/disp8 0x08000000/imm32 <span class="subxComment"># compare *(ebp+8)</span>
<span id="L54" class="LineNr"> 54 </span> 73/jump-if-addr>= $read:fake/disp8
<span id="L55" class="LineNr"> 55 </span> <span class="subxS2Comment"># . . push args</span>
<span id="L56" class="LineNr"> 56 </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="L57" class="LineNr"> 57 </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="L58" class="LineNr"> 58 </span> <span class="subxS2Comment"># . . call</span>
<span id="L59" class="LineNr"> 59 </span> e8/call <a href='111read.subx.html#L198'>_read</a>/disp32
<span id="L60" class="LineNr"> 60 </span> <span class="subxS2Comment"># . . discard args</span>
<span id="L61" class="LineNr"> 61 </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="L62" class="LineNr"> 62 </span> <span class="subxComment"># return</span>
<span id="L63" class="LineNr"> 63 </span> eb/jump $read:end/disp8
<span id="L64" class="LineNr"> 64 </span><span class="Constant">$read:fake</span>:
<span id="L65" class="LineNr"> 65 </span> <span class="subxComment"># otherwise, treat 'f' as a stream to scan from</span>
<span id="L66" class="LineNr"> 66 </span> <span class="subxS1Comment"># . save registers</span>
<span id="L67" class="LineNr"> 67 </span> 56/push-esi
<span id="L68" class="LineNr"> 68 </span> 57/push-edi
<span id="L69" class="LineNr"> 69 </span> <span class="subxComment"># esi = f</span>
<span id="L70" class="LineNr"> 70 </span> 8b/copy 1/mod/*+disp8 5/rm32/ebp <span class="Normal"> . </span> <span class="Normal"> . </span> <span class="Normal"> . </span> 6/r32/esi 8/disp8 <span class="Normal"> . </span> <span class="subxComment"># copy *(ebp+8) to esi</span>
<span id="L71" class="LineNr"> 71 </span> <span class="subxComment"># edi = s</span>
<span id="L72" class="LineNr"> 72 </span> 8b/copy 1/mod/*+disp8 5/rm32/ebp <span class="Normal"> . </span> <span class="Normal"> . </span> <span class="Normal"> . </span> 7/r32/edi 0xc/disp8 <span class="Normal"> . </span> <span class="subxComment"># copy *(ebp+12) to esi</span>
<span id="L73" class="LineNr"> 73 </span> <span class="subxComment"># eax = _buffer-4(out = &s->data[s->write], outend = &s->data[s->size],</span>
<span id="L74" class="LineNr"> 74 </span> <span class="subxComment"># in = &f->data[f->read], inend = &f->data[f->write])</span>
<span id="L75" class="LineNr"> 75 </span> <span class="subxS2Comment"># . . push &f->data[f->write]</span>
<span id="L76" class="LineNr"> 76 </span> 8b/copy 0/mod/indirect 6/rm32/esi <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"># copy *esi to eax</span>
<span id="L77" class="LineNr"> 77 </span> 8d/copy-address 1/mod/*+disp8 4/rm32/sib 6/base/esi 0/index/eax <span class="Normal"> . </span> 0/r32/eax 0xc/disp8 <span class="Normal"> . </span> <span class="subxComment"># copy esi+eax+12 to eax</span>
<span id="L78" class="LineNr"> 78 </span> 50/push-eax
<span id="L79" class="LineNr"> 79 </span> <span class="subxS2Comment"># . . push &f->data[f->read]</span>
<span id="L80" class="LineNr"> 80 </span> 8b/copy 1/mod/*+disp8 6/rm32/esi <span class="Normal"> . </span> <span class="Normal"> . </span> <span class="Normal"> . </span> 0/r32/eax 4/disp8 <span class="Normal"> . </span> <span class="subxComment"># copy *(esi+4) to eax</span>
<span id="L81" class="LineNr"> 81 </span> 8d/copy-address 1/mod/*+disp8 4/rm32/sib 6/base/esi 0/index/eax <span class="Normal"> . </span> 0/r32/eax 0xc/disp8 <span class="Normal"> . </span> <span class="subxComment"># copy esi+eax+12 to eax</span>
<span id="L82" class="LineNr"> 82 </span> 50/push-eax
<span id="L83" class="LineNr"> 83 </span> <span class="subxS2Comment"># . . push &s->data[s->size]</span>
<span id="L84" class="LineNr"> 84 </span> 8b/copy 1/mod/*+disp8 7/rm32/edi <span class="Normal"> . </span> <span class="Normal"> . </span> <span class="Normal"> . </span> 0/r32/eax 8/disp8 <span class="Normal"> . </span> <span class="subxComment"># copy *(edi+8) to eax</span>
<span id="L85" class="LineNr"> 85 </span> 8d/copy-address 1/mod/*+disp8 4/rm32/sib 7/base/edi 0/index/eax <span class="Normal"> . </span> 0/r32/eax 0xc/disp8 <span class="Normal"> . </span> <span class="subxComment"># copy edi+eax+12 to eax</span>
<span id="L86" class="LineNr"> 86 </span> 50/push-eax
<span id="L87" class="LineNr"> 87 </span> <span class="subxS2Comment"># . . push &s->data[s->write]</span>
<span id="L88" class="LineNr"> 88 </span> 8b/copy 0/mod/indirect 7/rm32/edi <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"># copy *edi to eax</span>
<span id="L89" class="LineNr"> 89 </span> 8d/copy-address 1/mod/*+disp8 4/rm32/sib 7/base/edi 0/index/eax <span class="Normal"> . </span> 0/r32/eax 0xc/disp8 <span class="Normal"> . </span> <span class="subxComment"># copy edi+eax+12 to eax</span>
<span id="L90" class="LineNr"> 90 </span> 50/push-eax
<span id="L91" class="LineNr"> 91 </span> <span class="subxS2Comment"># . . call</span>
<span id="L92" class="LineNr"> 92 </span> e8/call <a href='111read.subx.html#L145'>_buffer-4</a>/disp32
<span id="L93" class="LineNr"> 93 </span> <span class="subxS2Comment"># . . discard args</span>
<span id="L94" class="LineNr"> 94 </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="L95" class="LineNr"> 95 </span> <span class="subxComment"># s->write += eax</span>
<span id="L96" class="LineNr"> 96 </span> 01/add 0/mod/indirect 7/rm32/edi <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 *edi</span>
<span id="L97" class="LineNr"> 97 </span> <span class="subxComment"># f->read += eax</span>
<span id="L98" class="LineNr"> 98 </span> 01/add 1/mod/*+disp8 6/rm32/esi <span class="Normal"> . </span> <span class="Normal"> . </span> <span class="Normal"> . </span> 0/r32/eax 4/disp8 <span class="Normal"> . </span> <span class="subxComment"># add eax to *(esi+4)</span>
<span id="L99" class="LineNr"> 99 </span> <span class="subxS1Comment"># . restore registers</span>
<span id="L100" class="LineNr">100 </span> 5f/pop-to-edi
<span id="L101" class="LineNr">101 </span> 5e/pop-to-esi
<span id="L102" class="LineNr">102 </span><span class="Constant">$read:end</span>:
<span id="L103" class="LineNr">103 </span> <span class="subxS1Comment"># . epilogue</span>
<span id="L104" class="LineNr">104 </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="L105" class="LineNr">105 </span> 5d/pop-to-ebp
<span id="L106" class="LineNr">106 </span> c3/return
<span id="L107" class="LineNr">107 </span>
<span id="L108" class="LineNr">108 </span><span class="subxH1Comment"># - helpers</span>
<span id="L109" class="LineNr">109 </span>
<span id="L110" class="LineNr">110 </span><span class="subxComment"># '_buffer' is like '_append', but silently stops instead of aborting when it runs out of space</span>
<span id="L111" class="LineNr">111 </span>
<span id="L112" class="LineNr">112 </span><span class="subxComment"># 3-argument variant of _buffer</span>
<span id="L113" class="LineNr">113 </span><span class="subxMinorFunction">_buffer-3</span>: <span class="subxComment"># out: address, outend: address, s: (array byte) -> num_bytes_buffered/eax</span>
<span id="L114" class="LineNr">114 </span> <span class="subxS1Comment"># . prologue</span>
<span id="L115" class="LineNr">115 </span> 55/push-ebp
<span id="L116" class="LineNr">116 </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="L117" class="LineNr">117 </span> <span class="subxS1Comment"># . save registers</span>
<span id="L118" class="LineNr">118 </span> 51/push-ecx
<span id="L119" class="LineNr">119 </span> <span class="subxComment"># eax = _buffer-4(out, outend, &s->data[0], &s->data[s->size])</span>
<span id="L120" class="LineNr">120 </span> <span class="subxS2Comment"># . . push &s->data[s->size]</span>
<span id="L121" class="LineNr">121 </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="L122" class="LineNr">122 </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="L123" class="LineNr">123 </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="L124" class="LineNr">124 </span> 51/push-ecx
<span id="L125" class="LineNr">125 </span> <span class="subxS2Comment"># . . push &s->data[0]</span>
<span id="L126" class="LineNr">126 </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="L127" class="LineNr">127 </span> 51/push-ecx
<span id="L128" class="LineNr">128 </span> <span class="subxS2Comment"># . . push outend</span>
<span id="L129" class="LineNr">129 </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="L130" class="LineNr">130 </span> <span class="subxS2Comment"># . . push out</span>
<span id="L131" class="LineNr">131 </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="L132" class="LineNr">132 </span> <span class="subxS2Comment"># . . call</span>
<span id="L133" class="LineNr">133 </span> e8/call <a href='111read.subx.html#L145'>_buffer-4</a>/disp32
<span id="L134" class="LineNr">134 </span> <span class="subxS2Comment"># . . discard args</span>
<span id="L135" class="LineNr">135 </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="L136" class="LineNr">136 </span><span class="Constant">$_buffer-3:end</span>:
<span id="L137" class="LineNr">137 </span> <span class="subxS1Comment"># . restore registers</span>
<span id="L138" class="LineNr">138 </span> 59/pop-to-ecx
<span id="L139" class="LineNr">139 </span> <span class="subxS1Comment"># . epilogue</span>
<span id="L140" class="LineNr">140 </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="L141" class="LineNr">141 </span> 5d/pop-to-ebp
<span id="L142" class="LineNr">142 </span> c3/return
<span id="L143" class="LineNr">143 </span>
<span id="L144" class="LineNr">144 </span><span class="subxComment"># 4-argument variant of _buffer</span>
<span id="L145" class="LineNr">145 </span><span class="subxMinorFunction">_buffer-4</span>: <span class="subxComment"># out: address, outend: address, in: address, inend: address -> num_bytes_buffered/eax</span>
<span id="L146" class="LineNr">146 </span> <span class="subxS1Comment"># . prologue</span>
<span id="L147" class="LineNr">147 </span> 55/push-ebp
<span id="L148" class="LineNr">148 </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="L149" class="LineNr">149 </span> <span class="subxS1Comment"># . save registers</span>
<span id="L150" class="LineNr">150 </span> 51/push-ecx
<span id="L151" class="LineNr">151 </span> 52/push-edx
<span id="L152" class="LineNr">152 </span> 53/push-ebx
<span id="L153" class="LineNr">153 </span> 56/push-esi
<span id="L154" class="LineNr">154 </span> 57/push-edi
<span id="L155" class="LineNr">155 </span> <span class="subxComment"># eax/num_bytes_buffered = 0</span>
<span id="L156" class="LineNr">156 </span> b8/copy-to-eax 0/imm32
<span id="L157" class="LineNr">157 </span> <span class="subxComment"># edi = out</span>
<span id="L158" class="LineNr">158 </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="L159" class="LineNr">159 </span> <span class="subxComment"># edx = outend</span>
<span id="L160" class="LineNr">160 </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="L161" class="LineNr">161 </span> <span class="subxComment"># esi = in</span>
<span id="L162" class="LineNr">162 </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="L163" class="LineNr">163 </span> <span class="subxComment"># ecx = inend</span>
<span id="L164" class="LineNr">164 </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="L165" class="LineNr">165 </span><span class="Constant">$_buffer-4:loop</span>:
<span id="L166" class="LineNr">166 </span> <span class="subxComment"># if (in >= inend) break</span>
<span id="L167" class="LineNr">167 </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="L168" class="LineNr">168 </span> 73/jump-if-addr>= $_buffer-4:end/disp8
<span id="L169" class="LineNr">169 </span> <span class="subxComment"># if (out >= outend) break # for now silently ignore filled up buffer</span>
<span id="L170" class="LineNr">170 </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="L171" class="LineNr">171 </span> 73/jump-if-addr>= $_buffer-4:end/disp8
<span id="L172" class="LineNr">172 </span> <span class="subxComment"># *out = *in</span>
<span id="L173" class="LineNr">173 </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="L174" class="LineNr">174 </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="L175" class="LineNr">175 </span> <span class="subxComment"># ++num_bytes_buffered</span>
<span id="L176" class="LineNr">176 </span> 40/increment-eax
<span id="L177" class="LineNr">177 </span> <span class="subxComment"># ++in</span>
<span id="L178" class="LineNr">178 </span> 46/increment-esi
<span id="L179" class="LineNr">179 </span> <span class="subxComment"># ++out</span>
<span id="L180" class="LineNr">180 </span> 47/increment-edi
<span id="L181" class="LineNr">181 </span> eb/jump $_buffer-4:<span class="Constant">loop</span>/disp8
<span id="L182" class="LineNr">182 </span><span class="Constant">$_buffer-4:end</span>:
<span id="L183" class="LineNr">183 </span> <span class="subxS1Comment"># . restore registers</span>
<span id="L184" class="LineNr">184 </span> 5f/pop-to-edi
<span id="L185" class="LineNr">185 </span> 5e/pop-to-esi
<span id="L186" class="LineNr">186 </span> 5b/pop-to-ebx
<span id="L187" class="LineNr">187 </span> 5a/pop-to-edx
<span id="L188" class="LineNr">188 </span> 59/pop-to-ecx
<span id="L189" class="LineNr">189 </span> <span class="subxS1Comment"># . epilogue</span>
<span id="L190" class="LineNr">190 </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="L191" class="LineNr">191 </span> 5d/pop-to-ebp
<span id="L192" class="LineNr">192 </span> c3/return
<span id="L193" class="LineNr">193 </span>
<span id="L194" class="LineNr">194 </span><span class="subxComment"># idea: a clear-if-empty method on streams that clears only if f->read == f->write</span>
<span id="L195" class="LineNr">195 </span><span class="subxComment"># Unclear how I'd use it, though. Callers seem to need the check anyway.</span>
<span id="L196" class="LineNr">196 </span><span class="subxComment"># Maybe a better helper would be 'empty-stream?'</span>
<span id="L197" class="LineNr">197 </span>
<span id="L198" class="LineNr">198 </span><span class="subxMinorFunction">_read</span>: <span class="subxComment"># fd: int, s: (addr stream byte) -> num-bytes-read/eax: int</span>
<span id="L199" class="LineNr">199 </span> <span class="subxS1Comment"># . prologue</span>
<span id="L200" class="LineNr">200 </span> 55/push-ebp
<span id="L201" class="LineNr">201 </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="L202" class="LineNr">202 </span> <span class="subxS1Comment"># . save registers</span>
<span id="L203" class="LineNr">203 </span> 51/push-ecx
<span id="L204" class="LineNr">204 </span> 52/push-edx
<span id="L205" class="LineNr">205 </span> 53/push-ebx
<span id="L206" class="LineNr">206 </span> 56/push-esi
<span id="L207" class="LineNr">207 </span> <span class="subxComment"># esi = s</span>
<span id="L208" class="LineNr">208 </span> 8b/copy 1/mod/*+disp8 5/rm32/ebp <span class="Normal"> . </span> <span class="Normal"> . </span> <span class="Normal"> . </span> 6/r32/esi 0xc/disp8 <span class="Normal"> . </span> <span class="subxComment"># copy *(ebp+12) to esi</span>
<span id="L209" class="LineNr">209 </span> <span class="subxComment"># eax = s->write</span>
<span id="L210" class="LineNr">210 </span> 8b/copy 0/mod/indirect 6/rm32/esi <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"># copy *esi to eax</span>
<span id="L211" class="LineNr">211 </span> <span class="subxComment"># edx = s->size</span>
<span id="L212" class="LineNr">212 </span> 8b/copy 1/mod/*+disp8 6/rm32/esi <span class="Normal"> . </span> <span class="Normal"> . </span> <span class="Normal"> . </span> 2/r32/edx 8/disp8 <span class="Normal"> . </span> <span class="subxComment"># copy *(esi+8) to edx</span>
<span id="L213" class="LineNr">213 </span> <span class="subxComment"># syscall_read(fd, &s->data[s->write], s->size - s->write)</span>
<span id="L214" class="LineNr">214 </span> <span class="subxS2Comment"># . . fd: ebx</span>
<span id="L215" class="LineNr">215 </span> 8b/copy 1/mod/*+disp8 5/rm32/ebp <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 *(ebp+8) to ebx</span>
<span id="L216" class="LineNr">216 </span> <span class="subxS2Comment"># . . data: ecx = &s->data[s->write]</span>
<span id="L217" class="LineNr">217 </span> 8d/copy-address 1/mod/*+disp8 4/rm32/sib 6/base/esi 0/index/eax <span class="Normal"> . </span> 1/r32/ecx 0xc/disp8 <span class="Normal"> . </span> <span class="subxComment"># copy esi+eax+12 to ecx</span>
<span id="L218" class="LineNr">218 </span> <span class="subxS2Comment"># . . size: edx = s->size - s->write</span>
<span id="L219" class="LineNr">219 </span> 29/subtract 3/mod/direct 2/rm32/edx <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"># subtract eax from edx</span>
<span id="L220" class="LineNr">220 </span> <span class="subxS2Comment"># . . syscall</span>
<span id="L221" class="LineNr">221 </span> e8/call <a href='000init.subx.html#L23'>syscall_read</a>/disp32
<span id="L222" class="LineNr">222 </span> <span class="subxComment"># add the result eax to s->write</span>
<span id="L223" class="LineNr">223 </span> 01/add 0/mod/indirect 6/rm32/esi <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 *esi</span>
<span id="L224" class="LineNr">224 </span><span class="Constant">$_read:end</span>:
<span id="L225" class="LineNr">225 </span> <span class="subxS1Comment"># . restore registers</span>
<span id="L226" class="LineNr">226 </span> 5e/pop-to-esi
<span id="L227" class="LineNr">227 </span> 5b/pop-to-ebx
<span id="L228" class="LineNr">228 </span> 5a/pop-to-edx
<span id="L229" class="LineNr">229 </span> 59/pop-to-ecx
<span id="L230" class="LineNr">230 </span> <span class="subxS1Comment"># . epilogue</span>
<span id="L231" class="LineNr">231 </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="L232" class="LineNr">232 </span> 5d/pop-to-ebp
<span id="L233" class="LineNr">233 </span> c3/return
<span id="L234" class="LineNr">234 </span>
<span id="L235" class="LineNr">235 </span> <span class="subxComment"># Two options:</span>
<span id="L236" class="LineNr">236 </span> <span class="subxComment"># 1 (what we have above):</span>
<span id="L237" class="LineNr">237 </span> <span class="subxComment"># ecx = s</span>
<span id="L238" class="LineNr">238 </span> <span class="subxComment"># eax = s->write</span>
<span id="L239" class="LineNr">239 </span> <span class="subxComment"># edx = s->size</span>
<span id="L240" class="LineNr">240 </span> <span class="subxComment"># # syscall</span>
<span id="L241" class="LineNr">241 </span> <span class="subxComment"># ecx = lea ecx+eax+12</span>
<span id="L242" class="LineNr">242 </span> <span class="subxComment"># edx = sub edx eax</span>
<span id="L243" class="LineNr">243 </span> <span class="subxComment">#</span>
<span id="L244" class="LineNr">244 </span> <span class="subxComment"># 2:</span>
<span id="L245" class="LineNr">245 </span> <span class="subxComment"># ecx = s</span>
<span id="L246" class="LineNr">246 </span> <span class="subxComment"># edx = s->size</span>
<span id="L247" class="LineNr">247 </span> <span class="subxComment"># ecx = &s->data</span>
<span id="L248" class="LineNr">248 </span> <span class="subxComment"># # syscall</span>
<span id="L249" class="LineNr">249 </span> <span class="subxComment"># ecx = add ecx, s->write</span>
<span id="L250" class="LineNr">250 </span> <span class="subxComment"># edx = sub edx, s->write</span>
<span id="L251" class="LineNr">251 </span> <span class="subxComment">#</span>
<span id="L252" class="LineNr">252 </span> <span class="subxComment"># Not much to choose between the two? Option 2 performs a duplicate load to</span>
<span id="L253" class="LineNr">253 </span> <span class="subxComment"># use one less register, but doesn't increase the amount of spilling (ecx</span>
<span id="L254" class="LineNr">254 </span> <span class="subxComment"># and edx must be used, and eax must be clobbered anyway).</span>
<span id="L255" class="LineNr">255 </span>
<span id="L256" class="LineNr">256 </span><span class="subxH1Comment"># - tests</span>
<span id="L257" class="LineNr">257 </span>
<span id="L258" class="LineNr">258 </span><span class="subxTest">test-read-single</span>:
<span id="L259" class="LineNr">259 </span> <span class="subxH1Comment"># - write a single character into _test-stream, then read from it</span>
<span id="L260" class="LineNr">260 </span> <span class="subxComment"># clear-stream(_test-stream)</span>
<span id="L261" class="LineNr">261 </span> <span class="subxS2Comment"># . . push args</span>
<span id="L262" class="LineNr">262 </span> 68/push <a href='108write.subx.html#L151'>_test-stream</a>/imm32
<span id="L263" class="LineNr">263 </span> <span class="subxS2Comment"># . . call</span>
<span id="L264" class="LineNr">264 </span> e8/call <a href='106stream.subx.html#L17'>clear-stream</a>/disp32
<span id="L265" class="LineNr">265 </span> <span class="subxS2Comment"># . . discard args</span>
<span id="L266" class="LineNr">266 </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="L267" class="LineNr">267 </span> <span class="subxComment"># clear-stream(_test-tmp-stream)</span>
<span id="L268" class="LineNr">268 </span> <span class="subxS2Comment"># . . push args</span>
<span id="L269" class="LineNr">269 </span> 68/push <a href='111read.subx.html#L428'>_test-tmp-stream</a>/imm32
<span id="L270" class="LineNr">270 </span> <span class="subxS2Comment"># . . call</span>
<span id="L271" class="LineNr">271 </span> e8/call <a href='106stream.subx.html#L17'>clear-stream</a>/disp32
<span id="L272" class="LineNr">272 </span> <span class="subxS2Comment"># . . discard args</span>
<span id="L273" class="LineNr">273 </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="L274" class="LineNr">274 </span> <span class="subxComment"># write(_test-stream, "Ab")</span>
<span id="L275" class="LineNr">275 </span> <span class="subxS2Comment"># . . push args</span>
<span id="L276" class="LineNr">276 </span> 68/push <span class="Constant">"Ab"</span>/imm32
<span id="L277" class="LineNr">277 </span> 68/push <a href='108write.subx.html#L151'>_test-stream</a>/imm32
<span id="L278" class="LineNr">278 </span> <span class="subxS2Comment"># . . call</span>
<span id="L279" class="LineNr">279 </span> e8/call <a href='108write.subx.html#L24'>write</a>/disp32
<span id="L280" class="LineNr">280 </span> <span class="subxS2Comment"># . . discard args</span>
<span id="L281" class="LineNr">281 </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="L282" class="LineNr">282 </span> <span class="subxComment"># eax = read(_test-stream, _test-tmp-stream)</span>
<span id="L283" class="LineNr">283 </span> <span class="subxS2Comment"># . . push args</span>
<span id="L284" class="LineNr">284 </span> 68/push <a href='111read.subx.html#L428'>_test-tmp-stream</a>/imm32
<span id="L285" class="LineNr">285 </span> 68/push <a href='108write.subx.html#L151'>_test-stream</a>/imm32
<span id="L286" class="LineNr">286 </span> <span class="subxS2Comment"># . . call</span>
<span id="L287" class="LineNr">287 </span> e8/call <a href='111read.subx.html#L48'>read</a>/disp32
<span id="L288" class="LineNr">288 </span> <span class="subxS2Comment"># . . discard args</span>
<span id="L289" class="LineNr">289 </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="L290" class="LineNr">290 </span> <span class="subxComment"># check-ints-equal(eax, 2, msg)</span>
<span id="L291" class="LineNr">291 </span> <span class="subxS2Comment"># . . push args</span>
<span id="L292" class="LineNr">292 </span> 68/push <span class="Constant">"F - <a href='111read.subx.html#L258'>test-read-single</a>: return value"</span>/imm32
<span id="L293" class="LineNr">293 </span> 68/push 2/imm32
<span id="L294" class="LineNr">294 </span> 50/push-eax
<span id="L295" class="LineNr">295 </span> <span class="subxS2Comment"># . . call</span>
<span id="L296" class="LineNr">296 </span> e8/call <a href='102test.subx.html#L23'>check-ints-equal</a>/disp32
<span id="L297" class="LineNr">297 </span> <span class="subxS2Comment"># . . discard args</span>
<span id="L298" class="LineNr">298 </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="L299" class="LineNr">299 </span> <span class="subxComment"># check-stream-equal(_test-tmp-stream, "Ab", msg)</span>
<span id="L300" class="LineNr">300 </span> <span class="subxS2Comment"># . . push args</span>
<span id="L301" class="LineNr">301 </span> 68/push <span class="Constant">"F - test-read-single"</span>/imm32
<span id="L302" class="LineNr">302 </span> 68/push <span class="Constant">"Ab"</span>/imm32
<span id="L303" class="LineNr">303 </span> 68/push <a href='111read.subx.html#L428'>_test-tmp-stream</a>/imm32
<span id="L304" class="LineNr">304 </span> <span class="subxS2Comment"># . . call</span>
<span id="L305" class="LineNr">305 </span> e8/call <a href='109stream-equal.subx.html#L194'>check-stream-equal</a>/disp32
<span id="L306" class="LineNr">306 </span> <span class="subxS2Comment"># . . discard args</span>
<span id="L307" class="LineNr">307 </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="L308" class="LineNr">308 </span> <span class="subxComment"># end</span>
<span id="L309" class="LineNr">309 </span> c3/return
<span id="L310" class="LineNr">310 </span>
<span id="L311" class="LineNr">311 </span><span class="subxTest">test-read-is-stateful</span>:
<span id="L312" class="LineNr">312 </span> <span class="subxH1Comment"># - make two consecutive reads, check that their results are appended</span>
<span id="L313" class="LineNr">313 </span> <span class="subxComment"># clear-stream(_test-stream)</span>
<span id="L314" class="LineNr">314 </span> <span class="subxS2Comment"># . . push args</span>
<span id="L315" class="LineNr">315 </span> 68/push <a href='108write.subx.html#L151'>_test-stream</a>/imm32
<span id="L316" class="LineNr">316 </span> <span class="subxS2Comment"># . . call</span>
<span id="L317" class="LineNr">317 </span> e8/call <a href='106stream.subx.html#L17'>clear-stream</a>/disp32
<span id="L318" class="LineNr">318 </span> <span class="subxS2Comment"># . . discard args</span>
<span id="L319" class="LineNr">319 </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="L320" class="LineNr">320 </span> <span class="subxComment"># clear-stream(_test-tmp-stream)</span>
<span id="L321" class="LineNr">321 </span> <span class="subxS2Comment"># . . push args</span>
<span id="L322" class="LineNr">322 </span> 68/push <a href='111read.subx.html#L428'>_test-tmp-stream</a>/imm32
<span id="L323" class="LineNr">323 </span> <span class="subxS2Comment"># . . call</span>
<span id="L324" class="LineNr">324 </span> e8/call <a href='106stream.subx.html#L17'>clear-stream</a>/disp32
<span id="L325" class="LineNr">325 </span> <span class="subxS2Comment"># . . discard args</span>
<span id="L326" class="LineNr">326 </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="L327" class="LineNr">327 </span> <span class="subxComment"># write(_test-stream, "C")</span>
<span id="L328" class="LineNr">328 </span> <span class="subxS2Comment"># . . push args</span>
<span id="L329" class="LineNr">329 </span> 68/push <span class="Constant">"C"</span>/imm32
<span id="L330" class="LineNr">330 </span> 68/push <a href='108write.subx.html#L151'>_test-stream</a>/imm32
<span id="L331" class="LineNr">331 </span> <span class="subxS2Comment"># . . call</span>
<span id="L332" class="LineNr">332 </span> e8/call <a href='108write.subx.html#L24'>write</a>/disp32
<span id="L333" class="LineNr">333 </span> <span class="subxS2Comment"># . . discard args</span>
<span id="L334" class="LineNr">334 </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="L335" class="LineNr">335 </span> <span class="subxComment"># read(_test-stream, _test-tmp-stream)</span>
<span id="L336" class="LineNr">336 </span> <span class="subxS2Comment"># . . push args</span>
<span id="L337" class="LineNr">337 </span> 68/push <a href='111read.subx.html#L428'>_test-tmp-stream</a>/imm32
<span id="L338" class="LineNr">338 </span> 68/push <a href='108write.subx.html#L151'>_test-stream</a>/imm32
<span id="L339" class="LineNr">339 </span> <span class="subxS2Comment"># . . call</span>
<span id="L340" class="LineNr">340 </span> e8/call <a href='111read.subx.html#L48'>read</a>/disp32
<span id="L341" class="LineNr">341 </span> <span class="subxS2Comment"># . . discard args</span>
<span id="L342" class="LineNr">342 </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="L343" class="LineNr">343 </span> <span class="subxComment"># write(_test-stream, "D")</span>
<span id="L344" class="LineNr">344 </span> <span class="subxS2Comment"># . . push args</span>
<span id="L345" class="LineNr">345 </span> 68/push <span class="Constant">"D"</span>/imm32
<span id="L346" class="LineNr">346 </span> 68/push <a href='108write.subx.html#L151'>_test-stream</a>/imm32
<span id="L347" class="LineNr">347 </span> <span class="subxS2Comment"># . . call</span>
<span id="L348" class="LineNr">348 </span> e8/call <a href='108write.subx.html#L24'>write</a>/disp32
<span id="L349" class="LineNr">349 </span> <span class="subxS2Comment"># . . discard args</span>
<span id="L350" class="LineNr">350 </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="L351" class="LineNr">351 </span> <span class="subxComment"># read(_test-stream, _test-tmp-stream)</span>
<span id="L352" class="LineNr">352 </span> <span class="subxS2Comment"># . . push args</span>
<span id="L353" class="LineNr">353 </span> 68/push <a href='111read.subx.html#L428'>_test-tmp-stream</a>/imm32
<span id="L354" class="LineNr">354 </span> 68/push <a href='108write.subx.html#L151'>_test-stream</a>/imm32
<span id="L355" class="LineNr">355 </span> <span class="subxS2Comment"># . . call</span>
<span id="L356" class="LineNr">356 </span> e8/call <a href='111read.subx.html#L48'>read</a>/disp32
<span id="L357" class="LineNr">357 </span> <span class="subxS2Comment"># . . discard args</span>
<span id="L358" class="LineNr">358 </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="L359" class="LineNr">359 </span> <span class="subxComment"># check-stream-equal(_test-tmp-stream, "CD", msg)</span>
<span id="L360" class="LineNr">360 </span> <span class="subxS2Comment"># . . push args</span>
<span id="L361" class="LineNr">361 </span> 68/push <span class="Constant">"F - test-read-is-stateful"</span>/imm32
<span id="L362" class="LineNr">362 </span> 68/push <span class="Constant">"CD"</span>/imm32
<span id="L363" class="LineNr">363 </span> 68/push <a href='111read.subx.html#L428'>_test-tmp-stream</a>/imm32
<span id="L364" class="LineNr">364 </span> <span class="subxS2Comment"># . . call</span>
<span id="L365" class="LineNr">365 </span> e8/call <a href='109stream-equal.subx.html#L194'>check-stream-equal</a>/disp32
<span id="L366" class="LineNr">366 </span> <span class="subxS2Comment"># . . discard args</span>
<span id="L367" class="LineNr">367 </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="L368" class="LineNr">368 </span> <span class="subxComment"># end</span>
<span id="L369" class="LineNr">369 </span> c3/return
<span id="L370" class="LineNr">370 </span>
<span id="L371" class="LineNr">371 </span><span class="subxTest">test-read-returns-0-on-end-of-file</span>:
<span id="L372" class="LineNr">372 </span> <span class="subxH1Comment"># - read after hitting end-of-file, check that result is 0</span>
<span id="L373" class="LineNr">373 </span> <span class="subxComment"># setup</span>
<span id="L374" class="LineNr">374 </span> <span class="subxS1Comment"># . clear-stream(_test-stream)</span>
<span id="L375" class="LineNr">375 </span> <span class="subxS2Comment"># . . push args</span>
<span id="L376" class="LineNr">376 </span> 68/push <a href='108write.subx.html#L151'>_test-stream</a>/imm32
<span id="L377" class="LineNr">377 </span> <span class="subxS2Comment"># . . call</span>
<span id="L378" class="LineNr">378 </span> e8/call <a href='106stream.subx.html#L17'>clear-stream</a>/disp32
<span id="L379" class="LineNr">379 </span> <span class="subxS2Comment"># . . discard args</span>
<span id="L380" class="LineNr">380 </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="L381" class="LineNr">381 </span> <span class="subxS1Comment"># . clear-stream(_test-tmp-stream)</span>
<span id="L382" class="LineNr">382 </span> <span class="subxS2Comment"># . . push args</span>
<span id="L383" class="LineNr">383 </span> 68/push <a href='111read.subx.html#L428'>_test-tmp-stream</a>/imm32
<span id="L384" class="LineNr">384 </span> <span class="subxS2Comment"># . . call</span>
<span id="L385" class="LineNr">385 </span> e8/call <a href='106stream.subx.html#L17'>clear-stream</a>/disp32
<span id="L386" class="LineNr">386 </span> <span class="subxS2Comment"># . . discard args</span>
<span id="L387" class="LineNr">387 </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="L388" class="LineNr">388 </span> <span class="subxS1Comment"># . write(_test-stream, "Ab")</span>
<span id="L389" class="LineNr">389 </span> <span class="subxS2Comment"># . . push args</span>
<span id="L390" class="LineNr">390 </span> 68/push <span class="Constant">"Ab"</span>/imm32
<span id="L391" class="LineNr">391 </span> 68/push <a href='108write.subx.html#L151'>_test-stream</a>/imm32
<span id="L392" class="LineNr">392 </span> <span class="subxS2Comment"># . . call</span>
<span id="L393" class="LineNr">393 </span> e8/call <a href='108write.subx.html#L24'>write</a>/disp32
<span id="L394" class="LineNr">394 </span> <span class="subxS2Comment"># . . discard args</span>
<span id="L395" class="LineNr">395 </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="L396" class="LineNr">396 </span> <span class="subxComment"># first read gets to end-of-file</span>
<span id="L397" class="LineNr">397 </span> <span class="subxS1Comment"># . read(_test-stream, _test-tmp-stream)</span>
<span id="L398" class="LineNr">398 </span> <span class="subxS2Comment"># . . push args</span>
<span id="L399" class="LineNr">399 </span> 68/push <a href='111read.subx.html#L428'>_test-tmp-stream</a>/imm32
<span id="L400" class="LineNr">400 </span> 68/push <a href='108write.subx.html#L151'>_test-stream</a>/imm32
<span id="L401" class="LineNr">401 </span> <span class="subxS2Comment"># . . call</span>
<span id="L402" class="LineNr">402 </span> e8/call <a href='111read.subx.html#L48'>read</a>/disp32
<span id="L403" class="LineNr">403 </span> <span class="subxS2Comment"># . . discard args</span>
<span id="L404" class="LineNr">404 </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="L405" class="LineNr">405 </span> <span class="subxComment"># second read</span>
<span id="L406" class="LineNr">406 </span> <span class="subxS1Comment"># . read(_test-stream, _test-tmp-stream)</span>
<span id="L407" class="LineNr">407 </span> <span class="subxS2Comment"># . . push args</span>
<span id="L408" class="LineNr">408 </span> 68/push <a href='111read.subx.html#L428'>_test-tmp-stream</a>/imm32
<span id="L409" class="LineNr">409 </span> 68/push <a href='108write.subx.html#L151'>_test-stream</a>/imm32
<span id="L410" class="LineNr">410 </span> <span class="subxS2Comment"># . . call</span>
<span id="L411" class="LineNr">411 </span> e8/call <a href='111read.subx.html#L48'>read</a>/disp32
<span id="L412" class="LineNr">412 </span> <span class="subxS2Comment"># . . discard args</span>
<span id="L413" class="LineNr">413 </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="L414" class="LineNr">414 </span> <span class="subxComment"># check-ints-equal(eax, 0, msg)</span>
<span id="L415" class="LineNr">415 </span> <span class="subxS2Comment"># . . push args</span>
<span id="L416" class="LineNr">416 </span> 68/push <span class="Constant">"F - test-read-returns-0-on-end-of-file"</span>/imm32
<span id="L417" class="LineNr">417 </span> 68/push 0/imm32
<span id="L418" class="LineNr">418 </span> 50/push-eax
<span id="L419" class="LineNr">419 </span> <span class="subxS2Comment"># . . call</span>
<span id="L420" class="LineNr">420 </span> e8/call <a href='102test.subx.html#L23'>check-ints-equal</a>/disp32
<span id="L421" class="LineNr">421 </span> <span class="subxS2Comment"># . . discard args</span>
<span id="L422" class="LineNr">422 </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="L423" class="LineNr">423 </span> <span class="subxComment"># end</span>
<span id="L424" class="LineNr">424 </span> c3/return
<span id="L425" class="LineNr">425 </span>
<span id="L426" class="LineNr">426 </span>== data
<span id="L427" class="LineNr">427 </span>
<span id="L428" class="LineNr">428 </span><span class="subxMinorFunction">_test-tmp-stream</span>: <span class="subxComment"># (stream byte)</span>
<span id="L429" class="LineNr">429 </span> <span class="subxComment"># current write index</span>
<span id="L430" class="LineNr">430 </span> 0/imm32
<span id="L431" class="LineNr">431 </span> <span class="subxComment"># current read index</span>
<span id="L432" class="LineNr">432 </span> 0/imm32
<span id="L433" class="LineNr">433 </span> <span class="subxComment"># size</span>
<span id="L434" class="LineNr">434 </span> 8/imm32
<span id="L435" class="LineNr">435 </span> <span class="subxComment"># data</span>
<span id="L436" class="LineNr">436 </span> 00 00 00 00 00 00 00 00 <span class="subxComment"># 8 bytes</span>
<span id="L437" class="LineNr">437 </span>
<span id="L438" class="LineNr">438 </span><span class="subxS2Comment"># . . vim:nowrap:textwidth=0</span>
</pre>
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