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authorKartik Agaram <vc@akkartik.com>2018-12-03 17:08:04 -0800
committerKartik Agaram <vc@akkartik.com>2018-12-03 17:08:53 -0800
commit83822d63240cc4d03d00133719993f5e4b2c281f (patch)
tree31022cc8672e79670030aa279109bf6bc9b387ba
parent5e27c7f13e6a888484ccf144579ed2d3b676da89 (diff)
downloadmu-83822d63240cc4d03d00133719993f5e4b2c281f.tar.gz
4828 - writing to buffered-file
This is likely a sub-optimal interface, but I'm trying not to agonize.
The whole point of Mu is to permit radical changes at any point in time.
-rw-r--r--html/subx/059read-byte.subx.html385
-rw-r--r--html/subx/062write-byte.subx.html229
-rw-r--r--subx/059read-byte.subx5
-rw-r--r--subx/062write-byte.subx160
-rwxr-xr-xsubx/apps/crenshaw2-1bin6482 -> 6759 bytes
-rwxr-xr-xsubx/apps/crenshaw2-1bbin7043 -> 7320 bytes
-rwxr-xr-xsubx/apps/factorialbin5373 -> 5650 bytes
7 files changed, 583 insertions, 196 deletions
diff --git a/html/subx/059read-byte.subx.html b/html/subx/059read-byte.subx.html
index e23ec5a7..a3ebe17f 100644
--- a/html/subx/059read-byte.subx.html
+++ b/html/subx/059read-byte.subx.html
@@ -119,201 +119,200 @@ if ('onhashchange' in window) {
 <span id="L53" class="LineNr"> 53 </span>    8b/copy                         1/mod/*+disp8   4/rm32/sib    5/base/EBP  4/index/none <span class="CommentedCode"> . </span>          6/r32/ESI   8/disp8        <span class="CommentedCode"> . </span>                <span class="subxComment"># copy *(EBP+8) to ESI</span>
 <span id="L54" class="LineNr"> 54 </span>    <span class="subxComment"># ECX = f-&gt;read</span>
 <span id="L55" class="LineNr"> 55 </span>    8b/copy                         1/mod/*+disp8   6/rm32/ESI   <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>           <span class="CommentedCode"> . </span>          1/r32/ECX   8/disp8        <span class="CommentedCode"> . </span>                <span class="subxComment"># copy *(ESI+8) to ECX</span>
-<span id="L56" class="LineNr"> 56 </span>    <span class="subxComment"># if (f-&gt;read &lt; f-&gt;write) read byte from stream</span>
+<span id="L56" class="LineNr"> 56 </span>    <span class="subxComment"># if (f-&gt;read &gt;= f-&gt;write) populate stream from file</span>
 <span id="L57" class="LineNr"> 57 </span>    3b/compare                      1/mod/*+disp8   6/rm32/ESI   <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>           <span class="CommentedCode"> . </span>          1/r32/ECX   4/disp8        <span class="CommentedCode"> . </span>                <span class="subxComment"># compare ECX with *(ESI+4)</span>
 <span id="L58" class="LineNr"> 58 </span>    7c/jump-if-lesser  $read-byte:from-stream/disp8
-<span id="L59" class="LineNr"> 59 </span>    <span class="subxComment"># otherwise first populate stream from file</span>
-<span id="L60" class="LineNr"> 60 </span>    <span class="subxS1Comment"># . clear-stream(stream = f+4)</span>
-<span id="L61" class="LineNr"> 61 </span>    <span class="subxS2Comment"># . . push args</span>
-<span id="L62" class="LineNr"> 62 </span>    8d/copy-address                 1/mod/*+disp8   6/rm32/ESI   <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>           <span class="CommentedCode"> . </span>          0/r32/EAX   4/disp8        <span class="CommentedCode"> . </span>                <span class="subxComment"># copy ESI+4 to EAX</span>
-<span id="L63" class="LineNr"> 63 </span>    50/push-EAX
-<span id="L64" class="LineNr"> 64 </span>    <span class="subxS2Comment"># . . call</span>
-<span id="L65" class="LineNr"> 65 </span>    e8/call  clear-stream/disp32
-<span id="L66" class="LineNr"> 66 </span>    <span class="subxS2Comment"># . . discard args</span>
-<span id="L67" class="LineNr"> 67 </span>    81          0/subop/add         3/mod/direct    4/rm32/ESP   <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>           <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>              4/imm32           <span class="subxComment"># add to ESP</span>
-<span id="L68" class="LineNr"> 68 </span>    <span class="subxS1Comment"># . EAX = read(f-&gt;fd, stream = f+4)</span>
-<span id="L69" class="LineNr"> 69 </span>    <span class="subxS2Comment"># . . push args</span>
-<span id="L70" class="LineNr"> 70 </span>    50/push-EAX
-<span id="L71" class="LineNr"> 71 </span>    ff          6/subop/push        0/mod/indirect  6/rm32/ESI   <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>           <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>             <span class="CommentedCode"> . </span>                <span class="subxComment"># push *ESI</span>
-<span id="L72" class="LineNr"> 72 </span>    <span class="subxS2Comment"># . . call</span>
-<span id="L73" class="LineNr"> 73 </span>    e8/call  read/disp32
-<span id="L74" class="LineNr"> 74 </span>    <span class="subxS2Comment"># . . discard args</span>
-<span id="L75" class="LineNr"> 75 </span>    81          0/subop/add         3/mod/direct    4/rm32/ESP   <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>           <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>              8/imm32           <span class="subxComment"># add to ESP</span>
-<span id="L76" class="LineNr"> 76 </span>    <span class="subxComment"># if EAX = 0 return 0xffffffff</span>
-<span id="L77" class="LineNr"> 77 </span>    81          7/subop/compare     3/mod/direct    0/rm32/EAX   <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>           <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>              0/imm32           <span class="subxComment"># compare EAX</span>
-<span id="L78" class="LineNr"> 78 </span>    75/jump-if-not-equal  $read-byte:from-stream/disp8
-<span id="L79" class="LineNr"> 79 </span>    b8/copy-to-EAX  0xffffffff/imm32
-<span id="L80" class="LineNr"> 80 </span>    eb/jump  $read-byte:end/disp8
-<span id="L81" class="LineNr"> 81 </span><span class="Constant">$read-byte:from-stream</span>:
-<span id="L82" class="LineNr"> 82 </span>    <span class="subxComment"># reading from stream</span>
-<span id="L83" class="LineNr"> 83 </span>    <span class="subxComment"># AL = f-&gt;data[f-&gt;read]</span>
-<span id="L84" class="LineNr"> 84 </span>    31/xor                          3/mod/direct    0/rm32/EAX   <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>           <span class="CommentedCode"> . </span>          0/r32/EAX  <span class="CommentedCode"> . </span>             <span class="CommentedCode"> . </span>                <span class="subxComment"># clear EAX</span>
-<span id="L85" class="LineNr"> 85 </span>    8a/copy-byte                    1/mod/*+disp8   4/rm32/sib    6/base/ESI  1/index/ECX  <span class="CommentedCode"> . </span>          0/r32/AL    0x10/disp8     <span class="CommentedCode"> . </span>                <span class="subxComment"># copy *(ESI+ECX+16) to AL</span>
-<span id="L86" class="LineNr"> 86 </span>    <span class="subxComment"># ++f-&gt;read</span>
-<span id="L87" class="LineNr"> 87 </span>    ff          0/subop/increment   1/mod/*+disp8   6/rm32/ESI   <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>           <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>          8/disp8        <span class="CommentedCode"> . </span>                <span class="subxComment"># increment *(ESI+8)</span>
-<span id="L88" class="LineNr"> 88 </span><span class="Constant">$read-byte:end</span>:
-<span id="L89" class="LineNr"> 89 </span>    <span class="subxS1Comment"># . restore registers</span>
-<span id="L90" class="LineNr"> 90 </span>    5e/pop-to-ESI
-<span id="L91" class="LineNr"> 91 </span>    59/pop-to-ECX
-<span id="L92" class="LineNr"> 92 </span>    <span class="subxS1Comment"># . epilog</span>
-<span id="L93" class="LineNr"> 93 </span>    89/copy                         3/mod/direct    4/rm32/ESP   <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>           <span class="CommentedCode"> . </span>          5/r32/EBP  <span class="CommentedCode"> . </span>             <span class="CommentedCode"> . </span>                <span class="subxComment"># copy EBP to ESP</span>
-<span id="L94" class="LineNr"> 94 </span>    5d/pop-to-EBP
-<span id="L95" class="LineNr"> 95 </span>    c3/return
-<span id="L96" class="LineNr"> 96 </span>
-<span id="L97" class="LineNr"> 97 </span><span class="subxH1Comment"># - tests</span>
-<span id="L98" class="LineNr"> 98 </span>
-<span id="L99" class="LineNr"> 99 </span><span class="subxTest">test-read-byte-single</span>:
-<span id="L100" class="LineNr">100 </span>    <span class="subxH1Comment"># - check that read-byte returns first byte of 'file'</span>
-<span id="L101" class="LineNr">101 </span>    <span class="subxComment"># setup</span>
-<span id="L102" class="LineNr">102 </span>    <span class="subxS1Comment"># . clear-stream(_test-stream)</span>
-<span id="L103" class="LineNr">103 </span>    <span class="subxS2Comment"># . . push args</span>
-<span id="L104" class="LineNr">104 </span>    68/push  _test-stream/imm32
-<span id="L105" class="LineNr">105 </span>    <span class="subxS2Comment"># . . call</span>
-<span id="L106" class="LineNr">106 </span>    e8/call  clear-stream/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="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>           <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>              4/imm32           <span class="subxComment"># add to ESP</span>
-<span id="L109" class="LineNr">109 </span>    <span class="subxS1Comment"># . clear-stream(_test-buffered-file+4)</span>
-<span id="L110" class="LineNr">110 </span>    <span class="subxS2Comment"># . . push args</span>
-<span id="L111" class="LineNr">111 </span>    b8/copy-to-EAX  _test-buffered-file/imm32
-<span id="L112" class="LineNr">112 </span>    05/add-to-EAX  4/imm32
-<span id="L113" class="LineNr">113 </span>    50/push-EAX
-<span id="L114" class="LineNr">114 </span>    <span class="subxS2Comment"># . . call</span>
-<span id="L115" class="LineNr">115 </span>    e8/call  clear-stream/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="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>           <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>              4/imm32           <span class="subxComment"># add to ESP</span>
-<span id="L118" class="LineNr">118 </span>    <span class="subxS1Comment"># . write(_test-stream, &quot;Ab&quot;)</span>
-<span id="L119" class="LineNr">119 </span>    <span class="subxS2Comment"># . . push args</span>
-<span id="L120" class="LineNr">120 </span>    68/push  <span class="Constant">&quot;Ab&quot;</span>/imm32
-<span id="L121" class="LineNr">121 </span>    68/push  _test-stream/imm32
-<span id="L122" class="LineNr">122 </span>    <span class="subxS2Comment"># . . call</span>
-<span id="L123" class="LineNr">123 </span>    e8/call  write/disp32
-<span id="L124" class="LineNr">124 </span>    <span class="subxS2Comment"># . . discard args</span>
-<span id="L125" class="LineNr">125 </span>    81          0/subop/add         3/mod/direct    4/rm32/ESP   <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>           <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>              8/imm32           <span class="subxComment"># add to ESP</span>
-<span id="L126" class="LineNr">126 </span>    <span class="subxComment"># read-byte(_test-buffered-file)</span>
-<span id="L127" class="LineNr">127 </span>    <span class="subxS2Comment"># . . push args</span>
-<span id="L128" class="LineNr">128 </span>    68/push  _test-buffered-file/imm32
-<span id="L129" class="LineNr">129 </span>    <span class="subxS2Comment"># . . call</span>
-<span id="L130" class="LineNr">130 </span>    e8/call  read-byte/disp32
-<span id="L131" class="LineNr">131 </span>    <span class="subxS2Comment"># . . discard args</span>
-<span id="L132" class="LineNr">132 </span>    81          0/subop/add         3/mod/direct    4/rm32/ESP   <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>           <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>              4/imm32           <span class="subxComment"># add to ESP</span>
-<span id="L133" class="LineNr">133 </span>    <span class="subxComment"># check-ints-equal(EAX, 'A', msg)</span>
-<span id="L134" class="LineNr">134 </span>    <span class="subxS2Comment"># . . push args</span>
-<span id="L135" class="LineNr">135 </span>    68/push  <span class="Constant">&quot;F - test-read-byte-single&quot;</span>/imm32
-<span id="L136" class="LineNr">136 </span>    68/push  0x41/imm32
-<span id="L137" class="LineNr">137 </span>    50/push-EAX
-<span id="L138" class="LineNr">138 </span>    <span class="subxS2Comment"># . . call</span>
-<span id="L139" class="LineNr">139 </span>    e8/call  check-ints-equal/disp32
-<span id="L140" class="LineNr">140 </span>    <span class="subxS2Comment"># . . discard args</span>
-<span id="L141" class="LineNr">141 </span>    81          0/subop/add         3/mod/direct    4/rm32/ESP   <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>           <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>              0xc/imm32         <span class="subxComment"># add to ESP</span>
-<span id="L142" class="LineNr">142 </span>    <span class="subxS1Comment"># . end</span>
-<span id="L143" class="LineNr">143 </span>    c3/return
-<span id="L144" class="LineNr">144 </span>
-<span id="L145" class="LineNr">145 </span><span class="subxTest">test-read-byte-multiple</span>:
-<span id="L146" class="LineNr">146 </span>    <span class="subxH1Comment"># - call read-byte twice, check that second call returns second byte</span>
-<span id="L147" class="LineNr">147 </span>    <span class="subxComment"># setup</span>
-<span id="L148" class="LineNr">148 </span>    <span class="subxS1Comment"># . clear-stream(_test-stream)</span>
-<span id="L149" class="LineNr">149 </span>    <span class="subxS2Comment"># . . push args</span>
-<span id="L150" class="LineNr">150 </span>    68/push  _test-stream/imm32
-<span id="L151" class="LineNr">151 </span>    <span class="subxS2Comment"># . . call</span>
-<span id="L152" class="LineNr">152 </span>    e8/call  clear-stream/disp32
-<span id="L153" class="LineNr">153 </span>    <span class="subxS2Comment"># . . discard args</span>
-<span id="L154" class="LineNr">154 </span>    81          0/subop/add         3/mod/direct    4/rm32/ESP   <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>           <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>              4/imm32           <span class="subxComment"># add to ESP</span>
-<span id="L155" class="LineNr">155 </span>    <span class="subxS1Comment"># . clear-stream(_test-buffered-file+4)</span>
-<span id="L156" class="LineNr">156 </span>    <span class="subxS2Comment"># . . push args</span>
-<span id="L157" class="LineNr">157 </span>    b8/copy-to-EAX  _test-buffered-file/imm32
-<span id="L158" class="LineNr">158 </span>    05/add-to-EAX  4/imm32
-<span id="L159" class="LineNr">159 </span>    50/push-EAX
-<span id="L160" class="LineNr">160 </span>    <span class="subxS2Comment"># . . call</span>
-<span id="L161" class="LineNr">161 </span>    e8/call  clear-stream/disp32
-<span id="L162" class="LineNr">162 </span>    <span class="subxS2Comment"># . . discard args</span>
-<span id="L163" class="LineNr">163 </span>    81          0/subop/add         3/mod/direct    4/rm32/ESP   <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>           <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>              4/imm32           <span class="subxComment"># add to ESP</span>
-<span id="L164" class="LineNr">164 </span>    <span class="subxS1Comment"># . write(_test-stream, &quot;Ab&quot;)</span>
-<span id="L165" class="LineNr">165 </span>    <span class="subxS2Comment"># . . push args</span>
-<span id="L166" class="LineNr">166 </span>    68/push  <span class="Constant">&quot;Ab&quot;</span>/imm32
-<span id="L167" class="LineNr">167 </span>    68/push  _test-stream/imm32
-<span id="L168" class="LineNr">168 </span>    <span class="subxS2Comment"># . . call</span>
-<span id="L169" class="LineNr">169 </span>    e8/call  write/disp32
-<span id="L170" class="LineNr">170 </span>    <span class="subxS2Comment"># . . discard args</span>
-<span id="L171" class="LineNr">171 </span>    81          0/subop/add         3/mod/direct    4/rm32/ESP   <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>           <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>              8/imm32           <span class="subxComment"># add to ESP</span>
-<span id="L172" class="LineNr">172 </span>    <span class="subxComment"># read-byte(_test-buffered-file)</span>
-<span id="L173" class="LineNr">173 </span>    <span class="subxS2Comment"># . . push args</span>
-<span id="L174" class="LineNr">174 </span>    68/push  _test-buffered-file/imm32
-<span id="L175" class="LineNr">175 </span>    <span class="subxS2Comment"># . . call</span>
-<span id="L176" class="LineNr">176 </span>    e8/call  read-byte/disp32
-<span id="L177" class="LineNr">177 </span>    <span class="subxS2Comment"># . . discard args</span>
-<span id="L178" class="LineNr">178 </span>    81          0/subop/add         3/mod/direct    4/rm32/ESP   <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>           <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>              4/imm32           <span class="subxComment"># add to ESP</span>
-<span id="L179" class="LineNr">179 </span>    <span class="subxComment"># read-byte(_test-buffered-file)</span>
-<span id="L180" class="LineNr">180 </span>    <span class="subxS2Comment"># . . push args</span>
-<span id="L181" class="LineNr">181 </span>    68/push  _test-buffered-file/imm32
-<span id="L182" class="LineNr">182 </span>    <span class="subxS2Comment"># . . call</span>
-<span id="L183" class="LineNr">183 </span>    e8/call  read-byte/disp32
-<span id="L184" class="LineNr">184 </span>    <span class="subxS2Comment"># . . discard args</span>
-<span id="L185" class="LineNr">185 </span>    81          0/subop/add         3/mod/direct    4/rm32/ESP   <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>           <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>              4/imm32           <span class="subxComment"># add to ESP</span>
-<span id="L186" class="LineNr">186 </span>    <span class="subxComment"># check-ints-equal(EAX, 'b', msg)</span>
-<span id="L187" class="LineNr">187 </span>    <span class="subxS2Comment"># . . push args</span>
-<span id="L188" class="LineNr">188 </span>    68/push  <span class="Constant">&quot;F - test-read-byte-multiple&quot;</span>/imm32
-<span id="L189" class="LineNr">189 </span>    68/push  0x62/imm32
-<span id="L190" class="LineNr">190 </span>    50/push-EAX
-<span id="L191" class="LineNr">191 </span>    <span class="subxS2Comment"># . . call</span>
-<span id="L192" class="LineNr">192 </span>    e8/call  check-ints-equal/disp32
-<span id="L193" class="LineNr">193 </span>    <span class="subxS2Comment"># . . discard args</span>
-<span id="L194" class="LineNr">194 </span>    81          0/subop/add         3/mod/direct    4/rm32/ESP   <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>           <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>              0xc/imm32         <span class="subxComment"># add to ESP</span>
-<span id="L195" class="LineNr">195 </span>    <span class="subxS1Comment"># . end</span>
-<span id="L196" class="LineNr">196 </span>    c3/return
-<span id="L197" class="LineNr">197 </span>
-<span id="L198" class="LineNr">198 </span><span class="subxTest">test-read-byte-end-of-file</span>:
-<span id="L199" class="LineNr">199 </span>    <span class="subxH1Comment"># - call read-byte on an empty 'file', check that it returns -1</span>
-<span id="L200" class="LineNr">200 </span>    <span class="subxComment"># setup</span>
-<span id="L201" class="LineNr">201 </span>    <span class="subxS1Comment"># . clear-stream(_test-stream)</span>
-<span id="L202" class="LineNr">202 </span>    <span class="subxS2Comment"># . . push args</span>
-<span id="L203" class="LineNr">203 </span>    68/push  _test-stream/imm32
-<span id="L204" class="LineNr">204 </span>    <span class="subxS2Comment"># . . call</span>
-<span id="L205" class="LineNr">205 </span>    e8/call  clear-stream/disp32
-<span id="L206" class="LineNr">206 </span>    <span class="subxS2Comment"># . . discard args</span>
-<span id="L207" class="LineNr">207 </span>    81          0/subop/add         3/mod/direct    4/rm32/ESP   <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>           <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>              4/imm32           <span class="subxComment"># add to ESP</span>
-<span id="L208" class="LineNr">208 </span>    <span class="subxS1Comment"># . clear-stream(_test-buffered-file+4)</span>
-<span id="L209" class="LineNr">209 </span>    <span class="subxS2Comment"># . . push args</span>
-<span id="L210" class="LineNr">210 </span>    b8/copy-to-EAX  _test-buffered-file/imm32
-<span id="L211" class="LineNr">211 </span>    05/add-to-EAX  4/imm32
-<span id="L212" class="LineNr">212 </span>    50/push-EAX
-<span id="L213" class="LineNr">213 </span>    <span class="subxS2Comment"># . . call</span>
-<span id="L214" class="LineNr">214 </span>    e8/call  clear-stream/disp32
-<span id="L215" class="LineNr">215 </span>    <span class="subxS2Comment"># . . discard args</span>
-<span id="L216" class="LineNr">216 </span>    81          0/subop/add         3/mod/direct    4/rm32/ESP   <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>           <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>              4/imm32           <span class="subxComment"># add to ESP</span>
-<span id="L217" class="LineNr">217 </span>    <span class="subxComment"># read-byte(_test-buffered-file)</span>
-<span id="L218" class="LineNr">218 </span>    <span class="subxS2Comment"># . . push args</span>
-<span id="L219" class="LineNr">219 </span>    68/push  _test-buffered-file/imm32
-<span id="L220" class="LineNr">220 </span>    <span class="subxS2Comment"># . . call</span>
-<span id="L221" class="LineNr">221 </span>    e8/call  read-byte/disp32
-<span id="L222" class="LineNr">222 </span>    <span class="subxS2Comment"># . . discard args</span>
-<span id="L223" class="LineNr">223 </span>    81          0/subop/add         3/mod/direct    4/rm32/ESP   <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>           <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>              4/imm32           <span class="subxComment"># add to ESP</span>
-<span id="L224" class="LineNr">224 </span>    <span class="subxComment"># check-ints-equal(EAX, -1, msg)</span>
-<span id="L225" class="LineNr">225 </span>    <span class="subxS2Comment"># . . push args</span>
-<span id="L226" class="LineNr">226 </span>    68/push  <span class="Constant">&quot;F - test-read-byte-end-of-file&quot;</span>/imm32
-<span id="L227" class="LineNr">227 </span>    68/push  -1/imm32
-<span id="L228" class="LineNr">228 </span>    50/push-EAX
-<span id="L229" class="LineNr">229 </span>    <span class="subxS2Comment"># . . call</span>
-<span id="L230" class="LineNr">230 </span>    e8/call  check-ints-equal/disp32
-<span id="L231" class="LineNr">231 </span>    <span class="subxS2Comment"># . . discard args</span>
-<span id="L232" class="LineNr">232 </span>    81          0/subop/add         3/mod/direct    4/rm32/ESP   <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>           <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>              0xc/imm32         <span class="subxComment"># add to ESP</span>
-<span id="L233" class="LineNr">233 </span>    <span class="subxS1Comment"># . end</span>
-<span id="L234" class="LineNr">234 </span>    c3/return
-<span id="L235" class="LineNr">235 </span>
-<span id="L236" class="LineNr">236 </span>== data
-<span id="L237" class="LineNr">237 </span>
-<span id="L238" class="LineNr">238 </span><span class="subxMinorFunction">_test-buffered-file</span>:
-<span id="L239" class="LineNr">239 </span>    <span class="subxComment"># file descriptor or (address stream)</span>
-<span id="L240" class="LineNr">240 </span>    _test-stream/imm32
-<span id="L241" class="LineNr">241 </span>    <span class="subxComment"># current write index</span>
-<span id="L242" class="LineNr">242 </span>    00 00 00 00
-<span id="L243" class="LineNr">243 </span>    <span class="subxComment"># current read index</span>
-<span id="L244" class="LineNr">244 </span>    00 00 00 00
-<span id="L245" class="LineNr">245 </span>    <span class="subxComment"># length (8)</span>
-<span id="L246" class="LineNr">246 </span>    08 00 00 00
-<span id="L247" class="LineNr">247 </span>    <span class="subxComment"># data</span>
-<span id="L248" class="LineNr">248 </span>    00 00 00 00 00 00 00 00  <span class="subxComment"># 8 bytes</span>
-<span id="L249" class="LineNr">249 </span>
-<span id="L250" class="LineNr">250 </span><span class="subxS2Comment"># . . vim&#0058;nowrap:textwidth=0</span>
+<span id="L59" class="LineNr"> 59 </span>    <span class="subxS1Comment"># . clear-stream(stream = f+4)</span>
+<span id="L60" class="LineNr"> 60 </span>    <span class="subxS2Comment"># . . push args</span>
+<span id="L61" class="LineNr"> 61 </span>    8d/copy-address                 1/mod/*+disp8   6/rm32/ESI   <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>           <span class="CommentedCode"> . </span>          0/r32/EAX   4/disp8        <span class="CommentedCode"> . </span>                <span class="subxComment"># copy ESI+4 to EAX</span>
+<span id="L62" class="LineNr"> 62 </span>    50/push-EAX
+<span id="L63" class="LineNr"> 63 </span>    <span class="subxS2Comment"># . . call</span>
+<span id="L64" class="LineNr"> 64 </span>    e8/call  clear-stream/disp32
+<span id="L65" class="LineNr"> 65 </span>    <span class="subxS2Comment"># . . discard args</span>
+<span id="L66" class="LineNr"> 66 </span>    81          0/subop/add         3/mod/direct    4/rm32/ESP   <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>           <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>              4/imm32           <span class="subxComment"># add to ESP</span>
+<span id="L67" class="LineNr"> 67 </span>    <span class="subxS1Comment"># . EAX = read(f-&gt;fd, stream = f+4)</span>
+<span id="L68" class="LineNr"> 68 </span>    <span class="subxS2Comment"># . . push args</span>
+<span id="L69" class="LineNr"> 69 </span>    50/push-EAX
+<span id="L70" class="LineNr"> 70 </span>    ff          6/subop/push        0/mod/indirect  6/rm32/ESI   <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>           <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>             <span class="CommentedCode"> . </span>                <span class="subxComment"># push *ESI</span>
+<span id="L71" class="LineNr"> 71 </span>    <span class="subxS2Comment"># . . call</span>
+<span id="L72" class="LineNr"> 72 </span>    e8/call  read/disp32
+<span id="L73" class="LineNr"> 73 </span>    <span class="subxS2Comment"># . . discard args</span>
+<span id="L74" class="LineNr"> 74 </span>    81          0/subop/add         3/mod/direct    4/rm32/ESP   <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>           <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>              8/imm32           <span class="subxComment"># add to ESP</span>
+<span id="L75" class="LineNr"> 75 </span>    <span class="subxComment"># if EAX = 0 return 0xffffffff</span>
+<span id="L76" class="LineNr"> 76 </span>    81          7/subop/compare     3/mod/direct    0/rm32/EAX   <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>           <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>              0/imm32           <span class="subxComment"># compare EAX</span>
+<span id="L77" class="LineNr"> 77 </span>    75/jump-if-not-equal  $read-byte:from-stream/disp8
+<span id="L78" class="LineNr"> 78 </span>    b8/copy-to-EAX  0xffffffff/imm32
+<span id="L79" class="LineNr"> 79 </span>    eb/jump  $read-byte:end/disp8
+<span id="L80" class="LineNr"> 80 </span><span class="Constant">$read-byte:from-stream</span>:
+<span id="L81" class="LineNr"> 81 </span>    <span class="subxComment"># read byte from stream</span>
+<span id="L82" class="LineNr"> 82 </span>    <span class="subxComment"># AL = f-&gt;data[f-&gt;read]</span>
+<span id="L83" class="LineNr"> 83 </span>    31/xor                          3/mod/direct    0/rm32/EAX   <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>           <span class="CommentedCode"> . </span>          0/r32/EAX  <span class="CommentedCode"> . </span>             <span class="CommentedCode"> . </span>                <span class="subxComment"># clear EAX</span>
+<span id="L84" class="LineNr"> 84 </span>    8a/copy-byte                    1/mod/*+disp8   4/rm32/sib    6/base/ESI  1/index/ECX  <span class="CommentedCode"> . </span>          0/r32/AL    0x10/disp8     <span class="CommentedCode"> . </span>                <span class="subxComment"># copy *(ESI+ECX+16) to AL</span>
+<span id="L85" class="LineNr"> 85 </span>    <span class="subxComment"># ++f-&gt;read</span>
+<span id="L86" class="LineNr"> 86 </span>    ff          0/subop/increment   1/mod/*+disp8   6/rm32/ESI   <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>           <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>          8/disp8        <span class="CommentedCode"> . </span>                <span class="subxComment"># increment *(ESI+8)</span>
+<span id="L87" class="LineNr"> 87 </span><span class="Constant">$read-byte:end</span>:
+<span id="L88" class="LineNr"> 88 </span>    <span class="subxS1Comment"># . restore registers</span>
+<span id="L89" class="LineNr"> 89 </span>    5e/pop-to-ESI
+<span id="L90" class="LineNr"> 90 </span>    59/pop-to-ECX
+<span id="L91" class="LineNr"> 91 </span>    <span class="subxS1Comment"># . epilog</span>
+<span id="L92" class="LineNr"> 92 </span>    89/copy                         3/mod/direct    4/rm32/ESP   <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>           <span class="CommentedCode"> . </span>          5/r32/EBP  <span class="CommentedCode"> . </span>             <span class="CommentedCode"> . </span>                <span class="subxComment"># copy EBP to ESP</span>
+<span id="L93" class="LineNr"> 93 </span>    5d/pop-to-EBP
+<span id="L94" class="LineNr"> 94 </span>    c3/return
+<span id="L95" class="LineNr"> 95 </span>
+<span id="L96" class="LineNr"> 96 </span><span class="subxH1Comment"># - tests</span>
+<span id="L97" class="LineNr"> 97 </span>
+<span id="L98" class="LineNr"> 98 </span><span class="subxTest">test-read-byte-single</span>:
+<span id="L99" class="LineNr"> 99 </span>    <span class="subxH1Comment"># - check that read-byte returns first byte of 'file'</span>
+<span id="L100" class="LineNr">100 </span>    <span class="subxComment"># setup</span>
+<span id="L101" class="LineNr">101 </span>    <span class="subxS1Comment"># . clear-stream(_test-stream)</span>
+<span id="L102" class="LineNr">102 </span>    <span class="subxS2Comment"># . . push args</span>
+<span id="L103" class="LineNr">103 </span>    68/push  _test-stream/imm32
+<span id="L104" class="LineNr">104 </span>    <span class="subxS2Comment"># . . call</span>
+<span id="L105" class="LineNr">105 </span>    e8/call  clear-stream/disp32
+<span id="L106" class="LineNr">106 </span>    <span class="subxS2Comment"># . . discard args</span>
+<span id="L107" class="LineNr">107 </span>    81          0/subop/add         3/mod/direct    4/rm32/ESP   <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>           <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>              4/imm32           <span class="subxComment"># add to ESP</span>
+<span id="L108" class="LineNr">108 </span>    <span class="subxS1Comment"># . clear-stream(_test-buffered-file+4)</span>
+<span id="L109" class="LineNr">109 </span>    <span class="subxS2Comment"># . . push args</span>
+<span id="L110" class="LineNr">110 </span>    b8/copy-to-EAX  _test-buffered-file/imm32
+<span id="L111" class="LineNr">111 </span>    05/add-to-EAX  4/imm32
+<span id="L112" class="LineNr">112 </span>    50/push-EAX
+<span id="L113" class="LineNr">113 </span>    <span class="subxS2Comment"># . . call</span>
+<span id="L114" class="LineNr">114 </span>    e8/call  clear-stream/disp32
+<span id="L115" class="LineNr">115 </span>    <span class="subxS2Comment"># . . discard args</span>
+<span id="L116" class="LineNr">116 </span>    81          0/subop/add         3/mod/direct    4/rm32/ESP   <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>           <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>              4/imm32           <span class="subxComment"># add to ESP</span>
+<span id="L117" class="LineNr">117 </span>    <span class="subxS1Comment"># . write(_test-stream, &quot;Ab&quot;)</span>
+<span id="L118" class="LineNr">118 </span>    <span class="subxS2Comment"># . . push args</span>
+<span id="L119" class="LineNr">119 </span>    68/push  <span class="Constant">&quot;Ab&quot;</span>/imm32
+<span id="L120" class="LineNr">120 </span>    68/push  _test-stream/imm32
+<span id="L121" class="LineNr">121 </span>    <span class="subxS2Comment"># . . call</span>
+<span id="L122" class="LineNr">122 </span>    e8/call  write/disp32
+<span id="L123" class="LineNr">123 </span>    <span class="subxS2Comment"># . . discard args</span>
+<span id="L124" class="LineNr">124 </span>    81          0/subop/add         3/mod/direct    4/rm32/ESP   <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>           <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>              8/imm32           <span class="subxComment"># add to ESP</span>
+<span id="L125" class="LineNr">125 </span>    <span class="subxComment"># read-byte(_test-buffered-file)</span>
+<span id="L126" class="LineNr">126 </span>    <span class="subxS2Comment"># . . push args</span>
+<span id="L127" class="LineNr">127 </span>    68/push  _test-buffered-file/imm32
+<span id="L128" class="LineNr">128 </span>    <span class="subxS2Comment"># . . call</span>
+<span id="L129" class="LineNr">129 </span>    e8/call  read-byte/disp32
+<span id="L130" class="LineNr">130 </span>    <span class="subxS2Comment"># . . discard args</span>
+<span id="L131" class="LineNr">131 </span>    81          0/subop/add         3/mod/direct    4/rm32/ESP   <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>           <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>              4/imm32           <span class="subxComment"># add to ESP</span>
+<span id="L132" class="LineNr">132 </span>    <span class="subxComment"># check-ints-equal(EAX, 'A', msg)</span>
+<span id="L133" class="LineNr">133 </span>    <span class="subxS2Comment"># . . push args</span>
+<span id="L134" class="LineNr">134 </span>    68/push  <span class="Constant">&quot;F - test-read-byte-single&quot;</span>/imm32
+<span id="L135" class="LineNr">135 </span>    68/push  0x41/imm32
+<span id="L136" class="LineNr">136 </span>    50/push-EAX
+<span id="L137" class="LineNr">137 </span>    <span class="subxS2Comment"># . . call</span>
+<span id="L138" class="LineNr">138 </span>    e8/call  check-ints-equal/disp32
+<span id="L139" class="LineNr">139 </span>    <span class="subxS2Comment"># . . discard args</span>
+<span id="L140" class="LineNr">140 </span>    81          0/subop/add         3/mod/direct    4/rm32/ESP   <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>           <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>              0xc/imm32         <span class="subxComment"># add to ESP</span>
+<span id="L141" class="LineNr">141 </span>    <span class="subxS1Comment"># . end</span>
+<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="subxTest">test-read-byte-multiple</span>:
+<span id="L145" class="LineNr">145 </span>    <span class="subxH1Comment"># - call read-byte twice, check that second call returns second byte</span>
+<span id="L146" class="LineNr">146 </span>    <span class="subxComment"># setup</span>
+<span id="L147" class="LineNr">147 </span>    <span class="subxS1Comment"># . clear-stream(_test-stream)</span>
+<span id="L148" class="LineNr">148 </span>    <span class="subxS2Comment"># . . push args</span>
+<span id="L149" class="LineNr">149 </span>    68/push  _test-stream/imm32
+<span id="L150" class="LineNr">150 </span>    <span class="subxS2Comment"># . . call</span>
+<span id="L151" class="LineNr">151 </span>    e8/call  clear-stream/disp32
+<span id="L152" class="LineNr">152 </span>    <span class="subxS2Comment"># . . discard args</span>
+<span id="L153" class="LineNr">153 </span>    81          0/subop/add         3/mod/direct    4/rm32/ESP   <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>           <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>              4/imm32           <span class="subxComment"># add to ESP</span>
+<span id="L154" class="LineNr">154 </span>    <span class="subxS1Comment"># . clear-stream(_test-buffered-file+4)</span>
+<span id="L155" class="LineNr">155 </span>    <span class="subxS2Comment"># . . push args</span>
+<span id="L156" class="LineNr">156 </span>    b8/copy-to-EAX  _test-buffered-file/imm32
+<span id="L157" class="LineNr">157 </span>    05/add-to-EAX  4/imm32
+<span id="L158" class="LineNr">158 </span>    50/push-EAX
+<span id="L159" class="LineNr">159 </span>    <span class="subxS2Comment"># . . call</span>
+<span id="L160" class="LineNr">160 </span>    e8/call  clear-stream/disp32
+<span id="L161" class="LineNr">161 </span>    <span class="subxS2Comment"># . . discard args</span>
+<span id="L162" class="LineNr">162 </span>    81          0/subop/add         3/mod/direct    4/rm32/ESP   <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>           <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>              4/imm32           <span class="subxComment"># add to ESP</span>
+<span id="L163" class="LineNr">163 </span>    <span class="subxS1Comment"># . write(_test-stream, &quot;Ab&quot;)</span>
+<span id="L164" class="LineNr">164 </span>    <span class="subxS2Comment"># . . push args</span>
+<span id="L165" class="LineNr">165 </span>    68/push  <span class="Constant">&quot;Ab&quot;</span>/imm32
+<span id="L166" class="LineNr">166 </span>    68/push  _test-stream/imm32
+<span id="L167" class="LineNr">167 </span>    <span class="subxS2Comment"># . . call</span>
+<span id="L168" class="LineNr">168 </span>    e8/call  write/disp32
+<span id="L169" class="LineNr">169 </span>    <span class="subxS2Comment"># . . discard args</span>
+<span id="L170" class="LineNr">170 </span>    81          0/subop/add         3/mod/direct    4/rm32/ESP   <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>           <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>              8/imm32           <span class="subxComment"># add to ESP</span>
+<span id="L171" class="LineNr">171 </span>    <span class="subxComment"># read-byte(_test-buffered-file)</span>
+<span id="L172" class="LineNr">172 </span>    <span class="subxS2Comment"># . . push args</span>
+<span id="L173" class="LineNr">173 </span>    68/push  _test-buffered-file/imm32
+<span id="L174" class="LineNr">174 </span>    <span class="subxS2Comment"># . . call</span>
+<span id="L175" class="LineNr">175 </span>    e8/call  read-byte/disp32
+<span id="L176" class="LineNr">176 </span>    <span class="subxS2Comment"># . . discard args</span>
+<span id="L177" class="LineNr">177 </span>    81          0/subop/add         3/mod/direct    4/rm32/ESP   <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>           <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>              4/imm32           <span class="subxComment"># add to ESP</span>
+<span id="L178" class="LineNr">178 </span>    <span class="subxComment"># read-byte(_test-buffered-file)</span>
+<span id="L179" class="LineNr">179 </span>    <span class="subxS2Comment"># . . push args</span>
+<span id="L180" class="LineNr">180 </span>    68/push  _test-buffered-file/imm32
+<span id="L181" class="LineNr">181 </span>    <span class="subxS2Comment"># . . call</span>
+<span id="L182" class="LineNr">182 </span>    e8/call  read-byte/disp32
+<span id="L183" class="LineNr">183 </span>    <span class="subxS2Comment"># . . discard args</span>
+<span id="L184" class="LineNr">184 </span>    81          0/subop/add         3/mod/direct    4/rm32/ESP   <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>           <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>              4/imm32           <span class="subxComment"># add to ESP</span>
+<span id="L185" class="LineNr">185 </span>    <span class="subxComment"># check-ints-equal(EAX, 'b', msg)</span>
+<span id="L186" class="LineNr">186 </span>    <span class="subxS2Comment"># . . push args</span>
+<span id="L187" class="LineNr">187 </span>    68/push  <span class="Constant">&quot;F - test-read-byte-multiple&quot;</span>/imm32
+<span id="L188" class="LineNr">188 </span>    68/push  0x62/imm32
+<span id="L189" class="LineNr">189 </span>    50/push-EAX
+<span id="L190" class="LineNr">190 </span>    <span class="subxS2Comment"># . . call</span>
+<span id="L191" class="LineNr">191 </span>    e8/call  check-ints-equal/disp32
+<span id="L192" class="LineNr">192 </span>    <span class="subxS2Comment"># . . discard args</span>
+<span id="L193" class="LineNr">193 </span>    81          0/subop/add         3/mod/direct    4/rm32/ESP   <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>           <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>              0xc/imm32         <span class="subxComment"># add to ESP</span>
+<span id="L194" class="LineNr">194 </span>    <span class="subxS1Comment"># . end</span>
+<span id="L195" class="LineNr">195 </span>    c3/return
+<span id="L196" class="LineNr">196 </span>
+<span id="L197" class="LineNr">197 </span><span class="subxTest">test-read-byte-end-of-file</span>:
+<span id="L198" class="LineNr">198 </span>    <span class="subxH1Comment"># - call read-byte on an empty 'file', check that it returns -1</span>
+<span id="L199" class="LineNr">199 </span>    <span class="subxComment"># setup</span>
+<span id="L200" class="LineNr">200 </span>    <span class="subxS1Comment"># . clear-stream(_test-stream)</span>
+<span id="L201" class="LineNr">201 </span>    <span class="subxS2Comment"># . . push args</span>
+<span id="L202" class="LineNr">202 </span>    68/push  _test-stream/imm32
+<span id="L203" class="LineNr">203 </span>    <span class="subxS2Comment"># . . call</span>
+<span id="L204" class="LineNr">204 </span>    e8/call  clear-stream/disp32
+<span id="L205" class="LineNr">205 </span>    <span class="subxS2Comment"># . . discard args</span>
+<span id="L206" class="LineNr">206 </span>    81          0/subop/add         3/mod/direct    4/rm32/ESP   <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>           <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>              4/imm32           <span class="subxComment"># add to ESP</span>
+<span id="L207" class="LineNr">207 </span>    <span class="subxS1Comment"># . clear-stream(_test-buffered-file+4)</span>
+<span id="L208" class="LineNr">208 </span>    <span class="subxS2Comment"># . . push args</span>
+<span id="L209" class="LineNr">209 </span>    b8/copy-to-EAX  _test-buffered-file/imm32
+<span id="L210" class="LineNr">210 </span>    05/add-to-EAX  4/imm32
+<span id="L211" class="LineNr">211 </span>    50/push-EAX
+<span id="L212" class="LineNr">212 </span>    <span class="subxS2Comment"># . . call</span>
+<span id="L213" class="LineNr">213 </span>    e8/call  clear-stream/disp32
+<span id="L214" class="LineNr">214 </span>    <span class="subxS2Comment"># . . discard args</span>
+<span id="L215" class="LineNr">215 </span>    81          0/subop/add         3/mod/direct    4/rm32/ESP   <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>           <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>              4/imm32           <span class="subxComment"># add to ESP</span>
+<span id="L216" class="LineNr">216 </span>    <span class="subxComment"># read-byte(_test-buffered-file)</span>
+<span id="L217" class="LineNr">217 </span>    <span class="subxS2Comment"># . . push args</span>
+<span id="L218" class="LineNr">218 </span>    68/push  _test-buffered-file/imm32
+<span id="L219" class="LineNr">219 </span>    <span class="subxS2Comment"># . . call</span>
+<span id="L220" class="LineNr">220 </span>    e8/call  read-byte/disp32
+<span id="L221" class="LineNr">221 </span>    <span class="subxS2Comment"># . . discard args</span>
+<span id="L222" class="LineNr">222 </span>    81          0/subop/add         3/mod/direct    4/rm32/ESP   <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>           <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>              4/imm32           <span class="subxComment"># add to ESP</span>
+<span id="L223" class="LineNr">223 </span>    <span class="subxComment"># check-ints-equal(EAX, -1, msg)</span>
+<span id="L224" class="LineNr">224 </span>    <span class="subxS2Comment"># . . push args</span>
+<span id="L225" class="LineNr">225 </span>    68/push  <span class="Constant">&quot;F - test-read-byte-end-of-file&quot;</span>/imm32
+<span id="L226" class="LineNr">226 </span>    68/push  -1/imm32
+<span id="L227" class="LineNr">227 </span>    50/push-EAX
+<span id="L228" class="LineNr">228 </span>    <span class="subxS2Comment"># . . call</span>
+<span id="L229" class="LineNr">229 </span>    e8/call  check-ints-equal/disp32
+<span id="L230" class="LineNr">230 </span>    <span class="subxS2Comment"># . . discard args</span>
+<span id="L231" class="LineNr">231 </span>    81          0/subop/add         3/mod/direct    4/rm32/ESP   <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>           <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>              0xc/imm32         <span class="subxComment"># add to ESP</span>
+<span id="L232" class="LineNr">232 </span>    <span class="subxS1Comment"># . end</span>
+<span id="L233" class="LineNr">233 </span>    c3/return
+<span id="L234" class="LineNr">234 </span>
+<span id="L235" class="LineNr">235 </span>== data
+<span id="L236" class="LineNr">236 </span>
+<span id="L237" class="LineNr">237 </span><span class="subxMinorFunction">_test-buffered-file</span>:
+<span id="L238" class="LineNr">238 </span>    <span class="subxComment"># file descriptor or (address stream)</span>
+<span id="L239" class="LineNr">239 </span>    _test-stream/imm32
+<span id="L240" class="LineNr">240 </span>    <span class="subxComment"># current write index</span>
+<span id="L241" class="LineNr">241 </span>    00 00 00 00
+<span id="L242" class="LineNr">242 </span>    <span class="subxComment"># current read index</span>
+<span id="L243" class="LineNr">243 </span>    00 00 00 00
+<span id="L244" class="LineNr">244 </span>    <span class="subxComment"># length (8)</span>
+<span id="L245" class="LineNr">245 </span>    08 00 00 00
+<span id="L246" class="LineNr">246 </span>    <span class="subxComment"># data</span>
+<span id="L247" class="LineNr">247 </span>    00 00 00 00 00 00 00 00  <span class="subxComment"># 8 bytes</span>
+<span id="L248" class="LineNr">248 </span>
+<span id="L249" class="LineNr">249 </span><span class="subxS2Comment"># . . vim&#0058;nowrap:textwidth=0</span>
 </pre>
 </body>
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+<a href='https://github.com/akkartik/mu/blob/master/subx/062write-byte.subx'>https://github.com/akkartik/mu/blob/master/subx/062write-byte.subx</a>
+<pre id='vimCodeElement'>
+<span id="L1" class="LineNr">  1 </span><span class="subxComment"># write-byte: write a single byte to a buffered-file. The write may be buffered.</span>
+<span id="L2" class="LineNr">  2 </span><span class="subxComment"># flush: write out any buffered writes to disk.</span>
+<span id="L3" class="LineNr">  3 </span><span class="subxComment">#</span>
+<span id="L4" class="LineNr">  4 </span><span class="subxComment"># TODO: Come up with a way to signal failure to write to disk. This is hard</span>
+<span id="L5" class="LineNr">  5 </span><span class="subxComment"># since the failure may impact previous calls that were buffered.</span>
+<span id="L6" class="LineNr">  6 </span>
+<span id="L7" class="LineNr">  7 </span>== data
+<span id="L8" class="LineNr">  8 </span>
+<span id="L9" class="LineNr">  9 </span><span class="subxComment"># The buffered file for standard output.</span>
+<span id="L10" class="LineNr"> 10 </span>
+<span id="L11" class="LineNr"> 11 </span><span class="SpecialChar">Stdout</span>:
+<span id="L12" class="LineNr"> 12 </span>    <span class="subxComment"># file descriptor or (address stream)</span>
+<span id="L13" class="LineNr"> 13 </span>    01 00 00 00  <span class="subxComment"># 1 = standard output</span>
+<span id="L14" class="LineNr"> 14 </span>    <span class="subxComment"># current write index</span>
+<span id="L15" class="LineNr"> 15 </span>    00 00 00 00
+<span id="L16" class="LineNr"> 16 </span>    <span class="subxComment"># current read index</span>
+<span id="L17" class="LineNr"> 17 </span>    00 00 00 00
+<span id="L18" class="LineNr"> 18 </span>    <span class="subxComment"># length (8)</span>
+<span id="L19" class="LineNr"> 19 </span>    08 00 00 00
+<span id="L20" class="LineNr"> 20 </span>    <span class="subxComment"># data</span>
+<span id="L21" class="LineNr"> 21 </span>    00 00 00 00 00 00 00 00  <span class="subxComment"># 8 bytes</span>
+<span id="L22" class="LineNr"> 22 </span>
+<span id="L23" class="LineNr"> 23 </span><span class="subxComment"># TODO: 8 bytes is too small. We'll need to grow the buffer for efficiency. But</span>
+<span id="L24" class="LineNr"> 24 </span><span class="subxComment"># I don't want to type 1024 bytes here.</span>
+<span id="L25" class="LineNr"> 25 </span>
+<span id="L26" class="LineNr"> 26 </span>== code
+<span id="L27" class="LineNr"> 27 </span><span class="subxComment">#   instruction                     effective address                                                   register    displacement    immediate</span>
+<span id="L28" class="LineNr"> 28 </span><span class="subxS1Comment"># . op          subop               mod             rm32          base        index         scale       r32</span>
+<span id="L29" class="LineNr"> 29 </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="L30" class="LineNr"> 30 </span>
+<span id="L31" class="LineNr"> 31 </span><span class="subxComment"># main:</span>
+<span id="L32" class="LineNr"> 32 </span>    e8/call  run-tests/disp32  <span class="subxComment"># 'run-tests' is a function created automatically by SubX. It calls all functions that start with 'test-'.</span>
+<span id="L33" class="LineNr"> 33 </span>    <span class="subxComment"># syscall(exit, Num-test-failures)</span>
+<span id="L34" class="LineNr"> 34 </span>    8b/copy                         0/mod/indirect  5/rm32/.disp32           <span class="CommentedCode"> . </span>           <span class="CommentedCode"> . </span>          3/r32/EBX   <span class="SpecialChar">Num-test-failures</span>/disp32          <span class="subxComment"># copy *Num-test-failures to EBX</span>
+<span id="L35" class="LineNr"> 35 </span>    b8/copy-to-EAX  1/imm32
+<span id="L36" class="LineNr"> 36 </span>    cd/syscall  0x80/imm8
+<span id="L37" class="LineNr"> 37 </span>
+<span id="L38" class="LineNr"> 38 </span><span class="subxComment"># Write lower byte of 'n' to 'f'.</span>
+<span id="L39" class="LineNr"> 39 </span><span class="subxFunction">write-byte</span>:  <span class="subxComment"># f : (address buffered-file), n : num -&gt; &lt;void&gt;</span>
+<span id="L40" class="LineNr"> 40 </span>    <span class="subxS1Comment"># . prolog</span>
+<span id="L41" class="LineNr"> 41 </span>    55/push-EBP
+<span id="L42" class="LineNr"> 42 </span>    89/copy                         3/mod/direct    5/rm32/EBP   <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>           <span class="CommentedCode"> . </span>          4/r32/ESP  <span class="CommentedCode"> . </span>             <span class="CommentedCode"> . </span>                <span class="subxComment"># copy ESP to EBP</span>
+<span id="L43" class="LineNr"> 43 </span>    <span class="subxS1Comment"># . save registers</span>
+<span id="L44" class="LineNr"> 44 </span>    51/push-ECX
+<span id="L45" class="LineNr"> 45 </span>    56/push-ESI
+<span id="L46" class="LineNr"> 46 </span>    <span class="subxComment"># ESI = f</span>
+<span id="L47" class="LineNr"> 47 </span>    8b/copy                         1/mod/*+disp8   4/rm32/sib    5/base/EBP  4/index/none <span class="CommentedCode"> . </span>          6/r32/ESI   8/disp8        <span class="CommentedCode"> . </span>                <span class="subxComment"># copy *(EBP+8) to ESI</span>
+<span id="L48" class="LineNr"> 48 </span>    <span class="subxComment"># ECX = f-&gt;write</span>
+<span id="L49" class="LineNr"> 49 </span>    8b/copy                         1/mod/*+disp8   6/rm32/ESI   <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>           <span class="CommentedCode"> . </span>          1/r32/ECX   4/disp8        <span class="CommentedCode"> . </span>                <span class="subxComment"># copy *(ESI+4) to ECX</span>
+<span id="L50" class="LineNr"> 50 </span>    <span class="subxComment"># if (f-&gt;write &gt;= f-&gt;length) flush and clear stream</span>
+<span id="L51" class="LineNr"> 51 </span>    3b/compare                      1/mod/*+disp8   6/rm32/ESI   <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>           <span class="CommentedCode"> . </span>          1/r32/ECX   0xc/disp8      <span class="CommentedCode"> . </span>                <span class="subxComment"># compare ECX with *(ESI+12)</span>
+<span id="L52" class="LineNr"> 52 </span>    7c/jump-if-lesser  $write-byte:to-stream/disp8
+<span id="L53" class="LineNr"> 53 </span>    <span class="subxS1Comment"># . flush-buffered-file(f)</span>
+<span id="L54" class="LineNr"> 54 </span>    <span class="subxS2Comment"># . . push args</span>
+<span id="L55" class="LineNr"> 55 </span>    56/push-ESI
+<span id="L56" class="LineNr"> 56 </span>    <span class="subxS2Comment"># . . call</span>
+<span id="L57" class="LineNr"> 57 </span>    e8/call  flush/disp32
+<span id="L58" class="LineNr"> 58 </span>    <span class="subxS2Comment"># . . discard args</span>
+<span id="L59" class="LineNr"> 59 </span>    81          0/subop/add         3/mod/direct    4/rm32/ESP   <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>           <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>              4/imm32           <span class="subxComment"># add to ESP</span>
+<span id="L60" class="LineNr"> 60 </span>    <span class="subxS1Comment"># . clear-stream(stream = f+4)</span>
+<span id="L61" class="LineNr"> 61 </span>    <span class="subxS2Comment"># . . push args</span>
+<span id="L62" class="LineNr"> 62 </span>    8d/copy-address                 1/mod/*+disp8   6/rm32/ESI   <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>           <span class="CommentedCode"> . </span>          0/r32/EAX   4/disp8        <span class="CommentedCode"> . </span>                <span class="subxComment"># copy ESI+4 to EAX</span>
+<span id="L63" class="LineNr"> 63 </span>    50/push-EAX
+<span id="L64" class="LineNr"> 64 </span>    <span class="subxS2Comment"># . . call</span>
+<span id="L65" class="LineNr"> 65 </span>    e8/call  clear-stream/disp32
+<span id="L66" class="LineNr"> 66 </span>    <span class="subxS2Comment"># . . discard args</span>
+<span id="L67" class="LineNr"> 67 </span>    81          0/subop/add         3/mod/direct    4/rm32/ESP   <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>           <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>              4/imm32           <span class="subxComment"># add to ESP</span>
+<span id="L68" class="LineNr"> 68 </span><span class="Constant">$write-byte:to-stream</span>:
+<span id="L69" class="LineNr"> 69 </span>    <span class="subxComment"># write to stream</span>
+<span id="L70" class="LineNr"> 70 </span>    <span class="subxComment"># f-&gt;data[f-&gt;read] = LSB(n)</span>
+<span id="L71" class="LineNr"> 71 </span>    31/xor                          3/mod/direct    0/rm32/EAX   <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>           <span class="CommentedCode"> . </span>          0/r32/EAX  <span class="CommentedCode"> . </span>             <span class="CommentedCode"> . </span>                <span class="subxComment"># clear EAX</span>
+<span id="L72" class="LineNr"> 72 </span>    8a/copy-byte                    1/mod/*+disp8   4/rm32/sib    5/base/EBP  4/index/none <span class="CommentedCode"> . </span>          0/r32/AL    0xc/disp8      <span class="CommentedCode"> . </span>                <span class="subxComment"># copy byte at *(EBP+12) to AL</span>
+<span id="L73" class="LineNr"> 73 </span>    88/copy-byte                    1/mod/*+disp8   4/rm32/sib    6/base/ESI  1/index/ECX  <span class="CommentedCode"> . </span>          0/r32/AL    0x10/disp8     <span class="CommentedCode"> . </span>                <span class="subxComment"># copy AL to *(ESI+ECX+16)</span>
+<span id="L74" class="LineNr"> 74 </span>    <span class="subxComment"># ++f-&gt;read</span>
+<span id="L75" class="LineNr"> 75 </span>    ff          0/subop/increment   1/mod/*+disp8   6/rm32/ESI   <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>           <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>          4/disp8        <span class="CommentedCode"> . </span>                <span class="subxComment"># increment *(ESI+4)</span>
+<span id="L76" class="LineNr"> 76 </span>    <span class="subxS1Comment"># . restore registers</span>
+<span id="L77" class="LineNr"> 77 </span>    5e/pop-to-ESI
+<span id="L78" class="LineNr"> 78 </span>    59/pop-to-ECX
+<span id="L79" class="LineNr"> 79 </span>    <span class="subxS1Comment"># . epilog</span>
+<span id="L80" class="LineNr"> 80 </span>    89/copy                         3/mod/direct    4/rm32/ESP   <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>           <span class="CommentedCode"> . </span>          5/r32/EBP  <span class="CommentedCode"> . </span>             <span class="CommentedCode"> . </span>                <span class="subxComment"># copy EBP to ESP</span>
+<span id="L81" class="LineNr"> 81 </span>    5d/pop-to-EBP
+<span id="L82" class="LineNr"> 82 </span>    c3/return
+<span id="L83" class="LineNr"> 83 </span>
+<span id="L84" class="LineNr"> 84 </span><span class="subxFunction">flush</span>:  <span class="subxComment"># f : (address buffered-file) -&gt; &lt;void&gt;</span>
+<span id="L85" class="LineNr"> 85 </span>    <span class="subxS1Comment"># . prolog</span>
+<span id="L86" class="LineNr"> 86 </span>    55/push-EBP
+<span id="L87" class="LineNr"> 87 </span>    89/copy                         3/mod/direct    5/rm32/EBP   <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>           <span class="CommentedCode"> . </span>          4/r32/ESP  <span class="CommentedCode"> . </span>             <span class="CommentedCode"> . </span>                <span class="subxComment"># copy ESP to EBP</span>
+<span id="L88" class="LineNr"> 88 </span>    <span class="subxS1Comment"># . save registers</span>
+<span id="L89" class="LineNr"> 89 </span>    50/push-EAX
+<span id="L90" class="LineNr"> 90 </span>    51/push-ECX
+<span id="L91" class="LineNr"> 91 </span>    <span class="subxComment"># EAX = f</span>
+<span id="L92" class="LineNr"> 92 </span>    8b/copy                         1/mod/*+disp8   4/rm32/sib    5/base/EBP  4/index/none <span class="CommentedCode"> . </span>          0/r32/EAX   8/disp8        <span class="CommentedCode"> . </span>                <span class="subxComment"># copy *(EBP+8) to EAX</span>
+<span id="L93" class="LineNr"> 93 </span>    <span class="subxComment"># write-stream(f-&gt;fd, data = f+4)</span>
+<span id="L94" class="LineNr"> 94 </span>      <span class="subxS2Comment"># . . push args</span>
+<span id="L95" class="LineNr"> 95 </span>    8d/copy-address                 1/mod/*+disp8   0/rm32/EAX   <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>           <span class="CommentedCode"> . </span>          1/r32/ECX   4/disp8        <span class="CommentedCode"> . </span>                <span class="subxComment"># copy EAX+4 to ECX</span>
+<span id="L96" class="LineNr"> 96 </span>    51/push-ECX
+<span id="L97" class="LineNr"> 97 </span>    ff          6/subop/push        0/mod/indirect  0/rm32/EAX   <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>           <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>             <span class="CommentedCode"> . </span>                <span class="subxComment"># push *EAX</span>
+<span id="L98" class="LineNr"> 98 </span>      <span class="subxS2Comment"># . . call</span>
+<span id="L99" class="LineNr"> 99 </span>    e8/call  write-stream/disp32
+<span id="L100" class="LineNr">100 </span>      <span class="subxS2Comment"># . . discard args</span>
+<span id="L101" class="LineNr">101 </span>    81          0/subop/add         3/mod/direct    4/rm32/ESP   <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>           <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>              8/imm32           <span class="subxComment"># add to ESP</span>
+<span id="L102" class="LineNr">102 </span>    <span class="subxS1Comment"># . restore registers</span>
+<span id="L103" class="LineNr">103 </span>    59/pop-to-ECX
+<span id="L104" class="LineNr">104 </span>    58/pop-to-EAX
+<span id="L105" class="LineNr">105 </span>    <span class="subxS1Comment"># . epilog</span>
+<span id="L106" class="LineNr">106 </span>    89/copy                         3/mod/direct    4/rm32/ESP   <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>           <span class="CommentedCode"> . </span>          5/r32/EBP  <span class="CommentedCode"> . </span>             <span class="CommentedCode"> . </span>                <span class="subxComment"># copy EBP to ESP</span>
+<span id="L107" class="LineNr">107 </span>    5d/pop-to-EBP
+<span id="L108" class="LineNr">108 </span>    c3/return
+<span id="L109" class="LineNr">109 </span>
+<span id="L110" class="LineNr">110 </span><span class="subxH1Comment"># - tests</span>
+<span id="L111" class="LineNr">111 </span>
+<span id="L112" class="LineNr">112 </span><span class="subxTest">test-write-byte-single</span>:
+<span id="L113" class="LineNr">113 </span>    <span class="subxH1Comment"># - check that read-byte returns first byte of 'file'</span>
+<span id="L114" class="LineNr">114 </span>    <span class="subxComment"># setup</span>
+<span id="L115" class="LineNr">115 </span>    <span class="subxS1Comment"># . clear-stream(_test-stream)</span>
+<span id="L116" class="LineNr">116 </span>    <span class="subxS2Comment"># . . push args</span>
+<span id="L117" class="LineNr">117 </span>    68/push  _test-stream/imm32
+<span id="L118" class="LineNr">118 </span>    <span class="subxS2Comment"># . . call</span>
+<span id="L119" class="LineNr">119 </span>    e8/call  clear-stream/disp32
+<span id="L120" class="LineNr">120 </span>    <span class="subxS2Comment"># . . discard args</span>
+<span id="L121" class="LineNr">121 </span>    81          0/subop/add         3/mod/direct    4/rm32/ESP   <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>           <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>              4/imm32           <span class="subxComment"># add to ESP</span>
+<span id="L122" class="LineNr">122 </span>    <span class="subxS1Comment"># . clear-stream(_test-buffered-file+4)</span>
+<span id="L123" class="LineNr">123 </span>    <span class="subxS2Comment"># . . push args</span>
+<span id="L124" class="LineNr">124 </span>    b8/copy-to-EAX  _test-buffered-file/imm32
+<span id="L125" class="LineNr">125 </span>    05/add-to-EAX  4/imm32
+<span id="L126" class="LineNr">126 </span>    50/push-EAX
+<span id="L127" class="LineNr">127 </span>    <span class="subxS2Comment"># . . call</span>
+<span id="L128" class="LineNr">128 </span>    e8/call  clear-stream/disp32
+<span id="L129" class="LineNr">129 </span>    <span class="subxS2Comment"># . . discard args</span>
+<span id="L130" class="LineNr">130 </span>    81          0/subop/add         3/mod/direct    4/rm32/ESP   <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>           <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>              4/imm32           <span class="subxComment"># add to ESP</span>
+<span id="L131" class="LineNr">131 </span>    <span class="subxComment"># write-byte(_test-buffered-file, 'A')</span>
+<span id="L132" class="LineNr">132 </span>    <span class="subxS2Comment"># . . push args</span>
+<span id="L133" class="LineNr">133 </span>    68/push  0x41/imm32
+<span id="L134" class="LineNr">134 </span>    68/push  _test-buffered-file/imm32
+<span id="L135" class="LineNr">135 </span>    <span class="subxS2Comment"># . . call</span>
+<span id="L136" class="LineNr">136 </span>    e8/call  write-byte/disp32
+<span id="L137" class="LineNr">137 </span>    <span class="subxS2Comment"># . . discard args</span>
+<span id="L138" class="LineNr">138 </span>    81          0/subop/add         3/mod/direct    4/rm32/ESP   <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>           <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>              8/imm32           <span class="subxComment"># add to ESP</span>
+<span id="L139" class="LineNr">139 </span>    <span class="subxComment"># flush(_test-buffered-file)</span>
+<span id="L140" class="LineNr">140 </span>    <span class="subxS2Comment"># . . push args</span>
+<span id="L141" class="LineNr">141 </span>    68/push  _test-buffered-file/imm32
+<span id="L142" class="LineNr">142 </span>    <span class="subxS2Comment"># . . call</span>
+<span id="L143" class="LineNr">143 </span>    e8/call  flush/disp32
+<span id="L144" class="LineNr">144 </span>    <span class="subxS2Comment"># . . discard args</span>
+<span id="L145" class="LineNr">145 </span>    81          0/subop/add         3/mod/direct    4/rm32/ESP   <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>           <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>              4/imm32           <span class="subxComment"># add to ESP</span>
+<span id="L146" class="LineNr">146 </span>    <span class="subxComment"># check-ints-equal(*_test-stream-&gt;data, 'A', msg)</span>
+<span id="L147" class="LineNr">147 </span>    <span class="subxS2Comment"># . . push args</span>
+<span id="L148" class="LineNr">148 </span>    68/push  <span class="Constant">&quot;F - test-write-byte-single&quot;</span>/imm32
+<span id="L149" class="LineNr">149 </span>    68/push  0x41/imm32
+<span id="L150" class="LineNr">150 </span>    <span class="subxS2Comment"># . . push *_test-stream-&gt;data</span>
+<span id="L151" class="LineNr">151 </span>    b8/copy-to-EAX  _test-stream/imm32
+<span id="L152" class="LineNr">152 </span>    ff          6/subop/push        1/mod/*+disp8   0/rm32/EAX   <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>           <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>          0xc/disp8      <span class="CommentedCode"> . </span>                <span class="subxComment"># push *(EAX+12)</span>
+<span id="L153" class="LineNr">153 </span>    <span class="subxS2Comment"># . . call</span>
+<span id="L154" class="LineNr">154 </span>    e8/call  check-ints-equal/disp32
+<span id="L155" class="LineNr">155 </span>    <span class="subxS2Comment"># . . discard args</span>
+<span id="L156" class="LineNr">156 </span>    81          0/subop/add         3/mod/direct    4/rm32/ESP   <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>           <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>         <span class="CommentedCode"> . </span>              0xc/imm32         <span class="subxComment"># add to ESP</span>
+<span id="L157" class="LineNr">157 </span>    <span class="subxS1Comment"># . end</span>
+<span id="L158" class="LineNr">158 </span>    c3/return
+<span id="L159" class="LineNr">159 </span>
+<span id="L160" class="LineNr">160 </span><span class="subxS2Comment"># . . vim&#0058;nowrap:textwidth=0</span>
+</pre>
+</body>
+</html>
+<!-- vim: set foldmethod=manual : -->
diff --git a/subx/059read-byte.subx b/subx/059read-byte.subx
index 07958a63..305bcbb8 100644
--- a/subx/059read-byte.subx
+++ b/subx/059read-byte.subx
@@ -53,10 +53,9 @@ read-byte:  # f : (address buffered-file) -> byte-or-eof/EAX
     8b/copy                         1/mod/*+disp8   4/rm32/sib    5/base/EBP  4/index/none  .           6/r32/ESI   8/disp8         .                 # copy *(EBP+8) to ESI
     # ECX = f->read
     8b/copy                         1/mod/*+disp8   6/rm32/ESI    .           .             .           1/r32/ECX   8/disp8         .                 # copy *(ESI+8) to ECX
-    # if (f->read < f->write) read byte from stream
+    # if (f->read >= f->write) populate stream from file
     3b/compare                      1/mod/*+disp8   6/rm32/ESI    .           .             .           1/r32/ECX   4/disp8         .                 # compare ECX with *(ESI+4)
     7c/jump-if-lesser  $read-byte:from-stream/disp8
-    # otherwise first populate stream from file
     # . clear-stream(stream = f+4)
     # . . push args
     8d/copy-address                 1/mod/*+disp8   6/rm32/ESI    .           .             .           0/r32/EAX   4/disp8         .                 # copy ESI+4 to EAX
@@ -79,7 +78,7 @@ read-byte:  # f : (address buffered-file) -> byte-or-eof/EAX
     b8/copy-to-EAX  0xffffffff/imm32
     eb/jump  $read-byte:end/disp8
 $read-byte:from-stream:
-    # reading from stream
+    # read byte from stream
     # AL = f->data[f->read]
     31/xor                          3/mod/direct    0/rm32/EAX    .           .             .           0/r32/EAX   .               .                 # clear EAX
     8a/copy-byte                    1/mod/*+disp8   4/rm32/sib    6/base/ESI  1/index/ECX   .           0/r32/AL    0x10/disp8      .                 # copy *(ESI+ECX+16) to AL
diff --git a/subx/062write-byte.subx b/subx/062write-byte.subx
new file mode 100644
index 00000000..fedde5d9
--- /dev/null
+++ b/subx/062write-byte.subx
@@ -0,0 +1,160 @@
+# write-byte: write a single byte to a buffered-file. The write may be buffered.
+# flush: write out any buffered writes to disk.
+#
+# TODO: Come up with a way to signal failure to write to disk. This is hard
+# since the failure may impact previous calls that were buffered.
+
+== data
+
+# The buffered file for standard output.
+
+Stdout:
+    # file descriptor or (address stream)
+    01 00 00 00  # 1 = standard output
+    # current write index
+    00 00 00 00
+    # current read index
+    00 00 00 00
+    # length (8)
+    08 00 00 00
+    # data
+    00 00 00 00 00 00 00 00  # 8 bytes
+
+# TODO: 8 bytes is too small. We'll need to grow the buffer for efficiency. But
+# I don't want to type 1024 bytes here.
+
+== code
+#   instruction                     effective address                                                   register    displacement    immediate
+# . op          subop               mod             rm32          base        index         scale       r32
+# . 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
+
+# main:
+    e8/call  run-tests/disp32  # 'run-tests' is a function created automatically by SubX. It calls all functions that start with 'test-'.
+    # syscall(exit, Num-test-failures)
+    8b/copy                         0/mod/indirect  5/rm32/.disp32            .             .           3/r32/EBX   Num-test-failures/disp32          # copy *Num-test-failures to EBX
+    b8/copy-to-EAX  1/imm32
+    cd/syscall  0x80/imm8
+
+# Write lower byte of 'n' to 'f'.
+write-byte:  # f : (address buffered-file), n : num -> <void>
+    # . prolog
+    55/push-EBP
+    89/copy                         3/mod/direct    5/rm32/EBP    .           .             .           4/r32/ESP   .               .                 # copy ESP to EBP
+    # . save registers
+    51/push-ECX
+    56/push-ESI
+    # ESI = f
+    8b/copy                         1/mod/*+disp8   4/rm32/sib    5/base/EBP  4/index/none  .           6/r32/ESI   8/disp8         .                 # copy *(EBP+8) to ESI
+    # ECX = f->write
+    8b/copy                         1/mod/*+disp8   6/rm32/ESI    .           .             .           1/r32/ECX   4/disp8         .                 # copy *(ESI+4) to ECX
+    # if (f->write >= f->length) flush and clear stream
+    3b/compare                      1/mod/*+disp8   6/rm32/ESI    .           .             .           1/r32/ECX   0xc/disp8       .                 # compare ECX with *(ESI+12)
+    7c/jump-if-lesser  $write-byte:to-stream/disp8
+    # . flush-buffered-file(f)
+    # . . push args
+    56/push-ESI
+    # . . call
+    e8/call  flush/disp32
+    # . . discard args
+    81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               4/imm32           # add to ESP
+    # . clear-stream(stream = f+4)
+    # . . push args
+    8d/copy-address                 1/mod/*+disp8   6/rm32/ESI    .           .             .           0/r32/EAX   4/disp8         .                 # copy ESI+4 to EAX
+    50/push-EAX
+    # . . call
+    e8/call  clear-stream/disp32
+    # . . discard args
+    81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               4/imm32           # add to ESP
+$write-byte:to-stream:
+    # write to stream
+    # f->data[f->read] = LSB(n)
+    31/xor                          3/mod/direct    0/rm32/EAX    .           .             .           0/r32/EAX   .               .                 # clear EAX
+    8a/copy-byte                    1/mod/*+disp8   4/rm32/sib    5/base/EBP  4/index/none  .           0/r32/AL    0xc/disp8       .                 # copy byte at *(EBP+12) to AL
+    88/copy-byte                    1/mod/*+disp8   4/rm32/sib    6/base/ESI  1/index/ECX   .           0/r32/AL    0x10/disp8      .                 # copy AL to *(ESI+ECX+16)
+    # ++f->read
+    ff          0/subop/increment   1/mod/*+disp8   6/rm32/ESI    .           .             .           .           4/disp8         .                 # increment *(ESI+4)
+    # . restore registers
+    5e/pop-to-ESI
+    59/pop-to-ECX
+    # . epilog
+    89/copy                         3/mod/direct    4/rm32/ESP    .           .             .           5/r32/EBP   .               .                 # copy EBP to ESP
+    5d/pop-to-EBP
+    c3/return
+
+flush:  # f : (address buffered-file) -> <void>
+    # . prolog
+    55/push-EBP
+    89/copy                         3/mod/direct    5/rm32/EBP    .           .             .           4/r32/ESP   .               .                 # copy ESP to EBP
+    # . save registers
+    50/push-EAX
+    51/push-ECX
+    # EAX = f
+    8b/copy                         1/mod/*+disp8   4/rm32/sib    5/base/EBP  4/index/none  .           0/r32/EAX   8/disp8         .                 # copy *(EBP+8) to EAX
+    # write-stream(f->fd, data = f+4)
+      # . . push args
+    8d/copy-address                 1/mod/*+disp8   0/rm32/EAX    .           .             .           1/r32/ECX   4/disp8         .                 # copy EAX+4 to ECX
+    51/push-ECX
+    ff          6/subop/push        0/mod/indirect  0/rm32/EAX    .           .             .           .           .               .                 # push *EAX
+      # . . call
+    e8/call  write-stream/disp32
+      # . . discard args
+    81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
+    # . restore registers
+    59/pop-to-ECX
+    58/pop-to-EAX
+    # . epilog
+    89/copy                         3/mod/direct    4/rm32/ESP    .           .             .           5/r32/EBP   .               .                 # copy EBP to ESP
+    5d/pop-to-EBP
+    c3/return
+
+# - tests
+
+test-write-byte-single:
+    # - check that read-byte returns first byte of 'file'
+    # setup
+    # . clear-stream(_test-stream)
+    # . . push args
+    68/push  _test-stream/imm32
+    # . . call
+    e8/call  clear-stream/disp32
+    # . . discard args
+    81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               4/imm32           # add to ESP
+    # . clear-stream(_test-buffered-file+4)
+    # . . push args
+    b8/copy-to-EAX  _test-buffered-file/imm32
+    05/add-to-EAX  4/imm32
+    50/push-EAX
+    # . . call
+    e8/call  clear-stream/disp32
+    # . . discard args
+    81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               4/imm32           # add to ESP
+    # write-byte(_test-buffered-file, 'A')
+    # . . push args
+    68/push  0x41/imm32
+    68/push  _test-buffered-file/imm32
+    # . . call
+    e8/call  write-byte/disp32
+    # . . discard args
+    81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
+    # flush(_test-buffered-file)
+    # . . push args
+    68/push  _test-buffered-file/imm32
+    # . . call
+    e8/call  flush/disp32
+    # . . discard args
+    81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               4/imm32           # add to ESP
+    # check-ints-equal(*_test-stream->data, 'A', msg)
+    # . . push args
+    68/push  "F - test-write-byte-single"/imm32
+    68/push  0x41/imm32
+    # . . push *_test-stream->data
+    b8/copy-to-EAX  _test-stream/imm32
+    ff          6/subop/push        1/mod/*+disp8   0/rm32/EAX    .           .             .           .           0xc/disp8       .                 # push *(EAX+12)
+    # . . call
+    e8/call  check-ints-equal/disp32
+    # . . discard args
+    81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               0xc/imm32         # add to ESP
+    # . end
+    c3/return
+
+# . . vim:nowrap:textwidth=0
diff --git a/subx/apps/crenshaw2-1 b/subx/apps/crenshaw2-1
index 10003ae7..a9c23773 100755
--- a/subx/apps/crenshaw2-1
+++ b/subx/apps/crenshaw2-1
Binary files differdiff --git a/subx/apps/crenshaw2-1b b/subx/apps/crenshaw2-1b
index 20eaafe0..982a1f59 100755
--- a/subx/apps/crenshaw2-1b
+++ b/subx/apps/crenshaw2-1b
Binary files differdiff --git a/subx/apps/factorial b/subx/apps/factorial
index 7d867940..77ac0adb 100755
--- a/subx/apps/factorial
+++ b/subx/apps/factorial
Binary files differ