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<a href='https://github.com/akkartik/mu/blob/master/apps/arith.mu'>https://github.com/akkartik/mu/blob/master/apps/arith.mu</a>
<pre id='vimCodeElement'>
<span id="L1" class="LineNr"> 1 </span><span class="muComment"># Integer arithmetic using conventional precedence.</span>
<span id="L2" class="LineNr"> 2 </span><span class="muComment">#</span>
<span id="L3" class="LineNr"> 3 </span><span class="muComment"># Follows part 2 of Jack Crenshaw's "Let's build a compiler!"</span>
<span id="L4" class="LineNr"> 4 </span><span class="muComment"># <a href="https://compilers.iecc.com/crenshaw">https://compilers.iecc.com/crenshaw</a></span>
<span id="L5" class="LineNr"> 5 </span><span class="muComment">#</span>
<span id="L6" class="LineNr"> 6 </span><span class="muComment"># Limitations:</span>
<span id="L7" class="LineNr"> 7 </span><span class="muComment"># No division yet.</span>
<span id="L8" class="LineNr"> 8 </span><span class="muComment">#</span>
<span id="L9" class="LineNr"> 9 </span><span class="muComment"># To build:</span>
<span id="L10" class="LineNr"> 10 </span><span class="muComment"># $ ./translate_mu apps/arith.mu</span>
<span id="L11" class="LineNr"> 11 </span><span class="muComment">#</span>
<span id="L12" class="LineNr"> 12 </span><span class="muComment"># Example session:</span>
<span id="L13" class="LineNr"> 13 </span><span class="muComment"># $ ./a.elf</span>
<span id="L14" class="LineNr"> 14 </span><span class="muComment"># press ctrl-c or ctrl-d to exit</span>
<span id="L15" class="LineNr"> 15 </span><span class="muComment"># > 1</span>
<span id="L16" class="LineNr"> 16 </span><span class="muComment"># 1</span>
<span id="L17" class="LineNr"> 17 </span><span class="muComment"># > 1+1</span>
<span id="L18" class="LineNr"> 18 </span><span class="muComment"># 2</span>
<span id="L19" class="LineNr"> 19 </span><span class="muComment"># > 1 + 1</span>
<span id="L20" class="LineNr"> 20 </span><span class="muComment"># 2</span>
<span id="L21" class="LineNr"> 21 </span><span class="muComment"># > 1+2 +3</span>
<span id="L22" class="LineNr"> 22 </span><span class="muComment"># 6</span>
<span id="L23" class="LineNr"> 23 </span><span class="muComment"># > 1+2 *3</span>
<span id="L24" class="LineNr"> 24 </span><span class="muComment"># 7</span>
<span id="L25" class="LineNr"> 25 </span><span class="muComment"># > (1+2) *3</span>
<span id="L26" class="LineNr"> 26 </span><span class="muComment"># 9</span>
<span id="L27" class="LineNr"> 27 </span><span class="muComment"># > 1 + 3*4</span>
<span id="L28" class="LineNr"> 28 </span><span class="muComment"># 13</span>
<span id="L29" class="LineNr"> 29 </span><span class="muComment"># > ^D</span>
<span id="L30" class="LineNr"> 30 </span><span class="muComment"># $</span>
<span id="L31" class="LineNr"> 31 </span><span class="muComment">#</span>
<span id="L32" class="LineNr"> 32 </span><span class="muComment"># Error handling is non-existent. This is just a prototype.</span>
<span id="L33" class="LineNr"> 33 </span>
<span id="L34" class="LineNr"> 34 </span><span class="PreProc">fn</span> <span class="muFunction"><a href='arith.mu.html#L34'>main</a></span><span class="PreProc"> -> </span>_/<span class="Constant">ebx</span>: int <span class="Delimiter">{</span>
<span id="L35" class="LineNr"> 35 </span> <a href='../305keyboard.subx.html#L6'>enable-keyboard-immediate-mode</a>
<span id="L36" class="LineNr"> 36 </span> <span class="PreProc">var</span> look/<span class="Constant">esi</span>: grapheme <span class="SpecialChar"><-</span> copy <span class="Constant">0</span> <span class="muComment"># lookahead</span>
<span id="L37" class="LineNr"> 37 </span> <span class="PreProc">var</span> n/<span class="Constant">eax</span>: int <span class="SpecialChar"><-</span> copy <span class="Constant">0</span> <span class="muComment"># result of each expression</span>
<span id="L38" class="LineNr"> 38 </span> <a href='../405screen.mu.html#L169'>print-string</a> <span class="Constant">0</span>, <span class="Constant">"press ctrl-c or ctrl-d to exit\n"</span>
<span id="L39" class="LineNr"> 39 </span> <span class="muComment"># read-eval-print loop</span>
<span id="L40" class="LineNr"> 40 </span> <span class="Delimiter">{</span>
<span id="L41" class="LineNr"> 41 </span> <span class="muComment"># print prompt</span>
<span id="L42" class="LineNr"> 42 </span> <a href='../405screen.mu.html#L169'>print-string</a> <span class="Constant">0</span>, <span class="Constant">"> "</span>
<span id="L43" class="LineNr"> 43 </span> <span class="muComment"># read and eval</span>
<span id="L44" class="LineNr"> 44 </span> n, look <span class="SpecialChar"><-</span> <a href='arith.mu.html#L58'>simplify</a> <span class="muComment"># we explicitly thread 'look' everywhere</span>
<span id="L45" class="LineNr"> 45 </span> <span class="muComment"># if (look == 0) break</span>
<span id="L46" class="LineNr"> 46 </span> compare look, <span class="Constant">0</span>
<span id="L47" class="LineNr"> 47 </span> <span class="PreProc">break-if-=</span>
<span id="L48" class="LineNr"> 48 </span> <span class="muComment"># print</span>
<span id="L49" class="LineNr"> 49 </span> <a href='../405screen.mu.html#L481'>print-int32-decimal</a> <span class="Constant">0</span>, n
<span id="L50" class="LineNr"> 50 </span> <a href='../405screen.mu.html#L169'>print-string</a> <span class="Constant">0</span>, <span class="Constant">"\n"</span>
<span id="L51" class="LineNr"> 51 </span> <span class="muComment">#</span>
<span id="L52" class="LineNr"> 52 </span> <span class="PreProc">loop</span>
<span id="L53" class="LineNr"> 53 </span> <span class="Delimiter">}</span>
<span id="L54" class="LineNr"> 54 </span> <a href='../305keyboard.subx.html#L72'>enable-keyboard-type-mode</a>
<span id="L55" class="LineNr"> 55 </span> <span class="PreProc">return</span> <span class="Constant">0</span>
<span id="L56" class="LineNr"> 56 </span><span class="Delimiter">}</span>
<span id="L57" class="LineNr"> 57 </span>
<span id="L58" class="LineNr"> 58 </span><span class="PreProc">fn</span> <span class="muFunction"><a href='arith.mu.html#L58'>simplify</a></span><span class="PreProc"> -> </span>_/<span class="Constant">eax</span>: int, _/<span class="Constant">esi</span>: grapheme <span class="Delimiter">{</span>
<span id="L59" class="LineNr"> 59 </span> <span class="muComment"># prime the pump</span>
<span id="L60" class="LineNr"> 60 </span> <span class="PreProc">var</span> look/<span class="Constant">esi</span>: grapheme <span class="SpecialChar"><-</span> <a href='arith.mu.html#L248'>get-char</a>
<span id="L61" class="LineNr"> 61 </span> <span class="muComment"># do it</span>
<span id="L62" class="LineNr"> 62 </span> <span class="PreProc">var</span> result/<span class="Constant">eax</span>: int <span class="SpecialChar"><-</span> copy <span class="Constant">0</span>
<span id="L63" class="LineNr"> 63 </span> result, look <span class="SpecialChar"><-</span> <a href='arith.mu.html#L67'>expression</a> look
<span id="L64" class="LineNr"> 64 </span> <span class="PreProc">return</span> result, look
<span id="L65" class="LineNr"> 65 </span><span class="Delimiter">}</span>
<span id="L66" class="LineNr"> 66 </span>
<span id="L67" class="LineNr"> 67 </span><span class="PreProc">fn</span> <span class="muFunction"><a href='arith.mu.html#L67'>expression</a></span> _look: grapheme<span class="PreProc"> -> </span>_/<span class="Constant">eax</span>: int, _/<span class="Constant">esi</span>: grapheme <span class="Delimiter">{</span>
<span id="L68" class="LineNr"> 68 </span> <span class="PreProc">var</span> look/<span class="Constant">esi</span>: grapheme <span class="SpecialChar"><-</span> copy _look
<span id="L69" class="LineNr"> 69 </span> <span class="muComment"># read arg</span>
<span id="L70" class="LineNr"> 70 </span> <span class="PreProc">var</span> result/<span class="Constant">eax</span>: int <span class="SpecialChar"><-</span> copy <span class="Constant">0</span>
<span id="L71" class="LineNr"> 71 </span> result, look <span class="SpecialChar"><-</span> <a href='arith.mu.html#L112'>term</a> look
<span id="L72" class="LineNr"> 72 </span> $expression:<span class="PreProc">loop</span>: <span class="Delimiter">{</span>
<span id="L73" class="LineNr"> 73 </span> <span class="muComment"># while next non-space char in ['+', '-']</span>
<span id="L74" class="LineNr"> 74 </span> look <span class="SpecialChar"><-</span> <a href='arith.mu.html#L237'>skip-spaces</a> look
<span id="L75" class="LineNr"> 75 </span> <span class="Delimiter">{</span>
<span id="L76" class="LineNr"> 76 </span> <span class="PreProc">var</span> continue?/<span class="Constant">eax</span>: boolean <span class="SpecialChar"><-</span> <a href='arith.mu.html#L191'>is-add-or-sub?</a> look
<span id="L77" class="LineNr"> 77 </span> compare continue?, <span class="Constant">0</span> <span class="muComment"># false</span>
<span id="L78" class="LineNr"> 78 </span> <span class="PreProc">break-if-=</span> $expression:<span class="PreProc">loop</span>
<span id="L79" class="LineNr"> 79 </span> <span class="Delimiter">}</span>
<span id="L80" class="LineNr"> 80 </span> <span class="muComment"># read operator</span>
<span id="L81" class="LineNr"> 81 </span> <span class="PreProc">var</span> op/<span class="Constant">ecx</span>: byte <span class="SpecialChar"><-</span> copy <span class="Constant">0</span>
<span id="L82" class="LineNr"> 82 </span> op, look <span class="SpecialChar"><-</span> operator look
<span id="L83" class="LineNr"> 83 </span> <span class="muComment"># read next arg</span>
<span id="L84" class="LineNr"> 84 </span> <span class="PreProc">var</span> second/<span class="Constant">edx</span>: int <span class="SpecialChar"><-</span> copy <span class="Constant">0</span>
<span id="L85" class="LineNr"> 85 </span> look <span class="SpecialChar"><-</span> <a href='arith.mu.html#L237'>skip-spaces</a> look
<span id="L86" class="LineNr"> 86 </span> <span class="Delimiter">{</span>
<span id="L87" class="LineNr"> 87 </span> <span class="PreProc">var</span> tmp/<span class="Constant">eax</span>: int <span class="SpecialChar"><-</span> copy <span class="Constant">0</span>
<span id="L88" class="LineNr"> 88 </span> tmp, look <span class="SpecialChar"><-</span> <a href='arith.mu.html#L112'>term</a> look
<span id="L89" class="LineNr"> 89 </span> second <span class="SpecialChar"><-</span> copy tmp
<span id="L90" class="LineNr"> 90 </span> <span class="Delimiter">}</span>
<span id="L91" class="LineNr"> 91 </span> <span class="muComment"># reduce</span>
<span id="L92" class="LineNr"> 92 </span> $expression:perform-op: <span class="Delimiter">{</span>
<span id="L93" class="LineNr"> 93 </span> <span class="Delimiter">{</span>
<span id="L94" class="LineNr"> 94 </span> compare op, <span class="Constant">0x2b</span> <span class="muComment"># '+'</span>
<span id="L95" class="LineNr"> 95 </span> <span class="PreProc">break-if-!=</span>
<span id="L96" class="LineNr"> 96 </span> result <span class="SpecialChar"><-</span> add second
<span id="L97" class="LineNr"> 97 </span> <span class="PreProc">break</span> $expression:perform-op
<span id="L98" class="LineNr"> 98 </span> <span class="Delimiter">}</span>
<span id="L99" class="LineNr"> 99 </span> <span class="Delimiter">{</span>
<span id="L100" class="LineNr">100 </span> compare op, <span class="Constant">0x2d</span> <span class="muComment"># '-'</span>
<span id="L101" class="LineNr">101 </span> <span class="PreProc">break-if-!=</span>
<span id="L102" class="LineNr">102 </span> result <span class="SpecialChar"><-</span> subtract second
<span id="L103" class="LineNr">103 </span> <span class="PreProc">break</span> $expression:perform-op
<span id="L104" class="LineNr">104 </span> <span class="Delimiter">}</span>
<span id="L105" class="LineNr">105 </span> <span class="Delimiter">}</span>
<span id="L106" class="LineNr">106 </span> <span class="PreProc">loop</span>
<span id="L107" class="LineNr">107 </span> <span class="Delimiter">}</span>
<span id="L108" class="LineNr">108 </span> look <span class="SpecialChar"><-</span> <a href='arith.mu.html#L237'>skip-spaces</a> look
<span id="L109" class="LineNr">109 </span> <span class="PreProc">return</span> result, look
<span id="L110" class="LineNr">110 </span><span class="Delimiter">}</span>
<span id="L111" class="LineNr">111 </span>
<span id="L112" class="LineNr">112 </span><span class="PreProc">fn</span> <span class="muFunction"><a href='arith.mu.html#L112'>term</a></span> _look: grapheme<span class="PreProc"> -> </span>_/<span class="Constant">eax</span>: int, _/<span class="Constant">esi</span>: grapheme <span class="Delimiter">{</span>
<span id="L113" class="LineNr">113 </span> <span class="PreProc">var</span> look/<span class="Constant">esi</span>: grapheme <span class="SpecialChar"><-</span> copy _look
<span id="L114" class="LineNr">114 </span> <span class="muComment"># read arg</span>
<span id="L115" class="LineNr">115 </span> look <span class="SpecialChar"><-</span> <a href='arith.mu.html#L237'>skip-spaces</a> look
<span id="L116" class="LineNr">116 </span> <span class="PreProc">var</span> result/<span class="Constant">eax</span>: int <span class="SpecialChar"><-</span> copy <span class="Constant">0</span>
<span id="L117" class="LineNr">117 </span> result, look <span class="SpecialChar"><-</span> <a href='arith.mu.html#L157'>factor</a> look
<span id="L118" class="LineNr">118 </span> $term:<span class="PreProc">loop</span>: <span class="Delimiter">{</span>
<span id="L119" class="LineNr">119 </span> <span class="muComment"># while next non-space char in ['*', '/']</span>
<span id="L120" class="LineNr">120 </span> look <span class="SpecialChar"><-</span> <a href='arith.mu.html#L237'>skip-spaces</a> look
<span id="L121" class="LineNr">121 </span> <span class="Delimiter">{</span>
<span id="L122" class="LineNr">122 </span> <span class="PreProc">var</span> continue?/<span class="Constant">eax</span>: boolean <span class="SpecialChar"><-</span> <a href='arith.mu.html#L177'>is-mul-or-div?</a> look
<span id="L123" class="LineNr">123 </span> compare continue?, <span class="Constant">0</span> <span class="muComment"># false</span>
<span id="L124" class="LineNr">124 </span> <span class="PreProc">break-if-=</span> $term:<span class="PreProc">loop</span>
<span id="L125" class="LineNr">125 </span> <span class="Delimiter">}</span>
<span id="L126" class="LineNr">126 </span> <span class="muComment"># read operator</span>
<span id="L127" class="LineNr">127 </span> <span class="PreProc">var</span> op/<span class="Constant">ecx</span>: byte <span class="SpecialChar"><-</span> copy <span class="Constant">0</span>
<span id="L128" class="LineNr">128 </span> op, look <span class="SpecialChar"><-</span> operator look
<span id="L129" class="LineNr">129 </span> <span class="muComment"># read next arg</span>
<span id="L130" class="LineNr">130 </span> <span class="PreProc">var</span> second/<span class="Constant">edx</span>: int <span class="SpecialChar"><-</span> copy <span class="Constant">0</span>
<span id="L131" class="LineNr">131 </span> look <span class="SpecialChar"><-</span> <a href='arith.mu.html#L237'>skip-spaces</a> look
<span id="L132" class="LineNr">132 </span> <span class="Delimiter">{</span>
<span id="L133" class="LineNr">133 </span> <span class="PreProc">var</span> tmp/<span class="Constant">eax</span>: int <span class="SpecialChar"><-</span> copy <span class="Constant">0</span>
<span id="L134" class="LineNr">134 </span> tmp, look <span class="SpecialChar"><-</span> <a href='arith.mu.html#L157'>factor</a> look
<span id="L135" class="LineNr">135 </span> second <span class="SpecialChar"><-</span> copy tmp
<span id="L136" class="LineNr">136 </span> <span class="Delimiter">}</span>
<span id="L137" class="LineNr">137 </span> <span class="muComment"># reduce</span>
<span id="L138" class="LineNr">138 </span> $term:perform-op: <span class="Delimiter">{</span>
<span id="L139" class="LineNr">139 </span> <span class="Delimiter">{</span>
<span id="L140" class="LineNr">140 </span> compare op, <span class="Constant">0x2a</span> <span class="muComment"># '*'</span>
<span id="L141" class="LineNr">141 </span> <span class="PreProc">break-if-!=</span>
<span id="L142" class="LineNr">142 </span> result <span class="SpecialChar"><-</span> multiply second
<span id="L143" class="LineNr">143 </span> <span class="PreProc">break</span> $term:perform-op
<span id="L144" class="LineNr">144 </span> <span class="Delimiter">}</span>
<span id="L145" class="LineNr">145 </span><span class="CommentedCode">#? {</span>
<span id="L146" class="LineNr">146 </span><span class="CommentedCode">#? compare op, 0x2f # '/'</span>
<span id="L147" class="LineNr">147 </span><span class="CommentedCode">#? break-if-!=</span>
<span id="L148" class="LineNr">148 </span><span class="CommentedCode">#? result <- divide second # not in Mu yet</span>
<span id="L149" class="LineNr">149 </span><span class="CommentedCode">#? break $term:perform-op</span>
<span id="L150" class="LineNr">150 </span><span class="CommentedCode">#? }</span>
<span id="L151" class="LineNr">151 </span> <span class="Delimiter">}</span>
<span id="L152" class="LineNr">152 </span> <span class="PreProc">loop</span>
<span id="L153" class="LineNr">153 </span> <span class="Delimiter">}</span>
<span id="L154" class="LineNr">154 </span> <span class="PreProc">return</span> result, look
<span id="L155" class="LineNr">155 </span><span class="Delimiter">}</span>
<span id="L156" class="LineNr">156 </span>
<span id="L157" class="LineNr">157 </span><span class="PreProc">fn</span> <span class="muFunction"><a href='arith.mu.html#L157'>factor</a></span> _look: grapheme<span class="PreProc"> -> </span>_/<span class="Constant">eax</span>: int, _/<span class="Constant">esi</span>: grapheme <span class="Delimiter">{</span>
<span id="L158" class="LineNr">158 </span> <span class="PreProc">var</span> look/<span class="Constant">esi</span>: grapheme <span class="SpecialChar"><-</span> copy _look <span class="muComment"># should be a no-op</span>
<span id="L159" class="LineNr">159 </span> look <span class="SpecialChar"><-</span> <a href='arith.mu.html#L237'>skip-spaces</a> look
<span id="L160" class="LineNr">160 </span> <span class="muComment"># if next char is not '(', parse a number</span>
<span id="L161" class="LineNr">161 </span> compare look, <span class="Constant">0x28</span> <span class="muComment"># '('</span>
<span id="L162" class="LineNr">162 </span> <span class="Delimiter">{</span>
<span id="L163" class="LineNr">163 </span> <span class="PreProc">break-if-=</span>
<span id="L164" class="LineNr">164 </span> <span class="PreProc">var</span> result/<span class="Constant">eax</span>: int <span class="SpecialChar"><-</span> copy <span class="Constant">0</span>
<span id="L165" class="LineNr">165 </span> result, look <span class="SpecialChar"><-</span> <a href='arith.mu.html#L211'>num</a> look
<span id="L166" class="LineNr">166 </span> <span class="PreProc">return</span> result, look
<span id="L167" class="LineNr">167 </span> <span class="Delimiter">}</span>
<span id="L168" class="LineNr">168 </span> <span class="muComment"># otherwise recurse</span>
<span id="L169" class="LineNr">169 </span> look <span class="SpecialChar"><-</span> <a href='arith.mu.html#L248'>get-char</a> <span class="muComment"># '('</span>
<span id="L170" class="LineNr">170 </span> <span class="PreProc">var</span> result/<span class="Constant">eax</span>: int <span class="SpecialChar"><-</span> copy <span class="Constant">0</span>
<span id="L171" class="LineNr">171 </span> result, look <span class="SpecialChar"><-</span> <a href='arith.mu.html#L67'>expression</a> look
<span id="L172" class="LineNr">172 </span> look <span class="SpecialChar"><-</span> <a href='arith.mu.html#L237'>skip-spaces</a> look
<span id="L173" class="LineNr">173 </span> look <span class="SpecialChar"><-</span> <a href='arith.mu.html#L248'>get-char</a> <span class="muComment"># ')'</span>
<span id="L174" class="LineNr">174 </span> <span class="PreProc">return</span> result, look
<span id="L175" class="LineNr">175 </span><span class="Delimiter">}</span>
<span id="L176" class="LineNr">176 </span>
<span id="L177" class="LineNr">177 </span><span class="PreProc">fn</span> <span class="muFunction"><a href='arith.mu.html#L177'>is-mul-or-div?</a></span> c: grapheme<span class="PreProc"> -> </span>_/<span class="Constant">eax</span>: boolean <span class="Delimiter">{</span>
<span id="L178" class="LineNr">178 </span> compare c, <span class="Constant">0x2a</span> <span class="muComment"># '*'</span>
<span id="L179" class="LineNr">179 </span> <span class="Delimiter">{</span>
<span id="L180" class="LineNr">180 </span> <span class="PreProc">break-if-!=</span>
<span id="L181" class="LineNr">181 </span> <span class="PreProc">return</span> <span class="Constant">1</span> <span class="muComment"># true</span>
<span id="L182" class="LineNr">182 </span> <span class="Delimiter">}</span>
<span id="L183" class="LineNr">183 </span> compare c, <span class="Constant">0x2f</span> <span class="muComment"># '/'</span>
<span id="L184" class="LineNr">184 </span> <span class="Delimiter">{</span>
<span id="L185" class="LineNr">185 </span> <span class="PreProc">break-if-!=</span>
<span id="L186" class="LineNr">186 </span> <span class="PreProc">return</span> <span class="Constant">1</span> <span class="muComment"># true</span>
<span id="L187" class="LineNr">187 </span> <span class="Delimiter">}</span>
<span id="L188" class="LineNr">188 </span> <span class="PreProc">return</span> <span class="Constant">0</span> <span class="muComment"># false</span>
<span id="L189" class="LineNr">189 </span><span class="Delimiter">}</span>
<span id="L190" class="LineNr">190 </span>
<span id="L191" class="LineNr">191 </span><span class="PreProc">fn</span> <span class="muFunction"><a href='arith.mu.html#L191'>is-add-or-sub?</a></span> c: grapheme<span class="PreProc"> -> </span>_/<span class="Constant">eax</span>: boolean <span class="Delimiter">{</span>
<span id="L192" class="LineNr">192 </span> compare c, <span class="Constant">0x2b</span> <span class="muComment"># '+'</span>
<span id="L193" class="LineNr">193 </span> <span class="Delimiter">{</span>
<span id="L194" class="LineNr">194 </span> <span class="PreProc">break-if-!=</span>
<span id="L195" class="LineNr">195 </span> <span class="PreProc">return</span> <span class="Constant">1</span> <span class="muComment"># true</span>
<span id="L196" class="LineNr">196 </span> <span class="Delimiter">}</span>
<span id="L197" class="LineNr">197 </span> compare c, <span class="Constant">0x2d</span> <span class="muComment"># '-'</span>
<span id="L198" class="LineNr">198 </span> <span class="Delimiter">{</span>
<span id="L199" class="LineNr">199 </span> <span class="PreProc">break-if-!=</span>
<span id="L200" class="LineNr">200 </span> <span class="PreProc">return</span> <span class="Constant">1</span> <span class="muComment"># true</span>
<span id="L201" class="LineNr">201 </span> <span class="Delimiter">}</span>
<span id="L202" class="LineNr">202 </span> <span class="PreProc">return</span> <span class="Constant">0</span> <span class="muComment"># false</span>
<span id="L203" class="LineNr">203 </span><span class="Delimiter">}</span>
<span id="L204" class="LineNr">204 </span>
<span id="L205" class="LineNr">205 </span><span class="PreProc">fn</span> <span class="muFunction">operator</span> _look: grapheme<span class="PreProc"> -> </span>_/<span class="Constant">ecx</span>: byte, _/<span class="Constant">esi</span>: grapheme <span class="Delimiter">{</span>
<span id="L206" class="LineNr">206 </span> <span class="PreProc">var</span> op/<span class="Constant">ecx</span>: byte <span class="SpecialChar"><-</span> copy _look
<span id="L207" class="LineNr">207 </span> <span class="PreProc">var</span> look/<span class="Constant">esi</span>: grapheme <span class="SpecialChar"><-</span> <a href='arith.mu.html#L248'>get-char</a>
<span id="L208" class="LineNr">208 </span> <span class="PreProc">return</span> op, look
<span id="L209" class="LineNr">209 </span><span class="Delimiter">}</span>
<span id="L210" class="LineNr">210 </span>
<span id="L211" class="LineNr">211 </span><span class="PreProc">fn</span> <span class="muFunction"><a href='arith.mu.html#L211'>num</a></span> _look: grapheme<span class="PreProc"> -> </span>_/<span class="Constant">eax</span>: int, _/<span class="Constant">esi</span>: grapheme <span class="Delimiter">{</span>
<span id="L212" class="LineNr">212 </span> <span class="PreProc">var</span> look/<span class="Constant">esi</span>: grapheme <span class="SpecialChar"><-</span> copy _look
<span id="L213" class="LineNr">213 </span> <span class="PreProc">var</span> result/<span class="Constant">edi</span>: int <span class="SpecialChar"><-</span> copy <span class="Constant">0</span>
<span id="L214" class="LineNr">214 </span> <span class="Delimiter">{</span>
<span id="L215" class="LineNr">215 </span> <span class="PreProc">var</span> first-digit/<span class="Constant">eax</span>: int <span class="SpecialChar"><-</span> <a href='../126write-int-decimal.subx.html#L405'>to-decimal-digit</a> look
<span id="L216" class="LineNr">216 </span> result <span class="SpecialChar"><-</span> copy first-digit
<span id="L217" class="LineNr">217 </span> <span class="Delimiter">}</span>
<span id="L218" class="LineNr">218 </span> <span class="Delimiter">{</span>
<span id="L219" class="LineNr">219 </span> look <span class="SpecialChar"><-</span> <a href='arith.mu.html#L248'>get-char</a>
<span id="L220" class="LineNr">220 </span> <span class="muComment"># done?</span>
<span id="L221" class="LineNr">221 </span> <span class="PreProc">var</span> digit?/<span class="Constant">eax</span>: boolean <span class="SpecialChar"><-</span> <a href='../126write-int-decimal.subx.html#L306'>is-decimal-digit?</a> look
<span id="L222" class="LineNr">222 </span> compare digit?, <span class="Constant">0</span> <span class="muComment"># false</span>
<span id="L223" class="LineNr">223 </span> <span class="PreProc">break-if-=</span>
<span id="L224" class="LineNr">224 </span> <span class="muComment"># result *= 10</span>
<span id="L225" class="LineNr">225 </span> <span class="Delimiter">{</span>
<span id="L226" class="LineNr">226 </span> <span class="PreProc">var</span> ten/<span class="Constant">eax</span>: int <span class="SpecialChar"><-</span> copy <span class="Constant">0xa</span>
<span id="L227" class="LineNr">227 </span> result <span class="SpecialChar"><-</span> multiply ten
<span id="L228" class="LineNr">228 </span> <span class="Delimiter">}</span>
<span id="L229" class="LineNr">229 </span> <span class="muComment"># result += digit(look)</span>
<span id="L230" class="LineNr">230 </span> <span class="PreProc">var</span> digit/<span class="Constant">eax</span>: int <span class="SpecialChar"><-</span> <a href='../126write-int-decimal.subx.html#L405'>to-decimal-digit</a> look
<span id="L231" class="LineNr">231 </span> result <span class="SpecialChar"><-</span> add digit
<span id="L232" class="LineNr">232 </span> <span class="PreProc">loop</span>
<span id="L233" class="LineNr">233 </span> <span class="Delimiter">}</span>
<span id="L234" class="LineNr">234 </span> <span class="PreProc">return</span> result, look
<span id="L235" class="LineNr">235 </span><span class="Delimiter">}</span>
<span id="L236" class="LineNr">236 </span>
<span id="L237" class="LineNr">237 </span><span class="PreProc">fn</span> <span class="muFunction"><a href='arith.mu.html#L237'>skip-spaces</a></span> _look: grapheme<span class="PreProc"> -> </span>_/<span class="Constant">esi</span>: grapheme <span class="Delimiter">{</span>
<span id="L238" class="LineNr">238 </span> <span class="PreProc">var</span> look/<span class="Constant">esi</span>: grapheme <span class="SpecialChar"><-</span> copy _look <span class="muComment"># should be a no-op</span>
<span id="L239" class="LineNr">239 </span> <span class="Delimiter">{</span>
<span id="L240" class="LineNr">240 </span> compare look, <span class="Constant">0x20</span>
<span id="L241" class="LineNr">241 </span> <span class="PreProc">break-if-!=</span>
<span id="L242" class="LineNr">242 </span> look <span class="SpecialChar"><-</span> <a href='arith.mu.html#L248'>get-char</a>
<span id="L243" class="LineNr">243 </span> <span class="PreProc">loop</span>
<span id="L244" class="LineNr">244 </span> <span class="Delimiter">}</span>
<span id="L245" class="LineNr">245 </span> <span class="PreProc">return</span> look
<span id="L246" class="LineNr">246 </span><span class="Delimiter">}</span>
<span id="L247" class="LineNr">247 </span>
<span id="L248" class="LineNr">248 </span><span class="PreProc">fn</span> <span class="muFunction"><a href='arith.mu.html#L248'>get-char</a></span><span class="PreProc"> -> </span>_/<span class="Constant">esi</span>: grapheme <span class="Delimiter">{</span>
<span id="L249" class="LineNr">249 </span> <span class="PreProc">var</span> look/<span class="Constant">eax</span>: grapheme <span class="SpecialChar"><-</span> <a href='../305keyboard.subx.html#L132'>read-key-from-real-keyboard</a>
<span id="L250" class="LineNr">250 </span> <a href='../304screen.subx.html#L161'>print-grapheme-to-real-screen</a> look
<span id="L251" class="LineNr">251 </span> compare look, <span class="Constant">4</span>
<span id="L252" class="LineNr">252 </span> <span class="Delimiter">{</span>
<span id="L253" class="LineNr">253 </span> <span class="PreProc">break-if-!=</span>
<span id="L254" class="LineNr">254 </span> <a href='../405screen.mu.html#L169'>print-string</a> <span class="Constant">0</span>, <span class="Constant">"^D\n"</span>
<span id="L255" class="LineNr">255 </span> syscall_exit
<span id="L256" class="LineNr">256 </span> <span class="Delimiter">}</span>
<span id="L257" class="LineNr">257 </span> <span class="PreProc">return</span> look
<span id="L258" class="LineNr">258 </span><span class="Delimiter">}</span>
</pre>
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