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<span id="L1" class="LineNr"> 1 </span><span class="Comment">//: Continuations are a powerful primitive for constructing advanced kinds of</span>
<span id="L2" class="LineNr"> 2 </span><span class="Comment">//: control *policies* like back-tracking.</span>
<span id="L3" class="LineNr"> 3 </span><span class="Comment">//:</span>
<span id="L4" class="LineNr"> 4 </span><span class="Comment">//: In Mu, continuations are first-class and delimited, and are constructed</span>
<span id="L5" class="LineNr"> 5 </span><span class="Comment">//: out of two primitives:</span>
<span id="L6" class="LineNr"> 6 </span><span class="Comment">//:</span>
<span id="L7" class="LineNr"> 7 </span><span class="Comment">//: * 'call-with-continuation-mark' marks the top of the call stack and then</span>
<span id="L8" class="LineNr"> 8 </span><span class="Comment">//: calls the provided recipe.</span>
<span id="L9" class="LineNr"> 9 </span><span class="Comment">//: * 'return-continuation-until-mark' copies the top of the stack</span>
<span id="L10" class="LineNr"> 10 </span><span class="Comment">//: until the mark, and returns it as the result of</span>
<span id="L11" class="LineNr"> 11 </span><span class="Comment">//: 'call-with-continuation-mark' (which might be a distant ancestor on the</span>
<span id="L12" class="LineNr"> 12 </span><span class="Comment">//: call stack; intervening calls don't return)</span>
<span id="L13" class="LineNr"> 13 </span><span class="Comment">//:</span>
<span id="L14" class="LineNr"> 14 </span><span class="Comment">//: The resulting slice of the stack can now be called just like a regular</span>
<span id="L15" class="LineNr"> 15 </span><span class="Comment">//: recipe.</span>
<span id="L16" class="LineNr"> 16 </span><span class="Comment">//:</span>
<span id="L17" class="LineNr"> 17 </span><span class="Comment">//: See the example programs continuation*.mu to get a sense for the</span>
<span id="L18" class="LineNr"> 18 </span><span class="Comment">//: possibilities.</span>
<span id="L19" class="LineNr"> 19 </span><span class="Comment">//:</span>
<span id="L20" class="LineNr"> 20 </span><span class="Comment">//: Refinements:</span>
<span id="L21" class="LineNr"> 21 </span><span class="Comment">//: * You can call a single continuation multiple times, and it will preserve</span>
<span id="L22" class="LineNr"> 22 </span><span class="Comment">//: the state of its local variables at each stack frame between calls.</span>
<span id="L23" class="LineNr"> 23 </span><span class="Comment">//: The stack frames of a continuation are not destroyed until the</span>
<span id="L24" class="LineNr"> 24 </span><span class="Comment">//: continuation goes out of scope. See continuation2.mu.</span>
<span id="L25" class="LineNr"> 25 </span><span class="Comment">//: * 'return-continuation-until-mark' doesn't consume the mark, so you can</span>
<span id="L26" class="LineNr"> 26 </span><span class="Comment">//: return multiple continuations based on a single mark. In combination</span>
<span id="L27" class="LineNr"> 27 </span><span class="Comment">//: with the fact that 'return-continuation-until-mark' can return from</span>
<span id="L28" class="LineNr"> 28 </span><span class="Comment">//: regular calls, just as long as there was an earlier call to</span>
<span id="L29" class="LineNr"> 29 </span><span class="Comment">//: 'call-with-continuation-mark', this gives us a way to create resumable</span>
<span id="L30" class="LineNr"> 30 </span><span class="Comment">//: recipes. See continuation3.mu.</span>
<span id="L31" class="LineNr"> 31 </span><span class="Comment">//: * 'return-continuation-until-mark' can take ingredients to return just</span>
<span id="L32" class="LineNr"> 32 </span><span class="Comment">//: like other 'return' instructions. It just implicitly also returns a</span>
<span id="L33" class="LineNr"> 33 </span><span class="Comment">//: continuation as the first result. See continuation4.mu.</span>
<span id="L34" class="LineNr"> 34 </span><span class="Comment">//: * Conversely, you can pass ingredients to a continuation when calling it,</span>
<span id="L35" class="LineNr"> 35 </span><span class="Comment">//: to make it available to products of 'return-continuation-until-mark'.</span>
<span id="L36" class="LineNr"> 36 </span><span class="Comment">//: See continuation5.mu.</span>
<span id="L37" class="LineNr"> 37 </span><span class="Comment">//: * There can be multiple continuation marks on the stack at once;</span>
<span id="L38" class="LineNr"> 38 </span><span class="Comment">//: 'call-with-continuation-mark' and 'return-continuation-until-mark' both</span>
<span id="L39" class="LineNr"> 39 </span><span class="Comment">//: need to pass in a tag to coordinate on the correct mark. This allows us</span>
<span id="L40" class="LineNr"> 40 </span><span class="Comment">//: to save multiple continuations for different purposes (say if one is</span>
<span id="L41" class="LineNr"> 41 </span><span class="Comment">//: for exceptions) with overlapping stack frames. See exception.mu.</span>
<span id="L42" class="LineNr"> 42 </span><span class="Comment">//:</span>
<span id="L43" class="LineNr"> 43 </span><span class="Comment">//: Inspired by James and Sabry, "Yield: Mainstream delimited continuations",</span>
<span id="L44" class="LineNr"> 44 </span><span class="Comment">//: Workshop on the Theory and Practice of Delimited Continuations, 2011.</span>
<span id="L45" class="LineNr"> 45 </span><span class="Comment">//: <a href="https://www.cs.indiana.edu/~sabry/papers/yield.pdf">https://www.cs.indiana.edu/~sabry/papers/yield.pdf</a></span>
<span id="L46" class="LineNr"> 46 </span><span class="Comment">//:</span>
<span id="L47" class="LineNr"> 47 </span><span class="Comment">//: Caveats:</span>
<span id="L48" class="LineNr"> 48 </span><span class="Comment">//: * At the moment we can't statically type-check continuations. So we raise</span>
<span id="L49" class="LineNr"> 49 </span><span class="Comment">//: runtime errors for a call that doesn't return a continuation when the</span>
<span id="L50" class="LineNr"> 50 </span><span class="Comment">//: caller expects, or one that returns a continuation when the caller</span>
<span id="L51" class="LineNr"> 51 </span><span class="Comment">//: doesn't expect it. This shouldn't cause memory corruption, though.</span>
<span id="L52" class="LineNr"> 52 </span><span class="Comment">//: There should still be no way to lookup addresses that aren't allocated.</span>
<span id="L53" class="LineNr"> 53 </span>
<span id="L54" class="LineNr"> 54 </span><span class="Delimiter">:(before "End Mu Types Initialization")</span>
<span id="L55" class="LineNr"> 55 </span><a href='010vm.cc.html#L125'>type_ordinal</a> continuation = Type_ordinal[<span class="Constant">"continuation"</span>] = Next_type_ordinal++<span class="Delimiter">;</span>
<span id="L56" class="LineNr"> 56 </span>Type[continuation]<span class="Delimiter">.</span>name = <span class="Constant">"continuation"</span><span class="Delimiter">;</span>
<span id="L57" class="LineNr"> 57 </span>
<span id="L58" class="LineNr"> 58 </span><span class="Comment">//: A continuation can be called like a recipe.</span>
<span id="L59" class="LineNr"> 59 </span><span class="Delimiter">:(before "End <a href='072recipe.cc.html#L335'>is_mu_recipe</a> Atom Cases(r)")</span>
<span id="L60" class="LineNr"> 60 </span><span class="Normal">if</span> <span class="Delimiter">(</span>r<span class="Delimiter">.</span>type<span class="Delimiter">-></span>name == <span class="Constant">"continuation"</span><span class="Delimiter">)</span> <span class="Identifier">return</span><span class="Constant"> true</span><span class="Delimiter">;</span>
<span id="L61" class="LineNr"> 61 </span>
<span id="L62" class="LineNr"> 62 </span><span class="Comment">//: However, it can't be type-checked like most recipes. Pretend it's like a</span>
<span id="L63" class="LineNr"> 63 </span><span class="Comment">//: header-less recipe.</span>
<span id="L64" class="LineNr"> 64 </span><span class="Delimiter">:(after "Begin Reagent->Recipe(r, recipe_header)")</span>
<span id="L65" class="LineNr"> 65 </span><span class="Normal">if</span> <span class="Delimiter">(</span>r<span class="Delimiter">.</span>type<span class="Delimiter">-></span>atom && r<span class="Delimiter">.</span>type<span class="Delimiter">-></span>name == <span class="Constant">"continuation"</span><span class="Delimiter">)</span> <span class="Delimiter">{</span>
<span id="L66" class="LineNr"> 66 </span> result_header<span class="Delimiter">.</span>has_header =<span class="Constant"> false</span><span class="Delimiter">;</span>
<span id="L67" class="LineNr"> 67 </span> <span class="Identifier">return</span> result_header<span class="Delimiter">;</span>
<span id="L68" class="LineNr"> 68 </span><span class="Delimiter">}</span>
<span id="L69" class="LineNr"> 69 </span>
<span id="L70" class="LineNr"> 70 </span><span class="Delimiter">:(scenario delimited_continuation)</span>
<span id="L71" class="LineNr"> 71 </span><span class="muRecipe"><a href='010vm.cc.html#L19'>recipe</a></span> <a href='000organization.cc.html#L113'>main</a> [
<span id="L72" class="LineNr"> 72 </span> <span class="Constant">1</span>:continuation<span class="Special"> <- </span>call-with-continuation-mark <span class="Constant">233</span>/mark<span class="Delimiter">,</span> f<span class="Delimiter">,</span> <span class="Constant">77</span> <span class="Comment"># 77 is an argument to f</span>
<span id="L73" class="LineNr"> 73 </span> <span class="Constant">2</span>:num<span class="Special"> <- </span>copy <span class="Constant">5</span>
<span id="L74" class="LineNr"> 74 </span> <span class="Delimiter">{</span>
<span id="L75" class="LineNr"> 75 </span> <span class="Constant">2</span>:num<span class="Special"> <- </span>call <span class="Constant">1</span>:continuation<span class="Delimiter">,</span> <span class="Constant">2</span>:num <span class="Comment"># jump to 'return-continuation-until-mark' below</span>
<span id="L76" class="LineNr"> 76 </span> <span class="Constant">3</span>:<span class="Normal">bool</span><span class="Special"> <- </span>greater-<span class="Normal">or</span>-equal <span class="Constant">2</span>:num<span class="Delimiter">,</span> <span class="Constant">8</span>
<span id="L77" class="LineNr"> 77 </span> <span class="Identifier">break</span>-<span class="Normal">if</span> <span class="Constant">3</span>:<span class="Normal">bool</span>
<span id="L78" class="LineNr"> 78 </span> loop
<span id="L79" class="LineNr"> 79 </span> <span class="Delimiter">}</span>
<span id="L80" class="LineNr"> 80 </span>]
<span id="L81" class="LineNr"> 81 </span><span class="muRecipe"><a href='010vm.cc.html#L19'>recipe</a></span> f [
<span id="L82" class="LineNr"> 82 </span> <span class="Constant">11</span>:num<span class="Special"> <- </span>next-ingredient
<span id="L83" class="LineNr"> 83 </span> <span class="Constant">12</span>:num<span class="Special"> <- </span>g <span class="Constant">11</span>:num
<span id="L84" class="LineNr"> 84 </span> <span class="Identifier">return</span> <span class="Constant">12</span>:num
<span id="L85" class="LineNr"> 85 </span>]
<span id="L86" class="LineNr"> 86 </span><span class="muRecipe"><a href='010vm.cc.html#L19'>recipe</a></span> g [
<span id="L87" class="LineNr"> 87 </span> <span class="Constant">21</span>:num<span class="Special"> <- </span>next-ingredient
<span id="L88" class="LineNr"> 88 </span> <span class="Constant">22</span>:num<span class="Special"> <- </span><span class="Identifier">return</span>-continuation-until-mark <span class="Constant">233</span>/mark
<span id="L89" class="LineNr"> 89 </span> <span class="Constant">23</span>:num<span class="Special"> <- </span>add <span class="Constant">22</span>:num<span class="Delimiter">,</span> <span class="Constant">1</span>
<span id="L90" class="LineNr"> 90 </span> <span class="Identifier">return</span> <span class="Constant">23</span>:num
<span id="L91" class="LineNr"> 91 </span>]
<span id="L92" class="LineNr"> 92 </span><span class="Comment"># first call of 'g' executes the part before return-continuation-until-mark</span>
<span id="L93" class="LineNr"> 93 </span><span class="traceContains">+mem: storing 77 in location 21</span>
<span id="L94" class="LineNr"> 94 </span><span class="traceContains">+run: {2: "number"} <- copy {5: "literal"}</span>
<span id="L95" class="LineNr"> 95 </span><span class="traceContains">+mem: storing 5 in location 2</span>
<span id="L96" class="LineNr"> 96 </span><span class="Comment"># calls of the continuation execute the part after return-continuation-until-mark</span>
<span id="L97" class="LineNr"> 97 </span><span class="traceContains">+run: {2: "number"} <- call {1: "continuation"}, {2: "number"}</span>
<span id="L98" class="LineNr"> 98 </span><span class="traceContains">+mem: storing 5 in location 22</span>
<span id="L99" class="LineNr"> 99 </span><span class="traceContains">+mem: storing 6 in location 2</span>
<span id="L100" class="LineNr">100 </span><span class="traceContains">+run: {2: "number"} <- call {1: "continuation"}, {2: "number"}</span>
<span id="L101" class="LineNr">101 </span><span class="traceContains">+mem: storing 6 in location 22</span>
<span id="L102" class="LineNr">102 </span><span class="traceContains">+mem: storing 7 in location 2</span>
<span id="L103" class="LineNr">103 </span><span class="traceContains">+run: {2: "number"} <- call {1: "continuation"}, {2: "number"}</span>
<span id="L104" class="LineNr">104 </span><span class="traceContains">+mem: storing 7 in location 22</span>
<span id="L105" class="LineNr">105 </span><span class="traceContains">+mem: storing 8 in location 2</span>
<span id="L106" class="LineNr">106 </span><span class="Comment"># first call of 'g' does not execute the part after return-continuation-until-mark</span>
<span id="L107" class="LineNr">107 </span><span class="traceAbsent">-mem: storing 77 in location 22</span>
<span id="L108" class="LineNr">108 </span><span class="Comment"># calls of the continuation don't execute the part before return-continuation-until-mark</span>
<span id="L109" class="LineNr">109 </span><span class="traceAbsent">-mem: storing 5 in location 21</span>
<span id="L110" class="LineNr">110 </span><span class="traceAbsent">-mem: storing 6 in location 21</span>
<span id="L111" class="LineNr">111 </span><span class="traceAbsent">-mem: storing 7 in location 21</span>
<span id="L112" class="LineNr">112 </span><span class="Comment"># termination</span>
<span id="L113" class="LineNr">113 </span><span class="traceAbsent">-mem: storing 9 in location 2</span>
<span id="L114" class="LineNr">114 </span>
<span id="L115" class="LineNr">115 </span><span class="Delimiter">:(before "End call Fields")</span>
<span id="L116" class="LineNr">116 </span><span class="Normal">int</span> continuation_mark_tag<span class="Delimiter">;</span>
<span id="L117" class="LineNr">117 </span><span class="Delimiter">:(before "End call Constructor")</span>
<span id="L118" class="LineNr">118 </span>continuation_mark_tag = <span class="Constant">0</span><span class="Delimiter">;</span>
<span id="L119" class="LineNr">119 </span>
<span id="L120" class="LineNr">120 </span><span class="Delimiter">:(before "End Primitive Recipe Declarations")</span>
<span id="L121" class="LineNr">121 </span>CALL_WITH_CONTINUATION_MARK<span class="Delimiter">,</span>
<span id="L122" class="LineNr">122 </span><span class="Delimiter">:(before "End Primitive Recipe Numbers")</span>
<span id="L123" class="LineNr">123 </span>Recipe_ordinal[<span class="Constant">"call-with-continuation-mark"</span>] = CALL_WITH_CONTINUATION_MARK<span class="Delimiter">;</span>
<span id="L124" class="LineNr">124 </span><span class="Delimiter">:(before "End Primitive Recipe Checks")</span>
<span id="L125" class="LineNr">125 </span><span class="Normal">case</span> CALL_WITH_CONTINUATION_MARK: <span class="Delimiter">{</span>
<span id="L126" class="LineNr">126 </span> <span class="Normal">if</span> <span class="Delimiter">(</span><a href='001help.cc.html#L141'>SIZE</a><span class="Delimiter">(</span>inst<span class="Delimiter">.</span>ingredients<span class="Delimiter">)</span> < <span class="Constant">2</span><span class="Delimiter">)</span> <span class="Delimiter">{</span>
<span id="L127" class="LineNr">127 </span> <a href='003trace.cc.html#L197'>raise</a> << <a href='013update_operation.cc.html#L25'>maybe</a><span class="Delimiter">(</span>get<span class="Delimiter">(</span>Recipe<span class="Delimiter">,</span> r<span class="Delimiter">).</span>name<span class="Delimiter">)</span> << <span class="Constant">"'"</span> << to_original_string<span class="Delimiter">(</span>inst<span class="Delimiter">)</span> << <span class="Constant">"' requires at least two ingredients: a mark number and a <a href='010vm.cc.html#L19'>recipe</a> to call</span><span class="cSpecial">\n</span><span class="Constant">"</span> << <a href='003trace.cc.html#L226'>end</a><span class="Delimiter">();</span>
<span id="L128" class="LineNr">128 </span> <span class="Delimiter">}</span>
<span id="L129" class="LineNr">129 </span> <span class="Identifier">break</span><span class="Delimiter">;</span>
<span id="L130" class="LineNr">130 </span><span class="Delimiter">}</span>
<span id="L131" class="LineNr">131 </span><span class="Delimiter">:(before "End Primitive Recipe Implementations")</span>
<span id="L132" class="LineNr">132 </span><span class="Normal">case</span> CALL_WITH_CONTINUATION_MARK: <span class="Delimiter">{</span>
<span id="L133" class="LineNr">133 </span> <span class="Comment">// like call, but mark the current call as a 'base of continuation' call</span>
<span id="L134" class="LineNr">134 </span> <span class="Comment">// before pushing the next one on it</span>
<span id="L135" class="LineNr">135 </span> <span class="Normal">if</span> <span class="Delimiter">(</span>Trace_stream<span class="Delimiter">)</span> <span class="Delimiter">{</span>
<span id="L136" class="LineNr">136 </span> ++Trace_stream<span class="Delimiter">-></span>callstack_depth<span class="Delimiter">;</span>
<span id="L137" class="LineNr">137 </span> <a href='003trace.cc.html#L190'>trace</a><span class="Delimiter">(</span><span class="Constant">"trace"</span><span class="Delimiter">)</span> << <span class="Constant">"delimited continuation; incrementing callstack depth to "</span> << Trace_stream<span class="Delimiter">-></span>callstack_depth << <a href='003trace.cc.html#L226'>end</a><span class="Delimiter">();</span>
<span id="L138" class="LineNr">138 </span> assert<span class="Delimiter">(</span>Trace_stream<span class="Delimiter">-></span>callstack_depth < <span class="Constant">9000</span><span class="Delimiter">);</span> <span class="Comment">// 9998-101 plus cushion</span>
<span id="L139" class="LineNr">139 </span> <span class="Delimiter">}</span>
<span id="L140" class="LineNr">140 </span> <a href='010vm.cc.html#L33'>instruction</a><span class="Comment">/*</span><span class="Comment">copy</span><span class="Comment">*/</span> caller_instruction = <a href='026call.cc.html#L89'>current_instruction</a><span class="Delimiter">();</span>
<span id="L141" class="LineNr">141 </span> Current_routine<span class="Delimiter">-></span>calls<span class="Delimiter">.</span>front<span class="Delimiter">().</span>continuation_mark_tag = <a href='026call.cc.html#L89'>current_instruction</a><span class="Delimiter">().</span>ingredients<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">).</span>value<span class="Delimiter">;</span>
<span id="L142" class="LineNr">142 </span> Current_routine<span class="Delimiter">-></span>calls<span class="Delimiter">.</span>push_front<span class="Delimiter">(</span>call<span class="Delimiter">(</span>ingredients<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">1</span><span class="Delimiter">).</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">)));</span>
<span id="L143" class="LineNr">143 </span> <span class="Comment">// drop the mark</span>
<span id="L144" class="LineNr">144 </span> caller_instruction<span class="Delimiter">.</span>ingredients<span class="Delimiter">.</span>erase<span class="Delimiter">(</span>caller_instruction<span class="Delimiter">.</span>ingredients<span class="Delimiter">.</span>begin<span class="Delimiter">());</span>
<span id="L145" class="LineNr">145 </span> ingredients<span class="Delimiter">.</span>erase<span class="Delimiter">(</span>ingredients<span class="Delimiter">.</span>begin<span class="Delimiter">());</span>
<span id="L146" class="LineNr">146 </span> <span class="Comment">// drop the callee</span>
<span id="L147" class="LineNr">147 </span> caller_instruction<span class="Delimiter">.</span>ingredients<span class="Delimiter">.</span>erase<span class="Delimiter">(</span>caller_instruction<span class="Delimiter">.</span>ingredients<span class="Delimiter">.</span>begin<span class="Delimiter">());</span>
<span id="L148" class="LineNr">148 </span> ingredients<span class="Delimiter">.</span>erase<span class="Delimiter">(</span>ingredients<span class="Delimiter">.</span>begin<span class="Delimiter">());</span>
<span id="L149" class="LineNr">149 </span> finish_call_housekeeping<span class="Delimiter">(</span>caller_instruction<span class="Delimiter">,</span> ingredients<span class="Delimiter">);</span>
<span id="L150" class="LineNr">150 </span> <span class="Identifier">continue</span><span class="Delimiter">;</span>
<span id="L151" class="LineNr">151 </span><span class="Delimiter">}</span>
<span id="L152" class="LineNr">152 </span>
<span id="L153" class="LineNr">153 </span><span class="Delimiter">:(scenario next_ingredient_inside_continuation)</span>
<span id="L154" class="LineNr">154 </span><span class="muRecipe"><a href='010vm.cc.html#L19'>recipe</a></span> <a href='000organization.cc.html#L113'>main</a> [
<span id="L155" class="LineNr">155 </span> call-with-continuation-mark <span class="Constant">233</span>/mark<span class="Delimiter">,</span> f<span class="Delimiter">,</span><span class="Constant"> true</span>
<span id="L156" class="LineNr">156 </span>]
<span id="L157" class="LineNr">157 </span><span class="muRecipe"><a href='010vm.cc.html#L19'>recipe</a></span> f [
<span id="L158" class="LineNr">158 </span> <span class="Constant">10</span>:<span class="Normal">bool</span><span class="Special"> <- </span>next-input
<span id="L159" class="LineNr">159 </span>]
<span id="L160" class="LineNr">160 </span><span class="traceContains">+mem: storing 1 in location 10</span>
<span id="L161" class="LineNr">161 </span>
<span id="L162" class="LineNr">162 </span><span class="Delimiter">:(scenario delimited_continuation_out_of_recipe_variable)</span>
<span id="L163" class="LineNr">163 </span><span class="muRecipe"><a href='010vm.cc.html#L19'>recipe</a></span> <a href='000organization.cc.html#L113'>main</a> [
<span id="L164" class="LineNr">164 </span> <span class="Normal">x</span>:<a href='010vm.cc.html#L19'>recipe</a><span class="Special"> <- </span>copy f
<span id="L165" class="LineNr">165 </span> call-with-continuation-mark <span class="Constant">233</span>/mark<span class="Delimiter">,</span> x<span class="Delimiter">,</span><span class="Constant"> true</span>
<span id="L166" class="LineNr">166 </span>]
<span id="L167" class="LineNr">167 </span><span class="muRecipe"><a href='010vm.cc.html#L19'>recipe</a></span> f [
<span id="L168" class="LineNr">168 </span> <span class="Constant">10</span>:<span class="Normal">bool</span><span class="Special"> <- </span>next-input
<span id="L169" class="LineNr">169 </span>]
<span id="L170" class="LineNr">170 </span><span class="traceContains">+mem: storing 1 in location 10</span>
<span id="L171" class="LineNr">171 </span>
<span id="L172" class="LineNr">172 </span><span class="Comment">//: save the slice of current call stack until the 'call-with-continuation-mark'</span>
<span id="L173" class="LineNr">173 </span><span class="Comment">//: call, and return it as the result.</span>
<span id="L174" class="LineNr">174 </span><span class="Comment">//: todo: implement delimited continuations in Mu's memory</span>
<span id="L175" class="LineNr">175 </span><span class="Delimiter">:(before "End Types")</span>
<span id="L176" class="LineNr">176 </span><span class="Normal">struct</span> delimited_continuation <span class="Delimiter">{</span>
<span id="L177" class="LineNr">177 </span> call_stack frames<span class="Delimiter">;</span>
<span id="L178" class="LineNr">178 </span> <span class="Normal">int</span> nrefs<span class="Delimiter">;</span>
<span id="L179" class="LineNr">179 </span> delimited_continuation<span class="Delimiter">(</span>call_stack::iterator begin<span class="Delimiter">,</span> call_stack::iterator <a href='003trace.cc.html#L226'>end</a><span class="Delimiter">)</span> :frames<span class="Delimiter">(</span>call_stack<span class="Delimiter">(</span>begin<span class="Delimiter">,</span> <a href='003trace.cc.html#L226'>end</a><span class="Delimiter">)),</span> nrefs<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">)</span> <span class="Delimiter">{}</span>
<span id="L180" class="LineNr">180 </span><span class="Delimiter">};</span>
<span id="L181" class="LineNr">181 </span><span class="Delimiter">:(before "End Globals")</span>
<span id="L182" class="LineNr">182 </span>map<<span class="Normal">long</span> <span class="Normal">long</span> <span class="Normal">int</span><span class="Delimiter">,</span> delimited_continuation> Delimited_continuation<span class="Delimiter">;</span>
<span id="L183" class="LineNr">183 </span><span class="Normal">long</span> <span class="Normal">long</span> <span class="Normal">int</span> Next_delimited_continuation_id = <span class="Constant">1</span><span class="Delimiter">;</span> <span class="Comment">// 0 is null just like an address</span>
<span id="L184" class="LineNr">184 </span><span class="Delimiter">:(before "End Reset")</span>
<span id="L185" class="LineNr">185 </span>Delimited_continuation<span class="Delimiter">.</span><a href='050scenario.cc.html#L60'>clear</a><span class="Delimiter">();</span>
<span id="L186" class="LineNr">186 </span>Next_delimited_continuation_id = <span class="Constant">1</span><span class="Delimiter">;</span>
<span id="L187" class="LineNr">187 </span>
<span id="L188" class="LineNr">188 </span><span class="Delimiter">:(before "End Primitive Recipe Declarations")</span>
<span id="L189" class="LineNr">189 </span>RETURN_CONTINUATION_UNTIL_MARK<span class="Delimiter">,</span>
<span id="L190" class="LineNr">190 </span><span class="Delimiter">:(before "End Primitive Recipe Numbers")</span>
<span id="L191" class="LineNr">191 </span>Recipe_ordinal[<span class="Constant">"return-continuation-until-mark"</span>] = RETURN_CONTINUATION_UNTIL_MARK<span class="Delimiter">;</span>
<span id=&quo# Port of https://github.com/akkartik/crenshaw/blob/master/tutor2.1.pas
# which corresponds to the section "single digits" in https://compilers.iecc.com/crenshaw/tutor2.txt
# except that we support hex digits.
#
# To run:
# $ ./subx translate *.subx apps/crenshaw2-1.subx -o apps/crenshaw2-1
# $ echo '3' |./subx run apps/crenshaw2-1
# Expected output:
# # syscall(exit, 3)
# bb/copy-to-EBX 3/imm32
# b8/copy-to-EAX 1/imm32/exit
# cd/syscall 0x80/imm8
#
# To run the generated output:
# $ echo '3' |./subx run apps/crenshaw2-1 > z1.subx
# $ ./subx translate z1.subx -o z1
# $ ./subx run z1
# $ echo $?
# 3
#
# Stdin must contain just a single hex digit. Other input will print an error:
# $ echo 'xyz' |./subx run apps/crenshaw2-1
# Error: integer expected
#
# Names in this file sometimes follow Crenshaw's original rather than my usual
# naming conventions.
== 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
Entry: # run tests if necessary, call 'compile' if not
# initialize heap
# . Heap = new-segment(64KB)
# . . push args
68/push Heap/imm32
68/push 0x10000/imm32/64KB
# . . call
e8/call new-segment/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 8/imm32 # add to ESP
# . prolog
89/copy 3/mod/direct 5/rm32/EBP . . . 4/r32/ESP . . # copy ESP to EBP
# - if argc > 1 and argv[1] == "test", then return run_tests()
# . argc > 1
81 7/subop/compare 1/mod/*+disp8 5/rm32/EBP . . . . 0/disp8 1/imm32 # compare *EBP
7e/jump-if-lesser-or-equal $run-main/disp8
# . argv[1] == "test"
# . . push args
68/push "test"/imm32
ff 6/subop/push 1/mod/*+disp8 5/rm32/EBP . . . . 8/disp8 . # push *(EBP+8)
# . . call
e8/call kernel-string-equal?/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 8/imm32 # add to ESP
# . check result
3d/compare-EAX-and 1/imm32
75/jump-if-not-equal $run-main/disp8
# . run-tests()
e8/call run-tests/disp32
8b/copy 0/mod/indirect 5/rm32/.disp32 . . 3/r32/EBX Num-test-failures/disp32 # copy *Num-test-failures to EBX
eb/jump $main:end/disp8
$run-main:
# - otherwise read a program from stdin and emit its translation to stdout
# var ed/EAX : exit-descriptor
81 5/subop/subtract 3/mod/direct 4/rm32/ESP . . . . . 8/imm32 # subtract from ESP
89/copy 3/mod/direct 0/rm32/EAX . . . 4/r32/ESP . . # copy ESP to EAX
# configure ed to really exit()
# . ed->target = 0
c7 0/subop/copy 0/mod/direct 0/rm32/EAX . . . . . 0/imm32 # copy to *EAX
# return compile(Stdin, 1/stdout, 2/stderr, ed)
# . . push args
50/push-EAX/ed
68/push 2/imm32/stderr
68/push 1/imm32/stdout
68/push Stdin/imm32
# . . call
e8/call compile/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 0x10/imm32 # add to ESP
# . syscall(exit, 0)
bb/copy-to-EBX 0/imm32
$main:end:
b8/copy-to-EAX 1/imm32/exit
cd/syscall 0x80/imm8
# the main entry point
compile: # in : (address buffered-file), out : fd or (address stream), err : fd or (address stream), ed : (address exit-descriptor) -> <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
# prime the pump
# . Look = get-char(in)
# . . push args
ff 6/subop/push 1/mod/*+disp8 5/rm32/EBP . . . . 8/disp8 . # push *(EBP+8)
# . . call
e8/call get-char/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 4/imm32 # add to ESP
# var num/ECX : (address stream) on the stack
# Numbers can be 32 bits or 8 hex bytes long. One of them will be in 'Look', so we need space for 7 bytes.
# Sizing the stream just right buys us overflow-handling for free inside 'get-num'.
# Add 12 bytes for 'read', 'write' and 'length' fields, for a total of 19 bytes, or 0x13 in hex.
# The stack pointer is no longer aligned, so dump_stack() can be misleading past this point.
81 5/subop/subtract 3/mod/direct 4/rm32/ESP . . . . . 0x13/imm32 # subtract from ESP
89/copy 3/mod/direct 1/rm32/ECX . . . 4/r32/ESP . . # copy ESP to ECX
# initialize the stream
# . num->length = 7
c7 0/subop/copy 1/mod/*+disp8 1/rm32/ECX . . . . 8/disp8 7/imm32 # copy to *(ECX+8)
# . clear-stream(num)
# . . push args
51/push-ECX
# . . call
e8/call clear-stream/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 4/imm32 # add to ESP
# read a digit from 'in' into 'num'
# . get-num(in, num, err, ed)
# . . push args
ff 6/subop/push 1/mod/*+disp8 5/rm32/EBP . . . . 0x14/disp8 . # push *(EBP+20)
ff 6/subop/push 1/mod/*+disp8 5/rm32/EBP . . . . 0x10/disp8 . # push *(EBP+16)
51/push-ECX/num
ff 6/subop/push 1/mod/*+disp8 5/rm32/EBP . . . . 8/disp8 . # push *(EBP+8)
# . . call
e8/call get-num/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 0x10/imm32 # add to ESP
# render 'num' into the following template on 'out':
# bb/copy-to-EBX _num_
# b8/copy-to-EAX 1/imm32/exit
# cd/syscall 0x80/imm8
#
# . write(out, "bb/copy-to-EBX ")
# . . push args
68/push "bb/copy-to-EBX "/imm32
ff 6/subop/push 1/mod/*+disp8 5/rm32/EBP . . . . 0xc/disp8 . # push *(EBP+12)
# . . call
e8/call write/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 8/imm32 # add to ESP
# . write-stream(out, num)
# . . push args
51/push-ECX/num
ff 6/subop/push 1/mod/*+disp8 5/rm32/EBP . . . . 0xc/disp8 . # push *(EBP+12)
# . . call
e8/call write-stream/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 8/imm32 # add to ESP
# . write(out, Newline)
# . . push args
68/push Newline/imm32
ff 6/subop/push 1/mod/*+disp8 5/rm32/EBP . . . . 0xc/disp8 . # push *(EBP+12)
# . . call
e8/call write/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 8/imm32 # add to ESP
# . write(out, "b8/copy-to-EAX 1/imm32/exit\n")
# . . push args
68/push "b8/copy-to-EAX 1/imm32/exit\n"/imm32
ff 6/subop/push 1/mod/*+disp8 5/rm32/EBP . . . . 0xc/disp8 . # push *(EBP+12)
# . . call
e8/call write/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 8/imm32 # add to ESP
# . write(out, "cd/syscall 0x80/imm8\n")
# . . push args
68/push "cd/syscall 0x80/imm8\n"/imm32
ff 6/subop/push 1/mod/*+disp8 5/rm32/EBP . . . . 0xc/disp8 . # push *(EBP+12)
# . . call
e8/call write/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 8/imm32 # add to ESP
$compile:end:
# . 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
# Read a single digit into 'out'. Abort if there are none, or if there is no space in 'out'.
# Input comes from the global variable 'Look', and we leave the next byte from
# 'in' into it on exit.
get-num: # in : (address buffered-file), out : (address stream), err : fd or (address stream), ed : (address exit-descriptor) -> <void>
# pseudocode:
# if (!is-digit?(Look)) expected(ed, err, "integer")
# if out->write >= out->length
# write(err, "Error: too many digits in number\n")
# stop(ed, 1)
# out->data[out->write] = LSB(Look)
# ++out->write
# Look = get-char(in)
#
# registers:
# in: ESI
# out: EDI
# out->write: ECX (cached copy; need to keep in sync)
# out->length: EDX
# temporaries: EAX, EBX
# We can't allocate Look to a register because it gets written implicitly in
# get-char in each iteration of the loop. (Thereby demonstrating that it's
# not the right interface for us. But we'll keep it just to follow Crenshaw.)
#
# . prolog
55/push-EBP
89/copy 3/mod/direct 5/rm32/EBP . . . 4/r32/ESP . . # copy ESP to EBP
# - if (is-digit?(Look)) expected(ed, err, "integer")
# . EAX = is-digit?(Look)
# . . push args
ff 6/subop/push 0/mod/indirect 5/rm32/.disp32 . . . Look/disp32 . # push *Look
# . . call
e8/call is-digit?/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 4/imm32 # add to ESP
# . if (EAX == 0)
3d/compare-EAX-and 0/imm32
75/jump-if-not-equal $get-num:main/disp8
# . expected(ed, err, "integer")
# . . push args
68/push "integer"/imm32
ff 6/subop/push 1/mod/*+disp8 5/rm32/EBP . . . . 0x10/disp8 . # push *(EBP+16)
ff 6/subop/push 1/mod/*+disp8 5/rm32/EBP . . . . 0x14/disp8 . # push *(EBP+20)
# . . call
e8/call expected/disp32 # never returns
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 0xc/imm32 # add to ESP
$get-num:main:
# - otherwise read a digit
# . save registers
50/push-EAX
51/push-ECX
52/push-EDX
53/push-EBX
56/push-ESI
57/push-EDI
# read necessary variables to registers
# ESI = in
8b/copy 1/mod/*+disp8 5/rm32/EBP . . . 6/r32/ESI 8/disp8 . # copy *(EBP+8) to ESI
# EDI = out
8b/copy 1/mod/*+disp8 5/rm32/EBP . . . 7/r32/EDI 0xc/disp8 . # copy *(EBP+12) to EDI
# ECX = out->write
8b/copy 0/mod/indirect 7/rm32/EDI . . . 1/r32/ECX . . # copy *EDI to ECX
# EDX = out->length
8b/copy 1/mod/*+disp8 7/rm32/EDI . . . 2/r32/EDX 8/disp8 . # copy *(EDI+8) to EDX
# if (out->write >= out->length) error
39/compare 3/mod/direct 2/rm32/EDX . . . 1/r32/ECX . . # compare EDX with ECX
7d/jump-if-lesser $get-num:stage2/disp8
# . error(ed, err, msg) # TODO: show full number
# . . push args
68/push "get-num: too many digits in number"/imm32
ff 6/subop/push 1/mod/*+disp8 5/rm32/EBP . . . . 0x10/disp8 . # push *(EBP+16)
ff 6/subop/push 1/mod/*+disp8 5/rm32/EBP . . . . 0x14/disp8 . # push *(EBP+20)
# . . call
e8/call error/disp32 # never returns
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 0xc/imm32 # add to ESP
$get-num:stage2:
# out->data[out->write] = LSB(Look)
8d/copy-address 1/mod/*+disp8 4/rm32/sib 7/base/EDI 1/index/ECX . 3/r32/EBX 0xc/disp8 . # copy EDI+ECX+12 to EBX
8b/copy 0/mod/indirect 5/rm32/.disp32 . . 0/r32/EAX Look/disp32 . # copy *Look to EAX
88/copy-byte 0/mod/indirect 3/rm32/EBX . . . 0/r32/AL . . # copy byte at AL to *EBX
# ++out->write
41/increment-ECX
# Look = get-char(in)
# . . push args
56/push-ESI
# . . call
e8/call get-char/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 4/imm32 # add to ESP
$get-num:loop-end:
# persist necessary variables from registers
89/copy 0/mod/indirect 7/rm32/EDI . . . 1/r32/ECX . . # copy ECX to *EDI
$get-num:end:
# . restore registers
5f/pop-to-EDI
5e/pop-to-ESI
5b/pop-to-EBX
5a/pop-to-EDX
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
test-get-num-reads-single-digit:
# - check that get-num returns first character if it's a digit
# This test uses exit-descriptors. Use EBP for setting up local variables.
55/push-EBP
89/copy 3/mod/direct 5/rm32/EBP . . . 4/r32/ESP . . # copy ESP to EBP
# clear all streams
# . 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
# . clear-stream(_test-output-stream)
# . . push args
68/push _test-output-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-error-stream)
# . . push args
68/push _test-error-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
# initialize 'in'
# . write(_test-stream, "3")
# . . push args
68/push "3"/imm32
68/push _test-stream/imm32
# . . call
e8/call write/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 8/imm32 # add to ESP
# initialize exit-descriptor 'ed' for the call to 'get-num' below
# . var ed/EAX : exit-descriptor
81 5/subop/subtract 3/mod/direct 4/rm32/ESP . . . . . 8/imm32 # subtract from ESP
89/copy 3/mod/direct 0/rm32/EAX . . . 4/r32/ESP . . # copy ESP to EAX
# . tailor-exit-descriptor(ed, 16)
# . . push args
68/push 0x10/imm32/nbytes-of-args-for-get-num
50/push-EAX/ed
# . . call
e8/call tailor-exit-descriptor/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 8/imm32 # add to ESP
# prime the pump
# . get-char(_test-buffered-file)
# . . push args
68/push _test-buffered-file/imm32
# . . call
e8/call get-char/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 4/imm32 # add to ESP
# get-num(in, out, err, ed)
# . . push args
50/push-EAX/ed
68/push _test-error-stream/imm32
68/push _test-output-stream/imm32
68/push _test-buffered-file/imm32
# . . call
e8/call get-num/disp32
# registers except ESP may be clobbered at this point
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 0x10/imm32 # add to ESP
# check-ints-equal(*_test-output-stream->data, '3', msg)
# . . push args
68/push "F - test-get-num-reads-single-digit"/imm32
68/push 0x33/imm32
b8/copy-to-EAX _test-output-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
# . reclaim locals
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 8/imm32 # add to ESP
5d/pop-to-EBP
c3/return
test-get-num-aborts-on-non-digit-in-Look:
# - check that get-num returns first character if it's a digit
# This test uses exit-descriptors. Use EBP for setting up local variables.
55/push-EBP
89/copy 3/mod/direct 5/rm32/EBP . . . 4/r32/ESP . . # copy ESP to EBP
# clear all streams
# . 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
# . clear-stream(_test-output-stream)
# . . push args
68/push _test-output-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-error-stream)
# . . push args
68/push _test-error-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
# initialize 'in'
# . write(_test-stream, "3")
# . . push args
68/push "3"/imm32
68/push _test-stream/imm32
# . . call
e8/call write/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 8/imm32 # add to ESP
# initialize exit-descriptor 'ed' for the call to 'get-num' below
# . var ed/EAX : (address exit-descriptor)
81 5/subop/subtract 3/mod/direct 4/rm32/ESP . . . . . 8/imm32 # subtract from ESP
89/copy 3/mod/direct 0/rm32/EAX . . . 4/r32/ESP . . # copy ESP to EAX
# . tailor-exit-descriptor(ed, 16)
# . . push args
68/push 0x10/imm32/nbytes-of-args-for-get-num
50/push-EAX/ed
# . . call
e8/call tailor-exit-descriptor/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 8/imm32 # add to ESP
# *don't* prime the pump
# get-num(in, out, err, ed)
# . . push args
50/push-EAX/ed
68/push _test-error-stream/imm32
68/push _test-output-stream/imm32
68/push _test-buffered-file/imm32
# . . call
e8/call get-num/disp32
# registers except ESP may be clobbered at this point
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 0x10/imm32 # add to ESP
# check that get-num tried to call exit(1)
# . check-ints-equal(ed->value, 2, msg) # i.e. stop was called with value 1
# . . push args
68/push "F - test-get-num-aborts-on-non-digit-in-Look"/imm32
68/push 2/imm32
# . . push ed->value
ff 6/subop/push 1/mod/*+disp8 0/rm32/EAX . . . . 4/disp8 . # push *(EAX+4)
# . . call
e8/call check-ints-equal/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 0xc/imm32 # add to ESP
# . reclaim locals
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 8/imm32 # add to ESP
5d/pop-to-EBP
c3/return
## helpers
# write(f, "Error: "+s+" expected\n") then stop(ed, 1)
expected: # ed : (address exit-descriptor), f : fd or (address stream), s : (address array byte) -> <void>
# . prolog
55/push-EBP
89/copy 3/mod/direct 5/rm32/EBP . . . 4/r32/ESP . . # copy ESP to EBP
# write(f, "Error: ")
# . . push args
68/push "Error: "/imm32
ff 6/subop/push 1/mod/*+disp8 5/rm32/EBP . . . . 0xc/disp8 . # push *(EBP+12)
# . . call
e8/call write/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 8/imm32 # add to ESP
# write(f, s)
# . . push args
ff 6/subop/push 1/mod/*+disp8 5/rm32/EBP . . . . 0x10/disp8 . # push *(EBP+16)
ff 6/subop/push 1/mod/*+disp8 5/rm32/EBP . . . . 0xc/disp8 . # push *(EBP+12)
# . . call
e8/call write/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 8/imm32 # add to ESP
# write(f, " expected")
# . . push args
68/push " expected\n"/imm32
ff 6/subop/push 1/mod/*+disp8 5/rm32/EBP . . . . 0xc/disp8 . # push *(EBP+12)
# . . call
e8/call write/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 8/imm32 # add to ESP
# stop(ed, 1)
# . . push args
68/push 1/imm32
ff 6/subop/push 1/mod/*+disp8 5/rm32/EBP . . . . 8/disp8 . # push *(EBP+8)
# . . call
e8/call stop/disp32
# should never get past this point
$expected:dead-end:
# . epilog
89/copy 3/mod/direct 4/rm32/ESP . . . 5/r32/EBP . . # copy EBP to ESP
5d/pop-to-EBP
c3/return
# read a byte from 'f', and save it in 'Look'
get-char: # 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
# EAX = read-byte-buffered(f)
# . . push args
ff 6/subop/push 1/mod/*+disp8 5/rm32/EBP . . . . 8/disp8 . # push *(EBP+8)
# . . call
e8/call read-byte-buffered/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 4/imm32 # add to ESP
# save EAX to Look
89/copy 0/mod/indirect 5/rm32/.disp32 . . 0/r32/EAX Look/disp32 . # copy EAX to *Look
$get-char:end:
# . restore registers
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
is-digit?: # c : int -> EAX : boolean
# . prolog
55/push-EBP
89/copy 3/mod/direct 5/rm32/EBP . . . 4/r32/ESP . . # copy ESP to EBP
# EAX = false
b8/copy-to-EAX 0/imm32
# if (c < '0') return false
81 7/subop/compare 1/mod/*+disp8 5/rm32/EBP . . . . 8/disp8 0x30/imm32 # compare *(EBP+8)
7c/jump-if-lesser $is-digit?:end/disp8
# if (c > '9') return false
81 7/subop/compare 1/mod/*+disp8 5/rm32/EBP . . . . 8/disp8 0x39/imm32 # compare *(EBP+8)
7f/jump-if-greater $is-digit?:end/disp8
# otherwise return true
b8/copy-to-EAX 1/imm32
$is-digit?:end:
# . epilog
89/copy 3/mod/direct 4/rm32/ESP . . . 5/r32/EBP . . # copy EBP to ESP
5d/pop-to-EBP
c3/return
== data
Look: # (char with some extra padding)
0/imm32
# . . vim:nowrap:textwidth=0