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<!--Weave of 'Stack Frames' generated by Inweb-->
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<div class="breadcrumbs">
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<ul class="crumbs"><li><a href="../index.html">Home</a></li><li><a href="../inform7n.html">Inform7</a></li><li><a href="index.html">imperative</a></li><li><a href="index.html#3">Chapter 3: Functions</a></li><li><b>Stack Frames</b></li></ul></div>
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<p class="purpose">When Inform compiles imperative code, it does so in the context of a "stack frame".</p>
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<ul class="toc"><li><a href="3-sf.html#SP1">§1. Introduction</a></li><li><a href="3-sf.html#SP6">§6. Creation</a></li><li><a href="3-sf.html#SP7">§7. Kinds</a></li><li><a href="3-sf.html#SP10">§10. Shared variables</a></li><li><a href="3-sf.html#SP11">§11. Past tense</a></li><li><a href="3-sf.html#SP12">§12. Formal parameters</a></li><li><a href="3-sf.html#SP13">§13. It</a></li><li><a href="3-sf.html#SP16">§16. Local block values</a></li><li><a href="3-sf.html#SP22">§22. Logging</a></li></ul><hr class="tocbar">
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<p class="commentary firstcommentary"><a id="SP1" class="paragraph-anchor"></a><b>§1. Introduction. </b>The term "stack frame" is traditional in computer science. The idea is that
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there is a stack holding temporary data needed by the functions currently
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running. Each function, as it begins, claims a "frame" of memory on the stack,
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thus pushing the stack higher; when it ends, the memory in that frame is
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given up. It can thus be used only for temporary data.
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</p>
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<p class="commentary">Our object code, Inter, is designed for use with virtual machines on which the
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call stack is not directly addressable, so the term "stack frame" here is used
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a little loosely. What we mean is: the collection of everything that is distinctive
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about the function currently being compiled. In particular:
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</p>
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<ul class="items"><li>● its local variables;
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</li><li>● what shared variables it can see;
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</li><li>● what interpretations to place on the kind variables <span class="extract"><span class="extract-syntax">A</span></span> to <span class="extract"><span class="extract-syntax">Z</span></span>, if any;
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</li><li>● what kind of value we should be returning, if anything.
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</li></ul>
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<p class="commentary firstcommentary"><a id="SP2" class="paragraph-anchor"></a><b>§2. </b>Code can only be compiled "inside" a stack frame, and at any given time
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(when code is being compiled, anyway) there is a "current" frame.
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</p>
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<pre class="displayed-code all-displayed-code code-font">
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<span class="reserved-syntax">stack_frame</span><span class="plain-syntax"> *</span><span class="identifier-syntax">current_frame</span><span class="plain-syntax"> = </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">;</span>
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<span class="reserved-syntax">stack_frame</span><span class="plain-syntax"> *</span><span class="function-syntax">Frames::current_stack_frame</span><button class="popup" onclick="togglePopup('usagePopup1')"><span class="comment-syntax">?</span><span class="popuptext" id="usagePopup1">Usage of <span class="code-font"><span class="function-syntax">Frames::current_stack_frame</span></span>:<br/><a href="3-sf.html#SP7">§7</a>, <a href="3-sf.html#SP8">§8</a>, <a href="3-sf.html#SP10">§10</a>, <a href="3-sf.html#SP11">§11</a>, <a href="3-sf.html#SP12">§12</a>, <a href="3-sf.html#SP16">§16</a><br/>Local Variable Slates - <a href="3-lvs.html#SP17">§17</a><br/>Local Variables - <a href="3-lv.html#SP4">§4</a>, <a href="3-lv.html#SP5">§5</a>, <a href="3-lv.html#SP7">§7</a>, <a href="3-lv.html#SP9">§9</a>, <a href="3-lv.html#SP10">§10</a>, <a href="3-lv.html#SP12">§12</a>, <a href="3-lv.html#SP13">§13</a>, <a href="3-lv.html#SP14">§14</a>, <a href="3-lv.html#SP16">§16</a>, <a href="3-lv.html#SP18">§18</a>, <a href="3-lv.html#SP20">§20</a><br/>Code Blocks - <a href="3-cb.html#SP7">§7</a>, <a href="3-cb.html#SP17">§17</a>, <a href="3-cb.html#SP18">§18</a><br/>Compile Solutions to Equations - <a href="5-cste.html#SP3_3">§3.3</a></span></button><span class="plain-syntax">(</span><span class="reserved-syntax">void</span><span class="plain-syntax">) {</span>
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<span class="plain-syntax"> </span><span class="reserved-syntax">return</span><span class="plain-syntax"> </span><span class="identifier-syntax">current_frame</span><span class="plain-syntax">;</span>
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<span class="plain-syntax">}</span>
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</pre>
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<p class="commentary firstcommentary"><a id="SP3" class="paragraph-anchor"></a><b>§3. </b>This must be imposed and removed manually:
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</p>
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<pre class="displayed-code all-displayed-code code-font">
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<span class="reserved-syntax">void</span><span class="plain-syntax"> </span><span class="function-syntax">Frames::make_current</span><button class="popup" onclick="togglePopup('usagePopup2')"><span class="comment-syntax">?</span><span class="popuptext" id="usagePopup2">Usage of <span class="code-font"><span class="function-syntax">Frames::make_current</span></span>:<br/><a href="3-sf.html#SP4">§4</a><br/>Functions - <a href="3-fnc.html#SP5">§5</a></span></button><span class="plain-syntax">(</span><span class="reserved-syntax">stack_frame</span><span class="plain-syntax"> *</span><span class="identifier-syntax">frame</span><span class="plain-syntax">) {</span>
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<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">frame</span><span class="plain-syntax"> == </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">) </span><span class="identifier-syntax">internal_error</span><span class="plain-syntax">(</span><span class="string-syntax">"can't select null stack frame"</span><span class="plain-syntax">);</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">current_frame</span><span class="plain-syntax"> = </span><span class="identifier-syntax">frame</span><span class="plain-syntax">;</span>
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<span class="plain-syntax">}</span>
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<span class="reserved-syntax">void</span><span class="plain-syntax"> </span><span class="function-syntax">Frames::remove_current</span><button class="popup" onclick="togglePopup('usagePopup3')"><span class="comment-syntax">?</span><span class="popuptext" id="usagePopup3">Usage of <span class="code-font"><span class="function-syntax">Frames::remove_current</span></span>:<br/><a href="3-sf.html#SP4">§4</a><br/>Functions - <a href="3-fnc.html#SP6">§6</a></span></button><span class="plain-syntax">(</span><span class="reserved-syntax">void</span><span class="plain-syntax">) {</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">current_frame</span><span class="plain-syntax"> = </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">;</span>
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<span class="plain-syntax">}</span>
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</pre>
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<p class="commentary firstcommentary"><a id="SP4" class="paragraph-anchor"></a><b>§4. </b>There are three ways to get stack frames. First, every phrase or rule has
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one of its own. Second, though, we will also need a stack frame in order to
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compile the many functions which aren't directly corresponding to phrases or
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rules at all. Such a frame is called "nonphrasal":
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</p>
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<pre class="displayed-code all-displayed-code code-font">
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<span class="reserved-syntax">int</span><span class="plain-syntax"> </span><span class="identifier-syntax">nonphrasal_stack_frame_is_current</span><span class="plain-syntax"> = </span><span class="identifier-syntax">FALSE</span><span class="plain-syntax">;</span>
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<span class="reserved-syntax">stack_frame</span><span class="plain-syntax"> </span><span class="identifier-syntax">nonphrasal_stack_frame</span><span class="plain-syntax">;</span>
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<span class="reserved-syntax">stack_frame</span><span class="plain-syntax"> *</span><span class="function-syntax">Frames::new_nonphrasal</span><button class="popup" onclick="togglePopup('usagePopup4')"><span class="comment-syntax">?</span><span class="popuptext" id="usagePopup4">Usage of <span class="code-font"><span class="function-syntax">Frames::new_nonphrasal</span></span>:<br/>Functions - <a href="3-fnc.html#SP5">§5</a></span></button><span class="plain-syntax">(</span><span class="reserved-syntax">void</span><span class="plain-syntax">) {</span>
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<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">nonphrasal_stack_frame_is_current</span><span class="plain-syntax">)</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">internal_error</span><span class="plain-syntax">(</span><span class="string-syntax">"can't nest nonphrasal stack frames"</span><span class="plain-syntax">);</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">nonphrasal_stack_frame</span><span class="plain-syntax"> = </span><a href="3-sf.html#SP6" class="function-link"><span class="function-syntax">Frames::new</span></a><span class="plain-syntax">();</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">nonphrasal_stack_frame_is_current</span><span class="plain-syntax"> = </span><span class="identifier-syntax">TRUE</span><span class="plain-syntax">;</span>
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<span class="plain-syntax"> </span><a href="3-sf.html#SP3" class="function-link"><span class="function-syntax">Frames::make_current</span></a><span class="plain-syntax">(&</span><span class="identifier-syntax">nonphrasal_stack_frame</span><span class="plain-syntax">);</span>
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<span class="plain-syntax"> </span><span class="reserved-syntax">return</span><span class="plain-syntax"> &</span><span class="identifier-syntax">nonphrasal_stack_frame</span><span class="plain-syntax">;</span>
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<span class="plain-syntax">}</span>
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<span class="reserved-syntax">void</span><span class="plain-syntax"> </span><span class="function-syntax">Frames::remove_nonphrase_stack_frame</span><button class="popup" onclick="togglePopup('usagePopup5')"><span class="comment-syntax">?</span><span class="popuptext" id="usagePopup5">Usage of <span class="code-font"><span class="function-syntax">Frames::remove_nonphrase_stack_frame</span></span>:<br/>Functions - <a href="3-fnc.html#SP6">§6</a></span></button><span class="plain-syntax">(</span><span class="reserved-syntax">void</span><span class="plain-syntax">) {</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">nonphrasal_stack_frame</span><span class="plain-syntax"> = </span><a href="3-sf.html#SP6" class="function-link"><span class="function-syntax">Frames::new</span></a><span class="plain-syntax">(); </span><span class="comment-syntax"> to prevent accidental lucky misuse</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">nonphrasal_stack_frame_is_current</span><span class="plain-syntax"> = </span><span class="identifier-syntax">FALSE</span><span class="plain-syntax">;</span>
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<span class="plain-syntax"> </span><a href="3-sf.html#SP3" class="function-link"><span class="function-syntax">Frames::remove_current</span></a><span class="plain-syntax">();</span>
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<span class="plain-syntax">}</span>
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</pre>
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<p class="commentary firstcommentary"><a id="SP5" class="paragraph-anchor"></a><b>§5. </b><a href="3-sf.html#SP6" class="internal">stack_frame</a> is a small and potentially throwaway structure, and can
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sometimes exist only fleetingly in the compiler. If we want to preserve it,
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or take a snapshot of its current state, we need to make a "boxed" copy, and
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this is the third sort of stack frame which exists.
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</p>
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<p class="commentary">The following does so. <a href="3-sf.html#SP5" class="internal">stack_frame_box</a> objects provide a convenient permanent
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place in memory to stash these; pointers to them otherwise don't exist.
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</p>
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<pre class="displayed-code all-displayed-code code-font">
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<span class="reserved-syntax">typedef</span><span class="plain-syntax"> </span><span class="reserved-syntax">struct</span><span class="plain-syntax"> </span><span class="reserved-syntax">stack_frame_box</span><span class="plain-syntax"> {</span>
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<span class="plain-syntax"> </span><span class="reserved-syntax">struct</span><span class="plain-syntax"> </span><span class="reserved-syntax">stack_frame</span><span class="plain-syntax"> </span><span class="identifier-syntax">boxed_phsf</span><span class="plain-syntax">;</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">CLASS_DEFINITION</span>
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<span class="plain-syntax">} </span><span class="reserved-syntax">stack_frame_box</span><span class="plain-syntax">;</span>
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<span class="reserved-syntax">stack_frame</span><span class="plain-syntax"> *</span><span class="function-syntax">Frames::boxed_frame</span><span class="plain-syntax">(</span><span class="reserved-syntax">stack_frame</span><span class="plain-syntax"> *</span><span class="identifier-syntax">old_frame</span><span class="plain-syntax">) {</span>
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<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">old_frame</span><span class="plain-syntax"> == </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">) </span><span class="reserved-syntax">return</span><span class="plain-syntax"> </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">;</span>
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<span class="plain-syntax"> </span><span class="reserved-syntax">stack_frame_box</span><span class="plain-syntax"> *</span><span class="identifier-syntax">box</span><span class="plain-syntax"> = </span><span class="identifier-syntax">CREATE</span><span class="plain-syntax">(</span><span class="reserved-syntax">stack_frame_box</span><span class="plain-syntax">);</span>
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<span class="plain-syntax"> </span><span class="reserved-syntax">stack_frame</span><span class="plain-syntax"> *</span><span class="identifier-syntax">new_frame</span><span class="plain-syntax"> = &(</span><span class="identifier-syntax">box</span><span class="plain-syntax">-></span><span class="element-syntax">boxed_phsf</span><span class="plain-syntax">);</span>
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<span class="plain-syntax"> *</span><span class="identifier-syntax">new_frame</span><span class="plain-syntax"> = *</span><span class="identifier-syntax">old_frame</span><span class="plain-syntax">;</span>
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<span class="plain-syntax"> </span><a href="3-lvs.html#SP9" class="function-link"><span class="function-syntax">LocalVariableSlates::deep_copy</span></a><span class="plain-syntax">(&(</span><span class="identifier-syntax">new_frame</span><span class="plain-syntax">-></span><span class="element-syntax">local_variables</span><span class="plain-syntax">),</span>
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<span class="plain-syntax"> &(</span><span class="identifier-syntax">old_frame</span><span class="plain-syntax">-></span><span class="element-syntax">local_variables</span><span class="plain-syntax">));</span>
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<span class="plain-syntax"> </span><span class="reserved-syntax">return</span><span class="plain-syntax"> </span><span class="identifier-syntax">new_frame</span><span class="plain-syntax">;</span>
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<span class="plain-syntax">}</span>
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</pre>
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<ul class="endnotetexts"><li>The structure stack_frame_box is private to this section.</li></ul>
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<p class="commentary firstcommentary"><a id="SP6" class="paragraph-anchor"></a><b>§6. Creation. </b></p>
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<pre class="displayed-code all-displayed-code code-font">
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<span class="reserved-syntax">typedef</span><span class="plain-syntax"> </span><span class="reserved-syntax">struct</span><span class="plain-syntax"> </span><span class="reserved-syntax">stack_frame</span><span class="plain-syntax"> {</span>
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<span class="plain-syntax"> </span><span class="reserved-syntax">struct</span><span class="plain-syntax"> </span><span class="reserved-syntax">locals_slate</span><span class="plain-syntax"> </span><span class="identifier-syntax">local_variables</span><span class="plain-syntax">; </span><span class="comment-syntax"> those in scope here</span>
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<span class="plain-syntax"> </span><span class="reserved-syntax">struct</span><span class="plain-syntax"> </span><span class="identifier-syntax">shared_variable_access_list</span><span class="plain-syntax"> *</span><span class="identifier-syntax">shared_variables</span><span class="plain-syntax">; </span><span class="comment-syntax"> those in scope here</span>
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<span class="plain-syntax"> </span><span class="reserved-syntax">struct</span><span class="plain-syntax"> </span><span class="identifier-syntax">linked_list</span><span class="plain-syntax"> *</span><span class="identifier-syntax">local_block_values</span><span class="plain-syntax">; </span><span class="comment-syntax"> of </span><span class="extract"><span class="extract-syntax">local_block_value</span></span>
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<span class="plain-syntax"> </span><span class="reserved-syntax">int</span><span class="plain-syntax"> </span><span class="identifier-syntax">no_formal_parameters_needed</span><span class="plain-syntax">; </span><span class="comment-syntax"> usually 0, unless there are ambiguities</span>
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<span class="plain-syntax"> </span><span class="reserved-syntax">struct</span><span class="plain-syntax"> </span><span class="identifier-syntax">kind</span><span class="plain-syntax"> *</span><span class="identifier-syntax">kind_returned</span><span class="plain-syntax">; </span><span class="comment-syntax"> or </span><span class="extract"><span class="extract-syntax">NULL</span></span><span class="comment-syntax"> for no return value</span>
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<span class="plain-syntax"> </span><span class="reserved-syntax">struct</span><span class="plain-syntax"> </span><span class="identifier-syntax">kind</span><span class="plain-syntax"> **</span><span class="identifier-syntax">local_kind_variables</span><span class="plain-syntax">; </span><span class="comment-syntax"> points to an array indexed 1 to 26</span>
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<span class="plain-syntax"> </span><span class="reserved-syntax">int</span><span class="plain-syntax"> </span><span class="identifier-syntax">determines_past_conditions</span><span class="plain-syntax">; </span><span class="comment-syntax"> or rather, in the present, but for future use</span>
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<span class="plain-syntax">} </span><span class="reserved-syntax">stack_frame</span><span class="plain-syntax">;</span>
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<span class="reserved-syntax">stack_frame</span><span class="plain-syntax"> </span><span class="function-syntax">Frames::new</span><button class="popup" onclick="togglePopup('usagePopup6')"><span class="comment-syntax">?</span><span class="popuptext" id="usagePopup6">Usage of <span class="code-font"><span class="function-syntax">Frames::new</span></span>:<br/><a href="3-sf.html#SP4">§4</a><br/>Compile Imperative Definitions - <a href="3-cid.html#SP4">§4</a></span></button><span class="plain-syntax">(</span><span class="reserved-syntax">void</span><span class="plain-syntax">) {</span>
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<span class="plain-syntax"> </span><span class="reserved-syntax">stack_frame</span><span class="plain-syntax"> </span><span class="identifier-syntax">frame</span><span class="plain-syntax">;</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">frame</span><span class="plain-syntax">.</span><span class="identifier-syntax">local_variables</span><span class="plain-syntax"> = </span><a href="3-lvs.html#SP8" class="function-link"><span class="function-syntax">LocalVariableSlates::new</span></a><span class="plain-syntax">();</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">frame</span><span class="plain-syntax">.</span><span class="identifier-syntax">local_kind_variables</span><span class="plain-syntax"> = </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">;</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">frame</span><span class="plain-syntax">.</span><span class="identifier-syntax">shared_variables</span><span class="plain-syntax"> = </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">;</span>
|
|
<span class="plain-syntax"> </span><span class="identifier-syntax">frame</span><span class="plain-syntax">.</span><span class="identifier-syntax">determines_past_conditions</span><span class="plain-syntax"> = </span><span class="identifier-syntax">FALSE</span><span class="plain-syntax">;</span>
|
|
<span class="plain-syntax"> </span><span class="identifier-syntax">frame</span><span class="plain-syntax">.</span><span class="identifier-syntax">local_block_values</span><span class="plain-syntax"> = </span><span class="identifier-syntax">NEW_LINKED_LIST</span><span class="plain-syntax">(</span><span class="reserved-syntax">local_block_value</span><span class="plain-syntax">);</span>
|
|
<span class="plain-syntax"> </span><span class="identifier-syntax">frame</span><span class="plain-syntax">.</span><span class="identifier-syntax">kind_returned</span><span class="plain-syntax"> = </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">;</span>
|
|
<span class="plain-syntax"> </span><span class="identifier-syntax">frame</span><span class="plain-syntax">.</span><span class="identifier-syntax">no_formal_parameters_needed</span><span class="plain-syntax"> = </span><span class="constant-syntax">0</span><span class="plain-syntax">;</span>
|
|
<span class="plain-syntax"> </span><span class="reserved-syntax">return</span><span class="plain-syntax"> </span><span class="identifier-syntax">frame</span><span class="plain-syntax">;</span>
|
|
<span class="plain-syntax">}</span>
|
|
</pre>
|
|
<ul class="endnotetexts"><li>The structure stack_frame is accessed in 3/lvs, 3/lv, 3/fnc and here.</li></ul>
|
|
<p class="commentary firstcommentary"><a id="SP7" class="paragraph-anchor"></a><b>§7. Kinds. </b>The kind of value we expect to return from within this stack frame, if any.
|
|
</p>
|
|
|
|
<pre class="displayed-code all-displayed-code code-font">
|
|
<span class="reserved-syntax">void</span><span class="plain-syntax"> </span><span class="function-syntax">Frames::set_kind_returned</span><button class="popup" onclick="togglePopup('usagePopup7')"><span class="comment-syntax">?</span><span class="popuptext" id="usagePopup7">Usage of <span class="code-font"><span class="function-syntax">Frames::set_kind_returned</span></span>:<br/>Compile Imperative Definitions - <a href="3-cid.html#SP10">§10</a></span></button><span class="plain-syntax">(</span><span class="reserved-syntax">stack_frame</span><span class="plain-syntax"> *</span><span class="identifier-syntax">frame</span><span class="plain-syntax">, </span><span class="identifier-syntax">kind</span><span class="plain-syntax"> *</span><span class="identifier-syntax">K</span><span class="plain-syntax">) {</span>
|
|
<span class="plain-syntax"> </span><span class="identifier-syntax">frame</span><span class="plain-syntax">-></span><span class="identifier-syntax">kind_returned</span><span class="plain-syntax"> = </span><span class="identifier-syntax">K</span><span class="plain-syntax">;</span>
|
|
<span class="plain-syntax">}</span>
|
|
|
|
<span class="identifier-syntax">kind</span><span class="plain-syntax"> *</span><span class="function-syntax">Frames::get_kind_returned</span><button class="popup" onclick="togglePopup('usagePopup8')"><span class="comment-syntax">?</span><span class="popuptext" id="usagePopup8">Usage of <span class="code-font"><span class="function-syntax">Frames::get_kind_returned</span></span>:<br/>Compile Imperative Definitions - <a href="3-cid.html#SP2_3_1">§2.3.1</a><br/>Compile Invocations Inline - <a href="5-cii.html#SP6_1_1_4_7_1">§6.1.1.4.7.1</a>, <a href="5-cii.html#SP9">§9</a></span></button><span class="plain-syntax">(</span><span class="reserved-syntax">void</span><span class="plain-syntax">) {</span>
|
|
<span class="plain-syntax"> </span><span class="reserved-syntax">stack_frame</span><span class="plain-syntax"> *</span><span class="identifier-syntax">frame</span><span class="plain-syntax"> = </span><a href="3-sf.html#SP2" class="function-link"><span class="function-syntax">Frames::current_stack_frame</span></a><span class="plain-syntax">();</span>
|
|
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">frame</span><span class="plain-syntax"> == </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">) </span><span class="reserved-syntax">return</span><span class="plain-syntax"> </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">;</span>
|
|
<span class="plain-syntax"> </span><span class="reserved-syntax">return</span><span class="plain-syntax"> </span><span class="identifier-syntax">frame</span><span class="plain-syntax">-></span><span class="element-syntax">kind_returned</span><span class="plain-syntax">;</span>
|
|
<span class="plain-syntax">}</span>
|
|
</pre>
|
|
<p class="commentary firstcommentary"><a id="SP8" class="paragraph-anchor"></a><b>§8. </b>And the values of the kind variables A to Z:
|
|
</p>
|
|
|
|
<pre class="definitions code-font"><span class="definition-keyword">define</span> <span class="constant-syntax">KIND_VARIABLE_FROM_CONTEXT</span><span class="plain-syntax"> </span><a href="3-sf.html#SP8" class="function-link"><span class="function-syntax">Frames::get_kind_variable</span></a>
|
|
</pre>
|
|
<pre class="displayed-code all-displayed-code code-font">
|
|
<span class="reserved-syntax">void</span><span class="plain-syntax"> </span><span class="function-syntax">Frames::set_kind_variables</span><button class="popup" onclick="togglePopup('usagePopup9')"><span class="comment-syntax">?</span><span class="popuptext" id="usagePopup9">Usage of <span class="code-font"><span class="function-syntax">Frames::set_kind_variables</span></span>:<br/>Compile Imperative Definitions - <a href="3-cid.html#SP2_2">§2.2</a></span></button><span class="plain-syntax">(</span><span class="reserved-syntax">stack_frame</span><span class="plain-syntax"> *</span><span class="identifier-syntax">frame</span><span class="plain-syntax">, </span><span class="identifier-syntax">kind</span><span class="plain-syntax"> **</span><span class="identifier-syntax">vars</span><span class="plain-syntax">) {</span>
|
|
<span class="plain-syntax"> </span><span class="identifier-syntax">frame</span><span class="plain-syntax">-></span><span class="identifier-syntax">local_kind_variables</span><span class="plain-syntax"> = </span><span class="identifier-syntax">vars</span><span class="plain-syntax">;</span>
|
|
<span class="plain-syntax">}</span>
|
|
|
|
<span class="identifier-syntax">kind</span><span class="plain-syntax"> *</span><span class="function-syntax">Frames::get_kind_variable</span><button class="popup" onclick="togglePopup('usagePopup10')"><span class="comment-syntax">?</span><span class="popuptext" id="usagePopup10">Usage of <span class="code-font"><span class="function-syntax">Frames::get_kind_variable</span></span>:<br/>Compile Invocations Inline - <a href="5-cii.html#SP6_1_1_1">§6.1.1.1</a></span></button><span class="plain-syntax">(</span><span class="reserved-syntax">int</span><span class="plain-syntax"> </span><span class="identifier-syntax">N</span><span class="plain-syntax">) {</span>
|
|
<span class="plain-syntax"> </span><span class="reserved-syntax">stack_frame</span><span class="plain-syntax"> *</span><span class="identifier-syntax">frame</span><span class="plain-syntax"> = </span><a href="3-sf.html#SP2" class="function-link"><span class="function-syntax">Frames::current_stack_frame</span></a><span class="plain-syntax">();</span>
|
|
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> ((</span><span class="identifier-syntax">frame</span><span class="plain-syntax">) && (</span><span class="identifier-syntax">frame</span><span class="plain-syntax">-></span><span class="element-syntax">local_kind_variables</span><span class="plain-syntax">))</span>
|
|
<span class="plain-syntax"> </span><span class="reserved-syntax">return</span><span class="plain-syntax"> </span><span class="identifier-syntax">frame</span><span class="plain-syntax">-></span><span class="element-syntax">local_kind_variables</span><span class="plain-syntax">[</span><span class="identifier-syntax">N</span><span class="plain-syntax">];</span>
|
|
<span class="plain-syntax"> </span><span class="reserved-syntax">return</span><span class="plain-syntax"> </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">;</span>
|
|
<span class="plain-syntax">}</span>
|
|
|
|
<span class="identifier-syntax">kind</span><span class="plain-syntax"> **</span><span class="function-syntax">Frames::temporarily_set_kvs</span><button class="popup" onclick="togglePopup('usagePopup11')"><span class="comment-syntax">?</span><span class="popuptext" id="usagePopup11">Usage of <span class="code-font"><span class="function-syntax">Frames::temporarily_set_kvs</span></span>:<br/>Compile Invocations Inline - <a href="5-cii.html#SP6_1_1">§6.1.1</a>, <a href="5-cii.html#SP9">§9</a></span></button><span class="plain-syntax">(</span><span class="identifier-syntax">kind</span><span class="plain-syntax"> **</span><span class="identifier-syntax">vars</span><span class="plain-syntax">) {</span>
|
|
<span class="plain-syntax"> </span><span class="reserved-syntax">stack_frame</span><span class="plain-syntax"> *</span><span class="identifier-syntax">frame</span><span class="plain-syntax"> = </span><a href="3-sf.html#SP2" class="function-link"><span class="function-syntax">Frames::current_stack_frame</span></a><span class="plain-syntax">();</span>
|
|
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">frame</span><span class="plain-syntax"> == </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">) </span><span class="reserved-syntax">return</span><span class="plain-syntax"> </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">;</span>
|
|
<span class="plain-syntax"> </span><span class="identifier-syntax">kind</span><span class="plain-syntax"> **</span><span class="identifier-syntax">prev</span><span class="plain-syntax"> = </span><span class="identifier-syntax">frame</span><span class="plain-syntax">-></span><span class="element-syntax">local_kind_variables</span><span class="plain-syntax">;</span>
|
|
<span class="plain-syntax"> </span><span class="identifier-syntax">frame</span><span class="plain-syntax">-></span><span class="identifier-syntax">local_kind_variables</span><span class="plain-syntax"> = </span><span class="identifier-syntax">vars</span><span class="plain-syntax">;</span>
|
|
<span class="plain-syntax"> </span><span class="reserved-syntax">return</span><span class="plain-syntax"> </span><span class="identifier-syntax">prev</span><span class="plain-syntax">;</span>
|
|
<span class="plain-syntax">}</span>
|
|
</pre>
|
|
<p class="commentary firstcommentary"><a id="SP9" class="paragraph-anchor"></a><b>§9. </b>The "deduced kind" is what the kind of the code in this stack frame would
|
|
be, if it were seen as a function from its parameter variables to its return value.
|
|
</p>
|
|
|
|
<pre class="displayed-code all-displayed-code code-font">
|
|
<span class="identifier-syntax">kind</span><span class="plain-syntax"> *</span><span class="function-syntax">Frames::deduced_function_kind</span><button class="popup" onclick="togglePopup('usagePopup12')"><span class="comment-syntax">?</span><span class="popuptext" id="usagePopup12">Usage of <span class="code-font"><span class="function-syntax">Frames::deduced_function_kind</span></span>:<br/>Functions - <a href="3-fnc.html#SP6">§6</a></span></button><span class="plain-syntax">(</span><span class="reserved-syntax">stack_frame</span><span class="plain-syntax"> *</span><span class="identifier-syntax">frame</span><span class="plain-syntax">) {</span>
|
|
<span class="plain-syntax"> </span><span class="reserved-syntax">int</span><span class="plain-syntax"> </span><span class="identifier-syntax">pc</span><span class="plain-syntax"> = </span><span class="constant-syntax">0</span><span class="plain-syntax">;</span>
|
|
<span class="plain-syntax"> </span><span class="reserved-syntax">local_variable</span><span class="plain-syntax"> *</span><span class="identifier-syntax">lvar</span><span class="plain-syntax">;</span>
|
|
<span class="plain-syntax"> </span><span class="identifier-syntax">LOOP_OVER_LOCALS_IN_FRAME</span><span class="plain-syntax">(</span><span class="identifier-syntax">lvar</span><span class="plain-syntax">, </span><span class="identifier-syntax">frame</span><span class="plain-syntax">)</span>
|
|
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><a href="3-lv.html#SP6" class="function-link"><span class="function-syntax">LocalVariables::is_parameter</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">lvar</span><span class="plain-syntax">))</span>
|
|
<span class="plain-syntax"> </span><span class="identifier-syntax">pc</span><span class="plain-syntax">++;</span>
|
|
<span class="plain-syntax"> </span><span class="identifier-syntax">kind</span><span class="plain-syntax"> *</span><span class="identifier-syntax">K_array</span><span class="plain-syntax">[128];</span>
|
|
<span class="plain-syntax"> </span><span class="identifier-syntax">pc</span><span class="plain-syntax"> = </span><span class="constant-syntax">0</span><span class="plain-syntax">;</span>
|
|
<span class="plain-syntax"> </span><span class="identifier-syntax">LOOP_OVER_LOCALS_IN_FRAME</span><span class="plain-syntax">(</span><span class="identifier-syntax">lvar</span><span class="plain-syntax">, </span><span class="identifier-syntax">frame</span><span class="plain-syntax">)</span>
|
|
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><a href="3-lv.html#SP6" class="function-link"><span class="function-syntax">LocalVariables::is_parameter</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">lvar</span><span class="plain-syntax">))</span>
|
|
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">pc</span><span class="plain-syntax"> < </span><span class="constant-syntax">128</span><span class="plain-syntax">) {</span>
|
|
<span class="plain-syntax"> </span><span class="identifier-syntax">kind</span><span class="plain-syntax"> *</span><span class="identifier-syntax">OK</span><span class="plain-syntax"> = </span><span class="identifier-syntax">lvar</span><span class="plain-syntax">-></span><span class="identifier-syntax">current_usage</span><span class="plain-syntax">.</span><span class="element-syntax">kind_as_declared</span><span class="plain-syntax">;</span>
|
|
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> ((</span><span class="identifier-syntax">OK</span><span class="plain-syntax"> == </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">) || (</span><span class="identifier-syntax">OK</span><span class="plain-syntax"> == </span><span class="identifier-syntax">K_nil</span><span class="plain-syntax">)) </span><span class="identifier-syntax">OK</span><span class="plain-syntax"> = </span><span class="identifier-syntax">K_number</span><span class="plain-syntax">;</span>
|
|
<span class="plain-syntax"> </span><span class="identifier-syntax">K_array</span><span class="plain-syntax">[</span><span class="identifier-syntax">pc</span><span class="plain-syntax">++] = </span><span class="identifier-syntax">OK</span><span class="plain-syntax">;</span>
|
|
<span class="plain-syntax"> }</span>
|
|
<span class="plain-syntax"> </span><span class="reserved-syntax">return</span><span class="plain-syntax"> </span><span class="identifier-syntax">Kinds::function_kind</span><span class="plain-syntax">(</span><span class="identifier-syntax">pc</span><span class="plain-syntax">, </span><span class="identifier-syntax">K_array</span><span class="plain-syntax">, </span><span class="identifier-syntax">frame</span><span class="plain-syntax">-></span><span class="element-syntax">kind_returned</span><span class="plain-syntax">);</span>
|
|
<span class="plain-syntax">}</span>
|
|
</pre>
|
|
<p class="commentary firstcommentary"><a id="SP10" class="paragraph-anchor"></a><b>§10. Shared variables. </b>See <a href="../assertions-module/6-sv.html" class="internal">Shared Variables (in assertions)</a> for more on this.
|
|
</p>
|
|
|
|
<pre class="displayed-code all-displayed-code code-font">
|
|
<span class="reserved-syntax">void</span><span class="plain-syntax"> </span><span class="function-syntax">Frames::set_shared_variable_access_list</span><button class="popup" onclick="togglePopup('usagePopup13')"><span class="comment-syntax">?</span><span class="popuptext" id="usagePopup13">Usage of <span class="code-font"><span class="function-syntax">Frames::set_shared_variable_access_list</span></span>:<br/>Compile Imperative Definitions - <a href="3-cid.html#SP2_2">§2.2</a></span></button><span class="plain-syntax">(</span><span class="reserved-syntax">stack_frame</span><span class="plain-syntax"> *</span><span class="identifier-syntax">frame</span><span class="plain-syntax">,</span>
|
|
<span class="plain-syntax"> </span><span class="identifier-syntax">shared_variable_access_list</span><span class="plain-syntax"> *</span><span class="identifier-syntax">access</span><span class="plain-syntax">) {</span>
|
|
<span class="plain-syntax"> </span><span class="identifier-syntax">frame</span><span class="plain-syntax">-></span><span class="identifier-syntax">shared_variables</span><span class="plain-syntax"> = </span><span class="identifier-syntax">access</span><span class="plain-syntax">;</span>
|
|
<span class="plain-syntax">}</span>
|
|
|
|
<span class="identifier-syntax">shared_variable_access_list</span><span class="plain-syntax"> *</span><span class="function-syntax">Frames::get_shared_variable_access_list</span><span class="plain-syntax">(</span><span class="reserved-syntax">void</span><span class="plain-syntax">) {</span>
|
|
<span class="plain-syntax"> </span><span class="reserved-syntax">stack_frame</span><span class="plain-syntax"> *</span><span class="identifier-syntax">frame</span><span class="plain-syntax"> = </span><a href="3-sf.html#SP2" class="function-link"><span class="function-syntax">Frames::current_stack_frame</span></a><span class="plain-syntax">();</span>
|
|
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">frame</span><span class="plain-syntax">) </span><span class="reserved-syntax">return</span><span class="plain-syntax"> </span><span class="identifier-syntax">frame</span><span class="plain-syntax">-></span><span class="element-syntax">shared_variables</span><span class="plain-syntax">;</span>
|
|
<span class="plain-syntax"> </span><span class="reserved-syntax">return</span><span class="plain-syntax"> </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">;</span>
|
|
<span class="plain-syntax">}</span>
|
|
</pre>
|
|
<p class="commentary firstcommentary"><a id="SP11" class="paragraph-anchor"></a><b>§11. Past tense. </b>It turns out to be convenient to remember whether the current function makes
|
|
any reference to the past, which we do here:
|
|
</p>
|
|
|
|
<pre class="displayed-code all-displayed-code code-font">
|
|
<span class="reserved-syntax">void</span><span class="plain-syntax"> </span><span class="function-syntax">Frames::determines_the_past</span><span class="plain-syntax">(</span><span class="reserved-syntax">void</span><span class="plain-syntax">) {</span>
|
|
<span class="plain-syntax"> </span><span class="reserved-syntax">stack_frame</span><span class="plain-syntax"> *</span><span class="identifier-syntax">frame</span><span class="plain-syntax"> = </span><a href="3-sf.html#SP2" class="function-link"><span class="function-syntax">Frames::current_stack_frame</span></a><span class="plain-syntax">();</span>
|
|
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">frame</span><span class="plain-syntax"> == </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">) </span><span class="identifier-syntax">internal_error</span><span class="plain-syntax">(</span>
|
|
<span class="plain-syntax"> </span><span class="string-syntax">"tried to determine past where no stack frame exists"</span><span class="plain-syntax">);</span>
|
|
<span class="plain-syntax"> </span><span class="identifier-syntax">frame</span><span class="plain-syntax">-></span><span class="identifier-syntax">determines_past_conditions</span><span class="plain-syntax"> = </span><span class="identifier-syntax">TRUE</span><span class="plain-syntax">;</span>
|
|
<span class="plain-syntax"> </span><span class="identifier-syntax">LOGIF</span><span class="plain-syntax">(</span><span class="identifier-syntax">LOCAL_VARIABLES</span><span class="plain-syntax">, </span><span class="string-syntax">"Stack frame determines past\n"</span><span class="plain-syntax">);</span>
|
|
<span class="plain-syntax">}</span>
|
|
|
|
<span class="reserved-syntax">int</span><span class="plain-syntax"> </span><span class="function-syntax">Frames::used_for_past_tense</span><button class="popup" onclick="togglePopup('usagePopup14')"><span class="comment-syntax">?</span><span class="popuptext" id="usagePopup14">Usage of <span class="code-font"><span class="function-syntax">Frames::used_for_past_tense</span></span>:<br/>Compile Atoms - <a href="4-ca.html#SP1_1">§1.1</a></span></button><span class="plain-syntax">(</span><span class="reserved-syntax">void</span><span class="plain-syntax">) {</span>
|
|
<span class="plain-syntax"> </span><span class="reserved-syntax">stack_frame</span><span class="plain-syntax"> *</span><span class="identifier-syntax">frame</span><span class="plain-syntax"> = </span><a href="3-sf.html#SP2" class="function-link"><span class="function-syntax">Frames::current_stack_frame</span></a><span class="plain-syntax">();</span>
|
|
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">frame</span><span class="plain-syntax"> == </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">) </span><span class="reserved-syntax">return</span><span class="plain-syntax"> </span><span class="identifier-syntax">FALSE</span><span class="plain-syntax">;</span>
|
|
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">frame</span><span class="plain-syntax">-></span><span class="element-syntax">determines_past_conditions</span><span class="plain-syntax">) </span><span class="reserved-syntax">return</span><span class="plain-syntax"> </span><span class="identifier-syntax">TRUE</span><span class="plain-syntax">;</span>
|
|
<span class="plain-syntax"> </span><span class="reserved-syntax">return</span><span class="plain-syntax"> </span><span class="identifier-syntax">FALSE</span><span class="plain-syntax">;</span>
|
|
<span class="plain-syntax">}</span>
|
|
</pre>
|
|
<p class="commentary firstcommentary"><a id="SP12" class="paragraph-anchor"></a><b>§12. Formal parameters. </b>Some stack frames need access to additional Inter function parameters to handle
|
|
runtime invocation ambiguities, and this is how they're requested:
|
|
</p>
|
|
|
|
<pre class="displayed-code all-displayed-code code-font">
|
|
<span class="reserved-syntax">void</span><span class="plain-syntax"> </span><span class="function-syntax">Frames::need_at_least_this_many_formals</span><button class="popup" onclick="togglePopup('usagePopup15')"><span class="comment-syntax">?</span><span class="popuptext" id="usagePopup15">Usage of <span class="code-font"><span class="function-syntax">Frames::need_at_least_this_many_formals</span></span>:<br/>Compile Invocations - <a href="5-ci.html#SP1_3_1_2">§1.3.1.2</a></span></button><span class="plain-syntax">(</span><span class="reserved-syntax">int</span><span class="plain-syntax"> </span><span class="identifier-syntax">N</span><span class="plain-syntax">) {</span>
|
|
<span class="plain-syntax"> </span><span class="reserved-syntax">stack_frame</span><span class="plain-syntax"> *</span><span class="identifier-syntax">frame</span><span class="plain-syntax"> = </span><a href="3-sf.html#SP2" class="function-link"><span class="function-syntax">Frames::current_stack_frame</span></a><span class="plain-syntax">();</span>
|
|
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">frame</span><span class="plain-syntax"> == </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">)</span>
|
|
<span class="plain-syntax"> </span><span class="identifier-syntax">internal_error</span><span class="plain-syntax">(</span><span class="string-syntax">"requested formal parameters outside all stack frames"</span><span class="plain-syntax">);</span>
|
|
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">N</span><span class="plain-syntax"> > </span><span class="identifier-syntax">frame</span><span class="plain-syntax">-></span><span class="element-syntax">no_formal_parameters_needed</span><span class="plain-syntax">)</span>
|
|
<span class="plain-syntax"> </span><span class="identifier-syntax">frame</span><span class="plain-syntax">-></span><span class="element-syntax">no_formal_parameters_needed</span><span class="plain-syntax"> = </span><span class="identifier-syntax">N</span><span class="plain-syntax">;</span>
|
|
<span class="plain-syntax">}</span>
|
|
</pre>
|
|
<p class="commentary firstcommentary"><a id="SP13" class="paragraph-anchor"></a><b>§13. It. </b>In some stack frames, the pronoun "it" (perhaps inflected) is allowed to stand
|
|
for the first call parameter to the function being compiled; and in others not.
|
|
</p>
|
|
|
|
<pre class="displayed-code all-displayed-code code-font">
|
|
<span class="reserved-syntax">local_variable</span><span class="plain-syntax"> *</span><span class="function-syntax">Frames::enable_it</span><span class="plain-syntax">(</span><span class="reserved-syntax">stack_frame</span><span class="plain-syntax"> *</span><span class="identifier-syntax">frame</span><span class="plain-syntax">, </span><span class="identifier-syntax">wording</span><span class="plain-syntax"> </span><span class="identifier-syntax">W</span><span class="plain-syntax">, </span><span class="identifier-syntax">kind</span><span class="plain-syntax"> *</span><span class="identifier-syntax">K</span><span class="plain-syntax">) {</span>
|
|
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">frame</span><span class="plain-syntax"> == </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">) </span><span class="identifier-syntax">internal_error</span><span class="plain-syntax">(</span><span class="string-syntax">"no stack frame exists"</span><span class="plain-syntax">);</span>
|
|
<span class="plain-syntax"> </span><span class="identifier-syntax">frame</span><span class="plain-syntax">-></span><span class="identifier-syntax">local_variables</span><span class="plain-syntax">.</span><span class="element-syntax">it_variable_exists</span><span class="plain-syntax"> = </span><span class="identifier-syntax">TRUE</span><span class="plain-syntax">;</span>
|
|
<span class="plain-syntax"> </span><span class="reserved-syntax">return</span><span class="plain-syntax"> </span><a href="3-lv.html#SP2" class="function-link"><span class="function-syntax">LocalVariables::new_call_parameter</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">frame</span><span class="plain-syntax">, </span><span class="identifier-syntax">W</span><span class="plain-syntax">, </span><span class="identifier-syntax">K</span><span class="plain-syntax">);</span>
|
|
<span class="plain-syntax">}</span>
|
|
</pre>
|
|
<p class="commentary firstcommentary"><a id="SP14" class="paragraph-anchor"></a><b>§14. </b>If so, sometimes "its", "his", "her" or "their" are allowed too, but sometimes
|
|
not.
|
|
</p>
|
|
|
|
<pre class="displayed-code all-displayed-code code-font">
|
|
<span class="reserved-syntax">int</span><span class="plain-syntax"> </span><span class="function-syntax">Frames::is_its_enabled</span><span class="plain-syntax">(</span><span class="reserved-syntax">stack_frame</span><span class="plain-syntax"> *</span><span class="identifier-syntax">frame</span><span class="plain-syntax">) {</span>
|
|
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">frame</span><span class="plain-syntax">) </span><span class="reserved-syntax">return</span><span class="plain-syntax"> </span><span class="identifier-syntax">frame</span><span class="plain-syntax">-></span><span class="element-syntax">local_variables</span><span class="plain-syntax">.</span><span class="element-syntax">its_form_allowed</span><span class="plain-syntax">;</span>
|
|
<span class="plain-syntax"> </span><span class="reserved-syntax">return</span><span class="plain-syntax"> </span><span class="identifier-syntax">FALSE</span><span class="plain-syntax">;</span>
|
|
<span class="plain-syntax">}</span>
|
|
|
|
<span class="reserved-syntax">void</span><span class="plain-syntax"> </span><span class="function-syntax">Frames::enable_its</span><span class="plain-syntax">(</span><span class="reserved-syntax">stack_frame</span><span class="plain-syntax"> *</span><span class="identifier-syntax">frame</span><span class="plain-syntax">) {</span>
|
|
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">frame</span><span class="plain-syntax"> == </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">) </span><span class="identifier-syntax">internal_error</span><span class="plain-syntax">(</span><span class="string-syntax">"no stack frame exists"</span><span class="plain-syntax">);</span>
|
|
<span class="plain-syntax"> </span><span class="identifier-syntax">frame</span><span class="plain-syntax">-></span><span class="identifier-syntax">local_variables</span><span class="plain-syntax">.</span><span class="element-syntax">its_form_allowed</span><span class="plain-syntax"> = </span><span class="identifier-syntax">TRUE</span><span class="plain-syntax">;</span>
|
|
<span class="plain-syntax">}</span>
|
|
</pre>
|
|
<p class="commentary firstcommentary"><a id="SP15" class="paragraph-anchor"></a><b>§15. </b>In addition, a special name can optionally be given to the "it". This is only
|
|
likely to be useful if the first call parameter is nameless — but that does
|
|
sometimes happen.
|
|
</p>
|
|
|
|
<pre class="displayed-code all-displayed-code code-font">
|
|
<span class="reserved-syntax">void</span><span class="plain-syntax"> </span><span class="function-syntax">Frames::alias_it</span><span class="plain-syntax">(</span><span class="reserved-syntax">stack_frame</span><span class="plain-syntax"> *</span><span class="identifier-syntax">frame</span><span class="plain-syntax">, </span><span class="identifier-syntax">wording</span><span class="plain-syntax"> </span><span class="identifier-syntax">W</span><span class="plain-syntax">) {</span>
|
|
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">frame</span><span class="plain-syntax"> == </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">) </span><span class="identifier-syntax">internal_error</span><span class="plain-syntax">(</span><span class="string-syntax">"no stack frame exists"</span><span class="plain-syntax">);</span>
|
|
<span class="plain-syntax"> </span><span class="identifier-syntax">frame</span><span class="plain-syntax">-></span><span class="identifier-syntax">local_variables</span><span class="plain-syntax">.</span><span class="element-syntax">it_pseudonym</span><span class="plain-syntax"> = </span><span class="identifier-syntax">W</span><span class="plain-syntax">;</span>
|
|
<span class="plain-syntax">}</span>
|
|
</pre>
|
|
<p class="commentary firstcommentary"><a id="SP16" class="paragraph-anchor"></a><b>§16. Local block values. </b>Simple data at runtime, such as values of <span class="extract"><span class="extract-syntax">K_number</span></span> or <span class="extract"><span class="extract-syntax">K_truth_state</span></span>, occupy
|
|
a single Inter word. More involved data, such as values of <span class="extract"><span class="extract-syntax">K_text</span></span> or
|
|
<span class="extract"><span class="extract-syntax">K_stored_action</span></span>, cannot. Those are called "block values", because they occupy
|
|
entire multiple-word blocks of memory to store.
|
|
</p>
|
|
|
|
<p class="commentary">So when such data must be stored in a local variable, or some other memory location,
|
|
we will store the data itself if the kind is sufficiently simple, but a pointer
|
|
to an appropriate block of memory if not.
|
|
</p>
|
|
|
|
<p class="commentary">This is a particular issue for functions whose local variables need to have
|
|
block-value kinds, because that means the function must allocate suitable memory
|
|
when called and deallocate it on exit. Each stack frame must therefore track
|
|
what local block values it will need:
|
|
</p>
|
|
|
|
<pre class="displayed-code all-displayed-code code-font">
|
|
<span class="reserved-syntax">local_block_value</span><span class="plain-syntax"> *</span><span class="function-syntax">Frames::allocate_local_block_value</span><button class="popup" onclick="togglePopup('usagePopup16')"><span class="comment-syntax">?</span><span class="popuptext" id="usagePopup16">Usage of <span class="code-font"><span class="function-syntax">Frames::allocate_local_block_value</span></span>:<br/><a href="3-sf.html#SP21">§21</a></span></button><span class="plain-syntax">(</span><span class="identifier-syntax">kind</span><span class="plain-syntax"> *</span><span class="identifier-syntax">K</span><span class="plain-syntax">) {</span>
|
|
<span class="plain-syntax"> </span><span class="reserved-syntax">stack_frame</span><span class="plain-syntax"> *</span><span class="identifier-syntax">frame</span><span class="plain-syntax"> = </span><a href="3-sf.html#SP2" class="function-link"><span class="function-syntax">Frames::current_stack_frame</span></a><span class="plain-syntax">();</span>
|
|
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">frame</span><span class="plain-syntax"> == </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">)</span>
|
|
<span class="plain-syntax"> </span><span class="identifier-syntax">internal_error</span><span class="plain-syntax">(</span><span class="string-syntax">"tried to allocate block kind outside all stack frames"</span><span class="plain-syntax">);</span>
|
|
<span class="plain-syntax"> </span><span class="reserved-syntax">local_block_value</span><span class="plain-syntax"> *</span><span class="identifier-syntax">last</span><span class="plain-syntax"> =</span>
|
|
<span class="plain-syntax"> </span><span class="identifier-syntax">LAST_IN_LINKED_LIST</span><span class="plain-syntax">(</span><span class="reserved-syntax">local_block_value</span><span class="plain-syntax">, </span><span class="identifier-syntax">frame</span><span class="plain-syntax">-></span><span class="element-syntax">local_block_values</span><span class="plain-syntax">);</span>
|
|
<span class="plain-syntax"> </span><span class="reserved-syntax">local_block_value</span><span class="plain-syntax"> *</span><span class="identifier-syntax">bv</span><span class="plain-syntax"> = </span><a href="3-sf.html#SP18" class="function-link"><span class="function-syntax">Frames::new_lbv</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">K</span><span class="plain-syntax">, </span><span class="identifier-syntax">last</span><span class="plain-syntax">);</span>
|
|
<span class="plain-syntax"> </span><span class="identifier-syntax">ADD_TO_LINKED_LIST</span><span class="plain-syntax">(</span><span class="identifier-syntax">bv</span><span class="plain-syntax">, </span><span class="reserved-syntax">local_block_value</span><span class="plain-syntax">, </span><span class="identifier-syntax">frame</span><span class="plain-syntax">-></span><span class="element-syntax">local_block_values</span><span class="plain-syntax">);</span>
|
|
<span class="plain-syntax"> </span><span class="reserved-syntax">return</span><span class="plain-syntax"> </span><span class="identifier-syntax">bv</span><span class="plain-syntax">;</span>
|
|
<span class="plain-syntax">}</span>
|
|
|
|
<span class="reserved-syntax">int</span><span class="plain-syntax"> </span><span class="function-syntax">Frames::uses_local_block_values</span><button class="popup" onclick="togglePopup('usagePopup17')"><span class="comment-syntax">?</span><span class="popuptext" id="usagePopup17">Usage of <span class="code-font"><span class="function-syntax">Frames::uses_local_block_values</span></span>:<br/>Functions - <a href="3-fnc.html#SP6">§6</a></span></button><span class="plain-syntax">(</span><span class="reserved-syntax">stack_frame</span><span class="plain-syntax"> *</span><span class="identifier-syntax">frame</span><span class="plain-syntax">) {</span>
|
|
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> ((</span><span class="identifier-syntax">frame</span><span class="plain-syntax">) && (</span><span class="identifier-syntax">LinkedLists::len</span><span class="plain-syntax">(</span><span class="identifier-syntax">frame</span><span class="plain-syntax">-></span><span class="element-syntax">local_block_values</span><span class="plain-syntax">) > </span><span class="constant-syntax">0</span><span class="plain-syntax">)) </span><span class="reserved-syntax">return</span><span class="plain-syntax"> </span><span class="identifier-syntax">TRUE</span><span class="plain-syntax">;</span>
|
|
<span class="plain-syntax"> </span><span class="reserved-syntax">return</span><span class="plain-syntax"> </span><span class="identifier-syntax">FALSE</span><span class="plain-syntax">;</span>
|
|
<span class="plain-syntax">}</span>
|
|
</pre>
|
|
<p class="commentary firstcommentary"><a id="SP17" class="paragraph-anchor"></a><b>§17. </b>Where should temporary block values live, during the perhaps very brief
|
|
period while a function is running? We can't put it onto the virtual machine's
|
|
call stack, because it doesn't live in the VM's memory at all, and therefore
|
|
cannot be written or read. We could put it on the heap, but then allocation
|
|
and deallocation would be expensive.
|
|
</p>
|
|
|
|
<p class="commentary">Instead we put just the small blocks on a stack in memory: it fills downwards,
|
|
and at runtime the Inter identifier <span class="extract"><span class="extract-syntax">I7SFRAME</span></span> points to the current and therefore
|
|
bottom-most frame on this stack. So, for example, if the current stack frame has
|
|
just two local block values, a <span class="extract"><span class="extract-syntax">K_text</span></span> and a <span class="extract"><span class="extract-syntax">K_stored_action</span></span>, then we would have:
|
|
</p>
|
|
|
|
<pre class="displayed-code all-displayed-code code-font">
|
|
<span class="plain-syntax"> ...free space...</span>
|
|
<span class="plain-syntax"> I7SFRAME --> 0 } small block 0 (for a K_text), offset index 0</span>
|
|
<span class="plain-syntax"> 1 } may then --> more data on the heap offset past 2</span>
|
|
|
|
<span class="plain-syntax"> 2 } small block 1 (for a K_stored_action) offset index 2</span>
|
|
<span class="plain-syntax"> 3 } similarly --> more data on the heap offset past 8</span>
|
|
<span class="plain-syntax"> 4 }</span>
|
|
<span class="plain-syntax"> 5 }</span>
|
|
<span class="plain-syntax"> 6 }</span>
|
|
<span class="plain-syntax"> 7 }</span>
|
|
<span class="plain-syntax"> ...frames belonging to functions calling this one...</span>
|
|
</pre>
|
|
<p class="commentary">These small blocks may well point to larger blocks elsewhere on the heap (for
|
|
example, to accommodate the actual contents of a text, if they are non-constant).
|
|
But small blocks have the virtue of being of a size which is fixed for each
|
|
kind, and we can allocate space for them essentially immediately just by raising
|
|
the <span class="extract"><span class="extract-syntax">I7SFRAME</span></span> sufficiently.
|
|
</p>
|
|
|
|
<p class="commentary">Each local block value is kept track of with one of these:
|
|
</p>
|
|
|
|
<pre class="displayed-code all-displayed-code code-font">
|
|
<span class="reserved-syntax">typedef</span><span class="plain-syntax"> </span><span class="reserved-syntax">struct</span><span class="plain-syntax"> </span><span class="reserved-syntax">local_block_value</span><span class="plain-syntax"> {</span>
|
|
<span class="plain-syntax"> </span><span class="reserved-syntax">struct</span><span class="plain-syntax"> </span><span class="identifier-syntax">heap_allocation</span><span class="plain-syntax"> </span><span class="identifier-syntax">allocation</span><span class="plain-syntax">; </span><span class="comment-syntax"> needed to compile a function call returning a pointer to a new value</span>
|
|
<span class="plain-syntax"> </span><span class="reserved-syntax">struct</span><span class="plain-syntax"> </span><span class="identifier-syntax">i6_schema</span><span class="plain-syntax"> *</span><span class="identifier-syntax">to_refer</span><span class="plain-syntax">; </span><span class="comment-syntax"> a schema to access this data</span>
|
|
<span class="plain-syntax"> </span><span class="reserved-syntax">int</span><span class="plain-syntax"> </span><span class="identifier-syntax">offset_index</span><span class="plain-syntax">; </span><span class="comment-syntax"> start of small block wrt current stack frame</span>
|
|
<span class="plain-syntax"> </span><span class="reserved-syntax">int</span><span class="plain-syntax"> </span><span class="identifier-syntax">offset_past</span><span class="plain-syntax">; </span><span class="comment-syntax"> just past the end of the small block</span>
|
|
<span class="plain-syntax"> </span><span class="identifier-syntax">CLASS_DEFINITION</span>
|
|
<span class="plain-syntax">} </span><span class="reserved-syntax">local_block_value</span><span class="plain-syntax">;</span>
|
|
</pre>
|
|
<ul class="endnotetexts"><li>The structure local_block_value is private to this section.</li></ul>
|
|
<p class="commentary firstcommentary"><a id="SP18" class="paragraph-anchor"></a><b>§18. </b>Note that the schemas below for calculating offset positions from <span class="extract"><span class="extract-syntax">I7SFRAME</span></span>
|
|
will end up only as a single addition at runtime, because the multiplication of
|
|
<span class="extract"><span class="extract-syntax">WORDSIZE</span></span> by a literal positive integer will be constant-folded in code
|
|
generation.
|
|
</p>
|
|
|
|
<pre class="displayed-code all-displayed-code code-font">
|
|
<span class="reserved-syntax">local_block_value</span><span class="plain-syntax"> *</span><span class="function-syntax">Frames::new_lbv</span><button class="popup" onclick="togglePopup('usagePopup18')"><span class="comment-syntax">?</span><span class="popuptext" id="usagePopup18">Usage of <span class="code-font"><span class="function-syntax">Frames::new_lbv</span></span>:<br/><a href="3-sf.html#SP16">§16</a></span></button><span class="plain-syntax">(</span><span class="identifier-syntax">kind</span><span class="plain-syntax"> *</span><span class="identifier-syntax">K</span><span class="plain-syntax">, </span><span class="reserved-syntax">local_block_value</span><span class="plain-syntax"> *</span><span class="identifier-syntax">last</span><span class="plain-syntax">) {</span>
|
|
<span class="plain-syntax"> </span><span class="reserved-syntax">local_block_value</span><span class="plain-syntax"> *</span><span class="identifier-syntax">bv</span><span class="plain-syntax"> = </span><span class="identifier-syntax">CREATE</span><span class="plain-syntax">(</span><span class="reserved-syntax">local_block_value</span><span class="plain-syntax">);</span>
|
|
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">last</span><span class="plain-syntax"> == </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">) </span><span class="identifier-syntax">bv</span><span class="plain-syntax">-></span><span class="element-syntax">offset_index</span><span class="plain-syntax"> = </span><span class="constant-syntax">0</span><span class="plain-syntax">;</span>
|
|
<span class="plain-syntax"> </span><span class="reserved-syntax">else</span><span class="plain-syntax"> </span><span class="identifier-syntax">bv</span><span class="plain-syntax">-></span><span class="element-syntax">offset_index</span><span class="plain-syntax"> = </span><span class="identifier-syntax">last</span><span class="plain-syntax">-></span><span class="element-syntax">offset_past</span><span class="plain-syntax">;</span>
|
|
<span class="plain-syntax"> </span><span class="identifier-syntax">bv</span><span class="plain-syntax">-></span><span class="element-syntax">allocation</span><span class="plain-syntax"> = </span><span class="identifier-syntax">TheHeap::make_allocation</span><span class="plain-syntax">(</span><span class="identifier-syntax">K</span><span class="plain-syntax">, </span><span class="constant-syntax">0</span><span class="plain-syntax">, </span><span class="identifier-syntax">bv</span><span class="plain-syntax">-></span><span class="element-syntax">offset_index</span><span class="plain-syntax">);</span>
|
|
<span class="plain-syntax"> </span><span class="identifier-syntax">bv</span><span class="plain-syntax">-></span><span class="element-syntax">offset_past</span><span class="plain-syntax"> = </span><span class="identifier-syntax">bv</span><span class="plain-syntax">-></span><span class="element-syntax">offset_index</span><span class="plain-syntax"> + </span><span class="identifier-syntax">Kinds::Behaviour::get_small_block_size</span><span class="plain-syntax">(</span><span class="identifier-syntax">K</span><span class="plain-syntax">);</span>
|
|
<span class="plain-syntax"> </span><span class="identifier-syntax">TEMPORARY_TEXT</span><span class="plain-syntax">(</span><span class="identifier-syntax">ref</span><span class="plain-syntax">)</span>
|
|
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">bv</span><span class="plain-syntax">-></span><span class="element-syntax">offset_index</span><span class="plain-syntax"> == </span><span class="constant-syntax">0</span><span class="plain-syntax">) {</span>
|
|
<span class="plain-syntax"> </span><span class="identifier-syntax">WRITE_TO</span><span class="plain-syntax">(</span><span class="identifier-syntax">ref</span><span class="plain-syntax">, </span><span class="string-syntax">"I7SFRAME"</span><span class="plain-syntax">);</span>
|
|
<span class="plain-syntax"> } </span><span class="reserved-syntax">else</span><span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">bv</span><span class="plain-syntax">-></span><span class="element-syntax">offset_index</span><span class="plain-syntax"> == </span><span class="constant-syntax">1</span><span class="plain-syntax">) {</span>
|
|
<span class="plain-syntax"> </span><span class="identifier-syntax">WRITE_TO</span><span class="plain-syntax">(</span><span class="identifier-syntax">ref</span><span class="plain-syntax">, </span><span class="string-syntax">"(I7SFRAME+WORDSIZE)"</span><span class="plain-syntax">);</span>
|
|
<span class="plain-syntax"> } </span><span class="reserved-syntax">else</span><span class="plain-syntax"> {</span>
|
|
<span class="plain-syntax"> </span><span class="identifier-syntax">WRITE_TO</span><span class="plain-syntax">(</span><span class="identifier-syntax">ref</span><span class="plain-syntax">, </span><span class="string-syntax">"(I7SFRAME+WORDSIZE**%d)"</span><span class="plain-syntax">, </span><span class="identifier-syntax">bv</span><span class="plain-syntax">-></span><span class="element-syntax">offset_index</span><span class="plain-syntax">);</span>
|
|
<span class="plain-syntax"> }</span>
|
|
<span class="plain-syntax"> </span><span class="identifier-syntax">bv</span><span class="plain-syntax">-></span><span class="element-syntax">to_refer</span><span class="plain-syntax"> = </span><span class="identifier-syntax">Calculus::Schemas::new</span><span class="plain-syntax">(</span><span class="string-syntax">"%S"</span><span class="plain-syntax">, </span><span class="identifier-syntax">ref</span><span class="plain-syntax">);</span>
|
|
<span class="plain-syntax"> </span><span class="identifier-syntax">DISCARD_TEXT</span><span class="plain-syntax">(</span><span class="identifier-syntax">ref</span><span class="plain-syntax">)</span>
|
|
<span class="plain-syntax"> </span><span class="reserved-syntax">return</span><span class="plain-syntax"> </span><span class="identifier-syntax">bv</span><span class="plain-syntax">;</span>
|
|
<span class="plain-syntax">}</span>
|
|
</pre>
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<p class="commentary firstcommentary"><a id="SP19" class="paragraph-anchor"></a><b>§19. </b>The following code is executed when the stack frame is entered: we push the
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old value of <span class="extract"><span class="extract-syntax">I7SFRAME_HL</span></span> to the call stack to save it; then call a function
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in <a href="../BasicInformKit/S-blc.html" class="internal">BlockValues (in BasicInformKit)</a> to make space for the small
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blocks we need, which will move <span class="extract"><span class="extract-syntax">I7SFRAME_HL</span></span> downwards by <span class="extract"><span class="extract-syntax">size</span></span> words; and
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then initialise the small blocks one by one to default values.
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</p>
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<pre class="displayed-code all-displayed-code code-font">
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<span class="reserved-syntax">void</span><span class="plain-syntax"> </span><span class="function-syntax">Frames::compile_lbv_setup</span><button class="popup" onclick="togglePopup('usagePopup19')"><span class="comment-syntax">?</span><span class="popuptext" id="usagePopup19">Usage of <span class="code-font"><span class="function-syntax">Frames::compile_lbv_setup</span></span>:<br/>Functions - <a href="3-fnc.html#SP6_1_2">§6.1.2</a></span></button><span class="plain-syntax">(</span><span class="reserved-syntax">stack_frame</span><span class="plain-syntax"> *</span><span class="identifier-syntax">frame</span><span class="plain-syntax">) {</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">EmitCode::push</span><span class="plain-syntax">(</span><span class="identifier-syntax">Hierarchy::find</span><span class="plain-syntax">(</span><span class="identifier-syntax">I7SFRAME_HL</span><span class="plain-syntax">));</span>
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<span class="plain-syntax"> </span><span class="reserved-syntax">int</span><span class="plain-syntax"> </span><span class="identifier-syntax">size</span><span class="plain-syntax"> = </span><span class="constant-syntax">0</span><span class="plain-syntax">;</span>
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<span class="plain-syntax"> </span><span class="reserved-syntax">local_block_value</span><span class="plain-syntax"> *</span><span class="identifier-syntax">lbv</span><span class="plain-syntax">;</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">LOOP_OVER_LINKED_LIST</span><span class="plain-syntax">(</span><span class="identifier-syntax">lbv</span><span class="plain-syntax">, </span><span class="reserved-syntax">local_block_value</span><span class="plain-syntax">, </span><span class="identifier-syntax">frame</span><span class="plain-syntax">-></span><span class="element-syntax">local_block_values</span><span class="plain-syntax">) {</span>
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|
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">lbv</span><span class="plain-syntax">-></span><span class="element-syntax">offset_past</span><span class="plain-syntax"> > </span><span class="identifier-syntax">size</span><span class="plain-syntax">) </span><span class="identifier-syntax">size</span><span class="plain-syntax"> = </span><span class="identifier-syntax">lbv</span><span class="plain-syntax">-></span><span class="element-syntax">offset_past</span><span class="plain-syntax">;</span>
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<span class="plain-syntax"> }</span>
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|
<span class="plain-syntax"> </span><span class="identifier-syntax">EmitCode::call</span><span class="plain-syntax">(</span><span class="identifier-syntax">Hierarchy::find</span><span class="plain-syntax">(</span><span class="identifier-syntax">STACKFRAMECREATE_HL</span><span class="plain-syntax">));</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">EmitCode::down</span><span class="plain-syntax">();</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">EmitCode::val_number</span><span class="plain-syntax">((</span><span class="identifier-syntax">inter_ti</span><span class="plain-syntax">) </span><span class="identifier-syntax">size</span><span class="plain-syntax">);</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">EmitCode::up</span><span class="plain-syntax">();</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">LOOP_OVER_LINKED_LIST</span><span class="plain-syntax">(</span><span class="identifier-syntax">lbv</span><span class="plain-syntax">, </span><span class="reserved-syntax">local_block_value</span><span class="plain-syntax">, </span><span class="identifier-syntax">frame</span><span class="plain-syntax">-></span><span class="element-syntax">local_block_values</span><span class="plain-syntax">)</span>
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<span class="plain-syntax"> </span><span class="identifier-syntax">TheHeap::emit_allocation</span><span class="plain-syntax">(</span><span class="identifier-syntax">lbv</span><span class="plain-syntax">-></span><span class="element-syntax">allocation</span><span class="plain-syntax">);</span>
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|
<span class="plain-syntax">}</span>
|
|
</pre>
|
|
<p class="commentary firstcommentary"><a id="SP20" class="paragraph-anchor"></a><b>§20. </b>Symmetrically, this teardown code is executed when the stack frame is exited.
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|
We deallocate each small block, and then restore <span class="extract"><span class="extract-syntax">I7SFRAME_HL</span></span> by pulling the
|
|
value we pushed earlier.
|
|
</p>
|
|
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<pre class="displayed-code all-displayed-code code-font">
|
|
<span class="reserved-syntax">void</span><span class="plain-syntax"> </span><span class="function-syntax">Frames::compile_lbv_teardown</span><button class="popup" onclick="togglePopup('usagePopup20')"><span class="comment-syntax">?</span><span class="popuptext" id="usagePopup20">Usage of <span class="code-font"><span class="function-syntax">Frames::compile_lbv_teardown</span></span>:<br/>Functions - <a href="3-fnc.html#SP6_1_4">§6.1.4</a></span></button><span class="plain-syntax">(</span><span class="reserved-syntax">stack_frame</span><span class="plain-syntax"> *</span><span class="identifier-syntax">frame</span><span class="plain-syntax">) {</span>
|
|
<span class="plain-syntax"> </span><span class="reserved-syntax">local_block_value</span><span class="plain-syntax"> *</span><span class="identifier-syntax">lbv</span><span class="plain-syntax">;</span>
|
|
<span class="plain-syntax"> </span><span class="identifier-syntax">LOOP_OVER_LINKED_LIST</span><span class="plain-syntax">(</span><span class="identifier-syntax">lbv</span><span class="plain-syntax">, </span><span class="reserved-syntax">local_block_value</span><span class="plain-syntax">, </span><span class="identifier-syntax">frame</span><span class="plain-syntax">-></span><span class="element-syntax">local_block_values</span><span class="plain-syntax">) {</span>
|
|
<span class="plain-syntax"> </span><span class="identifier-syntax">inter_name</span><span class="plain-syntax"> *</span><span class="identifier-syntax">iname</span><span class="plain-syntax"> = </span><span class="identifier-syntax">Hierarchy::find</span><span class="plain-syntax">(</span><span class="identifier-syntax">BLKVALUEFREEONSTACK_HL</span><span class="plain-syntax">);</span>
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|
<span class="plain-syntax"> </span><span class="identifier-syntax">EmitCode::call</span><span class="plain-syntax">(</span><span class="identifier-syntax">iname</span><span class="plain-syntax">);</span>
|
|
<span class="plain-syntax"> </span><span class="identifier-syntax">EmitCode::down</span><span class="plain-syntax">();</span>
|
|
<span class="plain-syntax"> </span><span class="identifier-syntax">EmitCode::val_number</span><span class="plain-syntax">((</span><span class="identifier-syntax">inter_ti</span><span class="plain-syntax">) </span><span class="identifier-syntax">lbv</span><span class="plain-syntax">-></span><span class="element-syntax">offset_index</span><span class="plain-syntax">);</span>
|
|
<span class="plain-syntax"> </span><span class="identifier-syntax">EmitCode::up</span><span class="plain-syntax">();</span>
|
|
<span class="plain-syntax"> }</span>
|
|
|
|
<span class="plain-syntax"> </span><span class="identifier-syntax">EmitCode::pull</span><span class="plain-syntax">(</span><span class="identifier-syntax">Hierarchy::find</span><span class="plain-syntax">(</span><span class="identifier-syntax">I7SFRAME_HL</span><span class="plain-syntax">));</span>
|
|
<span class="plain-syntax">}</span>
|
|
</pre>
|
|
<p class="commentary firstcommentary"><a id="SP21" class="paragraph-anchor"></a><b>§21. </b>The net effect is that when the rest of Inform needs to compile the address
|
|
of a newly-allocated value of a block kind <span class="extract"><span class="extract-syntax">K</span></span>, it can simply call the
|
|
following, without having to worry about how any of this works:
|
|
</p>
|
|
|
|
<pre class="displayed-code all-displayed-code code-font">
|
|
<span class="reserved-syntax">void</span><span class="plain-syntax"> </span><span class="function-syntax">Frames::emit_new_local_value</span><button class="popup" onclick="togglePopup('usagePopup21')"><span class="comment-syntax">?</span><span class="popuptext" id="usagePopup21">Usage of <span class="code-font"><span class="function-syntax">Frames::emit_new_local_value</span></span>:<br/>Compile Values - <a href="2-cv.html#SP6_1">§6.1</a><br/>Compile Rvalues - <a href="2-cr.html#SP5">§5</a><br/>Deciding to Defer - <a href="4-dtd.html#SP11">§11</a>, <a href="4-dtd.html#SP17">§17</a><br/>Compile Invocations As Calls - <a href="5-ciac.html#SP2_2">§2.2</a><br/>Compile Invocations Inline - <a href="5-cii.html#SP3_2">§3.2</a>, <a href="5-cii.html#SP6_2_1">§6.2.1</a></span></button><span class="plain-syntax">(</span><span class="identifier-syntax">kind</span><span class="plain-syntax"> *</span><span class="identifier-syntax">K</span><span class="plain-syntax">) {</span>
|
|
<span class="plain-syntax"> </span><span class="reserved-syntax">local_block_value</span><span class="plain-syntax"> *</span><span class="identifier-syntax">bv</span><span class="plain-syntax"> = </span><a href="3-sf.html#SP16" class="function-link"><span class="function-syntax">Frames::allocate_local_block_value</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">K</span><span class="plain-syntax">);</span>
|
|
<span class="plain-syntax"> </span><a href="4-cs.html#SP1" class="function-link"><span class="function-syntax">CompileSchemas::from_terms_in_val_context</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">bv</span><span class="plain-syntax">-></span><span class="element-syntax">to_refer</span><span class="plain-syntax">, </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">, </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">);</span>
|
|
<span class="plain-syntax">}</span>
|
|
</pre>
|
|
<p class="commentary firstcommentary"><a id="SP22" class="paragraph-anchor"></a><b>§22. Logging. </b></p>
|
|
|
|
<pre class="displayed-code all-displayed-code code-font">
|
|
<span class="reserved-syntax">void</span><span class="plain-syntax"> </span><span class="function-syntax">Frames::log</span><span class="plain-syntax">(</span><span class="reserved-syntax">stack_frame</span><span class="plain-syntax"> *</span><span class="identifier-syntax">frame</span><span class="plain-syntax">) {</span>
|
|
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">frame</span><span class="plain-syntax"> == </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">) { </span><span class="identifier-syntax">LOG</span><span class="plain-syntax">(</span><span class="string-syntax">"<null stack frame>\n"</span><span class="plain-syntax">); </span><span class="reserved-syntax">return</span><span class="plain-syntax">; }</span>
|
|
<span class="plain-syntax"> </span><span class="identifier-syntax">LOG</span><span class="plain-syntax">(</span><span class="string-syntax">"Stack frame at %08x: it:%s, dpc:%s\n"</span><span class="plain-syntax">,</span>
|
|
<span class="plain-syntax"> </span><span class="identifier-syntax">frame</span><span class="plain-syntax">,</span>
|
|
<span class="plain-syntax"> (</span><span class="identifier-syntax">frame</span><span class="plain-syntax">-></span><span class="element-syntax">local_variables</span><span class="plain-syntax">.</span><span class="element-syntax">it_variable_exists</span><span class="plain-syntax">)?</span><span class="string-syntax">"yes"</span><span class="plain-syntax">:</span><span class="string-syntax">"no"</span><span class="plain-syntax">,</span>
|
|
<span class="plain-syntax"> (</span><span class="identifier-syntax">frame</span><span class="plain-syntax">-></span><span class="element-syntax">determines_past_conditions</span><span class="plain-syntax">)?</span><span class="string-syntax">"yes"</span><span class="plain-syntax">:</span><span class="string-syntax">"no"</span><span class="plain-syntax">);</span>
|
|
<span class="plain-syntax"> </span><span class="reserved-syntax">local_variable</span><span class="plain-syntax"> *</span><span class="identifier-syntax">lvar</span><span class="plain-syntax">;</span>
|
|
<span class="plain-syntax"> </span><span class="identifier-syntax">LOOP_OVER_LOCALS_IN_FRAME</span><span class="plain-syntax">(</span><span class="identifier-syntax">lvar</span><span class="plain-syntax">, </span><span class="identifier-syntax">frame</span><span class="plain-syntax">) {</span>
|
|
<span class="plain-syntax"> </span><span class="reserved-syntax">switch</span><span class="plain-syntax"> (</span><span class="identifier-syntax">lvar</span><span class="plain-syntax">-></span><span class="element-syntax">lv_purpose</span><span class="plain-syntax">) {</span>
|
|
<span class="plain-syntax"> </span><span class="reserved-syntax">case</span><span class="plain-syntax"> </span><span class="identifier-syntax">LET_VALUE_LV:</span><span class="plain-syntax"> </span><span class="identifier-syntax">LOG</span><span class="plain-syntax">(</span><span class="string-syntax">"Let/loop value: "</span><span class="plain-syntax">); </span><span class="reserved-syntax">break</span><span class="plain-syntax">;</span>
|
|
<span class="plain-syntax"> </span><span class="reserved-syntax">case</span><span class="plain-syntax"> </span><span class="identifier-syntax">TOKEN_CALL_PARAMETER_LV:</span><span class="plain-syntax"> </span><span class="identifier-syntax">LOG</span><span class="plain-syntax">(</span><span class="string-syntax">"Call value: "</span><span class="plain-syntax">); </span><span class="reserved-syntax">break</span><span class="plain-syntax">;</span>
|
|
<span class="plain-syntax"> </span><span class="reserved-syntax">case</span><span class="plain-syntax"> </span><span class="identifier-syntax">INTERNAL_USE_LV:</span><span class="plain-syntax"> </span><span class="identifier-syntax">LOG</span><span class="plain-syntax">(</span><span class="string-syntax">"Internal use: "</span><span class="plain-syntax">); </span><span class="reserved-syntax">break</span><span class="plain-syntax">;</span>
|
|
<span class="plain-syntax"> </span><span class="identifier-syntax">default:</span><span class="plain-syntax"> </span><span class="identifier-syntax">LOG</span><span class="plain-syntax">(</span><span class="string-syntax">"Other: "</span><span class="plain-syntax">); </span><span class="reserved-syntax">break</span><span class="plain-syntax">;</span>
|
|
<span class="plain-syntax"> }</span>
|
|
<span class="plain-syntax"> </span><span class="identifier-syntax">LOG</span><span class="plain-syntax">(</span><span class="string-syntax">"%~L: "</span><span class="plain-syntax">, </span><span class="identifier-syntax">lvar</span><span class="plain-syntax">);</span>
|
|
<span class="plain-syntax"> </span><a href="3-lv.html#SP26" class="function-link"><span class="function-syntax">LocalVariables::log</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">lvar</span><span class="plain-syntax">); </span><span class="identifier-syntax">LOG</span><span class="plain-syntax">(</span><span class="string-syntax">"\n"</span><span class="plain-syntax">);</span>
|
|
<span class="plain-syntax"> }</span>
|
|
<span class="plain-syntax">}</span>
|
|
</pre>
|
|
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