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Graham Nelson 2059114dd1 Tiding up fix for I7-2416
2023-08-30 22:09:04 +01:00

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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
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<title>State Template</title>
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<ul class="crumbs"><li><a href="../index.html">Home</a></li><li><a href="../extensions.html">Kits</a></li><li><a href="index.html">Architecture32Kit</a></li><li><b>State Template</b></li></ul></div>
<p class="purpose">Saving, restoring, restarting and verifying the program from within itself.</p>
<ul class="toc"><li><a href="S-stt.html#SP1">&#167;1. Environment</a></li><li><a href="S-stt.html#SP2">&#167;2. Verification</a></li><li><a href="S-stt.html#SP3">&#167;3. Save, restore, restart</a></li><li><a href="S-stt.html#SP4">&#167;4. Undo</a></li></ul><hr class="tocbar">
<p class="commentary firstcommentary"><a id="SP1" class="paragraph-anchor"></a><b>&#167;1. Environment. </b>The language "interpreter" here supposes that the eventual program is
running in a VM which is being interpreted, and that may not be the case,
but it's traditional.
</p>
<pre class="displayed-code all-displayed-code code-font">
<span class="plain-syntax">[ </span><span class="identifier-syntax">VM_ReportOnInterpreter</span><span class="plain-syntax"> </span><span class="identifier-syntax">ix</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> @</span><span class="identifier-syntax">gestalt</span><span class="plain-syntax"> </span><span class="constant-syntax">1</span><span class="plain-syntax"> </span><span class="constant-syntax">0</span><span class="plain-syntax"> </span><span class="identifier-syntax">ix</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">print</span><span class="plain-syntax"> </span><span class="string-syntax">"Interpreter version "</span><span class="plain-syntax">, </span><span class="identifier-syntax">ix</span><span class="plain-syntax"> / </span><span class="constant-syntax">$10000</span><span class="plain-syntax">, </span><span class="string-syntax">"."</span><span class="plain-syntax">, (</span><span class="identifier-syntax">ix</span><span class="plain-syntax"> &amp; </span><span class="constant-syntax">$FF00</span><span class="plain-syntax">) / </span><span class="constant-syntax">$100</span><span class="plain-syntax">,</span>
<span class="plain-syntax"> </span><span class="string-syntax">"."</span><span class="plain-syntax">, </span><span class="identifier-syntax">ix</span><span class="plain-syntax"> &amp; </span><span class="constant-syntax">$FF</span><span class="plain-syntax">, </span><span class="string-syntax">" / "</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> @</span><span class="identifier-syntax">gestalt</span><span class="plain-syntax"> </span><span class="constant-syntax">0</span><span class="plain-syntax"> </span><span class="constant-syntax">0</span><span class="plain-syntax"> </span><span class="identifier-syntax">ix</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">print</span><span class="plain-syntax"> </span><span class="string-syntax">"VM "</span><span class="plain-syntax">, </span><span class="identifier-syntax">ix</span><span class="plain-syntax"> / </span><span class="constant-syntax">$10000</span><span class="plain-syntax">, </span><span class="string-syntax">"."</span><span class="plain-syntax">, (</span><span class="identifier-syntax">ix</span><span class="plain-syntax"> &amp; </span><span class="constant-syntax">$FF00</span><span class="plain-syntax">) / </span><span class="constant-syntax">$100</span><span class="plain-syntax">, </span><span class="string-syntax">"."</span><span class="plain-syntax">, </span><span class="identifier-syntax">ix</span><span class="plain-syntax"> &amp; </span><span class="constant-syntax">$FF</span><span class="plain-syntax">, </span><span class="string-syntax">"^"</span><span class="plain-syntax">;</span>
<span class="plain-syntax">];</span>
</pre>
<p class="commentary firstcommentary"><a id="SP2" class="paragraph-anchor"></a><b>&#167;2. Verification. </b>This verifies that the current story file is intact.
</p>
<pre class="displayed-code all-displayed-code code-font">
<span class="plain-syntax">[ </span><span class="identifier-syntax">VM_Verify</span><span class="plain-syntax"> </span><span class="identifier-syntax">res</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> @</span><span class="identifier-syntax">verify</span><span class="plain-syntax"> </span><span class="identifier-syntax">res</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">res</span><span class="plain-syntax">;</span>
<span class="plain-syntax">];</span>
</pre>
<p class="commentary firstcommentary"><a id="SP3" class="paragraph-anchor"></a><b>&#167;3. Save, restore, restart. </b>Restart does what it says: restarts the program as if it had just loaded for
the first time.
</p>
<p class="commentary"><span class="extract"><span class="extract-syntax">VM_Save()</span></span> attempts to save the current state of the program to a file, and
returns 0 if this fails, 1 if this succeeds, or 2 if in fact a restore has
just succeeded. (A successful restoration should resume execution where the
save succeeded, but we want to distinguish those cases.)
</p>
<p class="commentary"><span class="extract"><span class="extract-syntax">VM_Restore()</span></span> pretends to return <span class="extract"><span class="extract-syntax">true</span></span> or <span class="extract"><span class="extract-syntax">false</span></span> according to whether or not
it succeeds, but in fact it can only return <span class="extract"><span class="extract-syntax">false</span></span> to indicate failure, because
a successful restoration means that execution has transferred to <span class="extract"><span class="extract-syntax">VM_Save</span></span>
instead.
</p>
<pre class="displayed-code all-displayed-code code-font">
<span class="plain-syntax">[ </span><span class="identifier-syntax">VM_Restart</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> @</span><span class="identifier-syntax">restart</span><span class="plain-syntax">;</span>
<span class="plain-syntax">];</span>
<span class="plain-syntax">[ </span><span class="identifier-syntax">VM_Restore</span><span class="plain-syntax"> </span><span class="identifier-syntax">res</span><span class="plain-syntax"> </span><span class="identifier-syntax">fref</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">fref</span><span class="plain-syntax"> = </span><span class="identifier-syntax">glk_fileref_create_by_prompt</span><span class="plain-syntax">(</span><span class="constant-syntax">$01</span><span class="plain-syntax">, </span><span class="constant-syntax">$02</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">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">fref</span><span class="plain-syntax"> == </span><span class="constant-syntax">0</span><span class="plain-syntax">) </span><span class="reserved-syntax">jump</span><span class="plain-syntax"> </span><span class="identifier-syntax">RFailed</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">gg_savestr</span><span class="plain-syntax"> = </span><span class="identifier-syntax">glk_stream_open_file</span><span class="plain-syntax">(</span><span class="identifier-syntax">fref</span><span class="plain-syntax">, </span><span class="constant-syntax">$02</span><span class="plain-syntax">, </span><span class="identifier-syntax">GG_SAVESTR_ROCK</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">glk_fileref_destroy</span><span class="plain-syntax">(</span><span class="identifier-syntax">fref</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">gg_savestr</span><span class="plain-syntax"> == </span><span class="constant-syntax">0</span><span class="plain-syntax">) </span><span class="reserved-syntax">jump</span><span class="plain-syntax"> </span><span class="identifier-syntax">RFailed</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> @</span><span class="reserved-syntax">restore</span><span class="plain-syntax"> </span><span class="identifier-syntax">gg_savestr</span><span class="plain-syntax"> </span><span class="identifier-syntax">res</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">glk_stream_close</span><span class="plain-syntax">(</span><span class="identifier-syntax">gg_savestr</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">gg_savestr</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">RFailed</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">rfalse</span><span class="plain-syntax">;</span>
<span class="plain-syntax">];</span>
<span class="plain-syntax">[ </span><span class="identifier-syntax">VM_Save</span><span class="plain-syntax"> </span><span class="identifier-syntax">fref</span><span class="plain-syntax"> </span><span class="identifier-syntax">len</span><span class="plain-syntax"> </span><span class="identifier-syntax">res</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">fref</span><span class="plain-syntax"> = </span><span class="identifier-syntax">glk_fileref_create_by_prompt</span><span class="plain-syntax">(</span><span class="identifier-syntax">fileusage_SavedGame</span><span class="plain-syntax">, </span><span class="identifier-syntax">filemode_Write</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">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">fref</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">gg_savestr</span><span class="plain-syntax"> = </span><span class="identifier-syntax">glk_stream_open_file</span><span class="plain-syntax">(</span><span class="identifier-syntax">fref</span><span class="plain-syntax">, </span><span class="identifier-syntax">filemode_Write</span><span class="plain-syntax">, </span><span class="identifier-syntax">GG_SAVESTR_ROCK</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">gg_savestr</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> @</span><span class="reserved-syntax">save</span><span class="plain-syntax"> </span><span class="identifier-syntax">gg_savestr</span><span class="plain-syntax"> </span><span class="identifier-syntax">res</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">res</span><span class="plain-syntax"> == -1) {</span>
<span class="plain-syntax"> </span><span class="comment-syntax">The player actually just typed "restore". We first have to recover</span>
<span class="plain-syntax"> </span><span class="comment-syntax">all the Glk objects; the values in our global variables are all wrong.</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">GGRecoverObjects</span><span class="plain-syntax">();</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">glk_stream_close</span><span class="plain-syntax">(</span><span class="identifier-syntax">gg_savestr</span><span class="plain-syntax">, </span><span class="identifier-syntax">GLK_NULL</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">gg_savestr</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="constant-syntax">2</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> }</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">glk_stream_close</span><span class="plain-syntax">(</span><span class="identifier-syntax">gg_savestr</span><span class="plain-syntax">, </span><span class="identifier-syntax">GLK_NULL</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">gg_savestr</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">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">res</span><span class="plain-syntax"> == </span><span class="constant-syntax">0</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><span class="comment-syntax">Check that the savefile was actually written - this is mostly to account for browser limits in Parchment</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">glk_fileref_does_file_exist</span><span class="plain-syntax">(</span><span class="identifier-syntax">fref</span><span class="plain-syntax">)) {</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">gg_savestr</span><span class="plain-syntax"> = </span><span class="identifier-syntax">glk_stream_open_file</span><span class="plain-syntax">(</span><span class="identifier-syntax">fref</span><span class="plain-syntax">, </span><span class="identifier-syntax">filemode_Read</span><span class="plain-syntax">, </span><span class="identifier-syntax">GG_SAVESTR_ROCK</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">gg_savestr</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">glk_stream_set_position</span><span class="plain-syntax">(</span><span class="identifier-syntax">gg_savestr</span><span class="plain-syntax">, </span><span class="constant-syntax">0</span><span class="plain-syntax">, </span><span class="identifier-syntax">seekmode_End</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">len</span><span class="plain-syntax"> = </span><span class="identifier-syntax">glk_stream_get_position</span><span class="plain-syntax">(</span><span class="identifier-syntax">gg_savestr</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">glk_stream_close</span><span class="plain-syntax">(</span><span class="identifier-syntax">gg_savestr</span><span class="plain-syntax">, </span><span class="identifier-syntax">GLK_NULL</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">gg_savestr</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">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">len</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><span class="comment-syntax">We've confirmed the file exists and has content, which is about all we can do</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">glk_fileref_destroy</span><span class="plain-syntax">(</span><span class="identifier-syntax">fref</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">return</span><span class="plain-syntax"> </span><span class="constant-syntax">1</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> }</span>
<span class="plain-syntax"> </span><span class="comment-syntax">Cleanup the empty file</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">glk_fileref_delete_file</span><span class="plain-syntax">(</span><span class="identifier-syntax">fref</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> }</span>
<span class="plain-syntax"> }</span>
<span class="plain-syntax"> }</span>
<span class="plain-syntax"> }</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">glk_fileref_destroy</span><span class="plain-syntax">(</span><span class="identifier-syntax">fref</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="constant-syntax">0</span><span class="plain-syntax">;</span>
<span class="plain-syntax">];</span>
</pre>
<p class="commentary firstcommentary"><a id="SP4" class="paragraph-anchor"></a><b>&#167;4. Undo. </b>These are really emulations of the Z-machine's conventions on UNDO.
</p>
<pre class="displayed-code all-displayed-code code-font">
<span class="plain-syntax">[ </span><span class="identifier-syntax">VM_Undo</span><span class="plain-syntax"> </span><span class="identifier-syntax">result_code</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> @</span><span class="identifier-syntax">restoreundo</span><span class="plain-syntax"> </span><span class="identifier-syntax">result_code</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">result_code</span><span class="plain-syntax">);</span>
<span class="plain-syntax">];</span>
<span class="plain-syntax">[ </span><span class="identifier-syntax">VM_Save_Undo</span><span class="plain-syntax"> </span><span class="identifier-syntax">result_code</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> @</span><span class="identifier-syntax">saveundo</span><span class="plain-syntax"> </span><span class="identifier-syntax">result_code</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">result_code</span><span class="plain-syntax"> == -1) { </span><span class="identifier-syntax">GGRecoverObjects</span><span class="plain-syntax">(); </span><span class="reserved-syntax">return</span><span class="plain-syntax"> </span><span class="constant-syntax">2</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">result_code</span><span class="plain-syntax">);</span>
<span class="plain-syntax">];</span>
</pre>
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