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<html>
<head>
<title>PM0044 5.4.4 Pipeline stalled, table 12</title>
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.pipetrace td.Sbus:before { content: " S₀"; }
.pipetrace td.Sfetch:before { content: " S₁"; }
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<h1>PM0044 5.4.4 Pipeline stalled, table 12</h1>
<table id="pipetrace_legend" class="pipetrace">
<tr><td colspan="2">Legend</td></tr>
<tr><td class="D" /><td class="defn">Decode</td></tr>
<tr><td class="E" /><td class="defn">Execute</td></tr>
<tr><td><span class="F" /></td><td class="defn">Fetch</td></tr>
<tr><td class="X" /><td class="defn">Flush</td></tr>
<tr><td><span class="FS" /></td><td class="defn">Fetch Stall - space in prefetch buffer but bus busy</td></tr>
<tr><td class="Sbus" /><td class="defn">Decode Stall - bus busy</td></tr>
<tr><td class="Sfetch" /><td class="defn">Decode Stall - insufficient data in prefetch buffer</td></tr>
<tr><td class="Sraw" /><td class="defn">Decode Stall - read after write</td></tr>
</table>
<h2>Errata</h2>
<ul>
<li>Table 12 shows the BTJT as taking 1 decode, 2 execute cycles but the
later documentation for the instruction implies the second execution
cycle is only used if the branch is taken - and this isn't.
</li>
<li>Table 12 has a jump in time (cycles) from 4 straight to 7.
</li>
<li>The last instruction is shown one cycle early in table 12. The decode stall
should line up with the execution cycle of the previous instruction
as the description above the table says.
</li>
</ul>
<a title="Click for legend">
<table class="pipetrace" onclick="toggle('pipetrace_legend')">
<tbody>
<tr><td /><td class="Flushed" /></tr>
<tr><td>0x080e0</td><td class="instr">sub SP,#0x14</td><td class=""><span class="F" /></td><td class=" D"><span class="F" /></td><td class=" E" /></tr>
<tr><td>0x080e2</td><td class="instr">ld A,#0x14</td><td class="" /><td class="" /><td class=" D"><span class="F" /></td><td class=" E" /></tr>
<tr><td>0x080e4</td><td class="instr">btjt 0x0010,#5,0x80f8</td><td class="" /><td class="" /><td class="" /><td class=" D"><span class="F" /></td><td class=" E" /></tr>
<tr><td>0x080e9</td><td class="instr">inc A</td><td class="" /><td class="" /><td class="" /><td class="" /><td class=" D"><span class="F" /></td><td class=" E" /></tr>
<tr><td>0x080ea</td><td class="instr">btjf 0x0020,#3,0x80f8</td><td class="" /><td class="" /><td class="" /><td class="" /><td class="" /><td class=" D"><span class="F" /></td><td class=" E X"></td><td class=" E" /></tr>
<tr><td /><td class="Flushed" /></tr>
<tr><td>0x080f8</td><td class="instr">incw Y</td><td class="" /><td class="" /><td class="" /><td class="" /><td class="" /><td class="" /><td class="" /><td class=""><span class="F" /></td><td class=" D"><span class="F" /></td><td class=" E" /></tr>
<tr><td>0x080fa</td><td class="instr">ld A,(X)</td><td class="" /><td class="" /><td class="" /><td class="" /><td class="" /><td class="" /><td class="" /><td class="" /><td class="" /><td class=" D Sraw"><span class="F" /></td><td class=" D"></td><td class=" E" /></tr>
</tbody>
<thead>
<tr><th>Address</th><th>Instruction</th><th class="n">1</th><th class="n">2</th><th class="n">3</th><th class="n">4</th><th class="n">5</th><th class="n">6</th><th class="n">7</th><th class="n">8</th><th class="n">9</th><th class="n">10</th><th class="n">11</th><th class="n">12</th>
</thead>
</table>
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