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<a name="1205449"> </a><font color="#003366" face="Verdana, Arial, Helvetica, sans-serif">8.5 Simulating traps</font>
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<a name="1205465"> </a><font size=2 face="Verdana, Arial, Helvetica, sans-serif">The <strong>causeerror</strong> instruction allows a process to cause a specific trap condition. A trap condition is signalled by setting the relevant trap bit in <span class=Signal>Areg</span> (only one trap bit must be set). If the relevant trap is enabled then that trap bit is set in the trap bits in the <span class=Signal>Status</span> register along with the <span class=Signal>CauseErrorFlag</span>.</font>
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<a name="1204709"> </a><font size=2 face="Verdana, Arial, Helvetica, sans-serif">If the trap being set is a scheduler trap then <span class=Signal>Breg</span> is used to contain further information. If the scheduler trap relates to a process scheduling event then <span class=Signal>Breg</span> holds the process descriptor of the process whose scheduling is considered to be the cause of the trap. For the other scheduler traps, the priority bits of the process descriptor in <span class=Signal>Breg</span> are used to indicate at which priority level this scheduler trap is to occur (this is also the case for process scheduling traps where the priority of the process to be scheduled determines the priority of the scheduler trap).
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<caption><b><i><font face="Verdana, Arial, Helvetica, sans-serif"><a name="1206107"> </a><font face="Helvetica">Table 59: Instruction to simulate a trap condition</font></font></i></b></caption>
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<th><font face="Verdana, Arial, Helvetica, sans-serif" color="#003366"><a name="1206098"> </a><font face="Verdana, Arial, Helvetica, sans-serif">Mnemonic</font></font></th>
<th><font face="Verdana, Arial, Helvetica, sans-serif" color="#003366"><a name="1206100"> </a><font face="Verdana, Arial, Helvetica, sans-serif">Name</font></font></th>
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<td><font face="Verdana, Arial, Helvetica, sans-serif"><a name="1206103"> </a><div ><font size=2><strong>causeerror</strong></font></div></font></td>
<td><font face="Verdana, Arial, Helvetica, sans-serif"><a name="1206105"> </a><div ><font size=2>Cause a trap condition</font></div></font></td>
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