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9<title>GXEnableBreakPt</title>
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14<h1 align="left">GXEnableBreakPt</h1>
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16
17<h2>C Specification</h2>
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19<dl>
20<dd><PRE><CODE>#include &lt;revolution/gx.h&gt;</CODE></PRE>
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22<dd><pre><CODE>void GXEnableBreakPt( void* break_pt );</CODE></pre>
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26<h2>Arguments</h2>
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30<TD width="120" bgcolor="#ffffe8"><code><strong><em>break_pt</em></strong></code></TD>
31<TD width="520">Breakpoint address.</TD>
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36<h2>Return Values</h2>
37<P>None.</P>
38<H2>Description</H2>
39<P>This function sets the break point address for the&nbsp; FIFO currently attached to the Graphics Processor (GP) (see <a href="GXSetGPFifo.html"><code>GXSetGPFifo</code></a>).&nbsp;FIFO reads will stall when the GP FIFO read pointer is equal to the break point address.&nbsp;To re-enable reads of the GP FIFO, use <a href="GXDisableBreakPt.html"><code>GXDisableBreakPoint</code></a>.</P>
40<P>You can install a callback to be invoked when the break point is encountered with the <code><a href="GXSetBreakPtCallback.html">GXSetBreakPtCallback</a></code> API.</P>
41<P>The break point feature allows the application to have two frames of graphics in the FIFO at the same time, overlapping one frame's processing by the graphics processor with another frame's processing by the CPU.&nbsp;</P>
42<P>For example, suppose you finish writing the graphics commands for one frame and are ready to start on the next.&nbsp;First, execute a <a href="../Management/GXFlush.html"><code>GXFlush</code></a> command to make sure all the data in the CPU write gatherer is flushed into the FIFO.&nbsp;This will also align the FIFO write pointer to a 32-byte boundary. Next, read the value of the current write pointer using <code>GXGetFifoPtrs</code>.&nbsp;Write the value of the write pointer as the break point address using <code>GXEnableBreakPt</code>. When the FIFO read pointer reaches the break point address the hardware will disable reads from the FIFO.&nbsp;The status <em><strong><code>brkpt</code></strong></em> returned by the <a href="GXGetGPStatus.html"><code>GXGetGPStatus</code></a> function can monitor the detection when the break point is reached.&nbsp;The application can then decide when to disable the break point, using <a href="GXDisableBreakPt.html"><code>GXDisableBreakPt</code></a>, which will allow the FIFO to resume reading graphics commands.</P>
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45<h2>See Also</h2>
46<P><a href="GXDisableBreakPt.html">GXDisableBreakPt</a><a href="GXSetBreakPtCallback.html"><br> GXSetBreakPtCallback</a><br></P>
47<H2>Revision History</H2>
48<P>2006/03/01 Initial version.</P>
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50<P>CONFIDENTIAL</p>
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