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11<H1 align="left">DC_LockdownRange <IMG src="../../image/NTR.gif" align="middle"><IMG src="../../image/TWL.gif" align="middle"></H1>
12<H2>Syntax</H2>
13<DL>
14  <DD>
15  <PRE><CODE>#include &lt;nitro/os.h&gt;</CODE></PRE>
16  <PRE><CODE>void DC_LockdownRange( const void* startAddr, u32 nBytes );</CODE></PRE>
17</DL>
18<H2>Arguments</H2>
19<TABLE border="1" width="100%">
20  <TBODY>
21    <TR>
22      <TD width="13%"><EM><STRONG>startAddr</STRONG></EM></TD>
23      <TD width="87%">Lowest address in the region to be locked down</TD>
24    </TR>
25    <TR>
26      <TD width="13%"><EM><STRONG>nBytes</STRONG></EM></TD>
27      <TD width="87%">Number of bytes of the region to be locked down (maximum is 1 KB)</TD>
28    </TR>
29  </TBODY>
30</TABLE>
31<H2>Return Values</H2>
32<P>None.</P>
33<H2>Description</H2>
34<P>Locks the contents of the data cache that is hit by the specified region, so that the cache won't be discarded.</P>
35<P>However, because the cache is locked in blocks of 1 KB, each time this function is called, the area that can be used as cache is locked by 1 KB more, boosting the miss rate. The function can lock down a maximum of three blocks of data cache.</P>
36<P><B><I>startAddr</I></B> is rounded down to the closest 32-byte boundary. The sum of <B><I>startAddr</I></B> + <B><I>nBytes</I></B> is rounded up to the closest 32-byte boundary.</P>
37<H2>Internal Operation</H2>
38<P>Operates registers 7 and 9 of the system control coprocessor. While the specified data is being loaded into the cache, interrupts are disabled internally.</P>
39<H2>See Also</H2>
40<P><CODE><A href="DC_TouchRange.html">DC_TouchRange</A>, <A href="DC_Unlockdown.html">DC_Unlockdown</A>, <A href="DC_UnlockdownAll.html">DC_UnlockdownAll</A></CODE></P>
41<H2>Revision History</H2>
42<P>
432005/11/14 Changed the type of startAddr to const void* <br> 2005/01/21 Added a description the lockdown block. <BR> 2003/12/22 Initial release.</P>
44<hr><p>CONFIDENTIAL</p></body>
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