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9<title>OSInitFastCast</title>
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13
14<h1>OSInitFastCast</h1>
15
16
17<h2>C Specification</h2>
18<BLOCKQUOTE>
19<pre><CODE>
20#include &lt;revolution/OSFastCast.h&gt;
21
22void OSInitFastCast (void);
23</CODE></pre>
24</BLOCKQUOTE>
25<h2>Arguments</h2>
26
27<p>None.</p>
28
29<h2>Return Values</h2>
30
31<p>None.</p>
32<H2>Description</H2>
33<P>Sets up the fast floating point number/integer casting feature.&nbsp;This function must be called before invoking any of the fast cast routines.</P>
34<P>The <CODE>OSInitFastCast</CODE> function must be invoked before&nbsp;any fast cast routines (in <CODE>OSFastCast.h</CODE>) are called.  In addition, the fast cast APIs require that applications not change Broadway GQRs (quantization registers) 2 through 5 (GCR0 is reserved in advance for single-precision floating points, and GCR1 is reserved for the compiler).</P>
35<P>The fast cast API group uses Broadway's single load/store instructions which includes a quantization instruction that converts a floating point number to an integer in only two instructions (load and store). </P>
36<P>The GQRs are set to the following values:</P>
37<DIV align="left">
38<TABLE border="1" cellpadding="3" cellspacing="0.1">
39  <TBODY>
40    <TR>
41<TD width="120">GQR 2</TD>
42<TD width="300">Load u8 / Store u8.&nbsp;No scaling.</TD>
43    </TR>
44    <TR>
45<TD width="120">GQR 3</TD>
46<TD width="300">Load u16 / Store u16.&nbsp;No scaling.</TD>
47    </TR>
48    <TR>
49<TD width="120">GQR 4</TD>
50<TD width="300">Load s8 / Store s8.&nbsp;No scaling.</TD>
51    </TR>
52    <TR>
53<TD width="120">GQR 5</TD>
54<TD width="300">Load s16 / Store s16.&nbsp;No scaling.</TD>
55    </TR>
56  </TBODY>
57</TABLE>
58</DIV>
59
60
61
62<h2>See Also</h2>
63
64<p><code><a href="OSInitFastCast.html">OSInitFastCast</a>, <a href="OSf32tos16.html">OSf32tos16</a>, <a href="OSf32tos8.html">OSf32tos8</a>, <a href="OSf32tou16.html">OSf32tou16</a>, <a href="OSf32tou8.html">OSf32tou8</a>, <a href="OSs16tof32.html">OSs16tof32</a>, <a href="OSs8tof32.html">OSs8tof32</a>, <a href="OSu16tof32.html">OSu16tof32</a>, <a href="OSu8tof32.html">OSu8tof32</a></code></p>
65<H2>Revision History</H2>
66<P>03/01/2006 Initial version.</P>
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