1<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> 2<html> 3 4<head> 5<META http-equiv="Content-Type" content="text/html; charset=windows-1252"> 6<META name="GENERATOR" content="Microsoft FrontPage 5.0"> 7<META http-equiv="Content-Style-Type" content="text/css"> 8<LINK rel="stylesheet" type="text/css" href="../../CSS/revolution.css"> 9<title>OSInitFastCast</title> 10</head> 11 12<body> 13 14<h1>OSInitFastCast</h1> 15 16 17<h2>C Specification</h2> 18<BLOCKQUOTE> 19<pre><CODE> 20#include <revolution/OSFastCast.h> 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 floating point number/integer fast cast feature. This function must be called before invoking any of the fast cast routines. Furthermore, the effect of <FONT face="Courier New">OSInitFastCast</FONT> is limited to threads that call this function.</P> 34<P>The <CODE>OSInitFastCast</CODE> function must be invoked before any fast cast routines (in <CODE>OSFastCast.h</CODE>) are called. In addition, the fast cast functions require that applications not touch Broadway GQRs (quantization registers) 2 through 5 (GCR0 is already reserved for basic single floats, and GCR1 is reserved by the compiler).</P> 35<P>The fast cast functions use Broadway's paired-single load/store instructions, including quantization, to convert floats to ints and vice versa using just 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. No scaling.</TD> 43 </TR> 44 <TR> 45<TD width="120">GQR 3</TD> 46<TD width="300">Load u16 / Store u16. No scaling.</TD> 47 </TR> 48 <TR> 49<TD width="120">GQR 4</TD> 50<TD width="300">Load s8 / Store s8. No scaling.</TD> 51 </TR> 52 <TR> 53<TD width="120">GQR 5</TD> 54<TD width="300">Load s16 / Store s16. No scaling.</TD> 55 </TR> 56 </TBODY> 57</TABLE> 58</DIV> 59 60<h2>See Also</h2> 61<p> 62<code><a href="OSf32tos16.html">OSf32tos16</a><BR> <a href="OSf32tos8.html">OSf32tos8</a><BR> <a href="OSf32tou16.html">OSf32tou16</a><BR> <a href="OSf32tou8.html">OSf32tou8</a><BR> <a href="OSs16tof32.html">OSs16tof32</a><BR> <a href="OSs8tof32.html">OSs8tof32</a><BR> <a href="OSu16tof32.html">OSu16tof32</a><BR> <a href="OSu8tof32.html">OSu8tof32</a></code> 63</p> 64 65<H2>Revision History</H2> 66<P> 672007/01/10 Added information about the effect of this function and its scope.<BR> 2006/03/01 Initial version. <BR> 68</P> 69<hr> 70<P>CONFIDENTIAL</p> 71</BODY> 72</HTML> 73