1<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> 2<html> 3<head> 4<META http-equiv="Content-Type" content="text/html; charset=windows-1252"> 5<META name="GENERATOR" content="IBM WebSphere Studio Homepage Builder Version 6.5.0.0 for Windows"> 6<META http-equiv="Content-Style-Type" content="text/css"> 7<LINK rel="stylesheet" type="text/css" href="../CSS/revolution.css"> 8<title>DVDReadPrio</title> 9</head> 10 11<body> 12 13<h1>DVDReadPrio<BR>DVDReadAsyncPrio</h1> 14<h2>C Specification</h2> 15 16<dl> 17 <dd><pre><code>#include <revolution/dvd.h></code></pre> 18<dd><pre><CODE>typedef void (*DVDCallback)(s32 result, DVDFileInfo* fileInfo);</CODE></pre> 19<dd><pre><CODE>s32 DVDReadPrio ( DVDFileInfo* fileInfo, void* addr, s32 length, 20s32 offset, s32 prio ); 21 22BOOL DVDReadAsyncPrio ( DVDFileInfo* fileInfo, void* addr, s32 length, 23s32 offset, 24DVDCallback callback, s32 prio );</CODE></pre> 25</dl> 26<h2>Arguments</h2> 27<TABLE border="1" cellpadding="3" cellspacing="0.1"> 28 <tr> 29<TD width="120" bgcolor="#ffffe8"><em><strong><code>fileInfo</code></strong></em></TD> 30<TD width="520">File information retrieved by calling the <A href="DVDOpen.html"><CODE>DVDOpen</CODE></A> function.</TD> 31 </tr> 32 <tr> 33<TD width="120" bgcolor="#ffffe8"><em><strong><code>addr</code></strong></em></TD> 34<TD width="520">Buffer address. Should be 32-byte aligned.</TD> 35 </tr> 36 <tr> 37<TD width="120" bgcolor="#ffffe8"><em><strong><code><STRONG><EM><CODE>length</CODE></EM></STRONG></code></strong></em></TD> 38<TD width="520">Number of bytes to read. Must be a multiple of 32.</TD> 39 </tr> 40 <tr> 41<TD width="120" bgcolor="#ffffe8"><em><strong><code><STRONG><EM><CODE>offset</CODE></EM></STRONG></code></strong></em></TD> 42<TD width="520">File position to start read from. Must be a multiple of 4.</TD> 43 </tr> 44 <tr> 45<TD width="120" bgcolor="#ffffe8"><em><strong><code>callback</code></strong></em></TD> 46<TD width="520">Address of callback function to notify about the read result (only for the <code>DVDReadAsyncPrio</code> function).</TD> 47 </tr> 48 <tr> 49<TD width="120" bgcolor="#ffffe8"><em><strong><code>prio</code></strong></em></TD> 50<TD width="520">Queue priority for entering a read request.</TD> 51 </tr> 52</TABLE> 53<h2>Return Values</h2> 54 55<P>The <CODE>DVDReadPrio</CODE> function returns the number of bytes read if the command completes successfully. Otherwise, returns a negative value.</P> 56<P>The <code>DVDReadAsyncPrio</code> function returns <CODE>TRUE</CODE> if the command is issued successfully and <CODE>FALSE</CODE> otherwise.</P> 57 58<H2>Description</H2> 59 60<P>The <A href="DVDReadAsync.html"><CODE>DVDReadAsync</CODE></A> and <CODE>DVDReadAsyncPrio</CODE> functions are essentially the same, but the <CODE>DVDReadAsyncPrio</CODE> function can specify the queue to use for entering read requests.</P> 61<P>Internally the DVD device driver manages four queues, queue 0 - 3; queue 0 has the highest priority and queue 3 has the lowest priority. Each queue is FIFO (First In First Out). The lead command of the queue with the highest priority is processed first.</P> 62<P>Normal DVD commands use queue 2.</P> 63<P>The <code>DVDSeekAsyncPrio</code> function lets you change the priority for read commands. In other words, you can specify the queue to use for a read request. </P> 64<P>For details, see the <A href="DVDReadAsync.html"><CODE>DVDReadAsync</CODE></A> function in the Function Reference.</P> 65<P>The <CODE>DVDReadPrio</CODE> function is the synchronous version of the <CODE>DVDReadAsyncPrio</CODE> function. For details, see the <A href="DVDRead.html"><CODE>DVDRead</CODE></A> function in the Function Reference.</P> 66<P><strong>Note:</strong> 67 Take care if you plan to use a synchronous function in a real game. Synchronous functions can only be used in a multithreaded game. In single thread games, synchronous functions can't be used because there is no way to check errors.</P> 68<h2>See Also</h2> 69 70<p><code><a href="DVDRead.html">DVDRead</a><BR> <a href="DVDReadAsync.html">DVDReadAsync</a><BR> <a href="DVDOpen.html">DVDOpen</a></code></p> 71<H2>Revision History</H2> 72<P>03/01/2006 Initial version.</P> 73</body> 74</html> 75