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>GXInitFifoLimits</title> 10</head> 11 12<body> 13 14<h1 align="left">GXInitFifoLimits</h1> 15 16<h2>Syntax</h2> 17<dl><dd><pre class="construction"> 18#include <revolution/gx.h> 19 20void GXInitFifoLimits( 21 <a href="../Structures/GXFifoObj.html">GXFifoObj</a>* fifo, 22 u32 hi_water_mark, 23 u32 lo_water_mark ); 24</pre></dd></dl> 25 26<h2>Arguments</h2> 27<TABLE class="arguments" border="1" > 28 <tr> 29<TH>fifo</TH> 30<TD>A pointer to the FIFO structure.</TD> 31 </tr> 32 <tr> 33<TH>hi_water_mark</TH> 34<TD>The byte count where the GX APIs halt command writes to FIFO. In 32-byte multiples.</TD> 35 </tr> 36 <tr> 37<TH>lo_water_mark</TH> 38<TD>The byte count where the GX APIs resume command writes to FIFO. In 32-byte multiples.</TD> 39 </tr> 40</TABLE> 41 42<h2>Return Values</h2> 43<p>None.</p> 44 45<H2>Description</H2> 46<P>This function sets the high and low water marks for the <SPAN class="argument">FIFO</SPAN>. The high and low water marks are used in <em>immediate mode</em>, that is, when the <SPAN class="argument">FIFO</SPAN> is attached to both the CPU and graphics processor (GP).(See <a href="GXSetCPUFifo.html"><code>GXSetCPUFifo</code></a> and <a href="GXSetGPFifo.html"><code>GXSetGPFifo</code></a>.)</P> 47<P>The hardware keeps track of the number of bytes between the read and write pointers. This number represents how full the FIFO is, and when it is greater than or equal to the <SPAN class="argument">hi_water_mark</SPAN>, the hardware issues an interrupt. GX functions will suspend sending graphics to the graphics FIFO until it has emptied to a certain point. The <SPAN class="argument">lo_water_mark</SPAN> is used to set the point where the FIFO is empty enough to resume sending graphics commands to the FIFO. Both the <SPAN class="argument">hi_water_mark</SPAN> and <SPAN class="argument">lo_water_mark</SPAN> should be in multiples of 32 bytes. The count for <SPAN class="argument">lo_water_mark</SPAN> should be less than <SPAN class="argument">hi_water_mark</SPAN>. Of course, <SPAN class="argument">hi_water_mark</SPAN> and <SPAN class="argument">lo_water_mark</SPAN> must both be less than the size of the FIFO.</P> 48<P>When the FIFO is only attached to the CPU or only attached to the GP, the high and low water mark interrupts are disabled.</P> 49 50<h2>See Also</h2> 51<P class="reference"> 52<A href="GXInitFifoBase.html">GXInitFifoBase</A>, 53<A href="GXInitFifoPtrs.html">GXInitFifoPtrs</A> 54</p> 55 56<H2>Revision History</H2> 57<P> 582007/03/05 Deleted old content in the Description section.<br>2006/03/01 Initial version.<br> 59</P> 60 61<hr><p>CONFIDENTIAL</p></body> 62</HTML>