Mercurial > sdl-ios-xcode
annotate docs/html/guidetimeexamples.html @ 765:4c2ba6161939
Editors Note: The original patch was modified to use SDL_Delay() instead of
nanosleep because nanosleep may not be portable to all systems
using SDL with the ALSA backend. This may be a moot point with
the switch to blocking writes anyway...
Date: Sat, 27 Dec 2003 21:47:36 +0100
From: Michel Daenzer
To: Debian Bug Tracking System
Subject: [SDL] Bug#225252: [PATCH] ALSA fixes
Package: libsdl1.2debian-all
Version: 1.2.6-2
Severity: normal
Tags: patch
For SDL 1.2.6, the ALSA backend was changed to call snd_pcm_open() with
SND_PCM_NONBLOCK. That's a good idea per se, however, it causes high CPU
usage, interrupted sound and stuttering in some games here. Taking a nanosleep
whenever snd_pcm_writei() returns -EAGAIN fixes this, but I think it's more
efficient to use blocking mode for the actual sound playback. Feedback from the
SDL and ALSA lists appreciated.
The patch also fixes the default ALSA device to be used.
| author | Sam Lantinga <slouken@libsdl.org> |
|---|---|
| date | Sun, 04 Jan 2004 15:40:50 +0000 |
| parents | e5bc29de3f0a |
| children | 355632dca928 |
| rev | line source |
|---|---|
| 0 | 1 <HTML |
| 2 ><HEAD | |
| 3 ><TITLE | |
| 4 >Time Examples</TITLE | |
| 5 ><META | |
| 6 NAME="GENERATOR" | |
|
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7 CONTENT="Modular DocBook HTML Stylesheet Version 1.64 |
| 0 | 8 "><LINK |
| 9 REL="HOME" | |
| 10 TITLE="SDL Library Documentation" | |
| 11 HREF="index.html"><LINK | |
| 12 REL="UP" | |
| 13 TITLE="Examples" | |
| 14 HREF="guideexamples.html"><LINK | |
| 15 REL="PREVIOUS" | |
| 16 TITLE="CDROM Examples" | |
| 17 HREF="guidecdromexamples.html"><LINK | |
| 18 REL="NEXT" | |
| 19 TITLE="SDL Reference" | |
| 20 HREF="reference.html"></HEAD | |
| 21 ><BODY | |
| 22 CLASS="SECT1" | |
| 23 BGCOLOR="#FFF8DC" | |
| 24 TEXT="#000000" | |
| 25 LINK="#0000ee" | |
| 26 VLINK="#551a8b" | |
| 27 ALINK="#ff0000" | |
| 28 ><DIV | |
| 29 CLASS="NAVHEADER" | |
| 30 ><TABLE | |
| 31 WIDTH="100%" | |
| 32 BORDER="0" | |
| 33 CELLPADDING="0" | |
| 34 CELLSPACING="0" | |
| 35 ><TR | |
| 36 ><TH | |
| 37 COLSPAN="3" | |
| 38 ALIGN="center" | |
| 39 >SDL Library Documentation</TH | |
| 40 ></TR | |
| 41 ><TR | |
| 42 ><TD | |
| 43 WIDTH="10%" | |
| 44 ALIGN="left" | |
| 45 VALIGN="bottom" | |
| 46 ><A | |
| 47 HREF="guidecdromexamples.html" | |
| 48 >Prev</A | |
| 49 ></TD | |
| 50 ><TD | |
| 51 WIDTH="80%" | |
| 52 ALIGN="center" | |
| 53 VALIGN="bottom" | |
| 54 >Chapter 4. Examples</TD | |
| 55 ><TD | |
| 56 WIDTH="10%" | |
| 57 ALIGN="right" | |
| 58 VALIGN="bottom" | |
| 59 ><A | |
| 60 HREF="reference.html" | |
| 61 >Next</A | |
| 62 ></TD | |
| 63 ></TR | |
| 64 ></TABLE | |
| 65 ><HR | |
| 66 ALIGN="LEFT" | |
| 67 WIDTH="100%"></DIV | |
| 68 ><DIV | |
| 69 CLASS="SECT1" | |
| 70 ><H1 | |
| 71 CLASS="SECT1" | |
| 72 ><A | |
| 73 NAME="GUIDETIMEEXAMPLES" | |
| 74 >Time Examples</A | |
| 75 ></H1 | |
| 76 ><P | |
| 77 ></P | |
| 78 ><DIV | |
| 79 CLASS="SECT2" | |
| 80 ><H2 | |
| 81 CLASS="SECT2" | |
| 82 ><A | |
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83 NAME="AEN412" |
| 0 | 84 >Time based game loop</A |
| 85 ></H2 | |
| 86 ><P | |
| 87 ><PRE | |
| 88 CLASS="PROGRAMLISTING" | |
| 89 >#define TICK_INTERVAL 30 | |
| 90 | |
|
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91 static Uint32 next_time; |
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92 |
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93 Uint32 time_left(void) |
| 0 | 94 { |
| 95 Uint32 now; | |
| 96 | |
| 97 now = SDL_GetTicks(); | |
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98 if(next_time <= now) |
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99 return 0; |
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100 else |
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101 return next_time - now; |
| 0 | 102 } |
| 103 | |
| 104 | |
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105 /* main game loop */ |
| 0 | 106 |
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107 next_time = SDL_GetTicks() + TICK_INTERVAL; |
| 0 | 108 while ( game_running ) { |
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109 update_game_state(); |
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110 SDL_Delay(time_left()); |
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111 next_time += TICK_INTERVAL; |
| 0 | 112 } </PRE |
| 113 ></P | |
| 114 ></DIV | |
| 115 ></DIV | |
| 116 ><DIV | |
| 117 CLASS="NAVFOOTER" | |
| 118 ><HR | |
| 119 ALIGN="LEFT" | |
| 120 WIDTH="100%"><TABLE | |
| 121 WIDTH="100%" | |
| 122 BORDER="0" | |
| 123 CELLPADDING="0" | |
| 124 CELLSPACING="0" | |
| 125 ><TR | |
| 126 ><TD | |
| 127 WIDTH="33%" | |
| 128 ALIGN="left" | |
| 129 VALIGN="top" | |
| 130 ><A | |
| 131 HREF="guidecdromexamples.html" | |
| 132 >Prev</A | |
| 133 ></TD | |
| 134 ><TD | |
| 135 WIDTH="34%" | |
| 136 ALIGN="center" | |
| 137 VALIGN="top" | |
| 138 ><A | |
| 139 HREF="index.html" | |
| 140 >Home</A | |
| 141 ></TD | |
| 142 ><TD | |
| 143 WIDTH="33%" | |
| 144 ALIGN="right" | |
| 145 VALIGN="top" | |
| 146 ><A | |
| 147 HREF="reference.html" | |
| 148 >Next</A | |
| 149 ></TD | |
| 150 ></TR | |
| 151 ><TR | |
| 152 ><TD | |
| 153 WIDTH="33%" | |
| 154 ALIGN="left" | |
| 155 VALIGN="top" | |
| 156 >CDROM Examples</TD | |
| 157 ><TD | |
| 158 WIDTH="34%" | |
| 159 ALIGN="center" | |
| 160 VALIGN="top" | |
| 161 ><A | |
| 162 HREF="guideexamples.html" | |
| 163 >Up</A | |
| 164 ></TD | |
| 165 ><TD | |
| 166 WIDTH="33%" | |
| 167 ALIGN="right" | |
| 168 VALIGN="top" | |
| 169 >SDL Reference</TD | |
| 170 ></TR | |
| 171 ></TABLE | |
| 172 ></DIV | |
| 173 ></BODY | |
| 174 ></HTML | |
| 175 > |