Mercurial > sdl-ios-xcode
annotate docs/html/sdlsempost.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 >SDL_SemPost</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="Multi-threaded Programming" | |
| 14 HREF="thread.html"><LINK | |
| 15 REL="PREVIOUS" | |
| 16 TITLE="SDL_SemWaitTimeout" | |
| 17 HREF="sdlsemwaittimeout.html"><LINK | |
| 18 REL="NEXT" | |
| 19 TITLE="SDL_SemValue" | |
| 20 HREF="sdlsemvalue.html"></HEAD | |
| 21 ><BODY | |
| 22 CLASS="REFENTRY" | |
| 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="sdlsemwaittimeout.html" | |
| 48 >Prev</A | |
| 49 ></TD | |
| 50 ><TD | |
| 51 WIDTH="80%" | |
| 52 ALIGN="center" | |
| 53 VALIGN="bottom" | |
| 54 ></TD | |
| 55 ><TD | |
| 56 WIDTH="10%" | |
| 57 ALIGN="right" | |
| 58 VALIGN="bottom" | |
| 59 ><A | |
| 60 HREF="sdlsemvalue.html" | |
| 61 >Next</A | |
| 62 ></TD | |
| 63 ></TR | |
| 64 ></TABLE | |
| 65 ><HR | |
| 66 ALIGN="LEFT" | |
| 67 WIDTH="100%"></DIV | |
| 68 ><H1 | |
| 69 ><A | |
| 70 NAME="SDLSEMPOST" | |
| 71 >SDL_SemPost</A | |
| 72 ></H1 | |
| 73 ><DIV | |
| 74 CLASS="REFNAMEDIV" | |
| 75 ><A | |
|
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76 NAME="AEN7782" |
| 0 | 77 ></A |
| 78 ><H2 | |
| 79 >Name</H2 | |
| 80 >SDL_SemPost -- Unlock a semaphore.</DIV | |
| 81 ><DIV | |
| 82 CLASS="REFSYNOPSISDIV" | |
| 83 ><A | |
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84 NAME="AEN7785" |
| 0 | 85 ></A |
| 86 ><H2 | |
| 87 >Synopsis</H2 | |
| 88 ><DIV | |
| 89 CLASS="FUNCSYNOPSIS" | |
| 90 ><A | |
|
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91 NAME="AEN7786" |
| 0 | 92 ></A |
| 93 ><P | |
| 94 ></P | |
| 95 ><PRE | |
| 96 CLASS="FUNCSYNOPSISINFO" | |
| 97 >#include "SDL.h" | |
| 98 #include "SDL_thread.h"</PRE | |
| 99 ><P | |
| 100 ><CODE | |
| 101 ><CODE | |
| 102 CLASS="FUNCDEF" | |
| 103 >int <B | |
| 104 CLASS="FSFUNC" | |
| 105 >SDL_SemPost</B | |
| 106 ></CODE | |
| 107 >(SDL_sem *sem);</CODE | |
| 108 ></P | |
| 109 ><P | |
| 110 ></P | |
| 111 ></DIV | |
| 112 ></DIV | |
| 113 ><DIV | |
| 114 CLASS="REFSECT1" | |
| 115 ><A | |
|
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116 NAME="AEN7792" |
| 0 | 117 ></A |
| 118 ><H2 | |
| 119 >Description</H2 | |
| 120 ><P | |
| 121 ><TT | |
| 122 CLASS="FUNCTION" | |
| 123 >SDL_SemPost</TT | |
| 124 > unlocks the semaphore pointed to by | |
| 125 <TT | |
| 126 CLASS="PARAMETER" | |
| 127 ><I | |
| 128 >sem</I | |
| 129 ></TT | |
| 130 > and atomically increments the semaphores value. | |
| 131 Threads that were blocking on the semaphore may be scheduled after this call | |
| 132 succeeds.</P | |
| 133 ><P | |
| 134 ><TT | |
| 135 CLASS="FUNCTION" | |
| 136 >SDL_SemPost</TT | |
| 137 > should be called after a semaphore is locked by a successful call to | |
| 138 <A | |
| 139 HREF="sdlsemwait.html" | |
| 140 >SDL_SemWait</A | |
| 141 >, | |
| 142 <A | |
| 143 HREF="sdlsemtrywait.html" | |
| 144 >SDL_SemTryWait</A | |
| 145 > or | |
| 146 <A | |
| 147 HREF="sdlsemwaittimeout.html" | |
| 148 >SDL_SemWaitTimeout</A | |
| 149 >.</P | |
| 150 ></DIV | |
| 151 ><DIV | |
| 152 CLASS="REFSECT1" | |
| 153 ><A | |
|
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154 NAME="AEN7802" |
| 0 | 155 ></A |
| 156 ><H2 | |
| 157 >Return Value</H2 | |
| 158 ><P | |
| 159 >Returns <SPAN | |
| 160 CLASS="RETURNVALUE" | |
| 161 >0</SPAN | |
| 162 > if successful or | |
| 163 <SPAN | |
| 164 CLASS="RETURNVALUE" | |
| 165 >-1</SPAN | |
| 166 > if there was an error (leaving the semaphore unchanged).</P | |
| 167 ></DIV | |
| 168 ><DIV | |
| 169 CLASS="REFSECT1" | |
| 170 ><A | |
|
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171 NAME="AEN7807" |
| 0 | 172 ></A |
| 173 ><H2 | |
| 174 >Examples</H2 | |
| 175 ><P | |
| 176 ><PRE | |
| 177 CLASS="PROGRAMLISTING" | |
| 178 >SDL_SemPost(my_sem);</PRE | |
| 179 ></P | |
| 180 ></DIV | |
| 181 ><DIV | |
| 182 CLASS="REFSECT1" | |
| 183 ><A | |
|
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184 NAME="AEN7811" |
| 0 | 185 ></A |
| 186 ><H2 | |
| 187 >See Also</H2 | |
| 188 ><P | |
| 189 ><A | |
| 190 HREF="sdlcreatesemaphore.html" | |
| 191 ><TT | |
| 192 CLASS="FUNCTION" | |
| 193 >SDL_CreateSemaphore</TT | |
| 194 ></A | |
| 195 >, | |
| 196 <A | |
| 197 HREF="sdldestroysemaphore.html" | |
| 198 ><TT | |
| 199 CLASS="FUNCTION" | |
| 200 >SDL_DestroySemaphore</TT | |
| 201 ></A | |
| 202 >, | |
| 203 <A | |
| 204 HREF="sdlsemwait.html" | |
| 205 ><TT | |
| 206 CLASS="FUNCTION" | |
| 207 >SDL_SemWait</TT | |
| 208 ></A | |
| 209 >, | |
| 210 <A | |
| 211 HREF="sdlsemtrywait.html" | |
| 212 ><TT | |
| 213 CLASS="FUNCTION" | |
| 214 >SDL_SemTryWait</TT | |
| 215 ></A | |
| 216 >, | |
| 217 <A | |
| 218 HREF="sdlsemwaittimeout.html" | |
| 219 ><TT | |
| 220 CLASS="FUNCTION" | |
| 221 >SDL_SemWaitTimeout</TT | |
| 222 ></A | |
| 223 >, | |
| 224 <A | |
| 225 HREF="sdlsemvalue.html" | |
| 226 ><TT | |
| 227 CLASS="FUNCTION" | |
| 228 >SDL_SemValue</TT | |
| 229 ></A | |
| 230 ></P | |
| 231 ></DIV | |
| 232 ><DIV | |
| 233 CLASS="NAVFOOTER" | |
| 234 ><HR | |
| 235 ALIGN="LEFT" | |
| 236 WIDTH="100%"><TABLE | |
| 237 WIDTH="100%" | |
| 238 BORDER="0" | |
| 239 CELLPADDING="0" | |
| 240 CELLSPACING="0" | |
| 241 ><TR | |
| 242 ><TD | |
| 243 WIDTH="33%" | |
| 244 ALIGN="left" | |
| 245 VALIGN="top" | |
| 246 ><A | |
| 247 HREF="sdlsemwaittimeout.html" | |
| 248 >Prev</A | |
| 249 ></TD | |
| 250 ><TD | |
| 251 WIDTH="34%" | |
| 252 ALIGN="center" | |
| 253 VALIGN="top" | |
| 254 ><A | |
| 255 HREF="index.html" | |
| 256 >Home</A | |
| 257 ></TD | |
| 258 ><TD | |
| 259 WIDTH="33%" | |
| 260 ALIGN="right" | |
| 261 VALIGN="top" | |
| 262 ><A | |
| 263 HREF="sdlsemvalue.html" | |
| 264 >Next</A | |
| 265 ></TD | |
| 266 ></TR | |
| 267 ><TR | |
| 268 ><TD | |
| 269 WIDTH="33%" | |
| 270 ALIGN="left" | |
| 271 VALIGN="top" | |
| 272 >SDL_SemWaitTimeout</TD | |
| 273 ><TD | |
| 274 WIDTH="34%" | |
| 275 ALIGN="center" | |
| 276 VALIGN="top" | |
| 277 ><A | |
| 278 HREF="thread.html" | |
| 279 >Up</A | |
| 280 ></TD | |
| 281 ><TD | |
| 282 WIDTH="33%" | |
| 283 ALIGN="right" | |
| 284 VALIGN="top" | |
| 285 >SDL_SemValue</TD | |
| 286 ></TR | |
| 287 ></TABLE | |
| 288 ></DIV | |
| 289 ></BODY | |
| 290 ></HTML | |
| 291 > |