Mercurial > sdl-ios-xcode
annotate docs/html/sdlsemvalue.html @ 968:4675910b0b7b
Date: Mon, 11 Oct 2004 15:17:27 +0300 (EEST)
From: Hannu Savolainen
Subject: Re: SDL uses obsolete OSS features
I did some work on getting OSS to work better with SDL. There have been
some problems with select which should be fixed now.
I'm having some problems in understanding what is the purpose of the
DSP_WaitAudio() routine. I added a return to the very beginning of this
routine and commendted out the define for USE_BLOCKING_WRITES. At least
lbreakout2 seems to work as well as earlier. The latencies are the same.
An ordinary blocking write does exactly the same thing than DSP_WaitAudio
does. So I would recommend using the USE_BLOCKING_WRITES approach and
removing everything from the DSP_WaitAudio routine. Also enabling
USE_BLOCKING_WRITES makes it possible to simplify DSP_PlayAudio() because
you don't need to handle the partial writes (the do-while loop).
Attached is a patch against SDL-1.2.7. After these changes SDL will use
OSS as it's designed to be used (make it as simple as possible). This code
should work with all OSS implementations because it uses only the very
fundamental features that have been there since the jurassic times.
author | Sam Lantinga <slouken@libsdl.org> |
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date | Fri, 12 Nov 2004 21:39:04 +0000 |
parents | 355632dca928 |
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rev | line source |
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0 | 1 <HTML |
2 ><HEAD | |
3 ><TITLE | |
4 >SDL_SemValue</TITLE | |
5 ><META | |
6 NAME="GENERATOR" | |
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7 CONTENT="Modular DocBook HTML Stylesheet Version 1.76b+ |
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_SemPost" | |
17 HREF="sdlsempost.html"><LINK | |
18 REL="NEXT" | |
19 TITLE="SDL_CreateCond" | |
20 HREF="sdlcreatecond.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 | |
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31 SUMMARY="Header navigation table" |
0 | 32 WIDTH="100%" |
33 BORDER="0" | |
34 CELLPADDING="0" | |
35 CELLSPACING="0" | |
36 ><TR | |
37 ><TH | |
38 COLSPAN="3" | |
39 ALIGN="center" | |
40 >SDL Library Documentation</TH | |
41 ></TR | |
42 ><TR | |
43 ><TD | |
44 WIDTH="10%" | |
45 ALIGN="left" | |
46 VALIGN="bottom" | |
47 ><A | |
48 HREF="sdlsempost.html" | |
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49 ACCESSKEY="P" |
0 | 50 >Prev</A |
51 ></TD | |
52 ><TD | |
53 WIDTH="80%" | |
54 ALIGN="center" | |
55 VALIGN="bottom" | |
56 ></TD | |
57 ><TD | |
58 WIDTH="10%" | |
59 ALIGN="right" | |
60 VALIGN="bottom" | |
61 ><A | |
62 HREF="sdlcreatecond.html" | |
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63 ACCESSKEY="N" |
0 | 64 >Next</A |
65 ></TD | |
66 ></TR | |
67 ></TABLE | |
68 ><HR | |
69 ALIGN="LEFT" | |
70 WIDTH="100%"></DIV | |
71 ><H1 | |
72 ><A | |
73 NAME="SDLSEMVALUE" | |
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74 ></A |
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75 >SDL_SemValue</H1 |
0 | 76 ><DIV |
77 CLASS="REFNAMEDIV" | |
78 ><A | |
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79 NAME="AEN8218" |
0 | 80 ></A |
81 ><H2 | |
82 >Name</H2 | |
83 >SDL_SemValue -- Return the current value of a semaphore.</DIV | |
84 ><DIV | |
85 CLASS="REFSYNOPSISDIV" | |
86 ><A | |
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87 NAME="AEN8221" |
0 | 88 ></A |
89 ><H2 | |
90 >Synopsis</H2 | |
91 ><DIV | |
92 CLASS="FUNCSYNOPSIS" | |
93 ><A | |
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94 NAME="AEN8222" |
0 | 95 ></A |
96 ><P | |
97 ></P | |
98 ><PRE | |
99 CLASS="FUNCSYNOPSISINFO" | |
100 >#include "SDL.h" | |
101 #include "SDL/SDL_thread.h"</PRE | |
102 ><P | |
103 ><CODE | |
104 ><CODE | |
105 CLASS="FUNCDEF" | |
106 >Uint32 <B | |
107 CLASS="FSFUNC" | |
108 >SDL_SemValue</B | |
109 ></CODE | |
110 >(SDL_sem *sem);</CODE | |
111 ></P | |
112 ><P | |
113 ></P | |
114 ></DIV | |
115 ></DIV | |
116 ><DIV | |
117 CLASS="REFSECT1" | |
118 ><A | |
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119 NAME="AEN8228" |
0 | 120 ></A |
121 ><H2 | |
122 >Description</H2 | |
123 ><P | |
124 ><TT | |
125 CLASS="FUNCTION" | |
126 >SDL_SemValue()</TT | |
127 > returns the current semaphore value from | |
128 the semaphore pointed to by <TT | |
129 CLASS="PARAMETER" | |
130 ><I | |
131 >sem</I | |
132 ></TT | |
133 >.</P | |
134 ></DIV | |
135 ><DIV | |
136 CLASS="REFSECT1" | |
137 ><A | |
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138 NAME="AEN8233" |
0 | 139 ></A |
140 ><H2 | |
141 >Return Value</H2 | |
142 ><P | |
143 >Returns current value of the semaphore.</P | |
144 ></DIV | |
145 ><DIV | |
146 CLASS="REFSECT1" | |
147 ><A | |
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148 NAME="AEN8236" |
0 | 149 ></A |
150 ><H2 | |
151 >Examples</H2 | |
152 ><P | |
153 ><PRE | |
154 CLASS="PROGRAMLISTING" | |
155 > sem_value = SDL_SemValue(my_sem);</PRE | |
156 ></P | |
157 ></DIV | |
158 ><DIV | |
159 CLASS="REFSECT1" | |
160 ><A | |
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161 NAME="AEN8240" |
0 | 162 ></A |
163 ><H2 | |
164 >See Also</H2 | |
165 ><P | |
166 ><A | |
167 HREF="sdlcreatesemaphore.html" | |
168 ><TT | |
169 CLASS="FUNCTION" | |
170 >SDL_CreateSemaphore</TT | |
171 ></A | |
172 >, | |
173 <A | |
174 HREF="sdldestroysemaphore.html" | |
175 ><TT | |
176 CLASS="FUNCTION" | |
177 >SDL_DestroySemaphore</TT | |
178 ></A | |
179 >, | |
180 <A | |
181 HREF="sdlsemwait.html" | |
182 ><TT | |
183 CLASS="FUNCTION" | |
184 >SDL_SemWait</TT | |
185 ></A | |
186 >, | |
187 <A | |
188 HREF="sdlsemtrywait.html" | |
189 ><TT | |
190 CLASS="FUNCTION" | |
191 >SDL_SemTryWait</TT | |
192 ></A | |
193 >, | |
194 <A | |
195 HREF="sdlsemwaittimeout.html" | |
196 ><TT | |
197 CLASS="FUNCTION" | |
198 >SDL_SemWaitTimeout</TT | |
199 ></A | |
200 >, | |
201 <A | |
202 HREF="sdlsempost.html" | |
203 ><TT | |
204 CLASS="FUNCTION" | |
205 >SDL_SemPost</TT | |
206 ></A | |
207 ></P | |
208 ></DIV | |
209 ><DIV | |
210 CLASS="NAVFOOTER" | |
211 ><HR | |
212 ALIGN="LEFT" | |
213 WIDTH="100%"><TABLE | |
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214 SUMMARY="Footer navigation table" |
0 | 215 WIDTH="100%" |
216 BORDER="0" | |
217 CELLPADDING="0" | |
218 CELLSPACING="0" | |
219 ><TR | |
220 ><TD | |
221 WIDTH="33%" | |
222 ALIGN="left" | |
223 VALIGN="top" | |
224 ><A | |
225 HREF="sdlsempost.html" | |
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226 ACCESSKEY="P" |
0 | 227 >Prev</A |
228 ></TD | |
229 ><TD | |
230 WIDTH="34%" | |
231 ALIGN="center" | |
232 VALIGN="top" | |
233 ><A | |
234 HREF="index.html" | |
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235 ACCESSKEY="H" |
0 | 236 >Home</A |
237 ></TD | |
238 ><TD | |
239 WIDTH="33%" | |
240 ALIGN="right" | |
241 VALIGN="top" | |
242 ><A | |
243 HREF="sdlcreatecond.html" | |
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244 ACCESSKEY="N" |
0 | 245 >Next</A |
246 ></TD | |
247 ></TR | |
248 ><TR | |
249 ><TD | |
250 WIDTH="33%" | |
251 ALIGN="left" | |
252 VALIGN="top" | |
253 >SDL_SemPost</TD | |
254 ><TD | |
255 WIDTH="34%" | |
256 ALIGN="center" | |
257 VALIGN="top" | |
258 ><A | |
259 HREF="thread.html" | |
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260 ACCESSKEY="U" |
0 | 261 >Up</A |
262 ></TD | |
263 ><TD | |
264 WIDTH="33%" | |
265 ALIGN="right" | |
266 VALIGN="top" | |
267 >SDL_CreateCond</TD | |
268 ></TR | |
269 ></TABLE | |
270 ></DIV | |
271 ></BODY | |
272 ></HTML | |
273 > |