Mercurial > sdl-ios-xcode
annotate docs/html/sdldestroysemaphore.html @ 773:da0a2ad35bf4
Date: Sun, 4 Jan 2004 23:48:19 +0100
From: Max Horn
Subject: Re: Again Audio CD patch
Am 04.01.2004 um 22:38 schrieb Sam Lantinga:
>
> Okay, I fixed the buffering problems by simply using a 4 second buffer
> instead of a 1 second buffer. However, using your code I can't play an
> entire CD - the playback stops after the first song.
>
Found the problem: FSReadFork returns eofErr when the file is finished.
However, we check its return value for errors, and if anything but
noErr occurs, the reader thread aborts its current iteration. That is
bad, because it aborts before it can ever set the flag which tells that
the file is over (also, any remaining data which FSRead did return is
lost - so you'd not hear about to 4 seconds from the end of the file.
Furthermore, the computed data size was 8 bytes to high (I forgot to
account for the fact that the size of an (A)IFF chunk always contains
the chunk header & size fields, too). This is enough to make it work.
However, the end condition is rather fragile, so I tuned some other
things to be pessimistic (check for <= 0 instead of == 0, when eofErr
is encountered enforce mReadFilePosition == mFileLength). You never
know...
The attached patch fixes the issue for me.
author | Sam Lantinga <slouken@libsdl.org> |
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date | Mon, 05 Jan 2004 00:57:51 +0000 (2004-01-05) |
parents | e5bc29de3f0a |
children | 355632dca928 |
rev | line source |
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0 | 1 <HTML |
2 ><HEAD | |
3 ><TITLE | |
4 >SDL_DestroySemaphore</TITLE | |
5 ><META | |
6 NAME="GENERATOR" | |
55
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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_CreateSemaphore" | |
17 HREF="sdlcreatesemaphore.html"><LINK | |
18 REL="NEXT" | |
19 TITLE="SDL_SemWait" | |
20 HREF="sdlsemwait.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="sdlcreatesemaphore.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="sdlsemwait.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="SDLDESTROYSEMAPHORE" | |
71 >SDL_DestroySemaphore</A | |
72 ></H1 | |
73 ><DIV | |
74 CLASS="REFNAMEDIV" | |
75 ><A | |
181
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76 NAME="AEN7594" |
0 | 77 ></A |
78 ><H2 | |
79 >Name</H2 | |
80 >SDL_DestroySemaphore -- Destroys a semaphore that was created by <A | |
81 HREF="sdlcreatesemaphore.html" | |
82 >SDL_CreateSemaphore</A | |
83 >.</DIV | |
84 ><DIV | |
85 CLASS="REFSYNOPSISDIV" | |
86 ><A | |
181
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87 NAME="AEN7598" |
0 | 88 ></A |
89 ><H2 | |
90 >Synopsis</H2 | |
91 ><DIV | |
92 CLASS="FUNCSYNOPSIS" | |
93 ><A | |
181
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94 NAME="AEN7599" |
0 | 95 ></A |
96 ><P | |
97 ></P | |
98 ><PRE | |
99 CLASS="FUNCSYNOPSISINFO" | |
100 >#include "SDL.h" | |
101 #include "SDL_thread.h"</PRE | |
102 ><P | |
103 ><CODE | |
104 ><CODE | |
105 CLASS="FUNCDEF" | |
106 >void <B | |
107 CLASS="FSFUNC" | |
108 >SDL_DestroySemaphore</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 | |
181
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119 NAME="AEN7605" |
0 | 120 ></A |
121 ><H2 | |
122 >Description</H2 | |
123 ><P | |
124 ><TT | |
125 CLASS="FUNCTION" | |
126 >SDL_DestroySemaphore</TT | |
127 > destroys the semaphore pointed to | |
128 by <TT | |
129 CLASS="PARAMETER" | |
130 ><I | |
131 >sem</I | |
132 ></TT | |
133 > that was created by | |
134 <A | |
135 HREF="sdlcreatesemaphore.html" | |
136 ><TT | |
137 CLASS="FUNCTION" | |
138 >SDL_CreateSemaphore</TT | |
139 ></A | |
140 >. | |
141 It is not safe to destroy a semaphore if there are threads currently blocked | |
142 waiting on it.</P | |
143 ></DIV | |
144 ><DIV | |
145 CLASS="REFSECT1" | |
146 ><A | |
181
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147 NAME="AEN7612" |
0 | 148 ></A |
149 ><H2 | |
150 >Examples</H2 | |
151 ><P | |
152 ><PRE | |
153 CLASS="PROGRAMLISTING" | |
154 >if (my_sem != NULL) { | |
155 SDL_DestroySemaphore(my_sem); | |
156 my_sem = NULL; | |
157 }</PRE | |
158 ></P | |
159 ></DIV | |
160 ><DIV | |
161 CLASS="REFSECT1" | |
162 ><A | |
181
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163 NAME="AEN7616" |
0 | 164 ></A |
165 ><H2 | |
166 >See Also</H2 | |
167 ><P | |
168 ><A | |
169 HREF="sdlcreatesemaphore.html" | |
170 ><TT | |
171 CLASS="FUNCTION" | |
172 >SDL_CreateSemaphore</TT | |
173 ></A | |
174 >, | |
175 <A | |
176 HREF="sdlsemwait.html" | |
177 ><TT | |
178 CLASS="FUNCTION" | |
179 >SDL_SemWait</TT | |
180 ></A | |
181 >, | |
182 <A | |
183 HREF="sdlsemtrywait.html" | |
184 ><TT | |
185 CLASS="FUNCTION" | |
186 >SDL_SemTryWait</TT | |
187 ></A | |
188 >, | |
189 <A | |
190 HREF="sdlsemwaittimeout.html" | |
191 ><TT | |
192 CLASS="FUNCTION" | |
193 >SDL_SemWaitTimeout</TT | |
194 ></A | |
195 >, | |
196 <A | |
197 HREF="sdlsempost.html" | |
198 ><TT | |
199 CLASS="FUNCTION" | |
200 >SDL_SemPost</TT | |
201 ></A | |
202 >, | |
203 <A | |
204 HREF="sdlsemvalue.html" | |
205 ><TT | |
206 CLASS="FUNCTION" | |
207 >SDL_SemValue</TT | |
208 ></A | |
209 ></P | |
210 ></DIV | |
211 ><DIV | |
212 CLASS="NAVFOOTER" | |
213 ><HR | |
214 ALIGN="LEFT" | |
215 WIDTH="100%"><TABLE | |
216 WIDTH="100%" | |
217 BORDER="0" | |
218 CELLPADDING="0" | |
219 CELLSPACING="0" | |
220 ><TR | |
221 ><TD | |
222 WIDTH="33%" | |
223 ALIGN="left" | |
224 VALIGN="top" | |
225 ><A | |
226 HREF="sdlcreatesemaphore.html" | |
227 >Prev</A | |
228 ></TD | |
229 ><TD | |
230 WIDTH="34%" | |
231 ALIGN="center" | |
232 VALIGN="top" | |
233 ><A | |
234 HREF="index.html" | |
235 >Home</A | |
236 ></TD | |
237 ><TD | |
238 WIDTH="33%" | |
239 ALIGN="right" | |
240 VALIGN="top" | |
241 ><A | |
242 HREF="sdlsemwait.html" | |
243 >Next</A | |
244 ></TD | |
245 ></TR | |
246 ><TR | |
247 ><TD | |
248 WIDTH="33%" | |
249 ALIGN="left" | |
250 VALIGN="top" | |
251 >SDL_CreateSemaphore</TD | |
252 ><TD | |
253 WIDTH="34%" | |
254 ALIGN="center" | |
255 VALIGN="top" | |
256 ><A | |
257 HREF="thread.html" | |
258 >Up</A | |
259 ></TD | |
260 ><TD | |
261 WIDTH="33%" | |
262 ALIGN="right" | |
263 VALIGN="top" | |
264 >SDL_SemWait</TD | |
265 ></TR | |
266 ></TABLE | |
267 ></DIV | |
268 ></BODY | |
269 ></HTML | |
270 > |