Mercurial > sdl-ios-xcode
annotate docs/html/sdlsempost.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 |
parents | e5bc29de3f0a |
children | 355632dca928 |
rev | line source |
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0 | 1 <HTML |
2 ><HEAD | |
3 ><TITLE | |
4 >SDL_SemPost</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_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 | |
181
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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 | |
181
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84 NAME="AEN7785" |
0 | 85 ></A |
86 ><H2 | |
87 >Synopsis</H2 | |
88 ><DIV | |
89 CLASS="FUNCSYNOPSIS" | |
90 ><A | |
181
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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 | |
181
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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 | |
181
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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 | |
181
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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 | |
181
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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 > |