Mercurial > sdl-ios-xcode
annotate docs/html/guidetimeexamples.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 >Time Examples</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="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 | |
181
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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(); | |
181
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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 | |
181
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105 /* main game loop */ |
0 | 106 |
181
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107 next_time = SDL_GetTicks() + TICK_INTERVAL; |
0 | 108 while ( game_running ) { |
181
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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 > |