Mercurial > sdl-ios-xcode
annotate docs/html/sdlsempost.html @ 3880:74e828c64315 SDL-1.2
Fixed bug #292
I might be on crack here.
It looks like SDL_ConvertMono() in src/audio/SDL_audiocvt.c adds the left and
right channels of a stereo stream together, and clamps the new mono channel if
it would overflow.
Shouldn't it be dividing by 2 to average the two sample points instead of
clamping? Otherwise the mono sample point's volume doubles in the conversion.
This would also make the conversion faster, as it replaces two branches per
sample frame with a bitwise shift.
--ryan.
| author | Sam Lantinga <slouken@libsdl.org> |
|---|---|
| date | Sun, 24 Sep 2006 15:45:37 +0000 |
| parents | 355632dca928 |
| children |
| 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 1.76b+ |
| 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_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 | |
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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="sdlsemwaittimeout.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="sdlsemvalue.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="SDLSEMPOST" | |
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74 ></A |
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75 >SDL_SemPost</H1 |
| 0 | 76 ><DIV |
| 77 CLASS="REFNAMEDIV" | |
| 78 ><A | |
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79 NAME="AEN8170" |
| 0 | 80 ></A |
| 81 ><H2 | |
| 82 >Name</H2 | |
| 83 >SDL_SemPost -- Unlock a semaphore.</DIV | |
| 84 ><DIV | |
| 85 CLASS="REFSYNOPSISDIV" | |
| 86 ><A | |
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87 NAME="AEN8173" |
| 0 | 88 ></A |
| 89 ><H2 | |
| 90 >Synopsis</H2 | |
| 91 ><DIV | |
| 92 CLASS="FUNCSYNOPSIS" | |
| 93 ><A | |
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94 NAME="AEN8174" |
| 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 >int <B | |
| 107 CLASS="FSFUNC" | |
| 108 >SDL_SemPost</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="AEN8180" |
| 0 | 120 ></A |
| 121 ><H2 | |
| 122 >Description</H2 | |
| 123 ><P | |
| 124 ><TT | |
| 125 CLASS="FUNCTION" | |
| 126 >SDL_SemPost</TT | |
| 127 > unlocks the semaphore pointed to by | |
| 128 <TT | |
| 129 CLASS="PARAMETER" | |
| 130 ><I | |
| 131 >sem</I | |
| 132 ></TT | |
| 133 > and atomically increments the semaphores value. | |
| 134 Threads that were blocking on the semaphore may be scheduled after this call | |
| 135 succeeds.</P | |
| 136 ><P | |
| 137 ><TT | |
| 138 CLASS="FUNCTION" | |
| 139 >SDL_SemPost</TT | |
| 140 > should be called after a semaphore is locked by a successful call to | |
| 141 <A | |
| 142 HREF="sdlsemwait.html" | |
| 143 >SDL_SemWait</A | |
| 144 >, | |
| 145 <A | |
| 146 HREF="sdlsemtrywait.html" | |
| 147 >SDL_SemTryWait</A | |
| 148 > or | |
| 149 <A | |
| 150 HREF="sdlsemwaittimeout.html" | |
| 151 >SDL_SemWaitTimeout</A | |
| 152 >.</P | |
| 153 ></DIV | |
| 154 ><DIV | |
| 155 CLASS="REFSECT1" | |
| 156 ><A | |
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157 NAME="AEN8190" |
| 0 | 158 ></A |
| 159 ><H2 | |
| 160 >Return Value</H2 | |
| 161 ><P | |
| 162 >Returns <SPAN | |
| 163 CLASS="RETURNVALUE" | |
| 164 >0</SPAN | |
| 165 > if successful or | |
| 166 <SPAN | |
| 167 CLASS="RETURNVALUE" | |
| 168 >-1</SPAN | |
| 169 > if there was an error (leaving the semaphore unchanged).</P | |
| 170 ></DIV | |
| 171 ><DIV | |
| 172 CLASS="REFSECT1" | |
| 173 ><A | |
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174 NAME="AEN8195" |
| 0 | 175 ></A |
| 176 ><H2 | |
| 177 >Examples</H2 | |
| 178 ><P | |
| 179 ><PRE | |
| 180 CLASS="PROGRAMLISTING" | |
| 181 >SDL_SemPost(my_sem);</PRE | |
| 182 ></P | |
| 183 ></DIV | |
| 184 ><DIV | |
| 185 CLASS="REFSECT1" | |
| 186 ><A | |
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187 NAME="AEN8199" |
| 0 | 188 ></A |
| 189 ><H2 | |
| 190 >See Also</H2 | |
| 191 ><P | |
| 192 ><A | |
| 193 HREF="sdlcreatesemaphore.html" | |
| 194 ><TT | |
| 195 CLASS="FUNCTION" | |
| 196 >SDL_CreateSemaphore</TT | |
| 197 ></A | |
| 198 >, | |
| 199 <A | |
| 200 HREF="sdldestroysemaphore.html" | |
| 201 ><TT | |
| 202 CLASS="FUNCTION" | |
| 203 >SDL_DestroySemaphore</TT | |
| 204 ></A | |
| 205 >, | |
| 206 <A | |
| 207 HREF="sdlsemwait.html" | |
| 208 ><TT | |
| 209 CLASS="FUNCTION" | |
| 210 >SDL_SemWait</TT | |
| 211 ></A | |
| 212 >, | |
| 213 <A | |
| 214 HREF="sdlsemtrywait.html" | |
| 215 ><TT | |
| 216 CLASS="FUNCTION" | |
| 217 >SDL_SemTryWait</TT | |
| 218 ></A | |
| 219 >, | |
| 220 <A | |
| 221 HREF="sdlsemwaittimeout.html" | |
| 222 ><TT | |
| 223 CLASS="FUNCTION" | |
| 224 >SDL_SemWaitTimeout</TT | |
| 225 ></A | |
| 226 >, | |
| 227 <A | |
| 228 HREF="sdlsemvalue.html" | |
| 229 ><TT | |
| 230 CLASS="FUNCTION" | |
| 231 >SDL_SemValue</TT | |
| 232 ></A | |
| 233 ></P | |
| 234 ></DIV | |
| 235 ><DIV | |
| 236 CLASS="NAVFOOTER" | |
| 237 ><HR | |
| 238 ALIGN="LEFT" | |
| 239 WIDTH="100%"><TABLE | |
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240 SUMMARY="Footer navigation table" |
| 0 | 241 WIDTH="100%" |
| 242 BORDER="0" | |
| 243 CELLPADDING="0" | |
| 244 CELLSPACING="0" | |
| 245 ><TR | |
| 246 ><TD | |
| 247 WIDTH="33%" | |
| 248 ALIGN="left" | |
| 249 VALIGN="top" | |
| 250 ><A | |
| 251 HREF="sdlsemwaittimeout.html" | |
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252 ACCESSKEY="P" |
| 0 | 253 >Prev</A |
| 254 ></TD | |
| 255 ><TD | |
| 256 WIDTH="34%" | |
| 257 ALIGN="center" | |
| 258 VALIGN="top" | |
| 259 ><A | |
| 260 HREF="index.html" | |
|
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261 ACCESSKEY="H" |
| 0 | 262 >Home</A |
| 263 ></TD | |
| 264 ><TD | |
| 265 WIDTH="33%" | |
| 266 ALIGN="right" | |
| 267 VALIGN="top" | |
| 268 ><A | |
| 269 HREF="sdlsemvalue.html" | |
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parents:
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270 ACCESSKEY="N" |
| 0 | 271 >Next</A |
| 272 ></TD | |
| 273 ></TR | |
| 274 ><TR | |
| 275 ><TD | |
| 276 WIDTH="33%" | |
| 277 ALIGN="left" | |
| 278 VALIGN="top" | |
| 279 >SDL_SemWaitTimeout</TD | |
| 280 ><TD | |
| 281 WIDTH="34%" | |
| 282 ALIGN="center" | |
| 283 VALIGN="top" | |
| 284 ><A | |
| 285 HREF="thread.html" | |
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286 ACCESSKEY="U" |
| 0 | 287 >Up</A |
| 288 ></TD | |
| 289 ><TD | |
| 290 WIDTH="33%" | |
| 291 ALIGN="right" | |
| 292 VALIGN="top" | |
| 293 >SDL_SemValue</TD | |
| 294 ></TR | |
| 295 ></TABLE | |
| 296 ></DIV | |
| 297 ></BODY | |
| 298 ></HTML | |
| 299 > |