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annotate docs/man3/SDL_CreateSemaphore.3 @ 4106:12bb6311fd5d SDL-1.2

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Hans de Goede fixed bug #495 When running boswars: http://www.boswars.org/ on a machine with intel integrathed graphics it crashes when it tries to play the initial theora splashscreen video: X Error of failed request: BadAlloc (insufficient resources for operation) Major opcode of failed request: 140 (XVideo) Minor opcode of failed request: 19 () Serial number of failed request: 25 Current serial number in output stream: 26 boswars: xcb_xlib.c:41: xcb_xlib_lock: Assertion `!c->xlib.lock' failed. Aborted I recognized this problem from a few years back, when I encountered it while working on the Xv blitter for xmame. The problem is that for some reason creation the Xvport and XvImage succeeds, and failure (lack of resources / hw capability?) is only indicated during the first XvPut[Shm]Image. I've written a patch for SDL using the work around for this I developed for xmame (and which is still used successfully in xmame after many years of usage). I'll admit it isn't very pretty, but after investigating several possibilities this was the best option, any other fixes would need changes to the SDL api and abi.
author Sam Lantinga <slouken@libsdl.org>
date Sat, 29 Dec 2007 02:23:48 +0000
parents e5bc29de3f0a
children 546f7c1eb755
rev   line source
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e5bc29de3f0a Updated from the SDL Documentation Project
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1 .TH "SDL_CreateSemaphore" "3" "Tue 11 Sep 2001, 23:00" "SDL" "SDL API Reference"
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2 .SH "NAME"
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3 SDL_CreateSemaphore\- Creates a new semaphore and assigns an initial value to it\&.
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4 .SH "SYNOPSIS"
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5 .PP
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6 \fB#include "SDL\&.h"
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7 #include "SDL_thread\&.h"
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8 .sp
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9 \fBSDL_sem *\fBSDL_CreateSemaphore\fP\fR(\fBUint32 initial_value\fR);
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10 .SH "DESCRIPTION"
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11 .PP
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12 \fBSDL_CreateSemaphore()\fP creates a new semaphore and initializes it with the value \fBinitial_value\fR\&. Each locking operation on the semaphore by \fISDL_SemWait\fR, \fISDL_SemTryWait\fR or \fISDL_SemWaitTimeout\fR will atomically decrement the semaphore value\&. The locking operation will be blocked if the semaphore value is not positive (greater than zero)\&. Each unlock operation by \fISDL_SemPost\fR will atomically increment the semaphore value\&.
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13 .SH "RETURN VALUE"
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14 .PP
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15 Returns a pointer to an initialized semaphore or \fBNULL\fR if there was an error\&.
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16 .SH "EXAMPLES"
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17 .PP
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18 .PP
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19 .nf
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20 \f(CWSDL_sem *my_sem;
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21
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22 my_sem = SDL_CreateSemaphore(INITIAL_SEM_VALUE);
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23
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24 if (my_sem == NULL) {
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25 return CREATE_SEM_FAILED;
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26 }\fR
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27 .fi
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28 .PP
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29 .SH "SEE ALSO"
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30 .PP
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31 \fI\fBSDL_DestroySemaphore\fP\fR, \fI\fBSDL_SemWait\fP\fR, \fI\fBSDL_SemTryWait\fP\fR, \fI\fBSDL_SemWaitTimeout\fP\fR, \fI\fBSDL_SemPost\fP\fR, \fI\fBSDL_SemValue\fP\fR
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32 ...\" created by instant / docbook-to-man, Tue 11 Sep 2001, 23:00