view docs/man3/SDL_SemWait.3 @ 1240:3b8a43c428bb

From Bug #36: There are a couple of issues with the selection of Altivec alpha-blitting routines in CalculateAlphaBlit() in src/video/SDL_Blit_A.c. 1) There's no check for the presence of Altivec when checking if the Blit32to565PixelAlphaAltivec() routine can be selected. 2) Altivec cannot be used in video memory, and there's no check if the destination surface is a hardware surface. (Alpha-blitting to a hardware surface with GPU support is a bad idea, but somebody's bound to do it anyway.) Patch to fix these attached.
author Ryan C. Gordon <icculus@icculus.org>
date Sun, 08 Jan 2006 21:18:15 +0000
parents e5bc29de3f0a
children 546f7c1eb755
line wrap: on
line source

.TH "SDL_SemWait" "3" "Tue 11 Sep 2001, 23:00" "SDL" "SDL API Reference" 
.SH "NAME"
SDL_SemWait\- Lock a semaphore and suspend the thread if the semaphore value is zero\&.
.SH "SYNOPSIS"
.PP
\fB#include "SDL\&.h"
#include "SDL_thread\&.h"
.sp
\fBint \fBSDL_SemWait\fP\fR(\fBSDL_sem *sem\fR);
.SH "DESCRIPTION"
.PP
\fBSDL_SemWait()\fP suspends the calling thread until either the semaphore pointed to by \fBsem\fR has a positive value, the call is interrupted by a signal or error\&. If the call is successful it will atomically decrement the semaphore value\&.
.PP
After \fBSDL_SemWait()\fP is successful, the semaphore can be released and its count atomically incremented by a successful call to \fISDL_SemPost\fR\&.
.SH "RETURN VALUE"
.PP
Returns \fB0\fR if successful or \fB-1\fR if there was an error (leaving the semaphore unchanged)\&.
.SH "EXAMPLES"
.PP
.PP
.nf
\f(CWif (SDL_SemWait(my_sem) == -1) {
        return WAIT_FAILED;
}

\&.\&.\&.

SDL_SemPost(my_sem);\fR
.fi
.PP
.SH "SEE ALSO"
.PP
\fI\fBSDL_CreateSemaphore\fP\fR, \fI\fBSDL_DestroySemaphore\fP\fR, \fI\fBSDL_SemTryWait\fP\fR, \fI\fBSDL_SemWaitTimeout\fP\fR, \fI\fBSDL_SemPost\fP\fR, \fI\fBSDL_SemValue\fP\fR
...\" created by instant / docbook-to-man, Tue 11 Sep 2001, 23:00