Mercurial > sdl-ios-xcode
view docs/man3/SDL_CreateSemaphore.3 @ 1555:780fd5b61df1
Fixed bug #89
Date: Sun, 23 Oct 2005 16:39:03 +0200
From: "A. Schmid" <sahib@phreaker.net>
Subject: [SDL] no software surfaces with svgalib driver?
Hi,
I noticed that the SDL (1.2.9) svgalib driver only makes use of linear
addressable (framebuffer) video modes. On older systems (like one of
mine), linear addressable modes are often not available.
Especially for cards with VESA VBE < 2.0 the svgalib vesa driver is
unusable, since VESA only supports framebuffering for VBE 2.0 and later.
The changes necessary to add support for software surfaces seem to be
relatively small. I only had to hack src/video/svga/SDL_svgavideo.c (see
attached patch). The code worked fine for me, but it is no more than a
proof of concept and should be reviewed (probably has a memory leak when
switching modes). It also uses the vgagl library (included in the
svgalib package) and needs to be linked against it.
-Alex
author | Sam Lantinga <slouken@libsdl.org> |
---|---|
date | Sun, 19 Mar 2006 12:05:16 +0000 |
parents | e5bc29de3f0a |
children | 546f7c1eb755 |
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.TH "SDL_CreateSemaphore" "3" "Tue 11 Sep 2001, 23:00" "SDL" "SDL API Reference" .SH "NAME" SDL_CreateSemaphore\- Creates a new semaphore and assigns an initial value to it\&. .SH "SYNOPSIS" .PP \fB#include "SDL\&.h" #include "SDL_thread\&.h" .sp \fBSDL_sem *\fBSDL_CreateSemaphore\fP\fR(\fBUint32 initial_value\fR); .SH "DESCRIPTION" .PP \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\&. .SH "RETURN VALUE" .PP Returns a pointer to an initialized semaphore or \fBNULL\fR if there was an error\&. .SH "EXAMPLES" .PP .PP .nf \f(CWSDL_sem *my_sem; my_sem = SDL_CreateSemaphore(INITIAL_SEM_VALUE); if (my_sem == NULL) { return CREATE_SEM_FAILED; }\fR .fi .PP .SH "SEE ALSO" .PP \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 ...\" created by instant / docbook-to-man, Tue 11 Sep 2001, 23:00