Mercurial > sdl-ios-xcode
view docs/man3/SDL_CreateSemaphore.3 @ 1626:a80e1e0880b8
Fixed bug #176
[I'm fixing this for the public headers, but I'm not going to bother for the SDL library code (yet)]
To clarify: Normaly, GCC (or, to be precise, the preprocessor) will ignore
this, and compile the code happily. However, one can specify -Wundef to get a
warning about this.
One can probably argue whether to consider this a bug or not; but I think that
(a) from a semantic point of view, using "#if FOO" when FOO is not defined is
strange, and (b) since it is possible to trigger a warning about this, and a
trivial fix exists, it should be corrected.
I can think of two alternative patches, BTW:
1) Simply use #define HAVE_FOO 0, instead of not defining HAVE_FOO at all
2) Change
#if HAVE_FOO
to
#if HAVE_FOO+0
which always does the right thing.
But I think I still prefer the attached patch :-).
| author | Sam Lantinga <slouken@libsdl.org> |
|---|---|
| date | Thu, 13 Apr 2006 13:38:40 +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