Locks the \fBmutex\fR, which was previously created with \fI\fBSDL_CreateMutex\fP\fR\&. If the mutex is already locked then \fBSDL_mutexP\fP will not return until it is \fIunlocked\fR\&. Returns \fB0\fR on success, or \fB-1\fR on an error\&.
.PP
SDL also defines a macro \fB#define SDL_LockMutex(m) SDL_mutexP(m)\fP\&.