1/*
2    SDL - Simple DirectMedia Layer
3    Copyright (C) 1997-2012 Sam Lantinga
4
5    This library is free software; you can redistribute it and/or
6    modify it under the terms of the GNU Lesser General Public
7    License as published by the Free Software Foundation; either
8    version 2.1 of the License, or (at your option) any later version.
9
10    This library is distributed in the hope that it will be useful,
11    but WITHOUT ANY WARRANTY; without even the implied warranty of
12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
13    Lesser General Public License for more details.
14
15    You should have received a copy of the GNU Lesser General Public
16    License along with this library; if not, write to the Free Software
17    Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
18
19    Sam Lantinga
20    slouken@libsdl.org
21*/
22#include "SDL_config.h"
23
24/* RISC OS implementations uses pthreads based on linux code */
25
26#include "SDL_thread.h"
27
28#if SDL_THREADS_DISABLED
29#include "../generic/SDL_sysmutex.c"
30#else
31
32#include <pthread.h>
33
34struct SDL_mutex {
35	pthread_mutex_t id;
36#if SDL_THREAD_PTHREAD_NO_RECURSIVE_MUTEX
37	int recursive;
38	pthread_t owner;
39#endif
40};
41
42SDL_mutex *SDL_CreateMutex (void)
43{
44	SDL_mutex *mutex;
45	pthread_mutexattr_t attr;
46
47	/* Allocate the structure */
48	mutex = (SDL_mutex *)SDL_calloc(1, sizeof(*mutex));
49	if ( mutex ) {
50		pthread_mutexattr_init(&attr);
51#if SDL_THREAD_PTHREAD_NO_RECURSIVE_MUTEX
52		/* No extra attributes necessary */
53#else
54		pthread_mutexattr_settype(&attr, PTHREAD_MUTEX_RECURSIVE);
55#endif /* SDL_THREAD_PTHREAD_NO_RECURSIVE_MUTEX */
56		if ( pthread_mutex_init(&mutex->id, &attr) != 0 ) {
57			SDL_SetError("pthread_mutex_init() failed");
58			SDL_free(mutex);
59			mutex = NULL;
60		}
61	} else {
62		SDL_OutOfMemory();
63	}
64	return(mutex);
65}
66
67void SDL_DestroyMutex(SDL_mutex *mutex)
68{
69	if ( mutex ) {
70		pthread_mutex_destroy(&mutex->id);
71		SDL_free(mutex);
72	}
73}
74
75/* Lock the mutex */
76int SDL_mutexP(SDL_mutex *mutex)
77{
78	int retval;
79#if SDL_THREAD_PTHREAD_NO_RECURSIVE_MUTEX
80	pthread_t this_thread;
81#endif
82
83	if ( mutex == NULL ) {
84		SDL_SetError("Passed a NULL mutex");
85		return -1;
86	}
87
88	retval = 0;
89#if SDL_THREAD_PTHREAD_NO_RECURSIVE_MUTEX
90	this_thread = pthread_self();
91	if ( mutex->owner == this_thread ) {
92		++mutex->recursive;
93	} else {
94		/* The order of operations is important.
95		   We set the locking thread id after we obtain the lock
96		   so unlocks from other threads will fail.
97		*/
98		if ( pthread_mutex_lock(&mutex->id) == 0 ) {
99			mutex->owner = this_thread;
100			mutex->recursive = 0;
101		} else {
102			SDL_SetError("pthread_mutex_lock() failed");
103			retval = -1;
104		}
105	}
106#else
107	if ( pthread_mutex_lock(&mutex->id) < 0 ) {
108		SDL_SetError("pthread_mutex_lock() failed");
109		retval = -1;
110	}
111#endif
112	return retval;
113}
114
115int SDL_mutexV(SDL_mutex *mutex)
116{
117	int retval;
118
119	if ( mutex == NULL ) {
120		SDL_SetError("Passed a NULL mutex");
121		return -1;
122	}
123
124	retval = 0;
125#if SDL_THREAD_PTHREAD_NO_RECURSIVE_MUTEX
126	/* We can only unlock the mutex if we own it */
127	if ( pthread_self() == mutex->owner ) {
128		if ( mutex->recursive ) {
129			--mutex->recursive;
130		} else {
131			/* The order of operations is important.
132			   First reset the owner so another thread doesn't lock
133			   the mutex and set the ownership before we reset it,
134			   then release the lock semaphore.
135			 */
136			mutex->owner = 0;
137			pthread_mutex_unlock(&mutex->id);
138		}
139	} else {
140		SDL_SetError("mutex not owned by this thread");
141		retval = -1;
142	}
143
144#else
145	if ( pthread_mutex_unlock(&mutex->id) < 0 ) {
146		SDL_SetError("pthread_mutex_unlock() failed");
147		retval = -1;
148	}
149#endif /* SDL_THREAD_PTHREAD_NO_RECURSIVE_MUTEX */
150
151	return retval;
152}
153#endif
154