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
23#include <errno.h>
24
25#include "SDL_config.h"
26
27/* An implementation of semaphores using mutexes and condition variables */
28
29#include "SDL_timer.h"
30#include "SDL_thread.h"
31#include "SDL_systhread_c.h"
32
33
34#if SDL_THREADS_DISABLED
35
36SDL_sem *SDL_CreateSemaphore(Uint32 initial_value)
37{
38	SDL_SetError("SDL not configured with thread support");
39	return (SDL_sem *)0;
40}
41
42void SDL_DestroySemaphore(SDL_sem *sem)
43{
44	return;
45}
46
47int SDL_SemTryWait(SDL_sem *sem)
48{
49	SDL_SetError("SDL not configured with thread support");
50	return -1;
51}
52
53int SDL_SemWaitTimeout(SDL_sem *sem, Uint32 timeout)
54{
55	SDL_SetError("SDL not configured with thread support");
56	return -1;
57}
58
59int SDL_SemWait(SDL_sem *sem)
60{
61	SDL_SetError("SDL not configured with thread support");
62	return -1;
63}
64
65Uint32 SDL_SemValue(SDL_sem *sem)
66{
67	return 0;
68}
69
70int SDL_SemPost(SDL_sem *sem)
71{
72	SDL_SetError("SDL not configured with thread support");
73	return -1;
74}
75
76#else
77
78#include <kos/sem.h>
79
80struct SDL_semaphore
81{
82	semaphore_t sem;
83};
84
85SDL_sem *SDL_CreateSemaphore(Uint32 initial_value)
86{
87	return (SDL_sem *)sem_create(initial_value);
88}
89
90/* WARNING:
91   You cannot call this function when another thread is using the semaphore.
92*/
93void SDL_DestroySemaphore(SDL_sem *sem)
94{
95	if ( ! sem ) {
96		SDL_SetError("Passed a NULL semaphore");
97		return;
98	}
99
100	sem_destroy(&sem->sem);
101}
102
103int SDL_SemTryWait(SDL_sem *sem)
104{
105	int retval;
106
107	if ( ! sem ) {
108		SDL_SetError("Passed a NULL semaphore");
109		return -1;
110	}
111
112	retval = sem_trywait(&sem->sem);
113	if (retval==0) return 0;
114	else return SDL_MUTEX_TIMEDOUT;
115
116	return retval;
117}
118
119int SDL_SemWaitTimeout(SDL_sem *sem, Uint32 timeout)
120{
121	int retval;
122
123	if ( ! sem ) {
124		SDL_SetError("Passed a NULL semaphore");
125		return -1;
126	}
127
128	/* A timeout of 0 is an easy case */
129	if ( timeout == 0 ) {
130		return SDL_SemTryWait(sem);
131	}
132
133	retval = sem_wait_timed(&sem->sem,timeout);
134	if (retval==-1) retval= SDL_MUTEX_TIMEDOUT;
135
136	return retval;
137}
138
139int SDL_SemWait(SDL_sem *sem)
140{
141	int retval;
142
143	if ( ! sem ) {
144		SDL_SetError("Passed a NULL semaphore");
145		return -1;
146	}
147
148	while ( ((retval = sem_wait(&sem->sem)) == -1) && (errno == EINTR) ) {}
149	return retval;
150}
151
152Uint32 SDL_SemValue(SDL_sem *sem)
153{
154	if ( ! sem ) {
155		SDL_SetError("Passed a NULL semaphore");
156		return -1;
157	}
158
159	return sem_count(&sem->sem);
160}
161
162int SDL_SemPost(SDL_sem *sem)
163{
164	if ( ! sem ) {
165		SDL_SetError("Passed a NULL semaphore");
166		return -1;
167	}
168
169	sem_signal(&sem->sem);
170	return 0;
171}
172
173#endif /* SDL_THREADS_DISABLED */
174