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/* Semaphore functions using the Win32 API */
25
26#define WIN32_LEAN_AND_MEAN
27#include <windows.h>
28
29#include "SDL_thread.h"
30#if defined(_WIN32_WCE) && (_WIN32_WCE < 300)
31#include "win_ce_semaphore.h"
32#endif
33
34
35struct SDL_semaphore {
36#if defined(_WIN32_WCE) && (_WIN32_WCE < 300)
37	SYNCHHANDLE id;
38#else
39	HANDLE id;
40#endif
41	volatile LONG count;
42};
43
44
45/* Create a semaphore */
46SDL_sem *SDL_CreateSemaphore(Uint32 initial_value)
47{
48	SDL_sem *sem;
49
50	/* Allocate sem memory */
51	sem = (SDL_sem *)SDL_malloc(sizeof(*sem));
52	if ( sem ) {
53		/* Create the semaphore, with max value 32K */
54#if defined(_WIN32_WCE) && (_WIN32_WCE < 300)
55		sem->id = CreateSemaphoreCE(NULL, initial_value, 32*1024, NULL);
56#else
57		sem->id = CreateSemaphore(NULL, initial_value, 32*1024, NULL);
58#endif
59		sem->count = (LONG) initial_value;
60		if ( ! sem->id ) {
61			SDL_SetError("Couldn't create semaphore");
62			SDL_free(sem);
63			sem = NULL;
64		}
65	} else {
66		SDL_OutOfMemory();
67	}
68	return(sem);
69}
70
71/* Free the semaphore */
72void SDL_DestroySemaphore(SDL_sem *sem)
73{
74	if ( sem ) {
75		if ( sem->id ) {
76#if defined(_WIN32_WCE) && (_WIN32_WCE < 300)
77			CloseSynchHandle(sem->id);
78#else
79			CloseHandle(sem->id);
80#endif
81			sem->id = 0;
82		}
83		SDL_free(sem);
84	}
85}
86
87int SDL_SemWaitTimeout(SDL_sem *sem, Uint32 timeout)
88{
89	int retval;
90	DWORD dwMilliseconds;
91
92	if ( ! sem ) {
93		SDL_SetError("Passed a NULL sem");
94		return -1;
95	}
96
97	if ( timeout == SDL_MUTEX_MAXWAIT ) {
98		dwMilliseconds = INFINITE;
99	} else {
100		dwMilliseconds = (DWORD)timeout;
101	}
102#if defined(_WIN32_WCE) && (_WIN32_WCE < 300)
103	switch (WaitForSemaphoreCE(sem->id, dwMilliseconds)) {
104#else
105	switch (WaitForSingleObject(sem->id, dwMilliseconds)) {
106#endif
107	    case WAIT_OBJECT_0:
108		InterlockedDecrement(&sem->count);
109		retval = 0;
110		break;
111	    case WAIT_TIMEOUT:
112		retval = SDL_MUTEX_TIMEDOUT;
113		break;
114	    default:
115		SDL_SetError("WaitForSingleObject() failed");
116		retval = -1;
117		break;
118	}
119	return retval;
120}
121
122int SDL_SemTryWait(SDL_sem *sem)
123{
124	return SDL_SemWaitTimeout(sem, 0);
125}
126
127int SDL_SemWait(SDL_sem *sem)
128{
129	return SDL_SemWaitTimeout(sem, SDL_MUTEX_MAXWAIT);
130}
131
132/* Returns the current count of the semaphore */
133Uint32 SDL_SemValue(SDL_sem *sem)
134{
135	if ( ! sem ) {
136		SDL_SetError("Passed a NULL sem");
137		return 0;
138	}
139	return (Uint32) sem->count;
140}
141
142int SDL_SemPost(SDL_sem *sem)
143{
144	if ( ! sem ) {
145		SDL_SetError("Passed a NULL sem");
146		return -1;
147	}
148	/* Increase the counter in the first place, because
149	 * after a successful release the semaphore may
150	 * immediately get destroyed by another thread which
151	 * is waiting for this semaphore.
152	 */
153	InterlockedIncrement(&sem->count);
154#if defined(_WIN32_WCE) && (_WIN32_WCE < 300)
155	if ( ReleaseSemaphoreCE(sem->id, 1, NULL) == FALSE ) {
156#else
157	if ( ReleaseSemaphore(sem->id, 1, NULL) == FALSE ) {
158#endif
159		InterlockedDecrement(&sem->count);	/* restore */
160		SDL_SetError("ReleaseSemaphore() failed");
161		return -1;
162	}
163	return 0;
164}
165