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comparison src/thread/riscos/SDL_syssem.c @ 955:d74fbf56f2f6

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Date: Fri, 25 Jun 2004 13:29:15 +0100 From: "alan buckley" Subject: Modification for RISC OS version of SDL Ive attached a zip file with the changes to this email, it contains the following: The file sdldiff.txt is the output from cvs diff u. . The directory thread/riscos contains all the new files to support threading. Readme.riscos is a new readme file to add.
author Sam Lantinga <slouken@libsdl.org>
date Fri, 17 Sep 2004 13:20:10 +0000
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children 1ccbb2b7d905
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954:3acd16ea0180 955:d74fbf56f2f6
1 /*
2 SDL - Simple DirectMedia Layer
3 Copyright (C) 1997-2004 Sam Lantinga
4
5 This library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Library General Public
7 License as published by the Free Software Foundation; either
8 version 2 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 Library General Public License for more details.
14
15 You should have received a copy of the GNU Library General Public
16 License along with this library; if not, write to the Free
17 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
18
19 Sam Lantinga
20 slouken@libsdl.org
21 */
22
23 /* RISC OS doesn't have semiphores so use code based on generic implementation */
24
25 #ifdef SAVE_RCSID
26 static char rcsid =
27 "@(#) $Id$";
28 #endif
29
30 /* An implementation of semaphores using mutexes and condition variables */
31
32 #include <stdlib.h>
33
34 #include "SDL_error.h"
35 #include "SDL_timer.h"
36 #include "SDL_thread.h"
37
38 #include "SDL_systhread_c.h"
39
40 #ifdef DISABLE_THREADS
41
42 SDL_sem *SDL_CreateSemaphore(Uint32 initial_value)
43 {
44 SDL_SetError("SDL not configured with thread support");
45 return (SDL_sem *)0;
46 }
47
48 void SDL_DestroySemaphore(SDL_sem *sem)
49 {
50 return;
51 }
52
53 int SDL_SemTryWait(SDL_sem *sem)
54 {
55 SDL_SetError("SDL not configured with thread support");
56 return -1;
57 }
58
59 int SDL_SemWaitTimeout(SDL_sem *sem, Uint32 timeout)
60 {
61 SDL_SetError("SDL not configured with thread support");
62 return -1;
63 }
64
65 int SDL_SemWait(SDL_sem *sem)
66 {
67 SDL_SetError("SDL not configured with thread support");
68 return -1;
69 }
70
71 Uint32 SDL_SemValue(SDL_sem *sem)
72 {
73 return 0;
74 }
75
76 int SDL_SemPost(SDL_sem *sem)
77 {
78 SDL_SetError("SDL not configured with thread support");
79 return -1;
80 }
81
82 #else
83
84 struct SDL_semaphore
85 {
86 Uint32 count;
87 Uint32 waiters_count;
88 SDL_mutex *count_lock;
89 SDL_cond *count_nonzero;
90 };
91
92 SDL_sem *SDL_CreateSemaphore(Uint32 initial_value)
93 {
94 SDL_sem *sem;
95
96 sem = (SDL_sem *)malloc(sizeof(*sem));
97 if ( ! sem ) {
98 SDL_OutOfMemory();
99 return(0);
100 }
101 sem->count = initial_value;
102 sem->waiters_count = 0;
103
104 sem->count_lock = SDL_CreateMutex();
105 sem->count_nonzero = SDL_CreateCond();
106 if ( ! sem->count_lock || ! sem->count_nonzero ) {
107 SDL_DestroySemaphore(sem);
108 return(0);
109 }
110
111 return(sem);
112 }
113
114 /* WARNING:
115 You cannot call this function when another thread is using the semaphore.
116 */
117 void SDL_DestroySemaphore(SDL_sem *sem)
118 {
119 if ( sem ) {
120 sem->count = 0xFFFFFFFF;
121 while ( sem->waiters_count > 0) {
122 SDL_CondSignal(sem->count_nonzero);
123 SDL_Delay(10);
124 }
125 SDL_DestroyCond(sem->count_nonzero);
126 SDL_mutexP(sem->count_lock);
127 SDL_mutexV(sem->count_lock);
128 SDL_DestroyMutex(sem->count_lock);
129 free(sem);
130 }
131 }
132
133 int SDL_SemTryWait(SDL_sem *sem)
134 {
135 int retval;
136
137 if ( ! sem ) {
138 SDL_SetError("Passed a NULL semaphore");
139 return -1;
140 }
141
142 retval = SDL_MUTEX_TIMEDOUT;
143 SDL_LockMutex(sem->count_lock);
144 if ( sem->count > 0 ) {
145 --sem->count;
146 retval = 0;
147 }
148 SDL_UnlockMutex(sem->count_lock);
149
150 return retval;
151 }
152
153 int SDL_SemWaitTimeout(SDL_sem *sem, Uint32 timeout)
154 {
155 int retval;
156
157 if ( ! sem ) {
158 SDL_SetError("Passed a NULL semaphore");
159 return -1;
160 }
161
162 /* A timeout of 0 is an easy case */
163 if ( timeout == 0 ) {
164 return SDL_SemTryWait(sem);
165 }
166
167 SDL_LockMutex(sem->count_lock);
168 ++sem->waiters_count;
169 retval = 0;
170 while ( (sem->count == 0) && (retval != SDL_MUTEX_TIMEDOUT) ) {
171 retval = SDL_CondWaitTimeout(sem->count_nonzero,
172 sem->count_lock, timeout);
173 }
174 --sem->waiters_count;
175 --sem->count;
176 SDL_UnlockMutex(sem->count_lock);
177
178 return retval;
179 }
180
181 int SDL_SemWait(SDL_sem *sem)
182 {
183 return SDL_SemWaitTimeout(sem, SDL_MUTEX_MAXWAIT);
184 }
185
186 Uint32 SDL_SemValue(SDL_sem *sem)
187 {
188 Uint32 value;
189
190 value = 0;
191 if ( sem ) {
192 SDL_LockMutex(sem->count_lock);
193 value = sem->count;
194 SDL_UnlockMutex(sem->count_lock);
195 }
196 return value;
197 }
198
199 int SDL_SemPost(SDL_sem *sem)
200 {
201 if ( ! sem ) {
202 SDL_SetError("Passed a NULL semaphore");
203 return -1;
204 }
205
206 SDL_LockMutex(sem->count_lock);
207 if ( sem->waiters_count > 0 ) {
208 SDL_CondSignal(sem->count_nonzero);
209 }
210 ++sem->count;
211 SDL_UnlockMutex(sem->count_lock);
212
213 return 0;
214 }
215
216 #endif /* DISABLE_THREADS */