summaryrefslogtreecommitdiffstats
path: root/uisimulator/sdl/kernel.c
blob: e01fbe65b9501f5e2b85e0185fe173fffa27e8ee (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
/***************************************************************************
 *             __________               __   ___.
 *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
 *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
 *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
 *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
 *                     \/            \/     \/    \/            \/
 * $Id$
 *
 * Copyright (C) 2002 by Felix Arends
 *
 * All files in this archive are subject to the GNU General Public License.
 * See the file COPYING in the source tree root for full license agreement.
 *
 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
 * KIND, either express or implied.
 *
 ****************************************************************************/

#include <stdlib.h>
#include "memory.h"
#include "uisdl.h"
#include "kernel.h"
#include "thread-sdl.h"
#include "thread.h"
#include "debug.h"

static void (*tick_funcs[MAX_NUM_TICK_TASKS])(void);

int set_irq_level (int level)
{
    static int _lv = 0;
    return (_lv = level);
}

#ifdef HAVE_EXTENDED_MESSAGING_AND_NAME
/* Moves waiting thread's descriptor to the current sender when a
   message is dequeued */
static void queue_fetch_sender(struct queue_sender_list *send,
                               unsigned int i)
{
    int old_level = set_irq_level(15<<4);
    struct queue_sender **spp = &send->senders[i];

    if(*spp)
    {
        send->curr_sender = *spp;
        *spp = NULL;
    }

    set_irq_level(old_level);
}

/* Puts the specified return value in the waiting thread's return value
   and wakes the thread  - a sender should be confirmed to exist first */
static void queue_release_sender(struct queue_sender **sender,
                                 intptr_t retval)
{
    (*sender)->retval = retval;
    *sender = NULL;
}

/* Releases any waiting threads that are queued with queue_send -
   reply with NULL */
static void queue_release_all_senders(struct event_queue *q)
{
    if(q->send)
    {
        unsigned int i;
        for(i = q->read; i != q->write; i++)
        {
            struct queue_sender **spp =
                &q->send->senders[i & QUEUE_LENGTH_MASK];
            if(*spp)
            {
                queue_release_sender(spp, 0);
            }
        }
    }
}

/* Enables queue_send on the specified queue - caller allocates the extra
   data structure */
void queue_enable_queue_send(struct event_queue *q,
                             struct queue_sender_list *send)
{
    q->send = send;
    memset(send, 0, sizeof(*send));
}
#endif /* HAVE_EXTENDED_MESSAGING_AND_NAME */

void queue_init(struct event_queue *q, bool register_queue)
{
    (void)register_queue;
    
    q->read   = 0;
    q->write  = 0;
    q->thread = NULL;
#ifdef HAVE_EXTENDED_MESSAGING_AND_NAME
    q->send   = NULL; /* No message sending by default */
#endif
}

void queue_delete(struct event_queue *q)
{
    (void)q;
}

void queue_wait(struct event_queue *q, struct event *ev)
{
    unsigned int rd;

    while(q->read == q->write)
    {
        switch_thread(true, NULL);
    }

    rd = q->read++ & QUEUE_LENGTH_MASK;
    *ev = q->events[rd];

#ifdef HAVE_EXTENDED_MESSAGING_AND_NAME
    if(q->send && q->send->senders[rd])
    {
        /* Get data for a waiting thread if one */
        queue_fetch_sender(q->send, rd);
    }
#endif
}

void queue_wait_w_tmo(struct event_queue *q, struct event *ev, int ticks)
{
    unsigned int timeout = current_tick + ticks;

    while(q->read == q->write && TIME_BEFORE( current_tick, timeout ))
    {
        sim_sleep(1);
    }

    if(q->read != q->write)
    {
        unsigned int rd = q->read++ & QUEUE_LENGTH_MASK;
        *ev = q->events[rd];

#ifdef HAVE_EXTENDED_MESSAGING_AND_NAME
        if(q->send && q->send->senders[rd])
        {
            /* Get data for a waiting thread if one */
            queue_fetch_sender(q->send, rd);
        }
#endif
    }
    else
    {
        ev->id = SYS_TIMEOUT;
    }
}

void queue_post(struct event_queue *q, long id, intptr_t data)
{
    int oldlevel = set_irq_level(15<<4);
    unsigned int wr = q->write++ & QUEUE_LENGTH_MASK;

    q->events[wr].id   = id;
    q->events[wr].data = data;

#ifdef HAVE_EXTENDED_MESSAGING_AND_NAME
    if(q->send)
    {
        struct queue_sender **spp = &q->send->senders[wr];

        if(*spp)
        {
            /* overflow protect - unblock any thread waiting at this index */
            queue_release_sender(spp, 0);
        }
    }
#endif

    set_irq_level(oldlevel);
}

#ifdef HAVE_EXTENDED_MESSAGING_AND_NAME
intptr_t queue_send(struct event_queue *q, long id, intptr_t data)
{
    int oldlevel = set_irq_level(15<<4);
    unsigned int wr = q->write++ & QUEUE_LENGTH_MASK;

    q->events[wr].id   = id;
    q->events[wr].data = data;

    if(q->send)
    {
        struct queue_sender **spp = &q->send->senders[wr];
        struct queue_sender sender;

        if(*spp)
        {
            /* overflow protect - unblock any thread waiting at this index */
            queue_release_sender(spp, 0);
        }

        *spp = &sender;

        set_irq_level(oldlevel);
        while (*spp != NULL)
        {
            switch_thread(true, NULL);
        }

        return sender.retval;
    }

    /* Function as queue_post if sending is not enabled */
    set_irq_level(oldlevel);
    return 0;
}

#if 0 /* not used now but probably will be later */
/* Query if the last message dequeued was added by queue_send or not */
bool queue_in_queue_send(struct event_queue *q)
{
    return q->send && q->send->curr_sender;
}
#endif

/* Replies with retval to any dequeued message sent with queue_send */
void queue_reply(struct event_queue *q, intptr_t retval)
{
    if(q->send && q->send->curr_sender)
    {
        queue_release_sender(&q->send->curr_sender, retval);
    }
}
#endif /* HAVE_EXTENDED_MESSAGING_AND_NAME */

bool queue_empty(const struct event_queue* q)
{
    return ( q->read == q->write );
}

void queue_clear(struct event_queue* q)
{
    /* fixme: This is potentially unsafe in case we do interrupt-like processing */
#ifdef HAVE_EXTENDED_MESSAGING_AND_NAME
    /* Release all thread waiting in the queue for a reply -
       dequeued sent message will be handled by owning thread */
    queue_release_all_senders(q);
#endif
    q->read = 0;
    q->write = 0;
}

void queue_remove_from_head(struct event_queue *q, long id)
{
    int oldlevel = set_irq_level(15<<4);
    
    while(q->read != q->write)
    {
        unsigned int rd = q->read & QUEUE_LENGTH_MASK;

        if(q->events[rd].id != id)
        {
            break;
        }

#ifdef HAVE_EXTENDED_MESSAGING_AND_NAME
        if(q->send)
        {
            struct queue_sender **spp = &q->send->senders[rd];

            if(*spp)
            {
                /* Release any thread waiting on this message */
                queue_release_sender(spp, 0);
            }
        }
#endif
        q->read++;
    }
    
    set_irq_level(oldlevel);
}

void switch_thread(bool save_context, struct thread_entry **blocked_list)
{
    (void)save_context;
    (void)blocked_list;
    
    yield ();
}

void sim_tick_tasks(void)
{
    int i;

    /* Run through the list of tick tasks */
    for(i = 0;i < MAX_NUM_TICK_TASKS;i++)
    {
        if(tick_funcs[i])
        {
            tick_funcs[i]();
        }
    }
}

int tick_add_task(void (*f)(void))
{
    int i;

    /* Add a task if there is room */
    for(i = 0;i < MAX_NUM_TICK_TASKS;i++)
    {
        if(tick_funcs[i] == NULL)
        {
            tick_funcs[i] = f;
            return 0;
        }
    }
    DEBUGF("Error! tick_add_task(): out of tasks");
    return -1;
}

int tick_remove_task(void (*f)(void))
{
    int i;

    /* Remove a task if it is there */
    for(i = 0;i < MAX_NUM_TICK_TASKS;i++)
    {
        if(tick_funcs[i] == f)
        {
            tick_funcs[i] = NULL;
            return 0;
        }
    }
    
    return -1;
}

/* Very simple mutex simulation - won't work with pre-emptive
   multitasking, but is better than nothing at all */
void mutex_init(struct mutex *m)
{
    m->locked = false;
}

void mutex_lock(struct mutex *m)
{
    while(m->locked)
        switch_thread(true, NULL);
    m->locked = true;
}

void mutex_unlock(struct mutex *m)
{
    m->locked = false;
}

void spinlock_lock(struct mutex *m)
{
    while(m->locked)
        switch_thread(true, NULL);
    m->locked = true;
}

void spinlock_unlock(struct mutex *m)
{
    m->locked = false;
}