SheepShaver/src/timer.cpp

/*
 *  timer.cpp - Time Manager emulation
 *
 *  SheepShaver (C) 1997-2002 Christian Bauer and Marc Hellwig
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

/*
 * TODO: Prime(0)
 */

#include "sysdeps.h"
#include "timer.h"
#include "macos_util.h"
#include "main.h"
#include "cpu_emulation.h"

#define DEBUG 0
#include "debug.h"


#if __BEOS__
#define PRECISE_TIMING 1
#else
#define PRECISE_TIMING 0
#endif

#define TM_QUEUE 0                      // Enable TMQueue management (doesn't work)


// Definitions for Time Manager
enum {  // TMTask struct
        tmAddr = 6,
        tmCount = 10,
        tmWakeUp = 14,
        tmReserved = 18
};


// Array of additional info for each installed TMTask
struct TMDesc {
        uint32 task;            // Mac address of associated TMTask
        tm_time_t wakeup;       // Time this task is scheduled for execution
        bool in_use;            // Flag: descriptor in use
};

const int NUM_DESCS = 64;               // Maximum number of descriptors
static TMDesc desc[NUM_DESCS];

#if PRECISE_TIMING
static thread_id timer_thread = -1;
static bool thread_active = true;
static volatile tm_time_t wakeup_time = 0x7fffffffffffffff;
static sem_id wakeup_time_sem = -1;
static int32 timer_func(void *arg);
#endif


/*
 *  Allocate descriptor for given TMTask in list
 */

static int alloc_desc(uint32 tm)
{
        // Search for first free descriptor
        for (int i=0; i<NUM_DESCS; i++)
                if (!desc[i].in_use) {
                        desc[i].task = tm;
                        desc[i].in_use = true;
                        return i;
                }
        return -1;
}


/*
 *  Free descriptor in list
 */

inline static void free_desc(int i)
{
        desc[i].in_use = false;
}


/*
 *  Find descriptor associated with given TMTask
 */

inline static int find_desc(uint32 tm)
{
        for (int i=0; i<NUM_DESCS; i++)
                if (desc[i].in_use && desc[i].task == tm)
                        return i;
        return -1;
}


/*
 *  Enqueue task in Time Manager queue
 */

static void enqueue_tm(uint32 tm)
{
#if TM_QUEUE
        uint32 tm_var = ReadMacInt32(0xb30);
        WriteMacInt32(tm + qLink, ReadMacInt32(tm_var));
        WriteMacInt32(tm_var, tm);
#endif
}


/*
 *  Remove task from Time Manager queue
 */

static void dequeue_tm(uint32 tm)
{
#if TM_QUEUE
        uint32 p = ReadMacInt32(0xb30);
        while (p) {
                uint32 next = ReadMacInt32(p + qLink);
                if (next == tm) {
                        WriteMacInt32(p + qLink, ReadMacInt32(next + qLink));
                        return;
                }
        }
#endif
}


/*
 *  Initialize Time Manager
 */

void TimerInit(void)
{
        // Mark all descriptors as inactive
        for (int i=0; i<NUM_DESCS; i++)
                free_desc(i);

#if PRECISE_TIMING
        // Start timer thread
        wakeup_time_sem = create_sem(1, "Wakeup Time");
        timer_thread = spawn_thread(timer_func, "Time Manager", B_REAL_TIME_PRIORITY, NULL);
        resume_thread(timer_thread);
#endif
}


/*
 *  Exit Time Manager
 */

void TimerExit(void)
{
#if PRECISE_TIMING
        // Quit timer thread
        if (timer_thread > 0) {
                status_t l;
                thread_active = false;
                suspend_thread(timer_thread);
                resume_thread(timer_thread);
                wait_for_thread(timer_thread, &l);
                delete_sem(wakeup_time_sem);
        }
#endif
}


/*
 *  Emulator reset, remove all timer tasks
 */

void TimerReset(void)
{
        // Mark all descriptors as inactive
        for (int i=0; i<NUM_DESCS; i++)
                free_desc(i);
}


/*
 *  Insert timer task
 */

int16 InsTime(uint32 tm, uint16 trap)
{
        D(bug("InsTime %08lx, trap %04x\n", tm, trap));
        WriteMacInt16((uint32)tm + qType, ReadMacInt16((uint32)tm + qType) & 0x1fff | (trap << 4) & 0x6000);
        if (find_desc(tm) >= 0)
                printf("WARNING: InsTime(): Task re-inserted\n");
        else {
                int i = alloc_desc(tm);
                if (i < 0)
                        printf("FATAL: InsTime(): No free Time Manager descriptor\n");
        }
        return 0;
}


/*
 *  Remove timer task
 */

int16 RmvTime(uint32 tm)
{
        D(bug("RmvTime %08lx\n", tm));

        // Find descriptor
        int i = find_desc(tm);
        if (i < 0) {
                printf("WARNING: RmvTime(%08lx): Descriptor not found\n", tm);
                return 0;
        }

        // Task active?
#if PRECISE_TIMING
        while (acquire_sem(wakeup_time_sem) == B_INTERRUPTED) ;
        suspend_thread(timer_thread);
#endif
        if (ReadMacInt16(tm + qType) & 0x8000) {

                // Yes, make task inactive and remove it from the Time Manager queue
                WriteMacInt16(tm + qType, ReadMacInt16(tm + qType) & 0x7fff);
                dequeue_tm(tm);
#if PRECISE_TIMING
                // Look for next task to be called and set wakeup_time
                wakeup_time = 0x7fffffffffffffff;
                for (int j=0; j<NUM_DESCS; j++) {
                        if (desc[j].in_use && (ReadMacInt16(desc[j].task + qType) & 0x8000))
                                if (desc[j].wakeup < wakeup_time)
                                        wakeup_time = desc[j].wakeup;
                }
#endif

                // Compute remaining time
                tm_time_t remaining, current;
                timer_current_time(current);
                timer_sub_time(remaining, desc[i].wakeup, current);
                WriteMacInt32(tm + tmCount, timer_host2mac_time(remaining));
        } else
                WriteMacInt32(tm + tmCount, 0);
        D(bug(" tmCount %ld\n", ReadMacInt32(tm + tmCount)));
#if PRECISE_TIMING
        release_sem(wakeup_time_sem);
        thread_info info;
        do {
                resume_thread(timer_thread);                    // This will unblock the thread
                get_thread_info(timer_thread, &info);
        } while (info.state == B_THREAD_SUSPENDED);     // Sometimes, resume_thread() doesn't work (BeOS bug?)
#endif

        // Free descriptor
        free_desc(i);
        return 0;
}


/*
 *  Start timer task
 */

int16 PrimeTime(uint32 tm, int32 time)
{
        D(bug("PrimeTime %08lx, time %ld\n", tm, time));

        // Find descriptor
        int i = find_desc(tm);
        if (i < 0) {
                printf("FATAL: PrimeTime(): Descriptor not found\n");
                return 0;
        }

        // Convert delay time
        tm_time_t delay;
        timer_mac2host_time(delay, time);

        // Extended task?
        if (ReadMacInt16(tm + qType) & 0x4000) {

                // Yes, tmWakeUp set?
                if (ReadMacInt32(tm + tmWakeUp)) {

                        //!! PrimeTime(0) means continue previous delay
                        // (save wakeup time in RmvTime?)
                        if (time == 0) {
                                printf("FATAL: Unsupported PrimeTime(0)\n");
                                return 0;
                        }

                        // Yes, calculate wakeup time relative to last scheduled time
                        tm_time_t wakeup;
                        timer_add_time(wakeup, desc[i].wakeup, delay);
                        desc[i].wakeup = wakeup;

                } else {

                        // No, calculate wakeup time relative to current time
                        tm_time_t now;
                        timer_current_time(now);
                        timer_add_time(desc[i].wakeup, now, delay);
                }

                // Set tmWakeUp to indicate that task was scheduled
                WriteMacInt32(tm + tmWakeUp, 0x12345678);

        } else {

                // Not extended task, calculate wakeup time relative to current time
                tm_time_t now;
                timer_current_time(now);
                timer_add_time(desc[i].wakeup, now, delay);
        }

        // Make task active and enqueue it in the Time Manager queue
#if PRECISE_TIMING
        while (acquire_sem(wakeup_time_sem) == B_INTERRUPTED) ;
        suspend_thread(timer_thread);
#endif
        WriteMacInt16(tm + qType, ReadMacInt16(tm + qType) | 0x8000);
        enqueue_tm(tm);
#if PRECISE_TIMING
        // Look for next task to be called and set wakeup_time
        wakeup_time = 0x7fffffffffffffff;
        for (int j=0; j<NUM_DESCS; j++) {
                if (desc[j].in_use && (ReadMacInt16(desc[j].task + qType) & 0x8000))
                        if (desc[j].wakeup < wakeup_time)
                                wakeup_time = desc[j].wakeup;
        }
        release_sem(wakeup_time_sem);
        thread_info info;
        do {
                resume_thread(timer_thread);                    // This will unblock the thread
                get_thread_info(timer_thread, &info);
        } while (info.state == B_THREAD_SUSPENDED);     // Sometimes, resume_thread() doesn't work (BeOS bug?)
#endif
        return 0;
}


#if PRECISE_TIMING
/*
 *  Time Manager thread
 */

static int32 timer_func(void *arg)
{
        while (thread_active) {

                // Wait until time specified by wakeup_time
                snooze_until(wakeup_time, B_SYSTEM_TIMEBASE);

                while (acquire_sem(wakeup_time_sem) == B_INTERRUPTED) ;
                if (wakeup_time < system_time()) {

                        // Timer expired, trigger interrupt
                        wakeup_time = 0x7fffffffffffffff;
                        SetInterruptFlag(INTFLAG_TIMER);
                        TriggerInterrupt();
                }
                release_sem(wakeup_time_sem);
        }
        return 0;
}
#endif


/*
 *  Timer interrupt function (executed as part of 60Hz interrupt)
 */

void TimerInterrupt(void)
{
//      D(bug("TimerIRQ\n"));

        // Look for active TMTasks that have expired
        tm_time_t now;
        timer_current_time(now);
        for (int i=0; i<NUM_DESCS; i++)
                if (desc[i].in_use) {
                        uint32 tm = desc[i].task;
                        if ((ReadMacInt16(tm + qType) & 0x8000) && timer_cmp_time(desc[i].wakeup, now) <= 0) {

                                // Found one, mark as inactive and remove it from the Time Manager queue
                                WriteMacInt16(tm + qType, ReadMacInt16(tm + qType) & 0x7fff);
                                dequeue_tm(tm);

                                // Call timer function
                                uint32 addr = ReadMacInt32(tm + tmAddr);
                                if (addr) {
                                        D(bug("Calling TimeTask %08lx, addr %08lx\n", tm, addr));
                                        M68kRegisters r;
                                        r.a[0] = addr;
                                        r.a[1] = tm;
                                        Execute68k(r.a[0], &r);
                                        D(bug(" returned from TimeTask\n"));
                                }
                        }
                }

#if PRECISE_TIMING
        // Look for next task to be called and set wakeup_time
        while (acquire_sem(wakeup_time_sem) == B_INTERRUPTED) ;
        suspend_thread(timer_thread);
        wakeup_time = 0x7fffffffffffffff;
        for (int j=0; j<NUM_DESCS; j++) {
                if (desc[j].in_use && (ReadMacInt16(desc[j].task + qType) & 0x8000))
                        if (desc[j].wakeup < wakeup_time)
                                wakeup_time = desc[j].wakeup;
        }
        release_sem(wakeup_time_sem);
        thread_info info;
        do {
                resume_thread(timer_thread);                    // This will unblock the thread
                get_thread_info(timer_thread, &info);
        } while (info.state == B_THREAD_SUSPENDED);     // Sometimes, resume_thread() doesn't work (BeOS bug?)
#endif
}
Revision:	1.1
Committed:	2002-02-04T16:58:13Z (22 years, 3 months ago) by cebix
Branch:	MAIN
Branch point for:	cebix
Log Message:	Initial revision
#	User	Rev	Content
1	cebix	1.1	/*
2			* timer.cpp - Time Manager emulation
3			*
4			* SheepShaver (C) 1997-2002 Christian Bauer and Marc Hellwig
5			*
6			* This program is free software; you can redistribute it and/or modify
7			* it under the terms of the GNU General Public License as published by
8			* the Free Software Foundation; either version 2 of the License, or
9			* (at your option) any later version.
10			*
11			* This program is distributed in the hope that it will be useful,
12			* but WITHOUT ANY WARRANTY; without even the implied warranty of
13			* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14			* GNU General Public License for more details.
15			*
16			* You should have received a copy of the GNU General Public License
17			* along with this program; if not, write to the Free Software
18			* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
19			*/
20
21			/*
22			* TODO: Prime(0)
23			*/
24
25			#include "sysdeps.h"
26			#include "timer.h"
27			#include "macos_util.h"
28			#include "main.h"
29			#include "cpu_emulation.h"
30
31			#define DEBUG 0
32			#include "debug.h"
33
34
35			#if __BEOS__
36			#define PRECISE_TIMING 1
37			#else
38			#define PRECISE_TIMING 0
39			#endif
40
41			#define TM_QUEUE 0 // Enable TMQueue management (doesn't work)
42
43
44			// Definitions for Time Manager
45			enum { // TMTask struct
46			tmAddr = 6,
47			tmCount = 10,
48			tmWakeUp = 14,
49			tmReserved = 18
50			};
51
52
53			// Array of additional info for each installed TMTask
54			struct TMDesc {
55			uint32 task; // Mac address of associated TMTask
56			tm_time_t wakeup; // Time this task is scheduled for execution
57			bool in_use; // Flag: descriptor in use
58			};
59
60			const int NUM_DESCS = 64; // Maximum number of descriptors
61			static TMDesc desc[NUM_DESCS];
62
63			#if PRECISE_TIMING
64			static thread_id timer_thread = -1;
65			static bool thread_active = true;
66			static volatile tm_time_t wakeup_time = 0x7fffffffffffffff;
67			static sem_id wakeup_time_sem = -1;
68			static int32 timer_func(void *arg);
69			#endif
70
71
72			/*
73			* Allocate descriptor for given TMTask in list
74			*/
75
76			static int alloc_desc(uint32 tm)
77			{
78			// Search for first free descriptor
79			for (int i=0; i<NUM_DESCS; i++)
80			if (!desc[i].in_use) {
81			desc[i].task = tm;
82			desc[i].in_use = true;
83			return i;
84			}
85			return -1;
86			}
87
88
89			/*
90			* Free descriptor in list
91			*/
92
93			inline static void free_desc(int i)
94			{
95			desc[i].in_use = false;
96			}
97
98
99			/*
100			* Find descriptor associated with given TMTask
101			*/
102
103			inline static int find_desc(uint32 tm)
104			{
105			for (int i=0; i<NUM_DESCS; i++)
106			if (desc[i].in_use && desc[i].task == tm)
107			return i;
108			return -1;
109			}
110
111
112			/*
113			* Enqueue task in Time Manager queue
114			*/
115
116			static void enqueue_tm(uint32 tm)
117			{
118			#if TM_QUEUE
119			uint32 tm_var = ReadMacInt32(0xb30);
120			WriteMacInt32(tm + qLink, ReadMacInt32(tm_var));
121			WriteMacInt32(tm_var, tm);
122			#endif
123			}
124
125
126			/*
127			* Remove task from Time Manager queue
128			*/
129
130			static void dequeue_tm(uint32 tm)
131			{
132			#if TM_QUEUE
133			uint32 p = ReadMacInt32(0xb30);
134			while (p) {
135			uint32 next = ReadMacInt32(p + qLink);
136			if (next == tm) {
137			WriteMacInt32(p + qLink, ReadMacInt32(next + qLink));
138			return;
139			}
140			}
141			#endif
142			}
143
144
145			/*
146			* Initialize Time Manager
147			*/
148
149			void TimerInit(void)
150			{
151			// Mark all descriptors as inactive
152			for (int i=0; i<NUM_DESCS; i++)
153			free_desc(i);
154
155			#if PRECISE_TIMING
156			// Start timer thread
157			wakeup_time_sem = create_sem(1, "Wakeup Time");
158			timer_thread = spawn_thread(timer_func, "Time Manager", B_REAL_TIME_PRIORITY, NULL);
159			resume_thread(timer_thread);
160			#endif
161			}
162
163
164			/*
165			* Exit Time Manager
166			*/
167
168			void TimerExit(void)
169			{
170			#if PRECISE_TIMING
171			// Quit timer thread
172			if (timer_thread > 0) {
173			status_t l;
174			thread_active = false;
175			suspend_thread(timer_thread);
176			resume_thread(timer_thread);
177			wait_for_thread(timer_thread, &l);
178			delete_sem(wakeup_time_sem);
179			}
180			#endif
181			}
182
183
184			/*
185			* Emulator reset, remove all timer tasks
186			*/
187
188			void TimerReset(void)
189			{
190			// Mark all descriptors as inactive
191			for (int i=0; i<NUM_DESCS; i++)
192			free_desc(i);
193			}
194
195
196			/*
197			* Insert timer task
198			*/
199
200			int16 InsTime(uint32 tm, uint16 trap)
201			{
202			D(bug("InsTime %08lx, trap %04x\n", tm, trap));
203			WriteMacInt16((uint32)tm + qType, ReadMacInt16((uint32)tm + qType) & 0x1fff \| (trap << 4) & 0x6000);
204			if (find_desc(tm) >= 0)
205			printf("WARNING: InsTime(): Task re-inserted\n");
206			else {
207			int i = alloc_desc(tm);
208			if (i < 0)
209			printf("FATAL: InsTime(): No free Time Manager descriptor\n");
210			}
211			return 0;
212			}
213
214
215			/*
216			* Remove timer task
217			*/
218
219			int16 RmvTime(uint32 tm)
220			{
221			D(bug("RmvTime %08lx\n", tm));
222
223			// Find descriptor
224			int i = find_desc(tm);
225			if (i < 0) {
226			printf("WARNING: RmvTime(%08lx): Descriptor not found\n", tm);
227			return 0;
228			}
229
230			// Task active?
231			#if PRECISE_TIMING
232			while (acquire_sem(wakeup_time_sem) == B_INTERRUPTED) ;
233			suspend_thread(timer_thread);
234			#endif
235			if (ReadMacInt16(tm + qType) & 0x8000) {
236
237			// Yes, make task inactive and remove it from the Time Manager queue
238			WriteMacInt16(tm + qType, ReadMacInt16(tm + qType) & 0x7fff);
239			dequeue_tm(tm);
240			#if PRECISE_TIMING
241			// Look for next task to be called and set wakeup_time
242			wakeup_time = 0x7fffffffffffffff;
243			for (int j=0; j<NUM_DESCS; j++) {
244			if (desc[j].in_use && (ReadMacInt16(desc[j].task + qType) & 0x8000))
245			if (desc[j].wakeup < wakeup_time)
246			wakeup_time = desc[j].wakeup;
247			}
248			#endif
249
250			// Compute remaining time
251			tm_time_t remaining, current;
252			timer_current_time(current);
253			timer_sub_time(remaining, desc[i].wakeup, current);
254			WriteMacInt32(tm + tmCount, timer_host2mac_time(remaining));
255			} else
256			WriteMacInt32(tm + tmCount, 0);
257			D(bug(" tmCount %ld\n", ReadMacInt32(tm + tmCount)));
258			#if PRECISE_TIMING
259			release_sem(wakeup_time_sem);
260			thread_info info;
261			do {
262			resume_thread(timer_thread); // This will unblock the thread
263			get_thread_info(timer_thread, &info);
264			} while (info.state == B_THREAD_SUSPENDED); // Sometimes, resume_thread() doesn't work (BeOS bug?)
265			#endif
266
267			// Free descriptor
268			free_desc(i);
269			return 0;
270			}
271
272
273			/*
274			* Start timer task
275			*/
276
277			int16 PrimeTime(uint32 tm, int32 time)
278			{
279			D(bug("PrimeTime %08lx, time %ld\n", tm, time));
280
281			// Find descriptor
282			int i = find_desc(tm);
283			if (i < 0) {
284			printf("FATAL: PrimeTime(): Descriptor not found\n");
285			return 0;
286			}
287
288			// Convert delay time
289			tm_time_t delay;
290			timer_mac2host_time(delay, time);
291
292			// Extended task?
293			if (ReadMacInt16(tm + qType) & 0x4000) {
294
295			// Yes, tmWakeUp set?
296			if (ReadMacInt32(tm + tmWakeUp)) {
297
298			//!! PrimeTime(0) means continue previous delay
299			// (save wakeup time in RmvTime?)
300			if (time == 0) {
301			printf("FATAL: Unsupported PrimeTime(0)\n");
302			return 0;
303			}
304
305			// Yes, calculate wakeup time relative to last scheduled time
306			tm_time_t wakeup;
307			timer_add_time(wakeup, desc[i].wakeup, delay);
308			desc[i].wakeup = wakeup;
309
310			} else {
311
312			// No, calculate wakeup time relative to current time
313			tm_time_t now;
314			timer_current_time(now);
315			timer_add_time(desc[i].wakeup, now, delay);
316			}
317
318			// Set tmWakeUp to indicate that task was scheduled
319			WriteMacInt32(tm + tmWakeUp, 0x12345678);
320
321			} else {
322
323			// Not extended task, calculate wakeup time relative to current time
324			tm_time_t now;
325			timer_current_time(now);
326			timer_add_time(desc[i].wakeup, now, delay);
327			}
328
329			// Make task active and enqueue it in the Time Manager queue
330			#if PRECISE_TIMING
331			while (acquire_sem(wakeup_time_sem) == B_INTERRUPTED) ;
332			suspend_thread(timer_thread);
333			#endif
334			WriteMacInt16(tm + qType, ReadMacInt16(tm + qType) \| 0x8000);
335			enqueue_tm(tm);
336			#if PRECISE_TIMING
337			// Look for next task to be called and set wakeup_time
338			wakeup_time = 0x7fffffffffffffff;
339			for (int j=0; j<NUM_DESCS; j++) {
340			if (desc[j].in_use && (ReadMacInt16(desc[j].task + qType) & 0x8000))
341			if (desc[j].wakeup < wakeup_time)
342			wakeup_time = desc[j].wakeup;
343			}
344			release_sem(wakeup_time_sem);
345			thread_info info;
346			do {
347			resume_thread(timer_thread); // This will unblock the thread
348			get_thread_info(timer_thread, &info);
349			} while (info.state == B_THREAD_SUSPENDED); // Sometimes, resume_thread() doesn't work (BeOS bug?)
350			#endif
351			return 0;
352			}
353
354
355			#if PRECISE_TIMING
356			/*
357			* Time Manager thread
358			*/
359
360			static int32 timer_func(void *arg)
361			{
362			while (thread_active) {
363
364			// Wait until time specified by wakeup_time
365			snooze_until(wakeup_time, B_SYSTEM_TIMEBASE);
366
367			while (acquire_sem(wakeup_time_sem) == B_INTERRUPTED) ;
368			if (wakeup_time < system_time()) {
369
370			// Timer expired, trigger interrupt
371			wakeup_time = 0x7fffffffffffffff;
372			SetInterruptFlag(INTFLAG_TIMER);
373			TriggerInterrupt();
374			}
375			release_sem(wakeup_time_sem);
376			}
377			return 0;
378			}
379			#endif
380
381
382			/*
383			* Timer interrupt function (executed as part of 60Hz interrupt)
384			*/
385
386			void TimerInterrupt(void)
387			{
388			// D(bug("TimerIRQ\n"));
389
390			// Look for active TMTasks that have expired
391			tm_time_t now;
392			timer_current_time(now);
393			for (int i=0; i<NUM_DESCS; i++)
394			if (desc[i].in_use) {
395			uint32 tm = desc[i].task;
396			if ((ReadMacInt16(tm + qType) & 0x8000) && timer_cmp_time(desc[i].wakeup, now) <= 0) {
397
398			// Found one, mark as inactive and remove it from the Time Manager queue
399			WriteMacInt16(tm + qType, ReadMacInt16(tm + qType) & 0x7fff);
400			dequeue_tm(tm);
401
402			// Call timer function
403			uint32 addr = ReadMacInt32(tm + tmAddr);
404			if (addr) {
405			D(bug("Calling TimeTask %08lx, addr %08lx\n", tm, addr));
406			M68kRegisters r;
407			r.a[0] = addr;
408			r.a[1] = tm;
409			Execute68k(r.a[0], &r);
410			D(bug(" returned from TimeTask\n"));
411			}
412			}
413			}
414
415			#if PRECISE_TIMING
416			// Look for next task to be called and set wakeup_time
417			while (acquire_sem(wakeup_time_sem) == B_INTERRUPTED) ;
418			suspend_thread(timer_thread);
419			wakeup_time = 0x7fffffffffffffff;
420			for (int j=0; j<NUM_DESCS; j++) {
421			if (desc[j].in_use && (ReadMacInt16(desc[j].task + qType) & 0x8000))
422			if (desc[j].wakeup < wakeup_time)
423			wakeup_time = desc[j].wakeup;
424			}
425			release_sem(wakeup_time_sem);
426			thread_info info;
427			do {
428			resume_thread(timer_thread); // This will unblock the thread
429			get_thread_info(timer_thread, &info);
430			} while (info.state == B_THREAD_SUSPENDED); // Sometimes, resume_thread() doesn't work (BeOS bug?)
431			#endif
432			}