WebSVN - shark - Blame - Rev 37 - /shark/trunk/kernel/int

Rev	Author	Line No.	Line
2	pj	1	/*
		2	* Project: S.Ha.R.K.
		3	*
		4	* Coordinators:
		5	* Giorgio Buttazzo <giorgio@sssup.it>
		6	* Paolo Gai <pj@gandalf.sssup.it>
		7	*
		8	* Authors :
		9	* Paolo Gai <pj@gandalf.sssup.it>
		10	* (see the web pages for full authors list)
		11	*
		12	* ReTiS Lab (Scuola Superiore S.Anna - Pisa - Italy)
		13	*
		14	* http://www.sssup.it
		15	* http://retis.sssup.it
		16	* http://shark.sssup.it
		17	*/
		18
		19	/**
		20	------------
29	pj	21	CVS : $Id: int_sem.c,v 1.2 2002-11-11 08:34:08 pj Exp $
2	pj	22
		23	File: $File$
29	pj	24	Revision: $Revision: 1.2 $
		25	Last update: $Date: 2002-11-11 08:34:08 $
2	pj	26	------------
		27
		28	Internal semaphores.
		29
		30	They are different from the Posix semaphores and the mutexes because:
		31	- internal_sem_wait is not a cancellation point
		32	- there are no limits on the semaphores that can be created
		33	(they works like a mutex_t...)
		34	- the queuing policy is FIFO
		35	- Be Careful!
		36	they are made to be fast... so not so many controls are done!!!
		37
		38	**/
		39
		40	/*
		41	* Copyright (C) 2000 Paolo Gai
		42	*
		43	* This program is free software; you can redistribute it and/or modify
		44	* it under the terms of the GNU General Public License as published by
		45	* the Free Software Foundation; either version 2 of the License, or
		46	* (at your option) any later version.
		47	*
		48	* This program is distributed in the hope that it will be useful,
		49	* but WITHOUT ANY WARRANTY; without even the implied warranty of
		50	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
		51	* GNU General Public License for more details.
		52	*
		53	* You should have received a copy of the GNU General Public License
		54	* along with this program; if not, write to the Free Software
		55	* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
		56	*
		57	*/
		58
		59
		60	#include <kernel/int_sem.h>
		61	#include <kernel/var.h>
		62	#include <kernel/func.h>
		63
		64	/* Wait status for this library */
		65	#define INTERNAL_SEM_WAIT LIB_STATUS_BASE
		66
		67
		68	void internal_sem_init(internal_sem_t *s, int value)
		69	{
		70	s->count = value;
29	pj	71	iq_init(&s->blocked,&freedesc,0);
2	pj	72	}
		73
		74	void internal_sem_wait(internal_sem_t *s)
		75	{
		76	SYS_FLAGS f;
		77
		78	//kern_cli();
		79	f = kern_fsave();
		80
		81	if (s->count) {
		82	s->count--;
		83	//kern_sti();
		84	kern_frestore(f);
		85	return;
		86	}
		87	else { /* We must block exec task */
		88	LEVEL l; /* for readableness only */
		89	TIME tx; /* a dummy TIME for timespec operations */
		90	struct timespec ty; /* a dummy timespec for timespec operations */
		91
		92	proc_table[exec_shadow].context = kern_context_save();
		93	/* SAME AS SCHEDULER... manage the capacity event and the load_info */
		94	ll_gettime(TIME_EXACT, &schedule_time);
		95	SUBTIMESPEC(&schedule_time, &cap_lasttime, &ty);
		96	tx = TIMESPEC2USEC(&ty);
		97	proc_table[exec_shadow].avail_time -= tx;
		98	jet_update_slice(tx);
		99	if (cap_timer != NIL) {
		100	event_delete(cap_timer);
		101	cap_timer = NIL;
		102	}
		103
		104	l = proc_table[exec_shadow].task_level;
		105	level_table[l]->task_extract(l,exec_shadow);
		106
		107	/* we insert the task in the semaphore queue */
		108	proc_table[exec_shadow].status = INTERNAL_SEM_WAIT;
29	pj	109	iq_insertlast(exec_shadow,&s->blocked);
2	pj	110
		111	/* and finally we reschedule */
		112	exec = exec_shadow = -1;
		113	scheduler();
		114
		115	ll_context_to(proc_table[exec_shadow].context);
		116	kern_after_dispatch();
		117	kern_frestore(f);
		118	}
		119
		120	}
		121
		122	/* return 0 if the counter is decremented, -1 if not */
		123	int internal_sem_trywait(internal_sem_t *s)
		124	{
		125	SYS_FLAGS f;
		126
		127	//kern_cli();
		128	f = kern_fsave();
		129
		130	if (s->count) {
		131	s->count--;
		132	//kern_sti();
		133	kern_frestore(f);
		134	return 0;
		135	}
		136
		137	//kern_sti();
		138	kern_frestore(f);
		139	return -1;
		140	}
		141
		142
		143	void internal_sem_post(internal_sem_t *s)
		144	{
		145	proc_table[exec_shadow].context = kern_context_save();
		146
		147	if (s->blocked.first != -1) {
		148	register PID p;
		149	register LEVEL l;
		150
29	pj	151	p = iq_getfirst(&s->blocked);
2	pj	152	l = proc_table[p].task_level;
		153	level_table[l]->task_insert(l,p);
		154
		155	scheduler();
		156	}
		157	else
		158	s->count++;
		159
		160	kern_context_load(proc_table[exec_shadow].context);
		161	}
		162
		163	int internal_sem_getvalue(internal_sem_t *s)
		164	{
		165	register int returnvalue;
		166	SYS_FLAGS f;
		167
		168	//kern_cli();
		169	f = kern_fsave();
		170	if (s->blocked.first == -1)
		171	returnvalue = s->count;
		172	else
		173	returnvalue = -1;
		174
		175	//kern_sti();
		176	kern_frestore(f);
		177	return returnvalue;
		178	}

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(root)/shark/trunk/kernel/int_sem.c - Rev 37