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/*
* Project: S.Ha.R.K.
*
* Coordinators:
* Giorgio Buttazzo <giorgio@sssup.it>
* Paolo Gai <pj@gandalf.sssup.it>
*
* Authors :
* Paolo Gai <pj@gandalf.sssup.it>
* Massimiliano Giorgi <massy@gandalf.sssup.it>
* Luca Abeni <luca@gandalf.sssup.it>
* (see the web pages for full authors list)
*
* ReTiS Lab (Scuola Superiore S.Anna - Pisa - Italy)
*
* http://www.sssup.it
* http://retis.sssup.it
* http://shark.sssup.it
*/
/**
------------
CVS : $Id: nop.c,v 1.1 2005-02-25 10:40:58 pj Exp $
File: $File$
Revision: $Revision: 1.1 $
Last update: $Date: 2005-02-25 10:40:58 $
------------
Binary Semaphores. see nop.h for more details...
**/
/*
* Copyright (C) 2000 Paolo Gai
*
* 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
*
*/
#include <nop/nop/nop.h>
#include <ll/ll.h>
#include <arch/stdio.h>
#include <arch/string.h>
#include <kernel/const.h>
#include <sys/types.h>
#include <kernel/descr.h>
#include <kernel/var.h>
#include <kernel/func.h>
/* The NOP resource level descriptor */
typedef struct {
mutex_resource_des m; /*+ the mutex interface +*/
} NOP_mutex_resource_des;
/* this is the structure normally pointed by the opt field in the
mutex_t structure */
typedef struct {
PID owner;
IQUEUE blocked;
} NOP_mutex_t;
/* Wait status for this library */
#define NOP_WAIT LIB_STATUS_BASE
static int NOP_res_register(RLEVEL l, PID p, RES_MODEL *r)
{
return -1;
}
static void NOP_res_detach(RLEVEL l, PID p)
{
}
static int NOP_init(RLEVEL l, mutex_t *m, const mutexattr_t *a)
{
NOP_mutex_t *p;
if (a->mclass != NOP_MCLASS)
return -1;
p = (NOP_mutex_t *) kern_alloc(sizeof(NOP_mutex_t));
/* control if there is enough memory; no control on init on a
non- destroyed mutex */
if (!p)
return (ENOMEM);
p->owner = NIL;
iq_init(&p->blocked, &freedesc, 0);
m->mutexlevel = l;
m->opt = (void *)p;
return 0;
}
static int NOP_destroy(RLEVEL l, mutex_t *m)
{
// NOP_mutex_resource_des *lev = (NOP_mutex_resource_des *)(resource_table[l]);
SYS_FLAGS f;
if ( ((NOP_mutex_t *)m->opt)->owner != NIL)
return (EBUSY);
f = kern_fsave();
if (m->opt) {
kern_free(m->opt,sizeof(NOP_mutex_t));
m->opt = NULL;
}
kern_frestore(f);
return 0;
}
static int NOP_lock(RLEVEL l, mutex_t *m)
{
NOP_mutex_t *p;
SYS_FLAGS f;
f = kern_fsave();
p = (NOP_mutex_t *)m->opt;
if (!p) {
/* if the mutex is not initialized, initialize it! */
NOP_mutexattr_t a;
NOP_mutexattr_default(a);
NOP_init(l, m, &a);
}
if (p->owner == exec_shadow) {
/* the task already owns the mutex */
kern_frestore(f);
return (EDEADLK);
}
if (p->owner != NIL) { /* We must block exec task */
LEVEL l; /* for readableness only */
proc_table[exec_shadow].context = kern_context_save();
kern_epilogue_macro();
l = proc_table[exec_shadow].task_level;
level_table[l]->public_block(l,exec_shadow);
/* we insert the task in the semaphore queue */
proc_table[exec_shadow].status = NOP_WAIT;
iq_insertlast(exec_shadow,&p->blocked);
/* and finally we reschedule */
exec = exec_shadow = -1;
scheduler();
kern_context_load(proc_table[exec_shadow].context);
}
else {
/* the mutex is free, We can lock it! */
p->owner = exec_shadow;
kern_frestore(f);
}
return 0;
}
static int NOP_trylock(RLEVEL l, mutex_t *m)
{
NOP_mutex_t *p;
SYS_FLAGS f;
f = kern_fsave();
p = (NOP_mutex_t *)m->opt;
if (!p) {
/* if the mutex is not initialized, initialize it! */
NOP_mutexattr_t a;
NOP_mutexattr_default(a);
NOP_init(l, m, &a);
}
if (p->owner != NIL) {
/* a task already owns the mutex */
kern_frestore(f);
return (EBUSY);
}
else {
/* the mutex is free, We can lock it! */
p->owner = exec_shadow;
kern_frestore(f);
}
return 0;
}
static int NOP_unlock(RLEVEL l, mutex_t *m)
{
NOP_mutex_t *p;
p = (NOP_mutex_t *)m->opt;
if (!p)
return (EINVAL);
if (p->owner != exec_shadow) {
/* the mutex is owned by another task!!! */
kern_sti();
return (EPERM);
}
proc_table[exec_shadow].context = kern_context_save();
/* the mutex is mine, pop the firsttask to extract */
p->owner = iq_getfirst(&p->blocked);
if (p->owner != NIL) {
l = proc_table[p->owner].task_level;
level_table[l]->public_unblock(l,p->owner);
}
scheduler();
kern_context_load(proc_table[exec_shadow].context);
return 0;
}
RLEVEL NOP_register_module(void)
{
RLEVEL l; /* the level that we register */
NOP_mutex_resource_des *m; /* for readableness only */
printk("NOP_register_module\n");
/* request an entry in the level_table */
l = resource_alloc_descriptor();
/* alloc the space needed for the EDF_level_des */
m = (NOP_mutex_resource_des *)kern_alloc(sizeof(NOP_mutex_resource_des));
/* update the level_table with the new entry */
resource_table[l] = (resource_des *)m;
/* fill the resource_des descriptor */
m->m.r.rtype = MUTEX_RTYPE;
m->m.r.res_register = NOP_res_register;
m->m.r.res_detach = NOP_res_detach;
/* fill the mutex_resource_des descriptor */
m->m.init = NOP_init;
m->m.destroy = NOP_destroy;
m->m.lock = NOP_lock;
m->m.trylock = NOP_trylock;
m->m.unlock = NOP_unlock;
return l;
}