nes-proj/os/sys/process.c

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/*
* Copyright (c) 2005, Swedish Institute of Computer Science
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the Institute nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* This file is part of the Contiki operating system.
*
*/
/**
* \addtogroup process
* @{
*/
/**
* \file
* Implementation of the Contiki process kernel.
* \author
* Adam Dunkels <adam@sics.se>
*
*/
#include <stdio.h>
#include "contiki.h"
#include "sys/process.h"
#include "sys/arg.h"
/*
* Pointer to the currently running process structure.
*/
struct process *process_list = NULL;
struct process *process_current = NULL;
static process_event_t lastevent;
/*
* Structure used for keeping the queue of active events.
*/
struct event_data {
process_event_t ev;
process_data_t data;
struct process *p;
};
static process_num_events_t nevents, fevent;
static struct event_data events[PROCESS_CONF_NUMEVENTS];
#if PROCESS_CONF_STATS
process_num_events_t process_maxevents;
#endif
static volatile unsigned char poll_requested;
#define PROCESS_STATE_NONE 0
#define PROCESS_STATE_RUNNING 1
#define PROCESS_STATE_CALLED 2
static void call_process(struct process *p, process_event_t ev, process_data_t data);
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#define DEBUG 0
#if DEBUG
#include <stdio.h>
#define PRINTF(...) printf(__VA_ARGS__)
#else
#define PRINTF(...)
#endif
/*---------------------------------------------------------------------------*/
process_event_t
process_alloc_event(void)
{
return lastevent++;
}
/*---------------------------------------------------------------------------*/
void
process_start(struct process *p, process_data_t data)
{
struct process *q;
/* First make sure that we don't try to start a process that is
already running. */
for(q = process_list; q != p && q != NULL; q = q->next);
/* If we found the process on the process list, we bail out. */
if(q == p) {
return;
}
/* Put on the procs list.*/
p->next = process_list;
process_list = p;
p->state = PROCESS_STATE_RUNNING;
PT_INIT(&p->pt);
PRINTF("process: starting '%s'\n", PROCESS_NAME_STRING(p));
/* Post a synchronous initialization event to the process. */
process_post_synch(p, PROCESS_EVENT_INIT, data);
}
/*---------------------------------------------------------------------------*/
static void
exit_process(struct process *p, struct process *fromprocess)
{
register struct process *q;
struct process *old_current = process_current;
PRINTF("process: exit_process '%s'\n", PROCESS_NAME_STRING(p));
/* Make sure the process is in the process list before we try to
exit it. */
for(q = process_list; q != p && q != NULL; q = q->next);
if(q == NULL) {
return;
}
if(process_is_running(p)) {
/* Process was running */
p->state = PROCESS_STATE_NONE;
/*
* Post a synchronous event to all processes to inform them that
* this process is about to exit. This will allow services to
* deallocate state associated with this process.
*/
for(q = process_list; q != NULL; q = q->next) {
if(p != q) {
call_process(q, PROCESS_EVENT_EXITED, (process_data_t)p);
}
}
if(p->thread != NULL && p != fromprocess) {
/* Post the exit event to the process that is about to exit. */
process_current = p;
p->thread(&p->pt, PROCESS_EVENT_EXIT, NULL);
}
}
if(p == process_list) {
process_list = process_list->next;
} else {
for(q = process_list; q != NULL; q = q->next) {
if(q->next == p) {
q->next = p->next;
break;
}
}
}
process_current = old_current;
}
/*---------------------------------------------------------------------------*/
static void
call_process(struct process *p, process_event_t ev, process_data_t data)
{
int ret;
#if DEBUG
if(p->state == PROCESS_STATE_CALLED) {
printf("process: process '%s' called again with event %d\n", PROCESS_NAME_STRING(p), ev);
}
#endif /* DEBUG */
if((p->state & PROCESS_STATE_RUNNING) &&
p->thread != NULL) {
PRINTF("process: calling process '%s' with event %d\n", PROCESS_NAME_STRING(p), ev);
process_current = p;
p->state = PROCESS_STATE_CALLED;
ret = p->thread(&p->pt, ev, data);
if(ret == PT_EXITED ||
ret == PT_ENDED ||
ev == PROCESS_EVENT_EXIT) {
exit_process(p, p);
} else {
p->state = PROCESS_STATE_RUNNING;
}
}
}
/*---------------------------------------------------------------------------*/
void
process_exit(struct process *p)
{
exit_process(p, PROCESS_CURRENT());
}
/*---------------------------------------------------------------------------*/
void
process_init(void)
{
lastevent = PROCESS_EVENT_MAX;
nevents = fevent = 0;
#if PROCESS_CONF_STATS
process_maxevents = 0;
#endif /* PROCESS_CONF_STATS */
process_current = process_list = NULL;
}
/*---------------------------------------------------------------------------*/
/*
* Call each process' poll handler.
*/
/*---------------------------------------------------------------------------*/
static void
do_poll(void)
{
struct process *p;
poll_requested = 0;
/* Call the processes that needs to be polled. */
for(p = process_list; p != NULL; p = p->next) {
if(p->needspoll) {
p->state = PROCESS_STATE_RUNNING;
p->needspoll = 0;
call_process(p, PROCESS_EVENT_POLL, NULL);
}
}
}
/*---------------------------------------------------------------------------*/
/*
* Process the next event in the event queue and deliver it to
* listening processes.
*/
/*---------------------------------------------------------------------------*/
static void
do_event(void)
{
process_event_t ev;
process_data_t data;
struct process *receiver;
struct process *p;
/*
* If there are any events in the queue, take the first one and walk
* through the list of processes to see if the event should be
* delivered to any of them. If so, we call the event handler
* function for the process. We only process one event at a time and
* call the poll handlers inbetween.
*/
if(nevents > 0) {
/* There are events that we should deliver. */
ev = events[fevent].ev;
data = events[fevent].data;
receiver = events[fevent].p;
/* Since we have seen the new event, we move pointer upwards
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and decrease the number of events. */
fevent = (fevent + 1) % PROCESS_CONF_NUMEVENTS;
--nevents;
/* If this is a broadcast event, we deliver it to all events, in
order of their priority. */
if(receiver == PROCESS_BROADCAST) {
for(p = process_list; p != NULL; p = p->next) {
/* If we have been requested to poll a process, we do this in
between processing the broadcast event. */
if(poll_requested) {
do_poll();
}
call_process(p, ev, data);
}
} else {
/* This is not a broadcast event, so we deliver it to the
specified process. */
/* If the event was an INIT event, we should also update the
state of the process. */
if(ev == PROCESS_EVENT_INIT) {
receiver->state = PROCESS_STATE_RUNNING;
}
/* Make sure that the process actually is running. */
call_process(receiver, ev, data);
}
}
}
/*---------------------------------------------------------------------------*/
int
process_run(void)
{
/* Process poll events. */
if(poll_requested) {
do_poll();
}
/* Process one event from the queue */
do_event();
return nevents + poll_requested;
}
/*---------------------------------------------------------------------------*/
int
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process_nevents(void)
{
return nevents + poll_requested;
}
/*---------------------------------------------------------------------------*/
int
process_post(struct process *p, process_event_t ev, process_data_t data)
{
process_num_events_t snum;
if(PROCESS_CURRENT() == NULL) {
PRINTF("process_post: NULL process posts event %d to process '%s', nevents %d\n",
ev,PROCESS_NAME_STRING(p), nevents);
} else {
PRINTF("process_post: Process '%s' posts event %d to process '%s', nevents %d\n",
PROCESS_NAME_STRING(PROCESS_CURRENT()), ev,
p == PROCESS_BROADCAST? "<broadcast>": PROCESS_NAME_STRING(p), nevents);
}
if(nevents == PROCESS_CONF_NUMEVENTS) {
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#if DEBUG
if(p == PROCESS_BROADCAST) {
printf("soft panic: event queue is full when broadcast event %d was posted from %s\n", ev, PROCESS_NAME_STRING(process_current));
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} else {
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printf("soft panic: event queue is full when event %d was posted to %s from %s\n", ev, PROCESS_NAME_STRING(p), PROCESS_NAME_STRING(process_current));
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}
#endif /* DEBUG */
return PROCESS_ERR_FULL;
}
snum = (process_num_events_t)(fevent + nevents) % PROCESS_CONF_NUMEVENTS;
events[snum].ev = ev;
events[snum].data = data;
events[snum].p = p;
++nevents;
#if PROCESS_CONF_STATS
if(nevents > process_maxevents) {
process_maxevents = nevents;
}
#endif /* PROCESS_CONF_STATS */
return PROCESS_ERR_OK;
}
/*---------------------------------------------------------------------------*/
void
process_post_synch(struct process *p, process_event_t ev, process_data_t data)
{
struct process *caller = process_current;
call_process(p, ev, data);
process_current = caller;
}
/*---------------------------------------------------------------------------*/
void
process_poll(struct process *p)
{
if(p != NULL) {
if(p->state == PROCESS_STATE_RUNNING ||
p->state == PROCESS_STATE_CALLED) {
p->needspoll = 1;
poll_requested = 1;
}
}
}
/*---------------------------------------------------------------------------*/
int
process_is_running(struct process *p)
{
return p->state != PROCESS_STATE_NONE;
}
/*---------------------------------------------------------------------------*/
/** @} */