Memory management between threads in RTEMS
m.shahverdi
sspardis2 at gmail.com
Wed Jul 18 15:58:11 UTC 2012
This is my application that is written in C,I write the main code till now.
this app is an elevator that goes up and down in a 4 floors building:
#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<stdbool.h>
#include<time.h>
#include <sys/time.h>
#include <sys/types.h>
#include <unistd.h>
#include <signal.h>
void handler(int signo)
{
return;
}
typedef struct person prs;
int elevator_run();
struct person
{
int place;
int distination;
char direction;
bool inout;// in:true,out:false
bool exit;//if person exits true
prs * next;
};
int stage[5];///////to know stop in which level
int up_down;///////to know direct 1 for up 0 for down 2 for none
int stop_move;/////to know if elevator is stop or no stop 0 move 1
int current_place;
int distination;
time_t base;
int xx;
int main()
{
int place;
int direct;
int counter_in=0;
int counter_out=0;
int in_out;////in=1;out=0
int dis;///to get distination of person in elevator
prs* headin;
prs* headout;
prs*newnode;
prs*nextnode;
prs*node;
headin=(prs*)malloc(sizeof(prs));
headout=(prs*)malloc(sizeof(prs));
pthread_t thread_id;
pthread_create(&thread_id, NULL, elevator_run, NULL);
struct sigaction sa;
sa.sa_handler = handler;
sigemptyset(&sa.sa_mask);
sa.sa_flags = 0;
sigaction(SIGALRM, &sa, NULL);
if(headin==NULL)
{
printf("\nError in memory allocation!\n ");
return 1;
}
if(headout==NULL)
{
printf("\nError in memory allocation!\n ");
return 1;
}
int update;
printf("This is elevator stopped at ground \n tell us your place and
distination ");
while(1)
{
update=0;
alarm(1);
if (scanf("%d", &in_out) == 1)
{
alarm(0); // cancel the alarm
}
else
{
continue;
}
// scanf("% d", & in_out);
if (in_out==1)
{
scanf("%d",& dis);
if(current_place==distination)
{
update=1;
distination=dis;
}
else if((up_down==1 && distination<dis) ||(up_down==0 &&
distination>dis))
{
update=1;
stage[distination]=1;
distination=dis;
}
else if((up_down==1 && current_place<dis<distination)
||(up_down==0 && distination<dis<current_place))
stage[dis]=1;
else
{
newnode=(prs*)malloc(sizeof(prs));
if(newnode==NULL)
{
printf("\nError in memory allocation!\n ");
return 1;
}
counter_in++;
newnode->exit=false;
newnode->distination=dis;
newnode->next=headin->next;
headin->next=newnode;
}
}
else {
scanf("%d %d",& place,& direct);
if(direct=='q')
return 1;
if(stop_move==0){
distination = place;
printf("/////");}
else {
if(direct==up_down &&((up_down==1&&
current_place<=place<=distination) ||(up_down==0&&
current_place>=place>=distination)))
stage[place]=1;
if(direct==up_down && ((up_down==1 && place > distination) ||
(up_down==0 && place < distination)))
{
stage[distination]=1;
distination=place;
update=1;
}
else
{
newnode=(prs*)malloc(sizeof(prs));
if(newnode==NULL)
{
printf("\nError in memory allocation!\n ");
return 1;
}
counter_out++;
newnode->exit=false;
newnode->next=headin->next;
headin->next=newnode;
newnode->place=place;
}
}
}
}
}
int elevator_run()
{
time_t current;
int i;
int y=0;
//float x=1;
for(i=0;i<5;i++)
stage[i]=0;
up_down=1;
stop_move=0;/////to know if elevator is stop or no
current_place=0;
distination=0;
while(1)
{
if(stop_move==1)
{
if(up_down==1)
{
current=time(NULL);
if(current==base + 5)
{
base=current;
y=y+1;
}
// printf("y = %f" ,y);
}
else
{
current=time(NULL);
if(current==base + 5)
{
base=current;
y=y-1;
}
}
}
if(stop_move==0 && distination > current_place)
{
stop_move=1;
base=time(NULL);
up_down=1;
printf("salam");
}
if(stop_move==0 && distination < current_place)
{
stop_move=1;
base=time(NULL);
up_down=0;
}
if(y == 0) {current_place=0;if(distination==0) stop_move=0;}
if(y == 1 && current_place !=1) { printf("place1"); current_place=1;
if(distination==1) stop_move=0;}
if(y == 2 && current_place != 2)
{current_place=2;printf("place2");if(distination==2) stop_move=0;}
if(y == 3 && current_place != 3)
{current_place=3;printf("place3");if(distination==3) stop_move=0;}
if(y == 4 && current_place != 4)
{current_place=4;printf("place4");if(distination==4) stop_move=0;}
}
}
On Wed, Jul 18, 2012 at 8:11 PM, Till Straumann
<strauman at slac.stanford.edu>wrote:
> Maybe you could share some example code so that we understand
> what exactly you're trying to do?
>
> T.
>
>
> On 07/18/2012 10:37 AM, m.shahverdi wrote:
>
> These two threads have some common fields that I use mutex on these fields
> but in general I read in c_user document of RTEMS that this OS has a flat
> memory and I'm worry about unsafe access to memory that each thread
> allocate in the beginning of execution.
>
> On Wed, Jul 18, 2012 at 7:42 PM, Thomas Doerfler <
> Thomas.Doerfler at embedded-brains.de> wrote:
>
>> Hi,
>>
>> funny topic: one question, many different answers, none of them is
>> wrong ;-)
>>
>> Maybe you can specify, what you expect from a "memory protection"
>> mechanism:
>> - A way to synchronize two threads, so only one is allowed to
>> access/write to a memory area?
>> - A way to detect, when a thread inadvertedly tries to access/write to
>> another thread's private area?
>> - Something different?
>>
>> wkr,
>>
>> Thomas.
>>
>> Am 18.07.2012 16:20, schrieb m.shahverdi:
>> > Hi, I have an application with two threads but I don't know how to
>> > protect memory of each thread against other thread.please help me.
>> >
>> > thanks
>> >
>> >
>> >
>> > _______________________________________________ rtems-users mailing
>> > list rtems-users at rtems.org
>> > http://www.rtems.org/mailman/listinfo/rtems-users
>> >
>>
>>
>> --
>> IMD Ingenieurbuero fuer Microcomputertechnik
>> Thomas Doerfler Herbststrasse 8
>> D-82178 Puchheim Germany
>> email: Thomas.Doerfler at imd-systems.de
>> PGP public key available on request
>>
>>
>> --
>> --------------------------------------------
>> embedded brains GmbH
>> Thomas Doerfler
>> Obere Lagerstrasse 30
>> D-82178 Puchheim
>> Germany
>> email: Thomas.Doerfler at embedded-brains.de
>> Phone: +49-89-18908079-2
>> Fax: +49-89-18908079-9
>> PGP: Public key available on request.
>>
>> Diese Nachricht ist keine geschäftliche Mitteilung im Sinne des EHUG.
>>
>> _______________________________________________
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>> http://www.rtems.org/mailman/listinfo/rtems-users
>>
>
>
>
> --
>
> به "هوالحی" زنده می کند؛
>
> آنسان که می میراند به "هوالممیت"..
>
> ما را به "هوالشهید" است که مدام می میراند و زنده می کند..
>
>
>
>
>
--
به "هوالحی" زنده می کند؛
آنسان که می میراند به "هوالممیت"..
ما را به "هوالشهید" است که مدام می میراند و زنده می کند..
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