Discussion in "Software" started by    bhagirath    Jul 5, 2011.
Tue Jul 05 2011, 04:19 AM
#1
Hi all,

I am a newbie to Keil. I was just working in one demo project and stuck in between due to some access violation error. I tried googleing to various forums but didn't work, also tried applying map command but no success may be anyone could provide proper steps to do so. So could can one please help me in this regards? My code is as follows

//start
#include<reg51.h>

#include<string.h>


char var1[1];
char var2[1];
char var3[1];
char var4[5];
char var5[5];
char var6[1];
char var7[1];

void main()
{
    while(1)
    {
        char str[]= "123456789123456";
        int idx1 = 0;
        int index2 = 1;
        strncpy (var1,str+idx1,index2);
        idx1+=1;
        index2+=1;
        strncpy (var2,str+idx1,index2);
        idx1+=1;
        index2+=1;
        strncpy (var3,str+idx1,index2);
        idx1+=5;
        index2+=5;
        strncpy (var4,str+idx1,index2);
        idx1+=1;
        index2+=5;
        strncpy (var5,str+idx1,index2);
        idx1+=5;
        index2+=1;
        strncpy (var6,str+idx1,index2);
        idx1+=1;
        index2+=1;
        strncpy (var7,str+idx1,index2);
    }
}
//end


The error comes while debugging the code, here any where in between it stops debugging and throws error 65 access violation error.
If possible please reply me with steps to resolve this. Let me know if you want further information.

Thanks in advance

Info: Keil version 3.0 eval, hardware : AT89S52
Tue Jul 05 2011, 06:22 PM
#2
For a start,to find an error remove all the code you can until the error disappears.
In this case everything in your while loop.
Then put back a bit at a time until the error comes back .
This tells you where to look.

Your error(s) come from the use of strncpy.
Most of your target buffers are only one byte long and yet you are often trying to copy
more than one byte into them.
This means you are "violating" memory space you "don't own"



[ Edited Wed Jul 06 2011, 03:28 PM ]
Wed Jul 06 2011, 07:52 AM
#3
Hi ExperimenterUK,

Thank you very much for reply,

As per your advice I have removed all the multiple characters trimming, now I am doing only on single character, but then also I am getting the same error. I had googled on this error and some where it was mentioned to keep the code in single loop thats why i have kept it under while(1).

#include<reg51.h>

#include<string.h>


char var1[1];
char var2[1];
char var3[1];
char var4[1];
char var5[1];
char var6[1];
char var7[1];

void main()
{
    while(1)
    {
        char str[]= "123456789123456";
        unsigned char idx1 = 0;
        unsigned char index2 = 1;
        strncpy (var1,str+idx1,index2);
        idx1+=1;
        index2+=1;
        strncpy (var2,str+idx1,index2);
        idx1+=1;
        index2+=1;
        strncpy (var3,str+idx1,index2);
		idx1+=1;
        index2+=1;
        strncpy (var4,str+idx1,index2);
        idx1+=1;
        index2+=1;
        strncpy (var5,str+idx1,index2);// here the location of error..
        idx1+=1;
        index2+=1;
        strncpy (var6,str+idx1,index2);
        idx1+=1;
        index2+=1;
       	strncpy (var7,str+idx1,index2);
		break;
    }
}


I will be really grateful to you if you could try this in your environment.

According to my requirement I need to perform substring function on one string, thats why i have kept strncpy().

Thanks once again.
Wed Jul 06 2011, 08:31 AM
#4
I tried your code on My keil, it didnt showed any error,
Check your keil with other programs(simple one)
Wed Jul 06 2011, 09:16 AM
#5
Hi kirangowle,

I am getting error on debugging the code line by line. The code compiles fine with keil. the only issue
is while debugging it throws error for access violation.

Could you please try debugging the code?

Thanks
Bhagirath
Wed Jul 06 2011, 10:22 AM
#6
Hi,
I debugged your code, it was getting halt at strncpy(var3,)

In array declaration i increased the array length to 5(var[5]) and keep the local variable declaration outside of the while(1).
Wed Jul 06 2011, 11:31 AM
#7
Hi Kirangowle,

Thanks for reply,

I have changed the code as you have suggested, for performance and testing issue i have changed the capacity for each var to 1 byte. But no success, in debugging it stops at var5, after which i have noticed that all variables are cleared which were holding their values before error. here is my changed code

char var1[1];
char var2[1];
///...
char var7[1];
char str[]= "123456789123456";
char idx1 = 0;
char index2 = 1;

void main()
{

    while(1)
    {
        strncpy (var1,str+idx1,index2);
        idx1+=1;
        index2+=1;
        strncpy (var2,str+idx1,index2);
        idx1+=1;
        index2+=1;
        strncpy (var3,str+idx1,index2);
		idx1+=1;
        index2+=1;
        strncpy (var4,str+idx1,index2);
        idx1+=1;
        index2+=1;
        strncpy (var5,str+idx1,index2);
        idx1+=1;
        index2+=1;
        strncpy (var6,str+idx1,index2);
        idx1+=1;
        index2+=1;
       	strncpy (var7,str+idx1,index2);
		
    }
}


Wed Jul 06 2011, 12:26 PM
#8
You didnt change the array length from var[1] to var[5].
i am not understanding what basically u are try to achieve .
Wed Jul 06 2011, 01:34 PM
#9
Hi,

Let me describe my workflow here, I want to substring the "str" in different segments. Let say that segments would be like
var1 = first character
var2 = 2nd - 4th
var3 = 5th - 8th
like wise, it is my custom requirement.

In given example i have created var1[1] - var7[1] just to check, because it was some times showing error in array with bigger ranges. Actually it will be as describe above.e.g.
var1[1], var2[3], var2[4], var4[1]....

Hope this clears it..

And in doing so keil is throwing the error of either access violation or it stops debugging.
Wed Jul 06 2011, 03:51 PM
#10


Hi ExperimenterUK,
As per your advice I have removed all the multiple characters trimming, now I am doing only on single character,

bhagirath


Actually I meant remove all the statements,then put back one statement at a time.


I had googled on this error and some where it was mentioned to keep the code in single
loop thats why i have kept it under while(1).

bhagirath


Whatever you Googled is not relevent here,remove the while() loop, or at least move it to the end

Remove this line for now " index2+=1; " it makes you copy more bytes each time


Try this
#include<reg51.h>
#include<string.h>
char var1[1];
char var2[1];
char var3[1];

void main()
{

    
        char str[]= "123456789123456";
        unsigned char idx1 = 0;
        unsigned char index2 = 1;
        strncpy (var1,str+idx1,index2);  //this should work
        idx1+=1;
 //;  index2+=1; don't do this as it copies 2 bytes next time

        strncpy (var2,str+idx1,index2);   //this should work
        idx1+=1;
        index2+=1;
        strncpy (var3,str+idx1,index2);   //this should not  work
//;		break;  // ??? not needed
    while(1);

}


Get Social

Information

Powered by e107 Forum System

Conversation

ExperimenterUK
Wed Apr 15 2015, 05:07 PM
@Bibek.. and everyone. Create threads if you need help. The chat box is just for chat
ExperimenterUK
Wed Apr 15 2015, 05:06 PM
@mohd atif ..login..create a post/thread,then I can post a copy of the missing file
Mon Apr 13 2015, 07:03 PM
mohd atif
@experimenteruk I didn't get you
Sun Apr 12 2015, 04:18 AM
Bibek
hello, i have made a digital clock using rtc DS12887 and AT89S52 with date n callender. Now i want to add alarm features to it.....can any body help me with the code in assembly language
Sun Apr 12 2015, 03:22 AM
SANJU123
Hello, I am planning to do simulaton of the ' 4-way traffic controller'. As a first stage of the project, I tried to compile the code given in this website in keil microvision which controls 4-way traffic . I am using AT89C51. But when I am trying to compile the code it shows an error " Device is not supported by Toolchain". Can u please help me...
Sat Apr 11 2015, 02:06 AM
Suryamoy Mondal
There is a little bit confusion to connect the rs232 connector to max232 ..By continuty test i cant able to find , which wire from the other side of the RS232 connector , i connect to max232..is there any colour coding?
ajay_bhargav
Fri Apr 10 2015, 06:19 PM
@Suryamoy, The PC control software is provided within the package. Follow the steps to install and test it.
Fri Apr 10 2015, 05:24 PM
Suryamoy Mondal
my final year btech project is pc remote control..i have made the hardware and microcontroller prograaming from yours project..bt i cant able to implement in PC..so wht kind of software need for pc to access this..please sir reply me ..i need your help
ExperimenterUK
Wed Apr 08 2015, 04:46 PM
@mohd atif If you create a thread, I may be able help
Tue Apr 07 2015, 03:59 PM
mohd atif
i am working on a project evm. i download the evm project from this site named Electronic Voting machine with Managed Control Unit . i face problem in this when i am trying to simulate this on proteus . there is an error " could not open MODDATA initializer file mem.bin" please help me to get out this problem

Downloads

Comments

lumines
Sat Apr 18 2015, 11:30 PM
[email protected]
Sat Apr 18 2015, 05:02 PM
arvindarunoday
Sat Apr 18 2015, 04:26 PM
samarhbk
Sat Apr 18 2015, 12:57 PM
chitty789
Tue Apr 14 2015, 06:14 PM
yaseenshaikh
Tue Apr 14 2015, 03:41 PM
sanju123
Mon Apr 13 2015, 03:51 PM
mohanadelnokaly
Wed Apr 08 2015, 07:02 PM

Online

Guests: 40, Members: 0 ...

most ever online: 182184
(Members: , Guests: 182184) on 06 Aug 2010: 05:37 AM

Members: 37626
Newest member: lumines
Forum Activity
gaurav7577 Avatar
Posted By gaurav7577
Mon Apr 20 2015, 07:04 AM
k..let me make all this simple for u so u can add...
ajay_bhargav Avatar
Posted By ajay_bhargav
Sun Apr 19 2015, 06:50 PM
Please zip and attach the code in future. You forg...
ajay_bhargav Avatar
Posted By ajay_bhargav
Sun Apr 19 2015, 06:48 PM
It is really hard to say which course and/or insti...
sanju123 Avatar
Posted By sanju123
Sun Apr 19 2015, 04:56 AM
Thanks rickey...I have reinstalled version.. Pro...
lumines Avatar
Posted By lumines
Sun Apr 19 2015, 12:19 AM
Dear everyone,We are currently looking for an embe...
gaurav7577 Avatar
Posted By gaurav7577
Fri Apr 17 2015, 03:26 PM
thanks ajay for ur concern .....passed out B.E.......
ajay_bhargav Avatar
Posted By ajay_bhargav
Fri Apr 17 2015, 12:49 PM
can you post screenshot or a picture of CRO output...
ajay_bhargav Avatar
Posted By ajay_bhargav
Fri Apr 17 2015, 12:45 PM
are you in a college or working?
ajay_bhargav Avatar
Posted By ajay_bhargav
Fri Apr 17 2015, 12:44 PM
GSM modem needs a power supply with minimum 2A pea...