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 May 25 2016, 05:05 AM
@ Ramanjaneyulu, post in forum,explain your problem
Mon May 23 2016, 11:34 PM
Ramanjaneyulu
Hi, I Am using at89c4051 for my application, I want 5u sec dely.. Up to 1milli sec iam able to producing delay. Beyond the 1milli second, I am unable to produce the acceurate dely. Plz any one help me
Sat May 21 2016, 09:51 PM
A K
i want to mak an auto dialer using gsm and atmega 16. please helpe me how to write a code to auto dial a number saved in sim
Sat May 21 2016, 10:42 AM
Alec
Hi im trying to program my 89s51 with a usbasp so any ideas on the circuit?
Wed May 18 2016, 10:08 AM
Tashu joshi
anyone know how to develop
Wed May 18 2016, 10:07 AM
Tashu joshi
i'm working for resporatry system using 8051,
Wed May 18 2016, 10:06 AM
Tashu joshi
i'm developing a respiratory system using Arduino
Fri May 13 2016, 11:03 AM
MEGHANA
i need c code for counting frequency of two sensors and compare these frequencies and it has to give high/ low signal after comparision
ExperimenterUK
Tue May 10 2016, 05:02 PM
@Suren ..create a thread in the 8051 Discussion Forum to discuss your problem
Tue May 10 2016, 04:04 PM
Suren Avushyan
how can I increment address not the content of it, like 0x70 and get 0x71

Downloads

Comments

zaft93
Sun May 15 2016, 01:52 AM
CELEBI
Thu May 12 2016, 08:28 AM
Suro1996
Wed May 11 2016, 06:07 PM
yigithan
Sat May 07 2016, 09:09 PM
jaque
Fri May 06 2016, 07:51 PM
afzal42
Wed May 04 2016, 11:16 AM
pd
Sun May 01 2016, 01:35 AM
uk2308
Fri Apr 29 2016, 12:27 PM

Online

Guests: 55, Members: 0 ...

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

Members: 37765
Newest member: zaft93
Forum Activity
ExperimenterUK Avatar
Posted By ExperimenterUK
Sun May 15 2016, 10:58 PM
zaft93 Avatar
Posted By zaft93
Sun May 15 2016, 01:55 AM
ExperimenterUK Avatar
Posted By ExperimenterUK
Fri May 13 2016, 07:59 PM
If you want only one relay to be on at a time the ...
CELEBI Avatar
Posted By CELEBI
Fri May 13 2016, 06:16 AM
Yes. It must be as you said. It must be 1.5 second...
ExperimenterUK Avatar
Posted By ExperimenterUK
Thu May 12 2016, 08:35 PM
Here is one way.If you have the Keil compiler you ...
ExperimenterUK Avatar
Posted By ExperimenterUK
Thu May 12 2016, 05:20 PM
Sorry I don't understand what you want.Is that 1.5...
CELEBI Avatar
Posted By CELEBI
Thu May 12 2016, 08:53 AM
Hello Guys, I want to make a Project with 89s51 bu...
ExperimenterUK Avatar
Posted By ExperimenterUK
Wed May 11 2016, 09:28 PM
No this is all I've got, the algorithm I think is ...
Suro1996 Avatar
Posted By Suro1996
Wed May 11 2016, 09:27 PM
Is this all the code you have ?As it is, it will n...
Suro1996 Avatar
Posted By Suro1996
Wed May 11 2016, 07:31 PM
Hello, I am new to assembly programming and I am h...