Segmentation fault

[psrujan]

Hi ,

I have little bit of knowledge in C++. When I run the following program its gives me segmentation error. I tried to do all the possible things by reading online but not able to figure out the error. I ran it suing gdb debugger but still it stays error is somewhere near n=atoi(argv[2]);
but i am not sure. Can somebdy please help me in finding the error.

my command line arguments are
./output 2 3 abc.pbm 1.2 abc2.pbm 1.3


#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <algorithm>
#include <iostream>
#include <time.h>

using namespace std;
#define MAX 90
#define Lwire 2 // length of the wire 2mm -- all values are for 130nm technology
#define Nwire 128 // Number of wires 128
#define Llink 0.5 // average link load .5
#define powerleakage 2032.8 // leakage power 2032.8nw
#define V 1 BIG_DYN[y] // voltage= 1V
#define Ibias 1 // Ibias=1nA
#define K1 0.39
#define K2 .12
#define POP_SIZE 50
#define R_CO .33
#define R_MUT .1


int pbm[MAX][MAX][MAX],pgm[MAX][MAX],dist[MAX][MAX]={0};
int a=0,b=0,nodes,arg;
//int m,n;
double TotalDynEnergy=0,minTotalDynEnergy=0;
char head[4],head1[4];
int maxd;
// int layoutnumber=0;
// int layoutminTotalDynEnergy;

/**** Dynamic Energy for each communication pattern ****/

double energy( void)
{ int i,j,d;
double powerdyn,powershtckt,powertotal,energy=0;

maxd=0;
powerdyn= ( K1 +( K2 * Lwire))* Nwire * Llink;// Dynamic power equation
// printf("\n power dyn %f \t",powerdyn);
//powershtckt=V*Ibias;
// powertotal=sumlinks*(powerdyn+powerleakage+powersh tckt);
// printf("\n %f\n ",powertotal);

for(j=0;j<b;j++)
{ for (i=0;i<a;i++)
{
d=dist[j][i]; // printf("\n value of d %d\t",d);
if(d > maxd)
maxd=d; // max distance in the layout
if (d!=0)
{// Dynamic Energy for each entry in comm pattern
energy= energy+(0.37*d)+(powerdyn*(d-1)); // printf("\n energy %f",energy);
}
}
}
// printf("\n Dynamic energy for this pattern is %f \n",energy);
// printf("pattmaxd %d ",maxd);
return(energy);
}

/**** Load Communication paterns ****/

void loadpatterns(int argc,char **argv,int index)
{ FILE *pbmread;
int i,j;


pbmread = fopen (argv[arg],"r"); // open communication pattern file
/* if (!pbmread)
printf("\n Cannot open the Communication Pattern file ");
else
printf("\nCommunication Pattern with weight %s",argv[arg+1]);*/

fscanf(pbmread,"%s\n%d %d\n",head,&a,&b); //printf("\n%s\n%d %d\n",head,a,b);

for (j=0;j<b;j++)
{ for(i=0;i< a;i++)
{ fscanf(pbmread,"%d",&pbm[index][j][i]); // printf("%d ",pbm[index][j][i]);
}
//printf("\n");
}
fclose(pbmread);
}


/**** Distance Matrix and Total Dynamic Energy ****/

void groute(int argc,char **argv)
{
int x1,y1,x2,y2,k,l;
int index;
double DynEnergy;
float weight;
int distance;
int i,j;

for (arg=3,index=0;arg<argc;arg+=2,index++)
{
weight=atof(argv[arg+1]);
loadpatterns(argc,argv,index); // FUNCTION Load Communication Pattern

for (j=0;j<b;j++)
for (i=0;i<a;i++)
{ if (pbm[index][j][i]!=0)
{for (l=0;l<m;l++)
for (k=0;k<n;k++)
{ if (pgm[l][k] == i)
{ x1=l;y1=k;}
if (pgm[l][k]==j)
{ x2=l;y2=k;}
}
distance=(abs(y2-y1)+abs(x2-x1));// 'x+y'or manhattan distance between nodes for pbm[i][j]!=0
dist[j][i]=distance; // Distance matrix
}
if (pbm[index][j][i]==0)
{dist[j][i]=0;}
}
/*printf("\nweight %f ",weight);
printf("\n\nDistance Matrix\n");
for ( j=0;j<b;j++)
{ for ( i=0;i<a;i++)
printf("%d ",dist[j][i]);
printf("\n");
}*/
DynEnergy= energy(); // FUNCTION Dynamic energy for the pattern
TotalDynEnergy=TotalDynEnergy+DynEnergy;//Total Dynamic Energy for all patterns
}

}



int main(int argc,char *argv[])
{
int N_CO,N_MUT;

int dim;
//m=2; n=3;
// int ext1,ext2;
//printf(" %d %s %s %s",argc,argv[1],argv[2],argv[3],argv[4]);
int q;
printf("break1\n");
m=atoi(argv[1]);
n=atoi(argv[2]); // mxn layout
printf("\n %d %d",m ,n );
dim=m*n;
int x[dim];
int POP[POP_SIZE][dim];
float POP_DYN[POP_SIZE];
int i,j,k,l;
int first,second;
// int* ptr_co;
int t1[i];
float t;
int gen;
int MAX_Gen=10;
int layoutnumber=0;

for ( i=0;i<dim;i++)
x[i]=i;
q=n;
printf(" q is %d",q);

/**** Initial pop ***/
do { printf("enter loop");

for(i=0;i<dim;i++)
POP[layoutnumber][i]=x[i];
printf("layout break1");

l=0;k=0;
for(i=0;i<dim;i++)
{if (l==q)
{k=k+1;l=0;}
pgm[k][l]=x[i]; // layout of the nodes
l++;
}
printf("node break/n");
// groute(argc,argv);
// Dynamic Energy array
POP_DYN[layoutnumber]=TotalDynEnergy;

layoutnumber++;
TotalDynEnergy=0;
pskreddy
}while((next_permutation(x,x+dim)) /*&& ( layoutnumber < POP_SIZE)*/);
}


when i run gdb it gives
#0 0xb7d9bd6c in __strtouq_internal () from /lib/tls/i686/cmov/libc.so.6
#1 0xb7d9baff in __strtol_internal () from /lib/tls/i686/cmov/libc.so.6
#2 0xb7d99166 in atoi () from /lib/tls/i686/cmov/libc.so.6
#3 0x08048b26 in main (argc=2, argv=0xbf8c2ac4) at groute.cpp:139
(gdb) up 3
#3 0x08048b26 in main (argc=2, argv=0xbf8c2ac4) at groute.cpp:139
139 m=atoi(argv[1]);n=atoi(argv[2]); // mxn layout
Current language: auto; currently c++


I appreciate any help

pskr

[Cabhan]

First off, in the future, please surround your code in [code] tags.

The best way to handle this is to add debug statements (just print to cerr) at various places so you can pinpoint exactly where the segmentation fault is happening. Then see what you're doing. In this case, I notice that you're accessing argv[1] and argv[2] without ever checking what the value of argc is. If no commandline arguments are given, then argv[1] and argv[2] are undefined, and will very possibly segfault. I recognize that you are including commandline arguments, but if you weren't, this would be bad.

Anyway, use debug statements, find out where the segfault is occurring, and examine that line and the variables used in it. If you have a more specific question, let us know.