C program to implement relocation loader

AIM:

To write a C program to implement relocation loader.

ALGORITHM:

STEP 1: Start the program execution.
STEP 2: Enter the starting address location for relocating the object code.
STEP 3: Transfer the input array into output array.
STEP 4: Convert the current string array into binary form,where current string is
relocating bit.
STEP 5: Relocating bit is subjected to required changes before transferring input to
output and also move object code
STEP 6: Stop the program execution.

PROGRAM:

#include<stdio.h>
#include<conio.h>
#include<string.h>
#include<stdlib.h>
struct object_code
{
int locctr;
char add[10];
}obcode[300];
void main()
{
char input[100][16],output[100][16],binary[20],address[20],stloc[10];
int len,bitmask,loc,tlen=0,tloc,textloc,i=0,location,j,k,count=0,start,n,num=0,inc=0;
FILE *fp1,*fp2;
clrscr();
fp1=fopen("z:\ssinput.dat","r");
fp2=fopen("z:\ssoutput.dat","w");
printf("Enter the location where the program has to be loaded:\n");
scanf("%s",stloc);
start=atoi(stloc);
location=start;
tloc=start;
fscanf(fp1,"%s",input[i]);
while(strcmp(input[i],"T")!=0)
{
strcpy(output[i],input[i]);
i++;
fscanf(fp1,"%s",input[i]);
strcpy(output[i],input[i]);
}
itoa(start,output[2],10);
while(strcmp(input[i],"E")!=0)
{
strcpy(output[i],input[i]);
if(strcmp(input[i],"T")==0)
{
for(j=0;j<3;j++)
{
i++;
fscanf(fp1,"%s",input[i]);
strcpy(output[i],input[i]);
}
bitmask=atoi(output[i]);
itoa(bitmask,binary,2);
strcpy(output[i],"NULL");
textloc=atoi(output[i-2]);
textloc=textloc+start;
itoa(textloc,output[i-2],10);
for(n=0;n<(textloc-(tloc+tlen));n++)
{
strcpy(obcode[inc].add,"xx");
obcode[inc++].locctr=location++;
}
tlen=atoi(output[i-1]);
tloc=textloc;
k=0;
}
else
{
if(binary[k]=='1')
{
num=0;
len=strlen(output[i]);
strcpy(address,NULL);
for(j=2;j<len;j++)
{
address[num]=output[i][j];
output[i][j]='\0';
num++;
}
loc=atoi(address);
loc=loc+start;
itoa(loc,address,10);
strcat(output[i],address);
}
k++;
len=strlen(output[i]);
num=0;
for(n=0;n<len;n++)
{
obcode[inc].add[num++]=output[i][n];
if(num>1)
{
obcode[inc++].locctr=location++;
num=0;
}
}
}
i++;
fscanf(fp1,"%s",input[i]);
}
strcpy(output[i],input[i]);
i++;
fscanf(fp1,"%s",input[i]);
loc=atoi(input[i]);
loc=loc+start;
strcpy(output[i],itoa(loc,address,10));
count=0;
i=0;
n=0;
fprintf(fp2,"%d\t",obcode[n].locctr);
for(n=0;n<inc;n++)
{
fprintf(fp2,"%s",obcode[n].add);
i++;
if(i>3)
{
fprintf(fp2,"\t");
i=0;
count++;
}
if(count>3)
{
fprintf(fp2,"\n%d\t",obcode[n+1].locctr);
count=0;
}
}
getch();
}

Posted in: C / C++ Program