lab report system software

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DEPARTMENT

OF

COMPUTER SCIENCE AND ENGINEERING

SYSTEM SOFTWARE

(CS651)

Prijo Cherry Mathews

1017422

A Laboratory Record submitted in partial fulfillmentof the

requirement of System Software Lab

of VIthB.Tech (CSE)

December, 2012



Certificate

This is to certify that the record titled System Software Lab (CS651) is a

bonafide record of work done by Pri jo Cherry Mathews in partial fulfillment of

requirement of VI th B.Tech CSE during the year 2012.

HEAD OF THE DEPARTMENT FACULTY-IN-

CHARGE

EXAMINER 1:

ASSOCIATE DEAN EXAMINER 2:

Name : Prijo Cherry Mathews

Register Number : 1017422

Examination Center : CUFE

Date of Examination : ___________________



System Software Lab (CS652)

Department of Computer Science and Engineering, Christ University 2

struct symbtab

{

char label[10];int addr;

struct symtab *next;

};

struct symbtab *first,*last;

void main()

{

int op;

int y;

char la[10];

clrscr();

do

{

printf("\n 1. Insert");

printf("\n 2. Display");

printf("\n 3. Delete");

printf("\n 4. Search");

printf("\n 5. Modify");

printf("\n 6. Exit");

printf("\n\n Enter your option : ");

scanf("%d",&op);

switch(op)

{

case 1:

insert();

printf("\n Inserted Successfully\n");

break;

case 2:

display();

break;





scanf("%s",l);

n=search(l);

if(n==1)

{ printf("\n The label already exists. Duplicate cant be inserted\n");

}

else

{

struct symbtab *p;

p=malloc(sizeof(struct symbtab));

strcpy(p->label,l);

printf("\n Enter the address : ");

scanf("%d",&p->addr);

p->next=null;

if(size==0)

{

first=p;

last=p;

}

else

{

last->next=p;

last=p;

}

size++;

}

}

void display()

{

int i;

struct symbtab *p;

p=first;





printf("\n\n\t\t LABEL\tADDRESS\n\n");

for(i=0;i<size;i++)

{

printf("\t\t %s\t%d\n\n",p->label,p->addr); p=p->next;

}

}

int search(char lab[])

{

int i,flag=0;

struct symbtab *p;

p=first;

for(i=0;i<size;i++)

{

if(strcmp(p->label,lab)==0)

{

flag=1;

}

p=p->next;

}

return flag;

}

void modify()

{

char l[10],nl[10];

int add, choice, i, s;

struct symbtab *p;

p=first;

printf("\n 1. Modify label");

printf("\n 2. Modify address");

printf("\n 3. Modify label and address");





printf("\n Enter your choice : ");

scanf("%d",&choice);

switch(choice)

{case 1:printf("\n Enter the old label\n");

scanf("%s",l);

printf("\n Enter the new label\n");

scanf("%s",nl);

s=search(l);

if(s==0)

{

printf("\n Doesn't Exist");

}

else

{

for(i=0;i<size;i++)

{

if(strcmp(p->label,l)==0)

{

strcpy(p->label,nl);

}

p=p->next;

}

}

break;

case 2:

printf("\n Enter the label whose address is to modified: ");

scanf("%s",l);

printf("\n Enter the new address: ");

scanf("%d",&add);

s=search(l);

if(s==0)

{






}

else

{for(i=0;i<size;i++)

{


{

p->addr=add;

}

p=p->next;

}

}

break;

case 3:

printf("\n Enter the old label : ");

scanf("%s",l);

printf(" Enter the new label : ");

scanf("%s",nl);

printf(" Enter the new address : ");scanf("%d",&add);

s=search(l);

if(s==0)

{


}

else

{

for(i=0;i<size;i++)

{


{

strcpy(p->label,nl);

p->addr=add;

}

p=p->next;

}

}

break;

}

}





void del()

{

int a;

char l[10];

struct symbtab *p,*q;

p=first; printf("\n Enter the label to be deleted: ");

scanf("%s",l);

a=search(l);

if(a==0)

{

printf("\n Doesn't Exist\n");

}

else

{

if(strcmp(first->label,l)==0)

{

first=first->next;

}

else if(strcmp(last->label,l)==0)

{

q=p->next;

while(strcmp(q->label,l)!=0)

{

p=p->next;

q=q->next;

} p->next=null;

last=p;

}

else

{

q=p->next;

while(strcmp(q->label,l)!=0)

{

p=p->next;

q=q->next;

} p->next=q->next;

}

size--;

}

}

Result: - The symbol table algorithm was implemented successfully in C.





MODIFY: -





Experiment 2 – Pass One of Two Pass Assembler

Aim: Write a program to implement single pass assembler.

Algorithm:

1. Open and Read the input file

2. If the input line has the opcode "START' do the following

a. Find if there is any operand field after "START', initialize the LOCCTR to the

operand value

b. Otherwise if there is no value in the operand field then LOCC TR is set to 0

3. Write the input line to the intermediate file

4. Do the following steps until the opcode is END

a. Check the Symbol table, if the symbol is not available then enter that symbol

into the SYMTAB, along with the memory address in which it is

stored.Otherwise, the error message should be displayed

b. If there is a opcode

i. If opcode is present in the OPTAB, then increment the LOCCTR by 3

ii. If opcode is "WORD", then increment LOCCTR. by 3;

iii. If opcode is "BYTE", then increment L OCC TR by 1;

iv. If opcode is 'RESW" then increment LOCCTR by the integer

equivalent of the operand value * 3;

v. If opcode is "FESS", then increment LOCCTR by the integer

equivalent of the operand value

c. Write the processed lines in the intermediate file along with their location

counters

5. To find the length of the program, Subtract the starting address of the progam from

the final value of the LOCCTR

6. Close all the files and exit

Program:

# include <stdio.h>

# include <conio.h>

# include <string.h>void main()





{

char opcode[10],mnemonic[3],operand[10],label[10],code[10];

int locctr,start,length;

FILE *fp1,*fp2,*fp3,*fp4;

clrscr();

fp1=fopen("input.txt","r");

fp2=fopen("symtab.txt","w");

fp3=fopen("out.txt","w");

fp4=fopen("optab.txt","r");

fscanf(fp1,"%s%s%s",label,opcode,operand);

if(strcmp(opcode,"START")==0)

{

start=atoi(operand);

locctr=start;

fprintf(fp3,"\t%s\t%s\t%s\n",label,opcode,operand);

fscanf(fp1,"%s%s%s",label,opcode,operand);}

else

locctr=0;

while(strcmp(opcode,"END")!=0)

{

fprintf(fp3,"%d\t",locctr);

if(strcmp(label,"**")!=0)

fprintf(fp2,"%s\t%d\n",label,locctr);

rewind(fp4);

fscanf(fp4,"%s",code);while(strcmp(code,"END")!=0)

{

if(strcmp(opcode,code)==0)

{

locctr+=3;

break;

}

fscanf(fp4,"%s",code);

}

if(strcmp(opcode,"WORD")==0)

locctr+=3;else if(strcmp(opcode,"RESW")==0)

locctr+=(3*(atoi(operand)));

else if(strcmp(opcode,"RESB")==0)

locctr+=(atoi(operand));

else if(strcmp(opcode,"BYTE")==0)

++locctr;

fprintf(fp3,"%s\t%s\t%s\n",label,opcode,operand);

fscanf(fp1,"%s%s%s",label,opcode,operand);}





fprintf(fp3,"%d\t%s\t%s\t\%s\n",locctr,label,opcode,operand);

length=locctr-start;

printf("The length of the program is %d",length);

fclose(fp1);

fclose(fp2);

fclose(fp3);

fclose(fp4);

getch();

}

Result: - Pass one of two-pass assembler was implemented successfully in C.

Output:

Input Files –

Output Files –





Experiment 3 – Pass Two of Two-Pass Assembler

Aim: Write a program to implement pass 2 assembler.

Algorithm:

1. Open and read the first line from the intermediate file.

2. If the first line contains the opcode "START', then write the label, opcode and

operand field values of the corresponding statement directly to the final output file.

3. Do the following steps, until an "END" statement is reached.

a. Start writing the location counter, opcode and operand fields of the

corresponding statement to the output file, along with the object code.

b. If them is no symbol label in the operand field, then the operand address is

assigned as zero and it is assembled with the object code of the instruction

c. If the opcode is BYTE, WORD, RESB etc convert the constants to the object

code.

4. Close the files and exit

Program:

#include<stdio.h>

#include<stdio.h>

#include<conio.h>

#include<string.h>

#include<stdlib.h>

void main()

{

char a[10],ad[10],label[10],opcode[10],operand[10],mnemonic[10],symbol[10];

int i,locctr,code,add,len,actual_len;FILE *fp1,*fp2,*fp3,*fp4;

clrscr();

fp1=fopen("twoout.dat","w");

fp2=fopen("symtab.dat","r");

fp3=fopen("out.dat","r");

fp4=fopen("optab.dat","r");

fscanf(fp3,"%s%s%s",label,opcode,operand);

if(strcmp(opcode,"START")==0)

{

fprintf(fp1,"\t%s\t%s\t%s\n",label,opcode,operand);

fscanf(fp3,"%d%s%s%s",&locctr,label,opcode,operand);

}





while(strcmp(opcode,"END")!=0)

{

if(strcmp(opcode,"BYTE")==0)

{

fprintf(fp1,"%d\t%s\t%s\t%s\t",locctr,label,opcode,operand);

len=strlen(operand);

actual_len=len-3;

for(i=2;i<(actual_len+2);i++)

{

itoa(operand[i],ad,16);

fprintf(fp1,"%s",ad);

}

fprintf(fp1,"\n");

}

else if(strcmp(opcode,"WORD")==0)

{len=strlen(operand);

itoa(atoi(operand),a,10);

fprintf(fp1,"%d\t%s\t%s\t%s\t00000%s\n",locctr,label,opcode,operand,a);

}

else if((strcmp(opcode,"RESB")==0)||(strcmp(opcode,"RESW")==0))

{

fprintf(fp1,"%d\t%s\t%s\t%s\n",locctr,label,opcode,operand);

}

else

{rewind(fp4);

fscanf(fp4,"%s%d",mnemonic,&code);

while(strcmp(opcode,mnemonic)!=0)

fscanf(fp4,"%s%d",mnemonic,&code);

if(strcmp(operand,"**")==0)

{

fprintf(fp1,"%d\t%s\t%s\t%s\t%d0000\n",locctr,label,opcode,operand,code);

}

Else

{

rewind(fp2);fscanf(fp2,"%s%d",symbol,&add);

while(strcmp(operand,symbol)!=0){fscanf(fp2,"%s%d",symbol,&add);

}

fprintf(fp1,"%d\t%s\t%s\t%s\t%d%d\n",locctr,label,opcode,operand,code,add);

}

}

fscanf(fp3,"%d%s%s%s\n",&locctr,label,opcode,operand);

}

fprintf(fp1,"%d\t%s\t%s\t%s\n",locctr,label,opcode,operand);

printf("FINISHED");fclose(fp1);





fclose(fp2);

fclose(fp3);

fclose(fp4);

getch();

}

Result: - Pass two of Two-Pass Assembler was implemented successfully in C.

Output:

Input Files: –

Output files: -





iv. If opcode is "RESW" then increment LC by the integer equivalent of

the operand value * 3

v. If opcode is "RESB", then increment LC by the integer equivalent of

the operand valuevi. If them is no symbol label in the operand field, then the operand

address is assigned as zero and it is assembled with the object code of

the instruction

vii. Writ the processed lines in the intermediate file along with their

location counters

5. 5. To find the length of the program, Subtract the starting address of the progam from

the final value of the LC

6. Close all the files and exit

Program:

#include<stdio.h>

#include<stdlib.h>

#include<conio.h>

#include<string.h>

void main()

{

FILE *f1,*f2,*f3,*f4,*f5;

int lc,sa,i=0,j=0,m[10],pgmlen,len,k,len1,l=0;

char name[10],opnd[10],la[10],mne[10],s1[10],mne1[10],opnd1[10];

char lcs[10],ms[10];

char sym[10],symaddr[10],obj1[10],obj2[10],s2[10],q[10],s3[10];

clrscr();

f1=fopen("input.txt","r");

f2=fopen("optab.txt","r");

f3=fopen("symtab.txt","w+");

f4=fopen("symtab1.txt","w+");

f5=fopen("output.txt","w+");

fscanf(f1,"%s%s%s",la,mne,opnd);

if(strcmp(mne,"START")==0)





{

sa=atoi(opnd);

strcpy(name,la);

lc=sa;}

strcpy(s1,"*");


while(strcmp(mne,"END")!=0)

{

if(strcmp(la,"-")==0)

{

fscanf(f2,"%s%s",mne1,opnd1);

while(!feof(f2))

{

if(strcmp(mne1,mne)==0)

{

m[i]=lc+1;

fprintf(f3,"%s\t%s\n",opnd,s1);

fprintf(f5,"%s\t0000\n",opnd1);

lc=lc+3;

i=i+1;

break;

}

else

fscanf(f2,"%s%s",mne1,opnd1);

}

}

else

{

fseek(f3,SEEK_SET,0);

fscanf(f3,"%s%s",sym,symaddr);





while(!feof(f3))

{

if(strcmp(sym,la)==0)

{itoa(lc,lcs,10);

fprintf(f4,"%s\t%s\n",la,lcs);

itoa(m[j],ms,10);

j=j+1;

fprintf(f5,"%s\t%s\n",ms,lcs);

i=i+1;

break;

}

else

fscanf(f3,"%s%s",sym,symaddr);

} //f3

if(strcmp(mne,"RESW")==0)

lc=lc+3*atoi(opnd);

else if(strcmp(mne,"BYTE")==0)

{

strcpy(s2,"-");

len=strlen(opnd);

lc=lc+len-2;

for(k=2;k<len;k++)

{

q[l]=opnd[k];

l=l+1;

}

fprintf(f5,"%s\t%s\n",q,s2);

break;

}

else if(strcmp(mne,"RESB")==0)

lc=lc+atoi(opnd);

else if(strcmp(mne,"WORD")==0)





{

strcpy(s3,"#");

lc=lc+3;

fprintf(f5,"%s\t%s\n",opnd,s3); break;

}

} // else la=-



}


pgmlen=lc-sa;

printf("H^%s^%d^0%x\n",name,sa,pgmlen);

printf("T^");

printf("00%d^0%x",sa,pgmlen);

fscanf(f5,"%s%s",obj1,obj2);

while(!feof(f5))

{

if(strcmp(obj2,"0000")==0)

printf("^%s%s",obj1,obj2);

else if(strcmp(obj2,"-")==0)

{

printf("^");

len1=strlen(obj1);

for(k=0;k<len1;k++)

printf("%d",obj1[k]);

}

else if(strcmp(obj2,"#")==0)

{

printf("^");

printf("%s",obj1);





}


}

fseek(f5,SEEK_SET,0);fscanf(f5,"%s%s",obj1,obj2);

while(!feof(f5))

{

if(strcmp(obj2,"0000")!=0)

{

if(strcmp(obj2,"-")!=0)

{

if(strcmp(obj2,"#")!=0)

{

printf("\n");

printf("T^%s^02^%s",obj1,obj2);

}

}

}


}

printf("\nE^00%d",sa);

getch();

}

Result: - The Single-Pass assembler was implemented successfully in C.

Output: -

INPUT FILE:- OPTAB FILE:-





SYMTAB FILE: - REFERENCE FILE: -

OUTPUT FILE: -

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