THREE ADDRESS CODE GENERATION [ System Software Lab ]











Ex. No.: 12

THREE ADDRESS CODE GENERATION


AIM :
            To write a C program to generate a three address code for a given expression.
ALGORITHM:

Step1: Begin the program
Step2 : The expression is read from the file using a file pointer
Step3 : Each string is read and the total no. of strings in the file is calculated.
Step4: Each string is compared with an operator; if any operator is seen then the previous string and next string are concatenated and stored in a first temporary value and the three address code expression is printed
Step5 : Suppose if another operand is seen then the first temporary value is concatenated to the next string using the operator and the expression is printed.
Step6 : The final temporary value is replaced to the left operand value.
Step7 : End the program.
PROGRAM:  //program for three address code generation
#include<stdio.h>
#include<conio.h>
#include<stdlib.h>
#include<string.h>

struct three
{
char data[10],temp[7];
}s[30];
void main()
{
char d1[7],d2[7]="t";
int i=0,j=1,len=0;
FILE *f1,*f2;
clrscr();
f1=fopen("sum.txt","r");
f2=fopen("out.txt","w");
while(fscanf(f1,"%s",s[len].data)!=EOF)
len++;
itoa(j,d1,7);
strcat(d2,d1);
strcpy(s[j].temp,d2);
strcpy(d1,"");
strcpy(d2,"t");
if(!strcmp(s[3].data,"+"))
{
fprintf(f2,"%s=%s+%s",s[j].temp,s[i+2].data,s[i+4].data);
j++;
}
else if(!strcmp(s[3].data,"-"))
{
fprintf(f2,"%s=%s-%s",s[j].temp,s[i+2].data,s[i+4].data);
j++;
}
for(i=4;i<len-2;i+=2)
{
itoa(j,d1,7);
strcat(d2,d1);
strcpy(s[j].temp,d2);
if(!strcmp(s[i+1].data,"+"))
fprintf(f2,"\n%s=%s+%s",s[j].temp,s[j-1].temp,s[i+2].data);
else if(!strcmp(s[i+1].data,"-"))
fprintf(f2,"\n%s=%s-%s",s[j].temp,s[j-1].temp,s[i+2].data);
strcpy(d1,"");
strcpy(d2,"t");
j++;
}
fprintf(f2,"\n%s=%s",s[0].data,s[j-1].temp);
fclose(f1);
fclose(f2);
getch();
}
Input:  sum.txt

out = in1 + in2 + in3 - in4

Output  :       out.txt

t1=in1+in2
t2=t1+in3
t3=t2-in4
out=t3


RESULT:
            Thus a C program to generate a three address code for a given expression is written, executed and the output is verified.











Ex. No.: 13

GENERATION OF ASSEMBLY LANGUAGE INSTRUCTION FROM THREE ADDRESS CODE


AIM :
            To write a C program to generate an assembly language instruction from three address code.

ALGORITHM:

Step1 : Begin the program
Step2 : The file containing the three address code is given as input to this program
Step3 : Each string is read from the file
Step4 : In an expression the string the left of the operator is printed with the ‘LDA’ string.
Step5 : Next if the operator is ‘+’ then ‘ADO’ is printed else ‘SUB’ is printed followed  by the string to the right of the operator.
Step6 : Then ‘STA’ string is printed followed by the string value left of the ‘=’ operator
Step7 : .End of the program

PROGRAM: //GENERATION OF ASSEMBLY LANGUAGE INSTRUCTION FROM THREE ADDRESS CODE

#include<stdio.h>
#include<conio.h>
#include<string.h>
struct three
{
char data[10],temp[7];
}s[30];
void main()
{
            char *d1,*d2;
            int i=0,len=0;
            FILE *f1,*f2;
            clrscr();
            f1=fopen("exe1.txt","r");
            f2=fopen("exe2.txt","w");
            while(fscanf(f1,"%s",s[len].data)!=EOF)
            len++;
            for(i=0;i<=len;i++)
            {
             if(!strcmp(s[i].data,"="))
             {
             fprintf(f2,"\nLDA\t%s",s[i+1].data);
             if(!strcmp(s[i+2].data,"+"))
             fprintf(f2,"\nADD\t%s",s[i+3].data);
             if(!strcmp(s[i+2].data,"-"))
             fprintf(f2,"\nSUB\t%s",s[i+3].data);
             fprintf(f2,"\nSTA\t%s",s[i-1].data);
             }
     }
     fclose(f1);
     fclose(f2);
     getch();
 }

Input: exe1.txt

t1 = in1 + in2
t2 = t1 + in3
t3 = t2 - in4
out = t3

Output: exe2.txt
LDA    in1
ADD   in2
STA    t1
LDA    t1
ADD   in3
STA    t2
LDA    t2
SUB    in4
STA    t3
LDA    t3
STA    out

RESULT:
            Thus a   C program to generate a assembly language instruction from three address code is written, executed and the output is verified.

Comments

  1. Sir,The social media plugin used on the left side of the page is very annoying since it blocks the view of the content.
    I think it is better to either remove it or replace with a small one.

    ReplyDelete
  2. This program has conio.h related errors

    ReplyDelete
  3. iota() is not declared and defined in code.

    ReplyDelete

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