Program to design and implement Pass 1 of 2 Pass Assembler > C and Assembly Program

Program to design and implement Pass 1 of 2 Pass Assembler > C and Assembly Program

System programming and Compiler Construction

.asm code:

PG1              START 1000

                    USING *, 15

                     L                    1, FOUR

                     A                    1, ='5'

                     ST                  1, TEMP

                     A                    1, ='4'

FOUR         DC                  F'4'

TEMP         DS                   '1'F

                     END

C Code:

#include<stdio.h>

#include<conio.h>

struct symtab

{

char sname[10];

int addr;

}stab[10];

struct littab

{

char lname[10];

int addr;

}ltab[10];

void main()

{

int lc=0,i=0,j=0,x;

FILE *fp1,*fp2;

char str[80],*s1,*s2,*s3;

int reg[16]={0};

clrscr();

fp1=fopen("pg1.ASM","r");

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

while(!feof(fp1))

{

fgets(str,80,fp1);

sscanf(str,"%s %s %s",s1,s2,s3);

if(strcmp(s2,"START")==0)

{

lc=atoi(s3);

strcpy(stab[i].sname,s1);

stab[i].addr=lc;

i++;

}

else if(strcmp(s1,"USING")==0)

reg[15]=1;

else if(strcmp(s2,"DC")==0||strcmp(s2,"DS")==0)

{

strcpy(stab[i].sname,s1);

stab[i].addr=lc;

i++;

lc+=4;

}

else if(strcmp(s1,"END")==0)

{

for(x=0;x<j;x++)

{

 ltab[x].addr=lc;

 lc+=4;

}

}

else

{

fprintf(fp2,"%d %s\n",lc,str);

if(s3[0]=='=')

{

strcpy(ltab[j].lname,s3);

j++;

}

lc+=4;

}

strcpy(s1," ");

strcpy(s2," ");

strcpy(s3," ");

}

fcloseall();

printf("Symbol Table\n");

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

printf("%s %d \n",stab[x].sname,stab[x].addr);

printf("Literal Table\n");

for(x=0;x<j;x++)

printf("%s %d \n",ltab[x].lname,ltab[x].addr);

printf("Base Register :\n");

for(x=0;x<=15;x++)

printf("reg[%d]=%d\n",x,reg[x]);

getch();

}

Output: