#include<stdio.h>
#include<conio.h>
#include<dos.h>
#include<stdlib.h>

struct chain
{
 char data;
 struct chain *next;
};
typedef struct chain chain;

int wait(int maxloop)
{
 int i;
 for(i=0;i<maxloop;i++)
  if(kbhit())
   break;
 if(i==maxloop)
  return(0);
 else
  return(1);
}

void sndgen(int freq)
{
 int i,del,rep=25;
 for(i=0,del=5;i<rep;i++,del=del+5)
 {
  sound(freq);
  if(wait(del)==0)
  {
   sound(10000);
   delay(2);
   nosound();
  }
  nosound();
  freq=freq+100;
 }
}

void main()
{
 int x=1,y=1,maxx=80,maxy=25,ers=2750,nrs=750,flag,sndvar;
 char ch,*textbuff;
 chain *first,*newlink,*old,*temp;
 clrscr();
 textcolor(LIGHTRED);
 first=NULL;
 while(1)
 {
  ch=getch();
  switch(ch)
  {
   case 26:if(first!=NULL)
	    old->next=NULL;
	   flag=1;
	   break;
   case 27:exit(EXIT_FAILURE);
   case 8: if(first==NULL)
	   {
	    sound(ers);
	    delay(50);
	    nosound();
	   }
	   else
	   {
	    if(old==first)
	    {
	     free(first);
	     first=NULL;
	    }
	    else
	    {
	     for(temp=first;temp->next!=NULL;temp=temp->next);
	     for(old=first;old->next!=temp;old=old->next);
	     old->next=NULL;
	     free(temp);
	    }
	   }
	   break;
   default:if(first==NULL)
	   {
	    first=(chain *)malloc(sizeof(chain));
	    first->data=ch;
	    first->next=NULL;
	    old=first;
	   }
	   else
	   {
	    newlink=(chain *)malloc(sizeof(chain));
	    newlink->data=ch;
	    newlink->next=NULL;
	    old->next=newlink;
	    old=newlink;
	   }
	   if(x>maxx||ch==13)
	   {
	    x=1;
	    y++;
	   }
	   if(y>maxy)
	   {
	    textbuff=(char *)malloc(maxx*(maxy-1));
	    gettext(1,2,maxx,maxy,textbuff);
	    puttext(1,1,maxx,maxy-1,textbuff);
	    free(textbuff);
	    x=1;
	    y=maxy;
	    insline();
	   }
	   gotoxy(x,y);
	   cprintf("%c",ch);
	   x++;
	   sndgen(nrs);
  }
  if(flag==1)
   break;
 }
 clrscr();
 for(old=first;old!=NULL;old=old->next)
 {
  if(kbhit())
   break;
  printf("%c",old->data);
 }
}