i/o scan disk scheduling using c, c++ or java -

learning system's programming,how can implement scan disk scheduling algorithm using c, c++ or java. requirements piece of code access disk handles. below example of code have been working on, problem merely simulation of taking place when scan disk algorithm running. header position , input data values user inserting program. want able read current header position, , en queue requests , implement scan disk scheduling or other scheduling algorithm

#include<stdio.h> #include<conio.h> #include<math.h> #define max 15 #define cymax 249  int i,j,req,ttl_tracks=0,cp,np,cposn,nposn; int cyposn[max],temp;  void input() {   {   clreol();   printf("\n enter current header position : ");   scanf("%d",&cposn);   /*cposn current cylinder position in case same   current header position*/  }while(cposn>cymax || cposn <=0);  printf("\n enter %d i/o requests : ",req);  cyposn[0] = cposn;  for(i=1;i<=req;i++)     /*this loop helps store different requests  inputs in array of cylinder positions cyposn: note initial array  cyposn stores value of initial header postion  , why  loop begins 1  */   scanf("%d",&cyposn[i]);    }  void scan()        /*function scanning schedule*/ { int tmp = cp;  /*the tmp integer used swapping values, current cylinder position next*/  int ind = 0;  for(i=0;i<=req;i++)/*this outer loops counts number of requests*/  {   for(j=0;j<req-i;j++)   /*this inner loop walks through different values in   cylinder array later become sorted */   {    if(cyposn[j] > cyposn[j+1])/*compares 2 values previous position    , next position, if previous greater next position,    positions swapped, taking next position tobecome current position    situation ensure current position become    small possible:    hence handle move left    */    {     temp = cyposn[j];     cyposn[j] = cyposn[j+1];     cyposn[j+1] = temp;    }   }  }  cp=0;  /*when  loop finishes untill finds minimal value:  handle assigned position '0' making current position zero*/   {   if(cyposn[cp] == cposn)    break;    /*if reaches possible maximum cylinder value    breaks else increments values*/   cp++;  }while(cp!=req);    printf("\ns.no.  current position    next position   displacement \n");  printf("---------------------------------------------------------- \n\n");  i=0;   cposn = cyposn[cp];   {   if(ind == 0)   {    if(cp == 0)    { nposn = 0; ind = 1; }    else     nposn = cyposn[--cp];   }   else   {    if(cp == 0)     cp = tmp;    nposn = cyposn[++cp];   }     printf(" %d\t\t%d\t\t%d\t\t%d\n",++i,cposn,nposn,abs(cposn-nposn));   ttl_tracks += (abs(cposn-nposn));   cposn = nposn;  }while(nposn!=cyposn[req]);  printf("---------------------------------------------------------- \n\n");  printf(" total tracks displaced : %d",ttl_tracks); }  void main() {   {   clrscr();   printf("\n enter number of requests : ");   scanf("%d",&req);  }while(req>max || req <=0);  input();  scan();  getch(); } 

you can send commands hard drive. protocol depends on hard drive.

check these out:
http://www.ata-atapi.com/pata.html
http://www.t13.org/documents/uploadeddocuments/docs2006/d1699r3f-ata8-acs.pdf

i suggest research sata, pata , atapi protocols. search "petzold writing device drivers".