/* diskedit.c - low level disk sector viewer/editor */
/* lrs - 2/13/89 */

#include <stdio.h>
#include <bios.h>
#include <dos.h>
#include "disks.h"
#include "video.h"
#include "keys.h"
#include "devideo.h"
#include "defiles.h"

#define FALSE 0
#define TRUE  ~FALSE

char WriteAllowed = FALSE;
int Drive = 0x80;
int HalfDisp = TRUE; int DispOffs = 0;

int Cyl = 0; int Head = 0; int Sec = 1;
int MaxCyl, MaxHead, MaxSec;
extern int scrrows;
char Done;
unsigned char SecBuf[BYTESPERSECTOR];

/*-----------------------------------------------------------------------*/
void limit (int* num, int lowest, int highest)
  {
  if (*num < lowest) *num = lowest;
  if (*num > highest) *num = highest;
  }
/*-----------------------------------------------------------------------*/
void ReadCurrent(void)
    {
    if (!ReadSector(Drive, Cyl, Head, Sec, (char far *) SecBuf))
      {
      ErrorMessage("READ ERROR!!!!");
      WriteAllowed = FALSE;
      ShowWriteAllowed(WriteAllowed);
      }
    }    /* ReadCurrent */

void WriteCurrent(void)
  {
  if (!WriteAllowed) 
    ErrorMessage("Sector Updates Not Allowed! (use alt+F10 to enable)");
  else
    if (getkey("Are You Sure? ") == 'Y')
      if (!WriteSector(Drive, Cyl, Head, Sec, (char far *) SecBuf))
        ErrorMessage("WRITE ERROR!!!!");
      else
        ErrorMessage("Write Successful");
  }    /* WriteCurrent */

/*-----------------------------------------------------------------------*/
void NextSector(void)
  {
  if ((DispOffs == 0) && (HalfDisp))
    DispOffs = 16;
  else
    {
    DispOffs = 0;
    if (++Sec > MaxSec) 
      {
      Sec = 1;
      if (++Head > MaxHead) 
        {
        Head = 0;
        if (++Cyl > MaxCyl) 
          Cyl = 0;
        }
      }
    ReadCurrent();
    }
  DisplaySector(Drive, Cyl, Head, Sec, SecBuf, DispOffs);
  }    /* NextSector */

void PrevSector(void)
  {
  if ((DispOffs != 0) && (HalfDisp))
    DispOffs = 0;
  else
    {
    if (HalfDisp) DispOffs = 16;
    if (--Sec < 1) 
      {
      Sec = MaxSec;
      if (--Head < 0) 
        {
        Head = MaxHead;
        if (--Cyl < 0) 
          Cyl = MaxCyl;
        }
      }
    ReadCurrent();
    }
  DisplaySector(Drive, Cyl, Head, Sec, SecBuf, DispOffs);
  }    /* PrevSector */

void GotoSector(void)
  {
  getdec("Cylinder:",&Cyl); limit(&Cyl,0,MaxCyl);
  getdec("Head:",&Head);    limit(&Head,0,MaxHead);
  getdec("Sector:",&Sec);   limit(&Sec,1,MaxSec);
  ReadCurrent();
  DispOffs = 0;
  DisplaySector(Drive, Cyl, Head, Sec, SecBuf, DispOffs);
  }    /* GotoSector */

/*-----------------------------------------------------------------------*/
void ReadSectorFromFile(void)
  {
  char filename[80];
  getline("Read from File:",filename);
  ReadFile(filename, SecBuf);
  DisplaySector(Drive, Cyl, Head, Sec, SecBuf, DispOffs);
  }    /* ReadSectorFromFile */

void WriteSectorToFile(void)
  {
  char filename[80];
  getline("Write To File:",filename);
  WriteFile(filename, SecBuf);
  }    /* WriteSectorToFile */

/*-----------------------------------------------------------------------*/
void ModifyByte(void)
  {
  int address, val;
  address = 0;
  gethex("Modify Byte at:",&address); 
  limit(&address,0,BYTESPERSECTOR-1);
  val = SecBuf[address];
  gethex("New Value:",&val);
  SecBuf[address] = val;
  ErrorMessage("Don't Forget to Update!");
  DisplaySector(Drive, Cyl, Head, Sec, SecBuf, DispOffs);
  }    /* ModifyByte */
/*-----------------------------------------------------------------------*/
void DoCommand(void)
  {
  int ch;

  ch = getcmd();
  ClearErrorMessage();
  switch (ch)
    {
    case PGDN: NextSector();         break;
    case PGUP: PrevSector();         break;
    case 'G':  GotoSector();         break;
    case 'W':  WriteSectorToFile();  break;
    case 'R':  ReadSectorFromFile(); break;
    case 'M':  ModifyByte();         break;
    case F10:  WriteCurrent();       break;
    case aF10: WriteAllowed = !WriteAllowed;
               ShowWriteAllowed(WriteAllowed);
               break;
    case ESC:  Done = TRUE;
               break;
    }
  }    /* DoCommand */

/*-----------------------------------------------------------------------*/
void SelectDrive(int drive)
  {
  InitDisks();
  GetDiskParams(Drive, &MaxCyl, &MaxHead, &MaxSec);
  ShowMaxes(MaxCyl, MaxHead, MaxSec);
  }

/*-----------------------------------------------------------------------*/
void main()
{
initvideo(); cursoroff();
scrrows = screenrows(); HalfDisp = (scrrows < 43);
DisplayFrame();
SelectDrive(0x80);
ReadCurrent();
DisplaySector(Drive, Cyl, Head, Sec, SecBuf, DispOffs);
Done = FALSE;
while (!Done)
   DoCommand();

clearscreen(); cursoron();
cprintf("diskedit is finished.");
}
/*---- end of diskedit.c ----*/