# include <stdio.h>
 # include <dos.h>
 # include <bios.h>
 # include <string.h>
 # include <stdio.h>
 # include <fcntl.h>
 # include <sys\stat.h>

 union  REGS    ipregs;
 union  REGS    opregs;
 struct SREGS   spregs;
 struct REGPACK reg;

struct DoubleWord
{
   unsigned int HiWord;
   unsigned int LoWord;
};
union  LongToWord
{
   long    dw;
   struct  DoubleWord w;
};

int GetLockMode();
int SetLockMode();
int LogFile();
int LockFileSet();
int ReleaseFile();
int ReleaseFileSet();
int ClearFile();
int ClearFileSet();
int LockPhysicalRecord();
int LockPhysicalRecordSet();
int ReleasePhysicalRecord();
int ReleasePhysicalRecordSet();
int ClearPhysicalRecord();
int ClearPhysicalRecordSet();


void main()
{
int  return_code;
char ch;
int  fp0,fp1,fp2;
long recordStartOffset=0;
long recordLength=10;
char lockDirective=0;
int  timeoutLimit=72;
char msg[] = "Hello world\n";
int  lockMode;

clrscr();
printf("\n                      The example for Synchronous DOS call\n\n");

lockMode=GetLockMode();
printf("The lockmode is  %d now .",lockMode);
printf("\nYou can change the lockmode to :");
scanf("%d",&lockMode);
return_code=SetLockMode(lockMode);

fp0 = creat("file0", S_IREAD |S_IWRITE);
return_code=LogPhysicalRecord (fp0, recordStartOffset, recordLength,
		       lockDirective, timeoutLimit);
if (return_code==0)
   {printf("\nThe first 10 bytes of file 'file0' is logged,press any key to continue!");
   ch=getch();}
return_code=LogPhysicalRecord (fp0, recordStartOffset+10, recordLength,
		       lockDirective+1, timeoutLimit);
if (return_code==0)
   {printf("\nThe next 10 bytes of file 'file0' is locked,press any key to continue!");
    ch=getch();}
LockPhysicalRecordSet(lockDirective, timeoutLimit);
if (return_code==0)
   {printf("\nAll logged record of file 'file0' are locked,press any key to continue!");
    ch=getch();
    write(fp0, msg, strlen(msg));
   }

ReleasePhysicalRecord(fp0, recordStartOffset, recordLength);
if (return_code==0)
   {printf("\n\nThe first 10 bytes of file 'file0' is released,press any key to continue!");
    ch=getch();}
ClearPhysicalRecord(fp0, recordStartOffset, recordLength);
if (return_code==0)
   {printf("\nThe first 10 bytes of file 'file0' is cleared,press any key to continue!");
    ch=getch();}
ReleasePhysicalRecordSet();
printf("\nAll locked record of file 'file0' are released,press any key to continue!");
ch=getch();
ClearPhysicalRecordSet();
printf("\nAll logged record of file 'file0' are cleared,press any key to continue!");
ch=getch();
close(fp0);

fp1 = creat("file1", S_IREAD |S_IWRITE);
fp2 = creat("file2", S_IREAD |S_IWRITE);
return_code=LogFile("file1", lockDirective, timeoutLimit);
if (return_code==0)
   {printf("\n\nFile 'file1' is logged,press any key to continue!");
    ch=getch();}
return_code=LogFile("file2", lockDirective+1, timeoutLimit);
if (return_code==0)
   {printf("\nFile 'file2' is locked,press any key to continue!");
     ch=getch();}
return_code=LockFileSet(timeoutLimit);
if (return_code==0)
   {printf("\nAll logged file are locked,press any key to continue!");
    ch=getch();
    write(fp1,msg,strlen(msg));
    close(fp1);
    write(fp2,msg,strlen(msg));
    close(fp2);
    }
return_code=ReleaseFile("file1");
if (return_code==0)
   {printf("\n\nFile 'file1' is released,press any key to continue!");
    ch=getch();}
return_code=ClearFile("file1");
if (return_code==0)
   {printf("\nFile 'file1' is cleared,press any key to continue!");
    ch=getch();}

ReleaseFileSet();
printf("\nAll locked file are released,press any key to continue!");
ch=getch();
ClearFileSet();
printf("\nAll logged file are cleared,press any key to quit!");
ch=getch();

 }

int GetLockMode()
{
   ipregs.h.al = 0x02;
   ipregs.h.ah = 0xC6;
   intdosx(&ipregs,&opregs,&spregs);

   return(opregs.h.al);
}

int SetLockMode(char lockMode)
{
   ipregs.h.al = lockMode;
   ipregs.h.ah = 0xC6;
   intdosx(&ipregs,&opregs,&spregs);

   return(opregs.h.al);
}

int LogFile(char *fileName, char lockDirective, int timeoutLimit)
{
   reg.r_ds = FP_SEG(fileName);
   reg.r_dx = FP_OFF(fileName);
   reg.r_ax = 0xEB<<8 | lockDirective;
   reg.r_bp = timeoutLimit;
   intr(0x21, &reg);

   return _AL;
}

int LockFileSet(int timeoutLimit)
{

   reg.r_ax = 0xCB<<8 ;
   reg.r_bp = timeoutLimit;
   intr(0x21, &reg);

   return _AL;
}

int ReleaseFile(char *fileName)
{

   spregs.ds   = FP_SEG(fileName);
   ipregs.x.dx = FP_OFF(fileName);
   ipregs.h.ah = 0xEC;
   intdosx(&ipregs,&opregs,&spregs);

   return(opregs.h.al);
}


int ReleaseFileSet()
{

   ipregs.h.ah = 0xCD;
   intdosx(&ipregs,&opregs,&spregs);

   return(opregs.h.al);
}

int ClearFile(char *fileName)
{
   spregs.ds   = FP_SEG(fileName);
   ipregs.x.dx = FP_OFF(fileName);
   ipregs.h.ah = 0xED;
   intdosx(&ipregs,&opregs,&spregs);

   return(opregs.h.al);
}

int ClearFileSet()
{

   ipregs.h.ah = 0xCF;
   intdosx(&ipregs,&opregs,&spregs);

   return(opregs.h.al);
}

int LockPhysicalRecordSet(char lockDirective, int timeoutLimit)
{

   reg.r_ax = 0xC2<<8 | lockDirective;
   reg.r_bp = timeoutLimit;
   intr(0x21, &reg);

   return _AL;
}

int ReleasePhysicalRecordSet()
{

   ipregs.h.ah = 0xC3;
   intdosx(&ipregs,&opregs,&spregs);

   return(opregs.h.al);
}

int ClearPhysicalRecordSet()
{

   ipregs.h.ah = 0xC4;
   intdosx(&ipregs,&opregs,&spregs);

   return(opregs.h.al);
}

int LogPhysicalRecord (fp0, recordStartOffset, recordLength,
		       lockDirective, timeoutLimit)
int     fp0;
long    recordStartOffset;
long    recordLength;
char    lockDirective;
int    timeoutLimit;

{
   union LongToWord tmp;

   tmp.dw = recordStartOffset;
   reg.r_dx = tmp.w.HiWord;
   reg.r_cx = tmp.w.LoWord;
   tmp.dw = recordLength;
   reg.r_di =tmp.w.HiWord;
   reg.r_si =tmp.w.LoWord;
   reg.r_ax = 0xBC<<8 | lockDirective;
   reg.r_bx = fp0;
   reg.r_bp = timeoutLimit;
   intr(0x21, &reg);

   return _AL;
}

int ReleasePhysicalRecord(fp0, recordStartOffset, recordLength)

int     fp0;
long    recordStartOffset;
long    recordLength;
{
   union LongToWord tmp;

   tmp.dw = recordStartOffset;
   reg.r_dx = tmp.w.HiWord;
   reg.r_cx = tmp.w.LoWord;
   tmp.dw = recordLength;
   reg.r_di =tmp.w.HiWord;
   reg.r_si =tmp.w.LoWord;
   reg.r_ax = 0xBD<<8 ;
   reg.r_bx = fp0;
   intr(0x21, &reg);

   return _AL;
}


int ClearPhysicalRecord(fp0, recordStartOffset, recordLength)

int     fp0;
long    recordStartOffset;
long    recordLength;
{
   union LongToWord tmp;

   tmp.dw = recordStartOffset;
   reg.r_dx = tmp.w.HiWord;
   reg.r_cx = tmp.w.LoWord;
   tmp.dw = recordLength;
   reg.r_di =tmp.w.HiWord;
   reg.r_si =tmp.w.LoWord;
   reg.r_ax = 0xBE<<8 ;
   reg.r_bx = fp0;
   intr(0x21, &reg);

   return _AL;
}