ctrl_c.c

Many C samples. It is a good sample for students to learn C language.

#include <stdio.h>
#include <dos.h>
#include <bios.h>

#define TRUE     1
#define FALSE    0

#define INTERCEPT       0
#define RELEASE         1
#define GET             0x00
#define SET             0x01
#define CHKON           0x01
#define CHKOFF          0x00

#define BREAKINTR       0x1B
#define DOS             0x21
#define CTRLCCHK        0x33
#define GETVECT         0x35
#define SETVECT         0x25
#define IOCTL           0x44
#define DEVFLAG         0x80
#define RAWFLAG         0x20

int get_ctrl_c_chk()
{
  union REGS regs;

  regs.h.ah = CTRLCCHK;
  regs.h.al = GET;
  int86(DOS, &regs, &regs);
  if (regs.x.cflag)
    return(FALSE);
  return(regs.h.dl);
}

int set_ctrl_c_chk(int value)
{
  union REGS regs;

  regs.h.ah = CTRLCCHK;
  regs.h.al = SET;
  regs.h.dl = value;
  int86(DOS, &regs, &regs);
  return(!regs.x.cflag);
}

unsigned int ioctl(int handle, int op, unsigned int value)
{
  union REGS regs;

  regs.h.ah = IOCTL;
  regs.h.al = op;
  regs.x.bx = handle;
  regs.x.dx = value & 0xFF;
  int86(DOS, &regs, &regs);

  if (regs.x.cflag)
    return(FALSE);
  return(regs.x.dx);
}

int rawio(int handle, int raw)
{
  unsigned int flags;

  flags = ioctl(handle, GET, 0);
  if (flags & DEVFLAG)
  {
    if (raw)
      ioctl(handle, SET, flags | RAWFLAG);
    else
      ioctl(handle, SET, flags & ~RAWFLAG);
  }
  return(flags & RAWFLAG);
}

static void interrupt far do_intcpt()
{
    return;
}

static void do_break(int op)
{
  union REGS regs;
  struct SREGS segs;
  static unsigned int oldseg;
  static unsigned int oldofs;

  if (op == INTERCEPT)
  {
    segread(&segs);
    regs.h.ah = GETVECT;
    regs.h.al = BREAKINTR;
    int86x(DOS, &regs, &regs, &segs);
    oldseg = segs.es;
    oldofs = regs.x.bx;

    segread(&segs);
    regs.x.dx = (unsigned int) do_intcpt;
    segs.ds   = ((unsigned long) do_intcpt) >> 16;
  }
  else
  {
    segread(&segs);
    regs.x.dx = oldofs;
    segs.ds   = oldseg;
  }
  regs.h.ah = SETVECT;
  regs.h.al = BREAKINTR;
  int86x(DOS, &regs, &regs, &segs);
}

int  ctrl_c(int op)
{
  static unsigned int outflg;
  static unsigned int inflg;
  static unsigned int ctrlcchk;

  if (op == INTERCEPT)
  {
    do_break(INTERCEPT);
    inflg  = rawio(fileno(stdin), TRUE);
    outflg = rawio(fileno(stdout), TRUE);
    if ((ctrlcchk = get_ctrl_c_chk()) == CHKON)
      set_ctrl_c_chk(CHKOFF);
  }
  else
  {
    set_ctrl_c_chk(ctrlcchk);
    rawio(fileno(stdout), outflg);
    rawio(fileno(stdin), inflg);
    do_break(RELEASE);
  }
  return(TRUE);
}

void main()
{
    int achar;

    ctrl_c(INTERCEPT);
    /* Chi co the ket thuc bang SpaceBar */
    while ((achar = _bios_keybrd(_KEYBRD_READ) & 0xFF) != ' ')
        putch(achar);
    ctrl_c(RELEASE);
}