ravmouse (external mouse driver for Hexen/Heretic)

#include <stdio.h>
#include <stdarg.h>
#include <stdlib.h>
#include <mem.h>
#include <i86.h>
#include <process.h>
#include <dos.h>
#include <malloc.h>
#include <io.h>
#include <stdint.h>

//
// From Heretic / Hexen source code, definition of the structure that an
// external input driver must fill and button action flags.
//

#define EBT_FIRE             1
#define EBT_OPENDOOR         2
#define EBT_SPEED            4
#define EBT_STRAFE           8
#define EBT_MAP              0x10
#define EBT_INVENTORYLEFT    0x20
#define EBT_INVENTORYRIGHT   0x40
#define EBT_USEARTIFACT      0x80
#define EBT_FLYDROP          0x100
#define EBT_CENTERVIEW       0x200
#define EBT_PAUSE            0x400
#define EBT_WEAPONCYCLE      0x800
#define EBT_JUMP             0x1000

typedef _Packed struct
{
  int16_t  vector;              // Interrupt vector
  int8_t   moveForward;         // forward/backward (-50 to 50)
  int8_t   moveSideways;        // strafe (-50 to 50)
  int16_t  angleTurn;           // turning speed (640 [slow] 1280 [fast])
  int16_t  angleHead;           // head angle (+2080 [left] : 0 [center] : -2048 [right])
  int8_t   pitch;               // look up/down (-110 : +90)
  int8_t   flyDirection;        // flyheight (+1/-1)
  uint16_t buttons;             // EBT_* flags
}
externdata_t;

#define MOUSE_INTNUM 0x33
#define MOUSE_RESET 0
#define MOUSE_GETMICKEYS 11
#define MOUSE_GETBUTTONS 3

#define MY_DEFAULT_INTNUM 0x64
#define DEFAULT_HSENS 40
#define DEFAULT_VSENS 1
#define DEFAULT_DCLICKTICS 20

externdata_t extdata;
void interrupt (*saved_vector) (void);
int vector_is_hooked = 0;
union REGPACK regs;

// these can be changed from the config file or command line
int myintnum = MY_DEFAULT_INTNUM;
int h_sensitivity = DEFAULT_HSENS;
int v_sensitivity = DEFAULT_VSENS;
int dclicktics = DEFAULT_DCLICKTICS;

#define NUM_BUTTONS 3
//                                left       right         middle
int clickactions[NUM_BUTTONS]  = {EBT_FIRE, EBT_STRAFE,   0};
int dclickactions[NUM_BUTTONS] = {0,        EBT_OPENDOOR, EBT_CENTERVIEW};

// need to know this to time double clicks properly
int ticdup;

int myargc;
char **myargv;

void Error (char *error, ...)
{
  va_list argptr;

  if (vector_is_hooked)
    _dos_setvect (myintnum, saved_vector);

  printf ("Error: ");

  va_start (argptr,error);
  vprintf (error,argptr);
  va_end (argptr);

  printf ("\n");
  exit(-1);
}

int CheckParmWithArgs(char *parm, int num_args)
{
  int i;

  for (i = 1; i < myargc-num_args; i++)
  {
    if (!stricmp(parm, myargv[i]))
      return i;
  }

  return 0;
}

int CheckParm (char *parm)
{
  return CheckParmWithArgs (parm, 0);
}

int InitMouse (void)
{
  regs.w.ax = MOUSE_RESET;
  intr (MOUSE_INTNUM, &regs);

  if (regs.w.ax == 0xFFFF)
    return 1; // mouse driver installed
  else
    return 0; // not installed
}

void interrupt ControlISR (void)
{
  static int pitch = 0;
  static int dclicktime[NUM_BUTTONS]={0,0,0};
  static int dclickstate[NUM_BUTTONS]={0,0,0};
  static int dclicks[NUM_BUTTONS]={0,0,0};
  int mbuttons[NUM_BUTTONS]={0,0,0};
  int i;
  long int mxmove, mymove;

  extdata.buttons = 0;

  regs.w.ax = MOUSE_GETBUTTONS;
  intr (MOUSE_INTNUM, &regs);

  if (regs.w.bx & 1) mbuttons[0] = 1;
  if (regs.w.bx & 2) mbuttons[1] = 1;
  if (regs.w.bx & 4) mbuttons[2] = 1;

  for (i=0; i<NUM_BUTTONS; i++)
  {
    if (mbuttons[i])
      extdata.buttons |= clickactions[i];

    if (mbuttons[i] != dclickstate[i] && dclicktime[i] > 1)
    {
      dclickstate[i] = mbuttons[i];
      if (dclickstate[i])
        dclicks[i]++;

      if (dclicks[i]==2)
      {
        extdata.buttons |= dclickactions[i];
    dclicks[i] = 0;
      }
      else
        dclicktime[i] = 0;
    }
    else
    {
      dclicktime[i] += ticdup;
      if (dclicktime[i] > dclicktics)
      {
        dclicks[i] = 0;
    dclickstate[i] = 0;
      }
    }
  }

  regs.w.ax = MOUSE_GETMICKEYS;
  intr (MOUSE_INTNUM, &regs);

  extdata.angleTurn = regs.w.cx * h_sensitivity;

  // must be inverted when not strafing
  if (!(extdata.buttons & EBT_STRAFE))
    extdata.angleTurn = -extdata.angleTurn;

  if (extdata.buttons & EBT_CENTERVIEW)
    pitch = 0;
  else
  {
    pitch -= regs.w.dx * v_sensitivity;

    if (pitch < -110)
      pitch = -110;
    else if (pitch > 90)
      pitch = 90;
  }

  extdata.pitch = pitch;

  return;
}

int main (int argc, char **argv)
{
  unsigned long flataddr;
  unsigned char far *vector;
  char *launchcmd;
  char **spawnargs;
  int p;

  printf ("\n"\
          "RAVMOUSE - External mouse driver with mouselook for Heretic/Hexen\n"\
          "by xttl@dwf, built on " __DATE__ " " __TIME__ "\n"\
          "\n");

  myargc = argc;
  myargv = argv;

  if (CheckParm("-?"))
  {
    printf ("-rmvec int......: Specify alternate interrupt vector (default 0x%02X).\n", myintnum);
    printf ("-hs/-vs num.....: Change horizontal/vertical sensitivity (defaults %i/%i).\n", h_sensitivity, v_sensitivity);
    printf ("-game/-exe/-exec: Specify game launch command other than \"heretic\"/\"hexen\".\n");
    printf ("-dctics num.....: Change double click timing window (default is %i gametics).\n", dclicktics);
    printf ("-mb#/-db# flags.: Change button single click (-mb#) or double click (-db#)\n"\
            "                  action flags. Left mouse button is #1, right button is #2\n"\
        "                  and middle button is #3. Defaults are MB1=fire, MB2=strafe,\n"\
            "                  MB3=do nothing, DB1=do nothing, DB2=open/use, and\n"\
        "                  DB3=center view.\n");

   printf ("\n"\
           "Action flags: 0x0001 = fire              0x0002 = use\n"\
           "              0x0004 = run               0x0008 = strafe\n"\
           "              0x0010 = automap           0x0020 = inventory left\n"\
           "              0x0040 = inventory right   0x0080 = use artifact\n"\
           "              0x0100 = stop flying       0x0200 = center view\n"\
           "              0x0400 = toggle pause      0x0800 = cycle weapons\n"\
           "              0x1000 = jump (Hexen only) \n"\
           " * Flags can be added together if you want to bind multiple actions to a\n"\
           "   single mouse button. For example: -mb3 0x81 = fire AND use artifact\n"\
           "   when you press the middle button.\n");

    return -1;
  }

  if (!InitMouse())
    Error ("Mouse driver not detected.");

  // must know this to time double clicks properly
  p = CheckParmWithArgs("-dup", 1);
  if (p)
    sscanf(myargv[p+1], "%i", &ticdup);
  else
    ticdup = 1;

  p = CheckParmWithArgs("-dctics", 1);
  if (p)
    dclicktics = atoi(myargv[p+1]);

  p = CheckParmWithArgs("-rmvec", 1);
  if (p)
    sscanf(myargv[p+1], "0x%x", &myintnum);

  p = CheckParmWithArgs("-hs",1);
  if (p)
    h_sensitivity = atoi(myargv[p+1]);

  p = CheckParmWithArgs("-vs", 1);
  if (p)
    v_sensitivity = atoi(myargv[p+1]);

  p = CheckParmWithArgs("-mb1",1);
  if (p) sscanf(myargv[p+1], "0x%x", &clickactions[0]);
  p = CheckParmWithArgs("-mb2",1);
  if (p) sscanf(myargv[p+1], "0x%x", &clickactions[1]);
  p = CheckParmWithArgs("-mb3",1);
  if (p) sscanf(myargv[p+1], "0x%x", &clickactions[2]);

  p = CheckParmWithArgs("-db1",1);
  if (p) sscanf(myargv[p+1], "0x%x", &dclickactions[0]);
  p = CheckParmWithArgs("-db2",1);
  if (p) sscanf(myargv[p+1], "0x%x", &dclickactions[1]);
  p = CheckParmWithArgs("-db3",1);
  if (p) sscanf(myargv[p+1], "0x%x", &dclickactions[2]);

  memset (&extdata, 0, sizeof(externdata_t));
  extdata.vector = myintnum;

  // add extra args for passing the address of the buffer to the game
  // and also to disable the game's internal mouse support
  spawnargs = malloc ((myargc+4)*sizeof(char*));
  memcpy (spawnargs, myargv, myargc*sizeof(char*));
  spawnargs[myargc] = "-externdriver";
  spawnargs[myargc+1] = alloca(32);
  flataddr = (long)FP_SEG(&extdata)*16 + (unsigned)(&extdata);
  sprintf (spawnargs[myargc+1], "%li", flataddr);
  spawnargs[myargc+2] = "-nomouse";
  spawnargs[myargc+3] = NULL;

  // custom game launch command specified?
  p = CheckParmWithArgs("-exec", 1);
  if (!p) p = CheckParmWithArgs("-game", 1);
  if (!p) p = CheckParmWithArgs("-exe", 1);

  if (p)
    launchcmd = myargv[p+1];
  // else try the defaults
  else
  {
    if (!access("HERETIC.EXE", 0) || !access("HERETIC.COM", 0))
      launchcmd = "heretic";
    else if (!access("HEXEN.EXE", 0) || !access("HEXEN.COM", 0))
      launchcmd = "hexen";
    else
    {
      Error ("No Heretic or Hexen executables in current directory and no\n"\
             "alternate launch command was specified.");
    }
  }

  // hook the interrupt
  vector = *(char far * far *)(myintnum*4);
  if (vector != NULL && *vector != 0xCF) // 0xCF = x86 IRET
    Error ("Interrupt vector 0x%02X is already hooked.", myintnum);

  saved_vector = _dos_getvect (myintnum);
  _dos_setvect (myintnum, (void interrupt (*)(void))MK_FP(FP_SEG(ControlISR),(int)ControlISR));
  vector_is_hooked = 1;

  // launch the game
  if (spawnv (P_WAIT, launchcmd, (const char **)spawnargs) == -1)
    printf ("spawnv(%s) failed: %i (%s)\n", launchcmd, errno, strerror(errno));

  // restore interrupt
  _dos_setvect (myintnum, saved_vector);

  return 0;
}