dos-vga-arena-shooter-game/system/mouse_io.c

#include <dos.h>
#include <conio.h>
#include <i86.h>

#include "mouse_io.h"

struct MouseStatus *_status;

int limitMouseArea(int sx, int sy, int ex, int ey) {
  union REGS regs;

  // set horiz and vert range
  regs.w.ax = 0x07;
  regs.w.cx = sx;
  regs.w.dx = ex;
  int386(MOUSE_DRIVER_INTERRUPT, &regs, &regs);

  regs.w.ax = 0x08;
  regs.w.cx = sy;
  regs.w.dx = ey;
  int386(MOUSE_DRIVER_INTERRUPT, &regs, &regs);
}

/**
 * Ensure this is called after setting the desired video mode.
 */
int activateMouse(struct MouseStatus *status) {
  union REGS regs;
  int mouseActivated;

  regs.w.ax = MOUSE_DRIVER_RESET;
  int386(MOUSE_DRIVER_INTERRUPT, &regs, &regs);

  mouseActivated = regs.w.ax;

  if (mouseActivated) {
    status->isActive = regs.w.ax;
    status->buttonCount = regs.w.bx;

    limitMouseArea(0, 0, VGA_DISPLAY_WIDTH - 1, VGA_DISPLAY_HEIGHT - 1);
  }

  _status = status;

  return mouseActivated;
}

void readMouse() {
  union REGS regs;
  int buttonStatus;

  regs.w.ax = MOUSE_DRIVER_READ_STATE;
  int386(MOUSE_DRIVER_INTERRUPT, &regs, &regs);

  buttonStatus = regs.w.bx;
  _status->xPosition = regs.w.cx;
  _status->yPosition = regs.w.dx;

  _status->leftButtonDown = buttonStatus & 1;
  _status->rightButtonDown = (buttonStatus >> 1) & 1;
}