php man page for mouse_b

mouse_x(3alleg4)						  Allegro manual						  mouse_x(3alleg4)

NAME
       mouse_x,  mouse_y,  mouse_z,  mouse_w,  mouse_b, mouse_pos - Global variable with the mouse position/button state. Allegro game programming
       library.

SYNOPSIS
       #include <allegro.h>

       extern volatile int mouse_x;

       extern volatile int mouse_y;

       extern volatile int mouse_z;

       extern volatile int mouse_w;

       extern volatile int mouse_b;

       extern volatile int mouse_pos;

DESCRIPTION
       Global variables containing the current mouse position and button state.  Wherever possible these values will  be  updated  asynchronously,
       but  if mouse_needs_poll() returns TRUE, you must manually call poll_mouse() to update them with the current input state. The `mouse_x' and
       `mouse_y' positions are integers ranging from zero to the bottom right corner of the screen. The `mouse_z' and `mouse_w' variables hold the
       current	vertical  and horizontal wheel position, when using an input driver that supports wheel mice. The `mouse_b' variable is a bitfield
       indicating the state of each button: bit 0 is the left button,  bit 1 the right, and bit 2 the middle button. Additional non standard mouse
       buttons might be available as higher bits in this variable. Usage example:

	  if (mouse_b & 1)
	     printf("Left button is pressed
");

	  if (!(mouse_b & 2))
	     printf("Right button is not pressed
");

       The  `mouse_pos'  variable  has	the current X coordinate in the upper 16 bits and  the Y in the lower 16 bits. This may be useful in tight
       polling loops where a mouse interrupt could occur between your reading of the two separate variables, since you can copy this value into  a
       local variable with a single instruction and then split it up at your leisure. Example:

	  int pos, x, y;

	  pos = mouse_pos;
	  x = pos >> 16;
	  y = pos & 0x0000ffff;

SEE ALSO
       install_mouse(3alleg4),	  poll_mouse(3alleg4),	  mouse_needs_poll(3alleg4),	exalpha(3alleg4),   exlights(3alleg4),	 exmouse(3alleg4),
       exshade(3alleg4), exspline(3alleg4), extrans(3alleg4)

Allegro 							   version 4.4.2						  mouse_x(3alleg4)