LOCK_VARIABLE - Locks the memory of a variable used by a timer. Allegro game programming library.

       Due  to  interrupts,  you  are  required  to  lock  all  the  memory used by your timer routines. See the
       description of install_int_ex() for a more detailed explanation and usage example.

       LOCK_VARIABLE - Locks the memory of a variable used by a timer. Allegro game programming library.

install_int(3alleg4), install_int_ex(3alleg4),  exscn3d(3alleg4),  exsprite(3alleg4),  exswitch(3alleg4),
       extimer(3alleg4), exupdate(3alleg4), exzbuf(3alleg4)

Allegro                                           version 4.4.3                           LOCK_VARIABLE(3alleg4)

#include<allegro.h>MacroLOCK_VARIABLE(variable_name);