Returns TRUE if interrupts were enabled prior to the function call, or FALSE if they were already disabled.

The arLock function disables global interrupts (thereby preventing task preemption) and retrieves the previous state of the interrupt enable flag. This returned status must be preserved and later passed to the arRestore function to correctly revert the interrupt state. This mechanism supports nested critical sections, allowing pairs of arLock and arRestore calls to be safely nested without prematurely re-enabling interrupts.