.TH SPLHI 10.2.SH NAMEsplhi, spllo, splx, islo \- enable and disable interrupts.SH SYNOPSIS.ta \w'\fLvoid 'u.Bint	spllo(void).PP.Bint	splhi(void).PP.Bvoid	splx(int x).PP.Bint	islo(void).SH DESCRIPTIONThese primitives enable and disable maskable interrupts on the currentprocessor.Generally, device drivers should use.I ilock(see.IR lock (10.2)),.IR sleep (10.2),or the functions in.IR qio (10.2)to control interaction between processes and interrupt handlers.Those routines (but not these) provide correct synchronisation on multiprocessors..PP.I Splloenables interrupts and returns a flag representing the previous interrupt enable state.It must not normally be called from interrupt level..PP.I Splhidisables all maskable interrupts and returns the previous interrupt enable state.The period during which interrupts are disabled had best be short,or real-time applications will suffer..PP.I Splxrestores the interrupt enable statestate to.IR x ,which must be a value returnedby a previous call to.I splhior.IR spllo ..PP.I Isloreturns true (non-zero) if interrupts are currently enabled, and 0 otherwise..SH SEE ALSO.IR lock (10.2),.IR qio (10.2),.IR sleep (10.2),.IR intrenable (10.2)