SPLHI(9) SPLHI(9)
NAME
splhi, spllo, splx, islo - enable and disable interrupts
SYNOPSIS
int spllo(void)
int splhi(void)
void splx(int x)
int islo(void)
DESCRIPTION
These primitives enable and disable maskable interrupts on
the current processor. Generally, device drivers should use
ilock (see lock(9)), sleep(9), or the functions in qio(9) to
control interaction between processes and interrupt han-
dlers. Those routines (but not these) provide correct syn-
chronisation on multiprocessors.
Spllo enables interrupts and returns a flag representing the
previous interrupt enable state. It must not normally be
called from interrupt level.
Splhi disables all maskable interrupts and returns the pre-
vious interrupt enable state. The period during which
interrupts are disabled had best be short, or real-time
applications will suffer.
Splx restores the interrupt enable state state to x, which
must be a value returned by a previous call to splhi or
spllo.
Islo returns true (non-zero) if interrupts are currently
enabled, and 0 otherwise.
SOURCE
/sys/src/9/*/l.s
SEE ALSO
lock(9), qio(9), sleep(9), intrenable(9)
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