NAME

mstohz, hztoms — convert between milliseconds and system clock ticks

SYNOPSIS

#include <sys/param.h>

unsigned int
mstohz(unsigned int ms);

unsigned int
hztoms(unsigned int hz);

DESCRIPTION

The mstohz() macro can be used to convert time in milliseconds to system clock ticks, as used by the callout(9) facility, in an integer-overflow safe way. Conversely, hztoms() converts system clock ticks to milliseconds.

These macros are defined in the ⟨sys/param.h⟩ header. Individual ports can have a processor-specific, more efficient version implemented in their ⟨machine/param.h⟩ header as a define.

RETURN VALUES

The return value is either the number of clock ticks or milliseconds for the specified value.

SEE ALSO

param(3), callout(9), tvtohz(9)

BUGS

Neither mstohz() nor hztoms() make use of expensive 64-bit integer arithmetic. The result from mstohz() will be rounded down to one second if the parameter is larger than 131072 milliseconds.