SVR5
drv_hztousec(D3)
drv_hztousec --
convert clock ticks to microseconds
Synopsis
#include <sys/types.h>
#include <sys/ddi.h>
clock_t drv_hztousec(clock_t ticks);
Description
drv_hztousec converts the length of time expressed by
ticks, which is in units of clock ticks,
into units of microseconds.
Arguments
ticks-
The number of clock ticks to convert to equivalent microseconds.
Return values
drv_hztousec returns the number of microseconds
equivalent to the ticks argument.
No error value is returned.
If the microsecond equivalent to ticks
is too large to be represented as a clock_t,
then the maximum clock_t value is returned.
Usage
Several functions either take time values expressed in clock ticks as
arguments
[timeout(D3),
timeout(D3),
delay(D3)]
or return time values expressed in clock ticks
[drv_getparm(D3)].
The length of a clock tick can vary across different implementations,
and therefore drivers should not include any hard-coded assumptions
about the length of a tick.
drv_hztousec and the complementary function
drv_usectohz(D3)
can be used, as necessary, to convert between clock
ticks and microseconds.
Note that the time value returned by drv_getparm
with an LBOLT argument
is often too large to represent in microseconds as a clock_t.
When using drv_getparm together with drv_hztousec to time
operations, drivers can help avoid overflow by converting the difference
between return values from successive calls to drv_getparm instead
of trying to convert the return values themselves.
Context and synchronization
All
contexts.
Hardware applicability
All
Version applicability
ddi:
1, 2, 3, 4, 5, 5mp, 6, 6mp, 7, 7mp, 7.1, 7.1mp, 8, 8mp
References
delay(D3),
drv_getparm(D3),
drv_usectohz(D3),
itimeout(D3)
timeout(D3)
``Delays and busy-waits'' in HDK Technical Reference
19 June 2005
© 2005 The SCO Group, Inc. All rights reserved.
OpenServer 6 and UnixWare (SVR5) HDK - June 2005