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