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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