drivers/staging/csr/csr_time.h

#ifndef CSR_TIME_H__
#define CSR_TIME_H__
/*****************************************************************************

(c) Cambridge Silicon Radio Limited 2010
All rights reserved and confidential information of CSR

Refer to LICENSE.txt included with this source for details
on the license terms.

*****************************************************************************/

#include <linux/types.h>

/*******************************************************************************

NAME
	CsrTimeGet

DESCRIPTION
	Returns the current system time in a low and a high part. The low part
	is expressed in microseconds. The high part is incremented when the low
	part wraps to provide an extended range.

	The caller may provide a NULL pointer as the high parameter.
	In this case the function just returns the low part and ignores the
	high parameter.

	Although the time is expressed in microseconds the actual resolution is
	platform dependent and can be less. It is recommended that the
	resolution is at least 10 milliseconds.

PARAMETERS
	high - Pointer to variable that will receive the high part of the
	       current system time. Passing NULL is valid.

RETURNS
	Low part of current system time in microseconds.

*******************************************************************************/
u32 CsrTimeGet(u32 *high);


/*------------------------------------------------------------------*/
/* CsrTime Macros */
/*------------------------------------------------------------------*/

/*----------------------------------------------------------------------------*
 *  NAME
 *      CsrTimeAdd
 *
 *  DESCRIPTION
 *      Add two time values. Adding the numbers can overflow the range of a
 *      CsrTime, so the user must be cautious.
 *
 *  RETURNS
 *      CsrTime - the sum of "t1" and "t2".
 *
 *----------------------------------------------------------------------------*/
#define CsrTimeAdd(t1, t2) ((t1) + (t2))

/*----------------------------------------------------------------------------*
 *  NAME
 *      CsrTimeSub
 *
 *  DESCRIPTION
 *      Subtract two time values. Subtracting the numbers can provoke an
 *      underflow, so the user must be cautious.
 *
 *  RETURNS
 *      CsrTime - "t1" - "t2".
 *
 *----------------------------------------------------------------------------*/
#define CsrTimeSub(t1, t2)    ((s32) (t1) - (s32) (t2))

#endif