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#ifndef _GPXE_RDTSC_TIMER_H
#define _GPXE_RDTSC_TIMER_H
/** @file
*
* RDTSC timer
*
*/
FILE_LICENCE ( GPL2_OR_LATER );
#ifdef TIMER_RDTSC
#define TIMER_PREFIX_rdtsc
#else
#define TIMER_PREFIX_rdtsc __rdtsc_
#endif
/**
* RDTSC values can easily overflow an unsigned long. We discard the
* low-order bits in order to obtain sensibly-scaled values.
*/
#define TSC_SHIFT 8
/**
* Get current system time in ticks
*
* @ret ticks Current time, in ticks
*/
static inline __always_inline unsigned long
TIMER_INLINE ( rdtsc, currticks ) ( void ) {
unsigned long ticks;
__asm__ __volatile__ ( "rdtsc\n\t"
"shrdl %1, %%edx, %%eax\n\t"
: "=a" ( ticks ) : "i" ( TSC_SHIFT ) : "edx" );
return ticks;
}
#endif /* _GPXE_RDTSC_TIMER_H */
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