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Viewing changes to src/VBox/Devices/PC/ipxe/src/arch/i386/include/ipxe/rdtsc_timer.h

  • Committer: Package Import Robot
  • Author(s): Gianfranco Costamagna
  • Date: 2016-02-23 14:28:26 UTC
  • Revision ID: package-import@ubuntu.com-20160223142826-bdu69el2z6wa2a44
Tags: upstream-4.3.36-dfsg
Import upstream version 4.3.36-dfsg

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src/VBox/Devices/PC/ipxe/src/arch/i386/include/ipxe/rdtsc_timer.h
 
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#ifndef _IPXE_RDTSC_TIMER_H
 
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#define _IPXE_RDTSC_TIMER_H
 
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/** @file
 
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 *
 
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 * RDTSC timer
 
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 *
 
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 */
 
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FILE_LICENCE ( GPL2_OR_LATER );
 
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#ifdef TIMER_RDTSC
 
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#define TIMER_PREFIX_rdtsc
 
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#else
 
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#define TIMER_PREFIX_rdtsc __rdtsc_
 
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#endif
 
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/**
 
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 * RDTSC values can easily overflow an unsigned long.  We discard the
 
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 * low-order bits in order to obtain sensibly-scaled values.
 
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 */
 
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#define TSC_SHIFT 8
 
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/**
 
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 * Get current system time in ticks
 
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 *
 
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 * @ret ticks           Current time, in ticks
 
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 */
 
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static inline __always_inline unsigned long
 
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TIMER_INLINE ( rdtsc, currticks ) ( void ) {
 
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        unsigned long ticks;
 
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        __asm__ __volatile__ ( "rdtsc\n\t"
 
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                               "shrdl %1, %%edx, %%eax\n\t"
 
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                               : "=a" ( ticks ) : "i" ( TSC_SHIFT ) : "edx" );
 
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        return ticks;
 
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}
 
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#endif /* _IPXE_RDTSC_TIMER_H */