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author | Sebastian Schmelzer | 2010-10-25 16:53:54 +0200 |
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committer | Sebastian Schmelzer | 2010-10-25 16:53:54 +0200 |
commit | 3050a9253437f4a4b5ad4bf3b3efdc3c660a5137 (patch) | |
tree | 91ac22153e416aac7ca20916b314b5e2ffa871b1 /contrib/syslinux-4.02/gpxe/src/arch/i386/include/gpxe/rdtsc_timer.h | |
download | preboot-3050a9253437f4a4b5ad4bf3b3efdc3c660a5137.tar.gz preboot-3050a9253437f4a4b5ad4bf3b3efdc3c660a5137.tar.xz preboot-3050a9253437f4a4b5ad4bf3b3efdc3c660a5137.zip |
Diffstat (limited to 'contrib/syslinux-4.02/gpxe/src/arch/i386/include/gpxe/rdtsc_timer.h')
-rw-r--r-- | contrib/syslinux-4.02/gpxe/src/arch/i386/include/gpxe/rdtsc_timer.h | 39 |
1 files changed, 39 insertions, 0 deletions
diff --git a/contrib/syslinux-4.02/gpxe/src/arch/i386/include/gpxe/rdtsc_timer.h b/contrib/syslinux-4.02/gpxe/src/arch/i386/include/gpxe/rdtsc_timer.h new file mode 100644 index 0000000..67ba22f --- /dev/null +++ b/contrib/syslinux-4.02/gpxe/src/arch/i386/include/gpxe/rdtsc_timer.h @@ -0,0 +1,39 @@ +#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 */ |