126 lines
3.5 KiB
C
126 lines
3.5 KiB
C
/* $Id:$ */
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/*
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* Copyright (c) 2008-2010 Aaron Turner.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the names of the copyright owners nor the names of its
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* contributors may be used to endorse or promote products derived from
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* this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
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* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
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* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
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* GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER
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* IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
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* OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
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* ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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/*
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* Read TimeStamp Counter (RDTSC)
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* http://www-unix.mcs.anl.gov/~kazutomo/rdtsc.html
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* I'm not really sure what the license is, but I'll assume Kazutomo Yoshii is
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* cool with me using it since he published it on his website.
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* Should also check out: http://www.fftw.org/cycle.h
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*/
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#ifndef __RDTSC_H__
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#define __RDTSC_H__
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u_int64_t rdtsc_calibrate(u_int32_t mhz);
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#if defined(__i386__)
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#define HAVE_RDTSC 1
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static inline u_int64_t
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rdtsc(void)
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{
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u_int64_t x;
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__asm__ volatile (".byte 0x0f, 0x31" : "=A" (x));
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return x;
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}
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#elif defined(__x86_64__)
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#define HAVE_RDTSC 1
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static inline u_int64_t
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rdtsc(void)
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{
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unsigned hi, lo;
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__asm__ __volatile__ ("rdtsc" : "=a"(lo), "=d"(hi));
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return ( (u_int64_t)lo)|( ((u_int64_t)hi)<<32 );
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}
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#elif defined(__powerpc__)
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#define HAVE_RDTSC 1
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static inline u_int64_t
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rdtsc(void)
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{
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u_int64_t result=0;
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u_int32_t upper, lower,tmp;
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__asm__ volatile(
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"0: \n"
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"\tmftbu %0 \n"
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"\tmftb %1 \n"
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"\tmftbu %2 \n"
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"\tcmpw %2,%0 \n"
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"\tbne 0b \n"
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: "=r"(upper),"=r"(lower),"=r"(tmp)
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);
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result = upper;
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result = result<<32;
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result = result|lower;
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return(result);
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}
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#else
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/* do not HAVE_RDTSC for your platform */
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#endif
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/* only define rdtsc_sleep() if we have rdtsc() */
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#ifdef HAVE_RDTSC
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/*
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* sleeps for sleep time, using the rdtsc counter for accuracy
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* you need to call rdtsc_calibrate() BEFORE this or you'll sleep for
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* an additional .1 sec the very first time you call it.
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*/
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static inline void
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rdtsc_sleep(const struct timespec sleep)
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{
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u_int64_t sleep_until;
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u_int64_t now = 0;
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static u_int64_t clicks_per_usec = 0;
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sleep_until = rdtsc();
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clicks_per_usec = clicks_per_usec > 0 ? clicks_per_usec : rdtsc_calibrate(0);
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sleep_until += clicks_per_usec * TIMESPEC_TO_MICROSEC(&sleep);
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while (now < sleep_until)
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now = rdtsc();
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}
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#endif
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#endif /* __RDTSC_H__ */
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