// Copyright (c) 2004, Google Inc.
// All rights reserved.
//
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// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
// ----------------------------------------------------------------------
// CycleClock
// A CycleClock tells you the current time in Cycles. The "time"
// is actually time since power-on. This is like time() but doesn't
// involve a system call and is much more precise.
//
// NOTE: Not all cpu/platform/kernel combinations guarantee that this
// clock increments at a constant rate or is synchronized across all logical
// cpus in a system.
//
// Also, in some out of order CPU implementations, the CycleClock is not
// serializing. So if you're trying to count at cycles granularity, your
// data might be inaccurate due to out of order instruction execution.
// ----------------------------------------------------------------------
#ifndef GOOGLE_BASE_CYCLECLOCK_H_
#define GOOGLE_BASE_CYCLECLOCK_H_
#include "base/basictypes.h" // make sure we get the def for int64
#include "base/arm_instruction_set_select.h"
// base/sysinfo.h is really big and we don't want to include it unless
// it is necessary.
#if defined(__arm__) || defined(__mips__)
# include "base/sysinfo.h"
#endif
#if defined(__MACH__) && defined(__APPLE__)
# include <mach/mach_time.h>
#endif
// For MSVC, we want to use '_asm rdtsc' when possible (since it works
// with even ancient MSVC compilers), and when not possible the
// __rdtsc intrinsic, declared in <intrin.h>. Unfortunately, in some
// environments, <windows.h> and <intrin.h> have conflicting
// declarations of some other intrinsics, breaking compilation.
// Therefore, we simply declare __rdtsc ourselves. See also
// http://connect.microsoft.com/VisualStudio/feedback/details/262047
#if defined(_MSC_VER) && !defined(_M_IX86)
extern "C" uint64 __rdtsc();
#pragma intrinsic(__rdtsc)
#endif
#if defined(ARMV3) || defined(__mips__)
#include <sys/time.h>
#endif
// NOTE: only i386 and x86_64 have been well tested.
// PPC, sparc, alpha, and ia64 are based on
// http://peter.kuscsik.com/wordpress/?p=14
// with modifications by m3b. See also
// https://setisvn.ssl.berkeley.edu/svn/lib/fftw-3.0.1/kernel/cycle.h
struct CycleClock {
// This should return the number of cycles since power-on. Thread-safe.
static inline int64 Now() {
#if defined(__MACH__) && defined(__APPLE__)
// this goes at the top because we need ALL Macs, regardless of
// architecture, to return the number of "mach time units" that
// have passed since startup. See sysinfo.cc where
// InitializeSystemInfo() sets the supposed cpu clock frequency of
// macs to the number of mach time units per second, not actual
// CPU clock frequency (which can change in the face of CPU
// frequency scaling). Also note that when the Mac sleeps, this
// counter pauses; it does not continue counting, nor does it
// reset to zero.
return mach_absolute_time();
#elif defined(__i386__)
int64 ret;
__asm__ volatile ("rdtsc" : "=A" (ret) );
return ret;
#elif defined(__x86_64__) || defined(__amd64__)
uint64 low, high;
__asm__ volatile ("rdtsc" : "=a" (low), "=d" (high));
return (high << 32) | low;
#elif defined(__powerpc__) || defined(__ppc__)
// This returns a time-base, which is not always precisely a cycle-count.
int64 tbl, tbu0, tbu1;
asm("mftbu %0" : "=r" (tbu0));
asm("mftb %0" : "=r" (tbl));
asm("mftbu %0" : "=r" (tbu1));
tbl &= -static_cast<int64>(tbu0 == tbu1);
// high 32 bits in tbu1; low 32 bits in tbl (tbu0 is garbage)
return (tbu1 << 32) | tbl;
#elif defined(__sparc__)
int64 tick;
asm(".byte 0x83, 0x41, 0x00, 0x00");
asm("mov %%g1, %0" : "=r" (tick));
return tick;
#elif defined(__ia64__)
int64 itc;
asm("mov %0 = ar.itc" : "=r" (itc));
return itc;
#elif defined(_MSC_VER) && defined(_M_IX86)
// Older MSVC compilers (like 7.x) don't seem to support the
// __rdtsc intrinsic properly, so I prefer to use _asm instead
// when I know it will work. Otherwise, I'll use __rdtsc and hope
// the code is being compiled with a non-ancient compiler.
_asm rdtsc
#elif defined(_MSC_VER)
return __rdtsc();
#elif defined(ARMV3)
#if defined(ARMV6) // V6 is the earliest arch that has a standard cyclecount
uint32 pmccntr;
uint32 pmuseren;
uint32 pmcntenset;
// Read the user mode perf monitor counter access permissions.
asm volatile ("mrc p15, 0, %0, c9, c14, 0" : "=r" (pmuseren));
if (pmuseren & 1) { // Allows reading perfmon counters for user mode code.
asm volatile ("mrc p15, 0, %0, c9, c12, 1" : "=r" (pmcntenset));
if (pmcntenset & 0x80000000ul) { // Is it counting?
asm volatile ("mrc p15, 0, %0, c9, c13, 0" : "=r" (pmccntr));
// The counter is set up to count every 64th cycle
return static_cast<int64>(pmccntr) * 64; // Should optimize to << 6
}
}
#endif
struct timeval tv;
gettimeofday(&tv, NULL);
return static_cast<int64>((tv.tv_sec + tv.tv_usec * 0.000001)
* CyclesPerSecond());
#elif defined(__mips__)
// mips apparently only allows rdtsc for superusers, so we fall
// back to gettimeofday. It's possible clock_gettime would be better.
struct timeval tv;
gettimeofday(&tv, NULL);
return static_cast<int64>((tv.tv_sec + tv.tv_usec * 0.000001)
* CyclesPerSecond());
#else
// The soft failover to a generic implementation is automatic only for ARM.
// For other platforms the developer is expected to make an attempt to create
// a fast implementation and use generic version if nothing better is available.
#error You need to define CycleTimer for your O/S and CPU
#endif
}
};
#endif // GOOGLE_BASE_CYCLECLOCK_H_