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Diffstat (limited to 'trunk/src/base/cycleclock.h')
| -rw-r--r-- | trunk/src/base/cycleclock.h | 110 |
1 files changed, 110 insertions, 0 deletions
diff --git a/trunk/src/base/cycleclock.h b/trunk/src/base/cycleclock.h new file mode 100644 index 0000000..8af664e --- /dev/null +++ b/trunk/src/base/cycleclock.h @@ -0,0 +1,110 @@ +// Copyright (c) 2004, Google Inc. +// All rights reserved. +// +// Redistribution and use in source and binary forms, with or without +// 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 +// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR +// 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 +#if defined(__MACH__) && defined(__APPLE__) +#include <mach/mach_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. cf +// 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 passes 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 resets + // 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) + _asm rdtsc +#else + // We could define __alpha here as well, but it only has a 32-bit + // timer (good for like 4 seconds), which isn't very useful. +#error You need to define CycleTimer for your O/S and CPU +#endif + } +}; + + +#endif // GOOGLE_BASE_CYCLECLOCK_H_ |