/* High precision, low overhead timing functions. x86 version. Copyright (C) 2018 Free Software Foundation, Inc. This file is part of the GNU C Library. The GNU C Library is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2.1 of the License, or (at your option) any later version. The GNU C Library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details. You should have received a copy of the GNU Lesser General Public License along with the GNU C Library; if not, see . */ #ifndef _HP_TIMING_H #define _HP_TIMING_H 1 #include #if MINIMUM_ISA == 686 || MINIMUM_ISA == 8664 # include /* We always assume having the timestamp register. */ # define HP_TIMING_AVAIL (1) # define HP_SMALL_TIMING_AVAIL (1) /* We indeed have inlined functions. */ # define HP_TIMING_INLINE (1) /* We use 64bit values for the times. */ typedef unsigned long long int hp_timing_t; /* That's quite simple. Use the `rdtsc' instruction. Note that the value might not be 100% accurate since there might be some more instructions running in this moment. This could be changed by using a barrier like 'cpuid' right before the `rdtsc' instruciton. But we are not interested in accurate clock cycles here so we don't do this. */ # define HP_TIMING_NOW(Var) ((Var) = _rdtsc ()) # include #else /* NB: Undefine _HP_TIMING_H so that will be included. */ # undef _HP_TIMING_H # include #endif #endif /* hp-timing.h */