/* * Copyright (c) 2003-2007 Apple Inc. All rights reserved. * * @APPLE_OSREFERENCE_LICENSE_HEADER_START@ * * This file contains Original Code and/or Modifications of Original Code * as defined in and that are subject to the Apple Public Source License * Version 2.0 (the 'License'). You may not use this file except in * compliance with the License. The rights granted to you under the License * may not be used to create, or enable the creation or redistribution of, * unlawful or unlicensed copies of an Apple operating system, or to * circumvent, violate, or enable the circumvention or violation of, any * terms of an Apple operating system software license agreement. * * Please obtain a copy of the License at * http://www.opensource.apple.com/apsl/ and read it before using this file. * * The Original Code and all software distributed under the License are * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES, * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT. * Please see the License for the specific language governing rights and * limitations under the License. * * @APPLE_OSREFERENCE_LICENSE_HEADER_END@ */ #include <sys/appleapiopts.h> #include <machine/cpu_capabilities.h> /* * 64-bit version _mach_absolute_time. We return the 64-bit nanotime in %rax, */ .globl _mach_absolute_time _mach_absolute_time: pushq %rbp // set up a frame for backtraces movq %rsp,%rbp movq $(_COMM_PAGE_TIME_DATA_START),%rsi 1: movl _NT_GENERATION(%rsi),%r8d // get generation testl %r8d,%r8d // if 0, data is being changed... jz 1b // ...so loop until stable lfence rdtsc // edx:eax := tsc lfence shlq $32,%rdx // rax := ((edx << 32) | eax), ie 64-bit tsc orq %rdx,%rax subq _NT_TSC_BASE(%rsi), %rax // rax := (tsc - base_tsc) movl _NT_SCALE(%rsi),%ecx mulq %rcx // rdx:rax := (tsc - base_tsc) * scale shrdq $32,%rdx,%rax // _COMM_PAGE_NT_SHIFT is always 32 addq _NT_NS_BASE(%rsi),%rax // (((tsc - base_tsc) * scale) >> 32) + ns_base cmpl _NT_GENERATION(%rsi),%r8d // did the data change during computation? jne 1b popq %rbp ret