1/* 2 * Copyright (c) 2004-2007 Apple Inc. All rights reserved. 3 * 4 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@ 5 * 6 * This file contains Original Code and/or Modifications of Original Code 7 * as defined in and that are subject to the Apple Public Source License 8 * Version 2.0 (the 'License'). You may not use this file except in 9 * compliance with the License. The rights granted to you under the License 10 * may not be used to create, or enable the creation or redistribution of, 11 * unlawful or unlicensed copies of an Apple operating system, or to 12 * circumvent, violate, or enable the circumvention or violation of, any 13 * terms of an Apple operating system software license agreement. 14 * 15 * Please obtain a copy of the License at 16 * http://www.opensource.apple.com/apsl/ and read it before using this file. 17 * 18 * The Original Code and all software distributed under the License are 19 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER 20 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES, 21 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY, 22 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT. 23 * Please see the License for the specific language governing rights and 24 * limitations under the License. 25 * 26 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@ 27 */ 28/* 29 * @OSF_COPYRIGHT@ 30 */ 31/* 32 * @APPLE_FREE_COPYRIGHT@ 33 */ 34/* 35 * File: rtclock.h 36 * Purpose: Routines for handling the machine dependent 37 * real-time clock. 38 */ 39 40#ifndef _I386_RTCLOCK_H_ 41#define _I386_RTCLOCK_H_ 42 43#ifndef ASSEMBLER 44typedef struct rtc_nanotime { 45 uint64_t tsc_base; /* timestamp */ 46 uint64_t ns_base; /* nanoseconds */ 47 uint32_t scale; /* tsc -> nanosec multiplier */ 48 uint32_t shift; /* tsc -> nanosec shift/div */ 49 /* shift is overloaded with 50 * lower 32bits of tsc_freq 51 * on slower machines (SLOW_TSC_THRESHOLD) */ 52 uint32_t generation; /* 0 == being updated */ 53 uint32_t spare1; 54} rtc_nanotime_t; 55 56#include <kern/etimer.h> 57 58struct cpu_data; 59 60extern void _rtc_nanotime_store( 61 uint64_t tsc, 62 uint64_t nsec, 63 uint32_t scale, 64 uint32_t shift, 65 rtc_nanotime_t *dst); 66 67extern uint64_t _rtc_nanotime_read( 68 rtc_nanotime_t *rntp, 69 int slow); 70 71extern rtc_nanotime_t rtc_nanotime_info; 72#endif 73 74#define SLOW_TSC_THRESHOLD 1000067800 /* TSC is too slow for regular nanotime() algorithm */ 75 76#if defined(__i386__) 77/* 78 * Assembly snippet included in exception handlers and rtc_nanotime_read() 79 * %edi points to nanotime info struct 80 * %edx:%eax returns nanotime 81 */ 82#define RTC_NANOTIME_READ_FAST() \ 830: movl RNT_GENERATION(%edi),%esi /* being updated? */ ; \ 84 testl %esi,%esi ; \ 85 jz 0b /* wait until done */ ; \ 86 lfence ; \ 87 rdtsc ; \ 88 lfence ; \ 89 subl RNT_TSC_BASE(%edi),%eax ; \ 90 sbbl RNT_TSC_BASE+4(%edi),%edx /* tsc - tsc_base */ ; \ 91 movl RNT_SCALE(%edi),%ecx /* * scale factor */ ; \ 92 movl %edx,%ebx ; \ 93 mull %ecx ; \ 94 movl %ebx,%eax ; \ 95 movl %edx,%ebx ; \ 96 mull %ecx ; \ 97 addl %ebx,%eax ; \ 98 adcl $0,%edx ; \ 99 addl RNT_NS_BASE(%edi),%eax /* + ns_base */ ; \ 100 adcl RNT_NS_BASE+4(%edi),%edx ; \ 101 cmpl RNT_GENERATION(%edi),%esi /* check for update */ ; \ 102 jne 0b /* do it all again */ 103 104#elif defined(__x86_64__) 105 106/* 107 * Assembly snippet included in exception handlers and rtc_nanotime_read() 108 * %rdi points to nanotime info struct. 109 * %rax returns nanotime 110 */ 111#define RTC_NANOTIME_READ_FAST() \ 1120: movl RNT_GENERATION(%rdi),%esi ; \ 113 test %esi,%esi /* info updating? */ ; \ 114 jz 0b /* - wait if so */ ; \ 115 lfence ; \ 116 rdtsc ; \ 117 lfence ; \ 118 shlq $32,%rdx ; \ 119 orq %rdx,%rax /* %rax := tsc */ ; \ 120 subq RNT_TSC_BASE(%rdi),%rax /* tsc - tsc_base */ ; \ 121 xorq %rcx,%rcx ; \ 122 movl RNT_SCALE(%rdi),%ecx ; \ 123 mulq %rcx /* delta * scale */ ; \ 124 shrdq $32,%rdx,%rax /* %rdx:%rax >>= 32 */ ; \ 125 addq RNT_NS_BASE(%rdi),%rax /* add ns_base */ ; \ 126 cmpl RNT_GENERATION(%rdi),%esi /* repeat if changed */ ; \ 127 jne 0b 128 129#endif 130 131#endif /* _I386_RTCLOCK_H_ */ 132