1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
|
/*
* Copyright (c), MM Weiss
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without modification,
* are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
*
* 2. 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.
*
* 3. Neither the name of the MM Weiss 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.
*/
/*
* clock_gettime_stub.c
* gcc -Wall -c clock_gettime_stub.c
* posix realtime functions; MacOS user space glue
*/
/* @comment
* other possible implementation using intel builtin rdtsc
* rdtsc-workaround: http://www.mcs.anl.gov/~kazutomo/rdtsc.html
*
* we could get the ticks by doing this
*
* __asm __volatile("mov %%ebx, %%esi\n\t"
* "cpuid\n\t"
* "xchg %%esi, %%ebx\n\t"
* "rdtsc"
* : "=a" (a),
* "=d" (d)
* );
* we could even replace our tricky sched_yield call by assembly code to get a better accurency,
* anyway the following C stub will satisfy 99% of apps using posix clock_gettime call,
* moreover, the setter version (clock_settime) could be easly written using mach primitives:
* http://www.opensource.apple.com/source/xnu/xnu-${VERSION}/osfmk/man/ (clock_[set|get]_time)
*
* hackers don't be crackers, don't you use a flush toilet?
*
*
* @see draft: ./posix-realtime-stub/posix-realtime-stub.c
*
*/
extern "C" {
#ifndef _GETTIME_H
#define _GETTIME_H
#ifdef __APPLE__
#pragma weak clock_gettime
#include <sys/time.h>
#include <sys/resource.h>
#include <mach/mach.h>
#include <mach/clock.h>
#include <mach/mach_time.h>
#include <errno.h>
#include <unistd.h>
#include <sched.h>
typedef enum {
CLOCK_REALTIME,
CLOCK_MONOTONIC,
CLOCK_PROCESS_CPUTIME_ID,
CLOCK_THREAD_CPUTIME_ID
} clockid_t;
static mach_timebase_info_data_t __clock_gettime_inf;
int clock_gettime(clockid_t clk_id, struct timespec *tp) {
kern_return_t ret;
clock_serv_t clk;
clock_id_t clk_serv_id;
mach_timespec_t tm;
uint64_t start, end, delta, nano;
int retval = -1;
switch (clk_id) {
case CLOCK_REALTIME:
case CLOCK_MONOTONIC:
clk_serv_id = clk_id == CLOCK_REALTIME ? CALENDAR_CLOCK : SYSTEM_CLOCK;
if (KERN_SUCCESS == (ret = host_get_clock_service(mach_host_self(), clk_serv_id, &clk))) {
if (KERN_SUCCESS == (ret = clock_get_time(clk, &tm))) {
tp->tv_sec = tm.tv_sec;
tp->tv_nsec = tm.tv_nsec;
retval = 0;
}
}
if (KERN_SUCCESS != ret) {
errno = EINVAL;
retval = -1;
}
break;
case CLOCK_PROCESS_CPUTIME_ID:
case CLOCK_THREAD_CPUTIME_ID:
start = mach_absolute_time();
if (clk_id == CLOCK_PROCESS_CPUTIME_ID) {
getpid();
} else {
sched_yield();
}
end = mach_absolute_time();
delta = end - start;
if (0 == __clock_gettime_inf.denom) {
mach_timebase_info(&__clock_gettime_inf);
}
nano = delta * __clock_gettime_inf.numer / __clock_gettime_inf.denom;
tp->tv_sec = nano * 1e-9;
tp->tv_nsec = nano - (tp->tv_sec * 1e9);
retval = 0;
break;
default:
errno = EINVAL;
retval = -1;
}
return retval;
}
#endif // __APPLE__
#endif // _GETTIME_H
}
|
