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
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
|
/****************************************************************************
* sched/sleep.c
*
* Copyright (C) 2007, 2009, 2012 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <gnutt@nuttx.org>
*
* 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 NuttX 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.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <unistd.h>
#include <signal.h>
#include <nuttx/clock.h>
#include <arch/irq.h>
/****************************************************************************
* Preprocessor Definitions
****************************************************************************/
/****************************************************************************
* Private Type Definitions
****************************************************************************/
/****************************************************************************
* Global Variables
****************************************************************************/
/****************************************************************************
* Private Variables
****************************************************************************/
/****************************************************************************
* Private Function Prototypes
****************************************************************************/
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: sleep
*
* Description:
* The sleep() function will cause the calling thread to be suspended from
* execution until either the number of real-time seconds specified by the
* argument 'seconds' has elapsed or a signal is delivered to the calling
* thread and its action is to invoke a signal-catching function or to
* terminate the process. The suspension time may be longer than requested
* due to the scheduling of other activity by the system.
*
* If a SIGALRM signal is generated for the calling process during
* execution of sleep() and if the SIGALRM signal is being ignored or
* blocked from delivery, it is unspecified whether sleep() returns
* when the SIGALRM signal is scheduled. If the signal is being blocked, it
* is also unspecified whether it remains pending after sleep() returns or
* it is discarded.
*
* If a SIGALRM signal is generated for the calling process during
* execution of sleep(), except as a result of a prior call to alarm(),
* and if the SIGALRM signal is not being ignored or blocked from delivery,
* it is unspecified whether that signal has any effect other than causing
* sleep() to return.
*
* If a signal-catching function interrupts sleep() and examines or changes
* either the time a SIGALRM is scheduled to be generated, the action
* associated with the SIGALRM signal, or whether the SIGALRM signal is
* blocked from delivery, the results are unspecified.
*
* If a signal-catching function interrupts sleep() and calls siglongjmp()
* or longjmp() to restore an environment saved prior to the sleep() call,
* the action associated with the SIGALRM signal and the time at which a
* SIGALRM signal is scheduled to be generated are unspecified. It is also
* unspecified whether the SIGALRM signal is blocked, unless the process'
* signal mask is restored as part of the environment.
*
* Implementations may place limitations on the granularity of timer values.
* For each interval timer, if the requested timer value requires a finer
* granularity than the implementation supports, the actual timer value will
* be rounded up to the next supported value.
*
* Interactions between sleep() and any of setitimer(), ualarm() or sleep()
* are unspecified.
*
* Parameters:
* seconds
*
* Returned Value:
* If sleep() returns because the requested time has elapsed, the value
* returned will be 0. If sleep() returns because of premature arousal due
* to delivery of a signal, the return value will be the "unslept" amount
* (the requested time minus the time actually slept) in seconds.
*
* Assumptions:
*
****************************************************************************/
unsigned int sleep(unsigned int seconds)
{
sigset_t set;
struct timespec ts;
struct siginfo value;
irqstate_t flags;
uint32_t start;
int32_t elapsed;
int32_t remaining = 0;
/* Don't sleep if seconds == 0 */
if (seconds)
{
/* Set up for the sleep. Using the empty set means that we are not
* waiting for any particular signal. However, any unmasked signal
* can still awaken sigtimedwait().
*/
(void)sigemptyset(&set);
ts.tv_sec = seconds;
ts.tv_nsec = 0;
/* Interrupts are disabled around the following so that it is atomic */
flags = irqsave();
/* Get the current time then sleep for the requested time.
* sigtimedwait() cannot succeed. It should always return error with
* either (1) EAGAIN meaning that the timeout occurred, or (2) EINTR
* meaning that some other unblocked signal was caught.
*/
start = clock_systimer();
(void)sigtimedwait(&set, &value, &ts);
/* Calculate the elapsed time (in clock ticks) when we wake up from the sleep.
* This is really only necessary if we were awakened from the sleep early
* due to the receipt of a signal.
*/
elapsed = clock_systimer() - start;
irqrestore(flags);
/* Get the remaining, un-waited seconds. Note that this calculation
* truncates the elapsed seconds in the division. We may have slept some
* fraction of a second longer than this! But if the calculation is less
* than the 'seconds', we certainly did not sleep for the complete
* requested interval.
*/
remaining = (int32_t)seconds - elapsed / TICK_PER_SEC;
/* Make sure that the elapsed time is non-negative (this should always
* be the case unless something exceptional happened while were we
* sleeping -- like the clock was reset or we went into a low power mode,
* OR if we had to wait a long time to run again after calling
* sigtimedwait() making 'elapsed' bigger than it should have been).
*/
if (remaining < 0)
{
remaining = 0;
}
}
return (unsigned int)remaining;
}
|
