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196 lines
8.0 KiB
196 lines
8.0 KiB
/**************************************************************************** |
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* sched/sleep.c |
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* |
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* Copyright (C) 2007, 2009, 2012 Gregory Nutt. All rights reserved. |
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* Author: Gregory Nutt <gnutt@nuttx.org> |
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* |
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* Redistribution and use in source and binary forms, with or without |
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* modification, are permitted provided that the following conditions |
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* are met: |
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* |
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* 1. Redistributions of source code must retain the above copyright |
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* notice, this list of conditions and the following disclaimer. |
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* 2. Redistributions in binary form must reproduce the above copyright |
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* notice, this list of conditions and the following disclaimer in |
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* the documentation and/or other materials provided with the |
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* distribution. |
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* 3. Neither the name NuttX nor the names of its contributors may be |
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* used to endorse or promote products derived from this software |
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* without specific prior written permission. |
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* |
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS |
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE |
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, |
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, |
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS |
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* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED |
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN |
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* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE |
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* POSSIBILITY OF SUCH DAMAGE. |
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* |
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****************************************************************************/ |
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/**************************************************************************** |
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* Included Files |
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****************************************************************************/ |
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#include <nuttx/config.h> |
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#include <unistd.h> |
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#include <signal.h> |
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#include <nuttx/clock.h> |
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#include <arch/irq.h> |
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/**************************************************************************** |
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* Preprocessor Definitions |
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****************************************************************************/ |
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/**************************************************************************** |
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* Private Type Definitions |
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****************************************************************************/ |
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/**************************************************************************** |
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* Global Variables |
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****************************************************************************/ |
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/**************************************************************************** |
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* Private Variables |
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****************************************************************************/ |
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/**************************************************************************** |
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* Private Function Prototypes |
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****************************************************************************/ |
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/**************************************************************************** |
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* Public Functions |
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****************************************************************************/ |
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/**************************************************************************** |
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* Name: sleep |
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* |
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* Description: |
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* The sleep() function will cause the calling thread to be suspended from |
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* execution until either the number of real-time seconds specified by the |
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* argument 'seconds' has elapsed or a signal is delivered to the calling |
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* thread and its action is to invoke a signal-catching function or to |
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* terminate the process. The suspension time may be longer than requested |
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* due to the scheduling of other activity by the system. |
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* |
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* If a SIGALRM signal is generated for the calling process during |
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* execution of sleep() and if the SIGALRM signal is being ignored or |
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* blocked from delivery, it is unspecified whether sleep() returns |
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* when the SIGALRM signal is scheduled. If the signal is being blocked, it |
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* is also unspecified whether it remains pending after sleep() returns or |
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* it is discarded. |
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* |
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* If a SIGALRM signal is generated for the calling process during |
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* execution of sleep(), except as a result of a prior call to alarm(), |
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* and if the SIGALRM signal is not being ignored or blocked from delivery, |
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* it is unspecified whether that signal has any effect other than causing |
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* sleep() to return. |
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* |
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* If a signal-catching function interrupts sleep() and examines or changes |
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* either the time a SIGALRM is scheduled to be generated, the action |
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* associated with the SIGALRM signal, or whether the SIGALRM signal is |
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* blocked from delivery, the results are unspecified. |
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* |
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* If a signal-catching function interrupts sleep() and calls siglongjmp() |
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* or longjmp() to restore an environment saved prior to the sleep() call, |
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* the action associated with the SIGALRM signal and the time at which a |
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* SIGALRM signal is scheduled to be generated are unspecified. It is also |
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* unspecified whether the SIGALRM signal is blocked, unless the process' |
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* signal mask is restored as part of the environment. |
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* |
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* Implementations may place limitations on the granularity of timer values. |
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* For each interval timer, if the requested timer value requires a finer |
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* granularity than the implementation supports, the actual timer value will |
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* be rounded up to the next supported value. |
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* |
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* Interactions between sleep() and any of setitimer(), ualarm() or sleep() |
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* are unspecified. |
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* |
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* Parameters: |
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* seconds |
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* |
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* Returned Value: |
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* If sleep() returns because the requested time has elapsed, the value |
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* returned will be 0. If sleep() returns because of premature arousal due |
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* to delivery of a signal, the return value will be the "unslept" amount |
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* (the requested time minus the time actually slept) in seconds. |
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* |
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* Assumptions: |
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* |
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****************************************************************************/ |
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unsigned int sleep(unsigned int seconds) |
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{ |
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sigset_t set; |
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struct timespec ts; |
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struct siginfo value; |
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irqstate_t flags; |
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uint32_t start; |
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int32_t elapsed; |
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int32_t remaining = 0; |
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/* Don't sleep if seconds == 0 */ |
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if (seconds) |
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{ |
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/* Set up for the sleep. Using the empty set means that we are not |
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* waiting for any particular signal. However, any unmasked signal |
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* can still awaken sigtimedwait(). |
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*/ |
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(void)sigemptyset(&set); |
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ts.tv_sec = seconds; |
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ts.tv_nsec = 0; |
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/* Interrupts are disabled around the following so that it is atomic */ |
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flags = irqsave(); |
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/* Get the current time then sleep for the requested time. |
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* sigtimedwait() cannot succeed. It should always return error with |
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* either (1) EAGAIN meaning that the timeout occurred, or (2) EINTR |
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* meaning that some other unblocked signal was caught. |
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*/ |
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start = clock_systimer(); |
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(void)sigtimedwait(&set, &value, &ts); |
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/* Calculate the elapsed time (in clock ticks) when we wake up from the sleep. |
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* This is really only necessary if we were awakened from the sleep early |
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* due to the receipt of a signal. |
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*/ |
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elapsed = clock_systimer() - start; |
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irqrestore(flags); |
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/* Get the remaining, un-waited seconds. Note that this calculation |
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* truncates the elapsed seconds in the division. We may have slept some |
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* fraction of a second longer than this! But if the calculation is less |
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* than the 'seconds', we certainly did not sleep for the complete |
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* requested interval. |
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*/ |
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remaining = (int32_t)seconds - elapsed / TICK_PER_SEC; |
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/* Make sure that the elapsed time is non-negative (this should always |
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* be the case unless something exceptional happened while were we |
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* sleeping -- like the clock was reset or we went into a low power mode, |
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* OR if we had to wait a long time to run again after calling |
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* sigtimedwait() making 'elapsed' bigger than it should have been). |
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*/ |
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if (remaining < 0) |
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{ |
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remaining = 0; |
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} |
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} |
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return (unsigned int)remaining; |
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}
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