nuttx/libs/libc/unistd/lib_alarm.c
2021-03-09 23:18:28 +08:00

74 lines
2.3 KiB
C

/****************************************************************************
* libs/libc/unistd/lib_alarm.c
*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership. The
* ASF licenses this file to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance with the
* License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations
* under the License.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <unistd.h>
#include <sys/time.h>
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: alarm
*
* Description:
* The alarm() function will arranges for a SIGALRM signal to be delivered
* to the calling process in seconds seconds.
*
* Interactions between alarm() and any of setitimer() are unspecified.
*
* Input Parameters:
* seconds - The number of seconds to alarm
*
* Returned Value:
* alarm() returns the number of seconds remaining until any previously
* scheduled alarm was due to be delivered, or zero if there was no
* previously scheduled alarm.
*
* Assumptions:
*
****************************************************************************/
unsigned int alarm(unsigned int seconds)
{
struct itimerval value =
{
{0, 0},
{0, 0}
};
struct itimerval ovalue =
{
{0, 0},
{0, 0}
};
value.it_value.tv_sec = seconds;
setitimer(ITIMER_REAL, &value, &ovalue);
return ovalue.it_value.tv_sec;
}