1 // Copyright (c) 2014 Adafruit Industries

     2 // Author: Tony DiCola

     3 

     4 // Permission is hereby granted, free of charge, to any person obtaining a copy

     5 // of this software and associated documentation files (the "Software"), to deal

     6 // in the Software without restriction, including without limitation the rights

     7 // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell

     8 // copies of the Software, and to permit persons to whom the Software is

     9 // furnished to do so, subject to the following conditions:

    10 

    11 // The above copyright notice and this permission notice shall be included in all

    12 // copies or substantial portions of the Software.

    13 

    14 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR

    15 // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,

    16 // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE

    17 // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER

    18 // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,

    19 // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE

    20 // SOFTWARE.

    21 #include <errno.h>

    22 #include <sched.h>

    23 #include <string.h>

    24 #include <sys/time.h>

    25 #include <time.h>

    26 

    27 #include "common_dht_read.h"

    28 

    29 void busy_wait_milliseconds(uint32_t millis) {

    30   // Set delay time period.

    31   struct timeval deltatime;

    32   deltatime.tv_sec = millis / 1000;

    33   deltatime.tv_usec = (millis % 1000) * 1000;

    34   struct timeval walltime;

    35   // Get current time and add delay to find end time.

    36   gettimeofday(&walltime, NULL);

    37   struct timeval endtime;

    38   timeradd(&walltime, &deltatime, &endtime);

    39   // Tight loop to waste time (and CPU) until enough time as elapsed.

    40   while (timercmp(&walltime, &endtime, <)) {

    41     gettimeofday(&walltime, NULL);

    42   }

    43 }

    44 

    45 void sleep_milliseconds(uint32_t millis) {

    46   struct timespec sleep;

    47   sleep.tv_sec = millis / 1000;

    48   sleep.tv_nsec = (millis % 1000) * 1000000L;

    49 //  while (clock_nanosleep(CLOCK_MONOTONIC, 0, &sleep, &sleep) && errno == EINTR);

    50   while (nanosleep(&sleep, &sleep) && errno == EINTR);

    51 }

    52 

    53 void set_max_priority(void) {

    54   struct sched_param sched;

    55   memset(&sched, 0, sizeof(sched));

    56   // Use FIFO scheduler with highest priority for the lowest chance of the kernel context switching.

    57   sched.sched_priority = sched_get_priority_max(SCHED_FIFO);

    58   sched_setscheduler(0, SCHED_FIFO, &sched);

    59 }

    60 

    61 void set_default_priority(void) {

    62   struct sched_param sched;

    63   memset(&sched, 0, sizeof(sched));

    64   // Go back to default scheduler with default 0 priority.

    65   sched.sched_priority = 0;

    66   sched_setscheduler(0, SCHED_OTHER, &sched);

    67 }