flight/pios/posix/pios_delay.c

   1 /**
   2  ******************************************************************************
   3  *
   4  * @file       pios_delay.c
   5  * @author     The OpenPilot Team, http://www.openpilot.org Copyright (C) 2010.
   6  *              Parts by Thorsten Klose (tk@midibox.org) (tk@midibox.org)
   7  * @brief      Delay Functions
   8  *                 - Provides a micro-second granular delay using a TIM
   9  * @see        The GNU Public License (GPL) Version 3
  10  * @defgroup   PIOS_DELAY Delay Functions
  11  * @{
  12  *
  13  *****************************************************************************/
  14 /*
  15  * This program is free software; you can redistribute it and/or modify
  16  * it under the terms of the GNU General Public License as published by
  17  * the Free Software Foundation; either version 3 of the License, or
  18  * (at your option) any later version.
  19  *
  20  * This program is distributed in the hope that it will be useful, but
  21  * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  22  * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
  23  * for more details.
  24  *
  25  * You should have received a copy of the GNU General Public License along
  26  * with this program; if not, write to the Free Software Foundation, Inc.,
  27  * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
  28  */
  29
  30
  31 /* Project Includes */
  32 #include "pios.h"
  33
  34 #if defined(PIOS_INCLUDE_DELAY)
  35
  36 /**
  37  * Initialises the Timer used by PIOS_DELAY functions<BR>
  38  * This is called from pios.c as part of the main() function
  39  * at system start up.
  40  * \return < 0 if initialisation failed
  41  */
  42 #include <time.h>
  43
  44 int32_t PIOS_DELAY_Init(void)
  45 {
  46     // stub
  47
  48     /* No error */
  49     return 0;
  50 }
  51
  52 /**
  53  * Waits for a specific number of uS<BR>
  54  * Example:<BR>
  55  * \code
  56  *   // Wait for 500 uS
  57  *   PIOS_DELAY_Wait_uS(500);
  58  * \endcode
  59  * \param[in] uS delay (1..65535 microseconds)
  60  * \return < 0 on errors
  61  */
  62 int32_t PIOS_DELAY_WaituS(uint32_t uS)
  63 {
  64     static struct timespec wait, rest;
  65
  66     wait.tv_sec  = 0;
  67     wait.tv_nsec = 1000 * uS;
  68     while (nanosleep(&wait, &rest) != 0) {
  69         wait = rest;
  70     }
  71
  72     /* No error */
  73     return 0;
  74 }
  75
  76
  77 /**
  78  * Waits for a specific number of mS<BR>
  79  * Example:<BR>
  80  * \code
  81  *   // Wait for 500 mS
  82  *   PIOS_DELAY_Wait_mS(500);
  83  * \endcode
  84  * \param[in] mS delay (1..65535 milliseconds)
  85  * \return < 0 on errors
  86  */
  87 int32_t PIOS_DELAY_WaitmS(uint32_t mS)
  88 {
  89     // for(int i = 0; i < mS; i++) {
  90     // PIOS_DELAY_WaituS(1000);
  91     static struct timespec wait, rest;
  92
  93     wait.tv_sec  = mS / 1000;
  94     wait.tv_nsec = (mS % 1000) * 1000000;
  95     while (nanosleep(&wait, &rest) != 0) {
  96         wait = rest;
  97     }
  98     // }
  99
 100     /* No error */
 101     return 0;
 102 }
 103
 104 /**
 105  * @brief Query the Delay timer for the current uS
 106  * @return A microsecond value
 107  */
 108 uint32_t PIOS_DELAY_GetuS()
 109 {
 110     static struct timespec current;
 111
 112     clock_gettime(CLOCK_REALTIME, &current);
 113     return (current.tv_sec * 1000000) + (current.tv_nsec / 1000);
 114 }
 115
 116 /**
 117  * @brief Calculate time in microseconds since a previous time
 118  * @param[in] t previous time
 119  * @return time in us since previous time t.
 120  */
 121 uint32_t PIOS_DELAY_GetuSSince(uint32_t t)
 122 {
 123     return PIOS_DELAY_GetuS() - t;
 124 }
 125
 126 /**
 127  * @brief Get the raw delay timer, useful for timing
 128  * @return Unitless value (uint32 wrap around)
 129  */
 130 uint32_t PIOS_DELAY_GetRaw()
 131 {
 132     return PIOS_DELAY_GetuS();
 133 }
 134
 135 /**
 136  * @brief Compare to raw times to and convert to us
 137  * @return A microsecond value
 138  */
 139 uint32_t PIOS_DELAY_DiffuS(uint32_t raw)
 140 {
 141     return PIOS_DELAY_GetuS() - raw;
 142 }
 143
 144
 145 #endif /* if defined(PIOS_INCLUDE_DELAY) */