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      1 /**************************************************************************
      2  *
      3  * Copyright 2008-2010 VMware, Inc.
      4  * All Rights Reserved.
      5  *
      6  * Permission is hereby granted, free of charge, to any person obtaining a
      7  * copy of this software and associated documentation files (the
      8  * "Software"), to deal in the Software without restriction, including
      9  * without limitation the rights to use, copy, modify, merge, publish,
     10  * distribute, sub license, and/or sell copies of the Software, and to
     11  * permit persons to whom the Software is furnished to do so, subject to
     12  * the following conditions:
     13  *
     14  * The above copyright notice and this permission notice (including the
     15  * next paragraph) shall be included in all copies or substantial portions
     16  * of the Software.
     17  *
     18  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
     19  * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
     20  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT.
     21  * IN NO EVENT SHALL VMWARE AND/OR ITS SUPPLIERS BE LIABLE FOR
     22  * ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
     23  * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
     24  * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
     25  *
     26  **************************************************************************/
     27 
     28 /**
     29  * @file
     30  * OS independent time-manipulation functions.
     31  *
     32  * @author Jose Fonseca <jfonseca (at) vmware.com>
     33  */
     34 
     35 #ifndef _OS_TIME_H_
     36 #define _OS_TIME_H_
     37 
     38 
     39 #include "pipe/p_config.h"
     40 
     41 #if defined(PIPE_OS_UNIX)
     42 #  include <unistd.h> /* usleep */
     43 #endif
     44 
     45 #include "pipe/p_compiler.h"
     46 
     47 
     48 #ifdef __cplusplus
     49 extern "C" {
     50 #endif
     51 
     52 
     53 /*
     54  * Get the current time in nanoseconds from an unknown base.
     55  */
     56 int64_t
     57 os_time_get_nano(void);
     58 
     59 
     60 /*
     61  * Get the current time in microseconds from an unknown base.
     62  */
     63 static inline int64_t
     64 os_time_get(void)
     65 {
     66    return os_time_get_nano() / 1000;
     67 }
     68 
     69 
     70 /*
     71  * Sleep.
     72  */
     73 void
     74 os_time_sleep(int64_t usecs);
     75 
     76 
     77 /*
     78  * Helper function for detecting time outs, taking in account overflow.
     79  *
     80  * Returns true if the current time has elapsed beyond the specified interval.
     81  */
     82 static inline boolean
     83 os_time_timeout(int64_t start,
     84                 int64_t end,
     85                 int64_t curr)
     86 {
     87    if (start <= end)
     88       return !(start <= curr && curr < end);
     89    else
     90       return !((start <= curr) || (curr < end));
     91 }
     92 
     93 
     94 /**
     95  * Convert a relative timeout in nanoseconds into an absolute timeout,
     96  * in other words, it returns current time + timeout.
     97  * os_time_get_nano() must be monotonic.
     98  * PIPE_TIMEOUT_INFINITE is passed through unchanged. If the calculation
     99  * overflows, PIPE_TIMEOUT_INFINITE is returned.
    100  */
    101 int64_t
    102 os_time_get_absolute_timeout(uint64_t timeout);
    103 
    104 
    105 /**
    106  * Wait until the variable at the given memory location is zero.
    107  *
    108  * \param var           variable
    109  * \param timeout       timeout in ns, can be anything from 0 (no wait) to
    110  *                      PIPE_TIME_INFINITE (wait forever)
    111  * \return     true if the variable is zero
    112  */
    113 bool
    114 os_wait_until_zero(volatile int *var, uint64_t timeout);
    115 
    116 
    117 /**
    118  * Wait until the variable at the given memory location is zero.
    119  * The timeout is the absolute time when the waiting should stop. If it is
    120  * less than or equal to the current time, it only returns the status and
    121  * doesn't wait. PIPE_TIME_INFINITE waits forever. This requires that
    122  * os_time_get_nano is monotonic.
    123  *
    124  * \param var       variable
    125  * \param timeout   the time in ns when the waiting should stop
    126  * \return     true if the variable is zero
    127  */
    128 bool
    129 os_wait_until_zero_abs_timeout(volatile int *var, int64_t timeout);
    130 
    131 #ifdef __cplusplus
    132 }
    133 #endif
    134 
    135 #endif /* _OS_TIME_H_ */
    136