ceph/src/dpdk/lib/librte_eal/common/include/rte_time.h

   1 /*-
   2  *   BSD LICENSE
   3  *
   4  *   Copyright(c) 2015 Intel Corporation. All rights reserved.
   5  *   All rights reserved.
   6  *
   7  *   Redistribution and use in source and binary forms, with or without
   8  *   modification, are permitted provided that the following conditions
   9  *   are met:
  10  *
  11  *     * Redistributions of source code must retain the above copyright
  12  *       notice, this list of conditions and the following disclaimer.
  13  *     * Redistributions in binary form must reproduce the above copyright
  14  *       notice, this list of conditions and the following disclaimer in
  15  *       the documentation and/or other materials provided with the
  16  *       distribution.
  17  *     * Neither the name of Intel Corporation nor the names of its
  18  *       contributors may be used to endorse or promote products derived
  19  *       from this software without specific prior written permission.
  20  *
  21  *   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  22  *   "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  23  *   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  24  *   A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  25  *   OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  26  *   SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  27  *   LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  28  *   DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  29  *   THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  30  *   (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  31  *   OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  32  */
  33
  34 #ifndef _RTE_TIME_H_
  35 #define _RTE_TIME_H_
  36
  37 #include <stdint.h>
  38 #include <time.h>
  39
  40 #define NSEC_PER_SEC             1000000000L
  41
  42 /**
  43  * Structure to hold the parameters of a running cycle counter to assist
  44  * in converting cycles to nanoseconds.
  45  */
  46 struct rte_timecounter {
  47         /** Last cycle counter value read. */
  48         uint64_t cycle_last;
  49         /** Nanoseconds count. */
  50         uint64_t nsec;
  51         /** Bitmask separating nanosecond and sub-nanoseconds. */
  52         uint64_t nsec_mask;
  53         /** Sub-nanoseconds count. */
  54         uint64_t nsec_frac;
  55         /** Bitmask for two's complement substraction of non-64 bit counters. */
  56         uint64_t cc_mask;
  57         /** Cycle to nanosecond divisor (power of two). */
  58         uint32_t cc_shift;
  59 };
  60
  61 /**
  62  * Converts cyclecounter cycles to nanoseconds.
  63  */
  64 static inline uint64_t
  65 rte_cyclecounter_cycles_to_ns(struct rte_timecounter *tc, uint64_t cycles)
  66 {
  67         uint64_t ns;
  68
  69         /* Add fractional nanoseconds. */
  70         ns = cycles + tc->nsec_frac;
  71         tc->nsec_frac = ns & tc->nsec_mask;
  72
  73         /* Shift to get only nanoseconds. */
  74         return ns >> tc->cc_shift;
  75 }
  76
  77 /**
  78  * Update the internal nanosecond count in the structure.
  79  */
  80 static inline uint64_t
  81 rte_timecounter_update(struct rte_timecounter *tc, uint64_t cycle_now)
  82 {
  83         uint64_t cycle_delta, ns_offset;
  84
  85         /* Calculate the delta since the last call. */
  86         if (tc->cycle_last <= cycle_now)
  87                 cycle_delta = (cycle_now - tc->cycle_last) & tc->cc_mask;
  88         else
  89                 /* Handle cycle counts that have wrapped around . */
  90                 cycle_delta = (~(tc->cycle_last - cycle_now) & tc->cc_mask) + 1;
  91
  92         /* Convert to nanoseconds. */
  93         ns_offset = rte_cyclecounter_cycles_to_ns(tc, cycle_delta);
  94
  95         /* Store current cycle counter for next call. */
  96         tc->cycle_last = cycle_now;
  97
  98         /* Update the nanosecond count. */
  99         tc->nsec += ns_offset;
 100
 101         return tc->nsec;
 102 }
 103
 104 /**
 105  * Convert from timespec structure into nanosecond units.
 106  */
 107 static inline uint64_t
 108 rte_timespec_to_ns(const struct timespec *ts)
 109 {
 110         return ((uint64_t) ts->tv_sec * NSEC_PER_SEC) + ts->tv_nsec;
 111 }
 112
 113 /**
 114  * Convert from nanosecond units into timespec structure.
 115  */
 116 static inline struct timespec
 117 rte_ns_to_timespec(uint64_t nsec)
 118 {
 119         struct timespec ts = {0, 0};
 120
 121         if (nsec == 0)
 122                 return ts;
 123
 124         ts.tv_sec = nsec / NSEC_PER_SEC;
 125         ts.tv_nsec = nsec % NSEC_PER_SEC;
 126
 127         return ts;
 128 }
 129
 130 #endif /* _RTE_TIME_H_ */