arm/sys/arm_commpage_gettimeofday.c

   1 /*
   2  * Copyright (c) 2008 Apple Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License. Please obtain a copy of the License at
  10  * http://www.opensource.apple.com/apsl/ and read it before using this
  11  * file.
  12  *
  13  * The Original Code and all software distributed under the License are
  14  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  15  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  16  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  17  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  18  * Please see the License for the specific language governing rights and
  19  * limitations under the License.
  20  *
  21  * @APPLE_LICENSE_HEADER_END@
  22  */
  23 #include <time.h>
  24 #include <tzfile.h>
  25 #include <sys/time.h>
  26 #include <errno.h>
  27 #include <sys/syscall.h>
  28 #include <unistd.h>
  29 #include <mach/clock_types.h>
  30 #include <mach/mach.h>
  31 #include <mach/mach_time.h>
  32 #include <machine/cpu_capabilities.h>
  33
  34 int __commpage_gettimeofday(struct timeval *);
  35
  36
  37 #define TIME_ADD(rsecs, secs, rfrac, frac, unit)        \
  38 {                                                       \
  39         (rfrac) += (frac);                              \
  40         while ((rfrac) >= (unit)) {                     \
  41                 (rfrac) -= (unit);                      \
  42                 (rsecs) += 1;                           \
  43         }                                               \
  44         (rsecs) += (secs);                              \
  45 }
  46
  47
  48 int __commpage_gettimeofday(struct timeval  *tp) {
  49         commpage_timeofday_data_t *commpage_timeofday_datap;
  50         uint64_t        tbr;
  51         uint64_t        t64;
  52         uint64_t        TimeBase;
  53         uint32_t        TimeStamp_usec;
  54         uint32_t        TimeStamp_sec;
  55         uint32_t        TimeBaseTicks_per_sec;
  56         uint64_t        TimeBase_magic;
  57         uint32_t        TimeBase_add;
  58         uint32_t        TimeBase_shift;
  59         uint32_t        x, q;
  60
  61
  62         commpage_timeofday_datap =  (commpage_timeofday_data_t *)_COMM_PAGE_TIMEOFDAY_DATA;
  63
  64         do {
  65                 TimeBase = commpage_timeofday_datap->TimeBase;
  66                 TimeStamp_sec = commpage_timeofday_datap->TimeStamp_sec;
  67                 TimeStamp_usec = commpage_timeofday_datap->TimeStamp_usec;
  68                 TimeBaseTicks_per_sec = commpage_timeofday_datap->TimeBaseTicks_per_sec;
  69                 TimeBase_magic = commpage_timeofday_datap->TimeBase_magic;
  70                 TimeBase_add = commpage_timeofday_datap->TimeBase_add;
  71                 TimeBase_shift = commpage_timeofday_datap->TimeBase_shift;
  72         } while (TimeBase != commpage_timeofday_datap->TimeBase);
  73
  74         if (TimeBase == 0)
  75                 return(1);
  76
  77         tbr = mach_absolute_time();
  78
  79         t64 = tbr - TimeBase;
  80
  81         if (t64 >= (uint64_t)TimeBaseTicks_per_sec)
  82                 return(1);
  83
  84         x = (uint32_t)t64;
  85         q = ((uint64_t)x * (uint32_t)(TimeBase_magic)) >> 32;
  86         tp->tv_usec = TimeBase_add ? (((x - q) >> 1) + q) >> (TimeBase_shift - 1) : q >> TimeBase_shift;
  87         tp->tv_sec = 0;
  88
  89         TIME_ADD(tp->tv_sec, TimeStamp_sec, tp->tv_usec, TimeStamp_usec, USEC_PER_SEC);
  90
  91         return(0);
  92 }