osfmk/kern/timer.c

   1 /*
   2  * Copyright (c) 2000-2007 Apple Inc. All rights reserved.
   3  *
   4  * @APPLE_OSREFERENCE_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. The rights granted to you under the License
  10  * may not be used to create, or enable the creation or redistribution of,
  11  * unlawful or unlicensed copies of an Apple operating system, or to
  12  * circumvent, violate, or enable the circumvention or violation of, any
  13  * terms of an Apple operating system software license agreement.
  14  *
  15  * Please obtain a copy of the License at
  16  * http://www.opensource.apple.com/apsl/ and read it before using this file.
  17  *
  18  * The Original Code and all software distributed under the License are
  19  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  20  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  21  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  22  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  23  * Please see the License for the specific language governing rights and
  24  * limitations under the License.
  25  *
  26  * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
  27  */
  28 /*
  29  * @OSF_COPYRIGHT@
  30  */
  31 /*
  32  * Mach Operating System
  33  * Copyright (c) 1991,1990,1989,1988,1987 Carnegie Mellon University
  34  * All Rights Reserved.
  35  *
  36  * Permission to use, copy, modify and distribute this software and its
  37  * documentation is hereby granted, provided that both the copyright
  38  * notice and this permission notice appear in all copies of the
  39  * software, derivative works or modified versions, and any portions
  40  * thereof, and that both notices appear in supporting documentation.
  41  *
  42  * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
  43  * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
  44  * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
  45  *
  46  * Carnegie Mellon requests users of this software to return to
  47  *
  48  *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
  49  *  School of Computer Science
  50  *  Carnegie Mellon University
  51  *  Pittsburgh PA 15213-3890
  52  *
  53  * any improvements or extensions that they make and grant Carnegie Mellon
  54  * the rights to redistribute these changes.
  55  */
  56 /*
  57  */
  58
  59 #include <stat_time.h>
  60 #include <machine_timer_routines.h>
  61
  62 #include <mach/kern_return.h>
  63 #include <mach/port.h>
  64 #include <kern/queue.h>
  65 #include <kern/processor.h>
  66 #include <kern/thread.h>
  67 #include <kern/sched_prim.h>
  68 #include <kern/timer.h>
  69
  70 /*
  71  *      timer_init initializes a timer.
  72  */
  73 void
  74 timer_init(
  75         timer_t         timer)
  76 {
  77 #if     !STAT_TIME
  78         timer->tstamp = 0;
  79 #endif  /* STAT_TIME */
  80         timer->low_bits = 0;
  81         timer->high_bits = 0;
  82         timer->high_bits_check = 0;
  83 }
  84
  85 /*
  86  *      Calculate the difference between a timer
  87  *      and saved value, and update the saved value.
  88  */
  89 uint64_t
  90 timer_delta(
  91         timer_t         timer,
  92         uint64_t        *save)
  93 {
  94         uint64_t        new, old = *save;
  95
  96         *save = new = timer_grab(timer);
  97
  98         return (new - old);
  99 }
 100
 101 void
 102 timer_advance(
 103         timer_t         timer,
 104         uint64_t        delta)
 105 {
 106         uint64_t        low;
 107
 108         low = delta + timer->low_bits;
 109         if (low >> 32)
 110                 timer_update(timer, timer->high_bits + (low >> 32), low);
 111         else
 112                 timer->low_bits = low;
 113 }
 114
 115 #if     !STAT_TIME
 116
 117 void
 118 timer_start(
 119         timer_t         timer,
 120         uint64_t        tstamp)
 121 {
 122         timer->tstamp = tstamp;
 123 }
 124
 125 void
 126 timer_stop(
 127         timer_t         timer,
 128         uint64_t        tstamp)
 129 {
 130         timer_advance(timer, tstamp - timer->tstamp);
 131 }
 132
 133 /*
 134  *      Update the timer and start a new one.
 135  */
 136 void
 137 timer_switch(
 138         timer_t                 timer,
 139         uint64_t                tstamp,
 140         timer_t                 new_timer)
 141 {
 142         timer_advance(timer, tstamp - timer->tstamp);
 143         new_timer->tstamp = tstamp;
 144 }
 145
 146 #if     MACHINE_TIMER_ROUTINES
 147
 148 /*
 149  *      Machine-dependent code implements the timer event routine.
 150  */
 151
 152 #else   /* MACHINE_TIMER_ROUTINES */
 153
 154 /*
 155  *      Update the current thread timer and
 156  *      start the new timer.  Requires a current
 157  *      and new timer.
 158  *
 159  *      Called with interrupts disabled.
 160  */
 161 void
 162 thread_timer_event(
 163         uint64_t                tstamp,
 164         timer_t                 new_timer)
 165 {
 166         processor_t             processor = current_processor();
 167         timer_t                 timer;
 168
 169         /*
 170          *      Update current timer.
 171          */
 172         timer = PROCESSOR_DATA(processor, thread_timer);
 173         timer_advance(timer, tstamp - timer->tstamp);
 174
 175         /*
 176          *      Start new timer.
 177          */
 178         PROCESSOR_DATA(processor, thread_timer) = new_timer;
 179         new_timer->tstamp = tstamp;
 180 }
 181
 182 #endif  /* MACHINE_TIMER_ROUTINES */
 183
 184 #endif  /* STAT_TIME */