osfmk/kern/timer.c

   1 /*
   2  * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_OSREFERENCE_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
  10  * License may not be used to create, or enable the creation or
  11  * redistribution of, unlawful or unlicensed copies of an Apple operating
  12  * system, or to circumvent, violate, or enable the circumvention or
  13  * violation of, any terms of an Apple operating system software license
  14  * agreement.
  15  *
  16  * Please obtain a copy of the License at
  17  * http://www.opensource.apple.com/apsl/ and read it before using this
  18  * file.
  19  *
  20  * The Original Code and all software distributed under the License are
  21  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  22  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  23  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  24  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  25  * Please see the License for the specific language governing rights and
  26  * limitations under the License.
  27  *
  28  * @APPLE_LICENSE_OSREFERENCE_HEADER_END@
  29  */
  30 /*
  31  * @OSF_COPYRIGHT@
  32  */
  33 /*
  34  * Mach Operating System
  35  * Copyright (c) 1991,1990,1989,1988,1987 Carnegie Mellon University
  36  * All Rights Reserved.
  37  *
  38  * Permission to use, copy, modify and distribute this software and its
  39  * documentation is hereby granted, provided that both the copyright
  40  * notice and this permission notice appear in all copies of the
  41  * software, derivative works or modified versions, and any portions
  42  * thereof, and that both notices appear in supporting documentation.
  43  *
  44  * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
  45  * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
  46  * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
  47  *
  48  * Carnegie Mellon requests users of this software to return to
  49  *
  50  *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
  51  *  School of Computer Science
  52  *  Carnegie Mellon University
  53  *  Pittsburgh PA 15213-3890
  54  *
  55  * any improvements or extensions that they make and grant Carnegie Mellon
  56  * the rights to redistribute these changes.
  57  */
  58 /*
  59  */
  60
  61 #include <stat_time.h>
  62 #include <machine_timer_routines.h>
  63
  64 #include <mach/kern_return.h>
  65 #include <mach/port.h>
  66 #include <kern/queue.h>
  67 #include <kern/processor.h>
  68 #include <kern/thread.h>
  69 #include <kern/sched_prim.h>
  70 #include <kern/timer.h>
  71
  72 /*
  73  *      timer_init initializes a timer.
  74  */
  75 void
  76 timer_init(
  77         timer_t         timer)
  78 {
  79         timer->low_bits = 0;
  80         timer->high_bits = 0;
  81         timer->high_bits_check = 0;
  82 #if     !STAT_TIME
  83         timer->tstamp = 0;
  84 #endif  /* STAT_TIME */
  85 }
  86
  87 /*
  88  *      Calculate the difference between a timer
  89  *      and saved value, and update the saved value.
  90  */
  91 uint64_t
  92 timer_delta(
  93         timer_t         timer,
  94         uint64_t        *save)
  95 {
  96         uint64_t        new, old = *save;
  97
  98         *save = new = timer_grab(timer);
  99
 100         return (new - old);
 101 }
 102
 103 #if     !STAT_TIME
 104
 105 /*
 106  *      Update the current timer (if any)
 107  *      and start the new timer, which
 108  *      could be either the same or NULL.
 109  *
 110  *      Called with interrupts disabled.
 111  */
 112 void
 113 timer_switch(
 114         uint32_t                tstamp,
 115         timer_t                 new_timer)
 116 {
 117         processor_t             processor = current_processor();
 118         timer_t                 timer;
 119         uint32_t                old_low, low;
 120
 121         /*
 122          *      Update current timer.
 123          */
 124         timer = PROCESSOR_DATA(processor, current_timer);
 125         if (timer != NULL) {
 126                 old_low = timer->low_bits;
 127                 low = old_low + tstamp - timer->tstamp;
 128                 if (low < old_low)
 129                         timer_update(timer, timer->high_bits + 1, low);
 130                 else
 131                         timer->low_bits = low;
 132         }
 133
 134         /*
 135          *      Start new timer.
 136          */
 137         PROCESSOR_DATA(processor, current_timer) = new_timer;
 138         if (new_timer != NULL)
 139                 new_timer->tstamp = tstamp;
 140 }
 141
 142 #if     MACHINE_TIMER_ROUTINES
 143
 144 /*
 145  *      Machine-dependent code implements the timer event routine.
 146  */
 147
 148 #else   /* MACHINE_TIMER_ROUTINES */
 149
 150 /*
 151  *      Update the current timer and start
 152  *      the new timer.  Requires a current
 153  *      and new timer.
 154  *
 155  *      Called with interrupts disabled.
 156  */
 157 void
 158 timer_event(
 159         uint32_t                tstamp,
 160         timer_t                 new_timer)
 161 {
 162         processor_t             processor = current_processor();
 163         timer_t                 timer;
 164         uint32_t                old_low, low;
 165
 166         /*
 167          *      Update current timer.
 168          */
 169         timer = PROCESSOR_DATA(processor, current_timer);
 170         old_low = timer->low_bits;
 171         low = old_low + tstamp - timer->tstamp;
 172         if (low < old_low)
 173                 timer_update(timer, timer->high_bits + 1, low);
 174         else
 175                 timer->low_bits = low;
 176
 177         /*
 178          *      Start new timer.
 179          */
 180         PROCESSOR_DATA(processor, current_timer) = new_timer;
 181         new_timer->tstamp = tstamp;
 182 }
 183
 184 #endif  /* MACHINE_TIMER_ROUTINES */
 185
 186 #endif  /* STAT_TIME */