osfmk/kern/timer.c

   1 /*
   2  * Copyright (c) 2000 Apple Computer, 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         timer->low_bits = 0;
  78         timer->high_bits = 0;
  79         timer->high_bits_check = 0;
  80 #if     !STAT_TIME
  81         timer->tstamp = 0;
  82 #endif  /* STAT_TIME */
  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 #if     !STAT_TIME
 102
 103 /*
 104  *      Update the current timer (if any)
 105  *      and start the new timer, which
 106  *      could be either the same or NULL.
 107  *
 108  *      Called with interrupts disabled.
 109  */
 110 void
 111 timer_switch(
 112         uint32_t                tstamp,
 113         timer_t                 new_timer)
 114 {
 115         processor_t             processor = current_processor();
 116         timer_t                 timer;
 117         uint32_t                old_low, low;
 118
 119         /*
 120          *      Update current timer.
 121          */
 122         timer = PROCESSOR_DATA(processor, current_timer);
 123         if (timer != NULL) {
 124                 old_low = timer->low_bits;
 125                 low = old_low + tstamp - timer->tstamp;
 126                 if (low < old_low)
 127                         timer_update(timer, timer->high_bits + 1, low);
 128                 else
 129                         timer->low_bits = low;
 130         }
 131
 132         /*
 133          *      Start new timer.
 134          */
 135         PROCESSOR_DATA(processor, current_timer) = new_timer;
 136         if (new_timer != NULL)
 137                 new_timer->tstamp = tstamp;
 138 }
 139
 140 #if     MACHINE_TIMER_ROUTINES
 141
 142 /*
 143  *      Machine-dependent code implements the timer event routine.
 144  */
 145
 146 #else   /* MACHINE_TIMER_ROUTINES */
 147
 148 /*
 149  *      Update the current timer and start
 150  *      the new timer.  Requires a current
 151  *      and new timer.
 152  *
 153  *      Called with interrupts disabled.
 154  */
 155 void
 156 timer_event(
 157         uint32_t                tstamp,
 158         timer_t                 new_timer)
 159 {
 160         processor_t             processor = current_processor();
 161         timer_t                 timer;
 162         uint32_t                old_low, low;
 163
 164         /*
 165          *      Update current timer.
 166          */
 167         timer = PROCESSOR_DATA(processor, current_timer);
 168         old_low = timer->low_bits;
 169         low = old_low + tstamp - timer->tstamp;
 170         if (low < old_low)
 171                 timer_update(timer, timer->high_bits + 1, low);
 172         else
 173                 timer->low_bits = low;
 174
 175         /*
 176          *      Start new timer.
 177          */
 178         PROCESSOR_DATA(processor, current_timer) = new_timer;
 179         new_timer->tstamp = tstamp;
 180 }
 181
 182 #endif  /* MACHINE_TIMER_ROUTINES */
 183
 184 #endif  /* STAT_TIME */