osfmk/kern/timer.c

   1 /*
   2  * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * The contents of this file constitute Original Code as defined in and
   7  * are subject to the Apple Public Source License Version 1.1 (the
   8  * "License").  You may not use this file except in compliance with the
   9  * License.  Please obtain a copy of the License at
  10  * http://www.apple.com/publicsource and read it before using this file.
  11  *
  12  * This Original Code and all software distributed under the License are
  13  * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  14  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  15  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  16  * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
  17  * License for the specific language governing rights and limitations
  18  * under the License.
  19  *
  20  * @APPLE_LICENSE_HEADER_END@
  21  */
  22 /*
  23  * @OSF_COPYRIGHT@
  24  */
  25 /*
  26  * Mach Operating System
  27  * Copyright (c) 1991,1990,1989,1988,1987 Carnegie Mellon University
  28  * All Rights Reserved.
  29  *
  30  * Permission to use, copy, modify and distribute this software and its
  31  * documentation is hereby granted, provided that both the copyright
  32  * notice and this permission notice appear in all copies of the
  33  * software, derivative works or modified versions, and any portions
  34  * thereof, and that both notices appear in supporting documentation.
  35  *
  36  * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
  37  * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
  38  * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
  39  *
  40  * Carnegie Mellon requests users of this software to return to
  41  *
  42  *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
  43  *  School of Computer Science
  44  *  Carnegie Mellon University
  45  *  Pittsburgh PA 15213-3890
  46  *
  47  * any improvements or extensions that they make and grant Carnegie Mellon
  48  * the rights to redistribute these changes.
  49  */
  50 /*
  51  */
  52
  53 #include <stat_time.h>
  54 #include <machine_timer_routines.h>
  55
  56 #include <mach/kern_return.h>
  57 #include <mach/port.h>
  58 #include <kern/queue.h>
  59 #include <kern/processor.h>
  60 #include <kern/thread.h>
  61 #include <kern/sched_prim.h>
  62 #include <kern/timer.h>
  63
  64 /*
  65  *      timer_init initializes a timer.
  66  */
  67 void
  68 timer_init(
  69         timer_t         timer)
  70 {
  71         timer->low_bits = 0;
  72         timer->high_bits = 0;
  73         timer->high_bits_check = 0;
  74 #if     !STAT_TIME
  75         timer->tstamp = 0;
  76 #endif  /* STAT_TIME */
  77 }
  78
  79 /*
  80  *      Calculate the difference between a timer
  81  *      and saved value, and update the saved value.
  82  */
  83 uint64_t
  84 timer_delta(
  85         timer_t         timer,
  86         uint64_t        *save)
  87 {
  88         uint64_t        new, old = *save;
  89
  90         *save = new = timer_grab(timer);
  91
  92         return (new - old);
  93 }
  94
  95 #if     !STAT_TIME
  96
  97 /*
  98  *      Update the current timer (if any)
  99  *      and start the new timer, which
 100  *      could be either the same or NULL.
 101  *
 102  *      Called with interrupts disabled.
 103  */
 104 void
 105 timer_switch(
 106         uint32_t                tstamp,
 107         timer_t                 new_timer)
 108 {
 109         processor_t             processor = current_processor();
 110         timer_t                 timer;
 111         uint32_t                old_low, low;
 112
 113         /*
 114          *      Update current timer.
 115          */
 116         timer = PROCESSOR_DATA(processor, current_timer);
 117         if (timer != NULL) {
 118                 old_low = timer->low_bits;
 119                 low = old_low + tstamp - timer->tstamp;
 120                 if (low < old_low)
 121                         timer_update(timer, timer->high_bits + 1, low);
 122                 else
 123                         timer->low_bits = low;
 124         }
 125
 126         /*
 127          *      Start new timer.
 128          */
 129         PROCESSOR_DATA(processor, current_timer) = new_timer;
 130         if (new_timer != NULL)
 131                 new_timer->tstamp = tstamp;
 132 }
 133
 134 #if     MACHINE_TIMER_ROUTINES
 135
 136 /*
 137  *      Machine-dependent code implements the timer event routine.
 138  */
 139
 140 #else   /* MACHINE_TIMER_ROUTINES */
 141
 142 /*
 143  *      Update the current timer and start
 144  *      the new timer.  Requires a current
 145  *      and new timer.
 146  *
 147  *      Called with interrupts disabled.
 148  */
 149 void
 150 timer_event(
 151         uint32_t                tstamp,
 152         timer_t                 new_timer)
 153 {
 154         processor_t             processor = current_processor();
 155         timer_t                 timer;
 156         uint32_t                old_low, low;
 157
 158         /*
 159          *      Update current timer.
 160          */
 161         timer = PROCESSOR_DATA(processor, current_timer);
 162         old_low = timer->low_bits;
 163         low = old_low + tstamp - timer->tstamp;
 164         if (low < old_low)
 165                 timer_update(timer, timer->high_bits + 1, low);
 166         else
 167                 timer->low_bits = low;
 168
 169         /*
 170          *      Start new timer.
 171          */
 172         PROCESSOR_DATA(processor, current_timer) = new_timer;
 173         new_timer->tstamp = tstamp;
 174 }
 175
 176 #endif  /* MACHINE_TIMER_ROUTINES */
 177
 178 #endif  /* STAT_TIME */