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Annotation of kernel/kern/timer.h, revision 1.1

1.1     ! root        1: /*
        !             2:  * Copyright (c) 1999 Apple Computer, Inc. All rights reserved.
        !             3:  *
        !             4:  * @APPLE_LICENSE_HEADER_START@
        !             5:  * 
        !             6:  * Portions Copyright (c) 1999 Apple Computer, Inc.  All Rights
        !             7:  * Reserved.  This file contains Original Code and/or Modifications of
        !             8:  * Original Code as defined in and that are subject to the Apple Public
        !             9:  * Source License Version 1.1 (the "License").  You may not use this file
        !            10:  * except in compliance with the License.  Please obtain a copy of the
        !            11:  * License at http://www.apple.com/publicsource and read it before using
        !            12:  * this file.
        !            13:  * 
        !            14:  * The Original Code and all software distributed under the License are
        !            15:  * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
        !            16:  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
        !            17:  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
        !            18:  * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
        !            19:  * License for the specific language governing rights and limitations
        !            20:  * under the License.
        !            21:  * 
        !            22:  * @APPLE_LICENSE_HEADER_END@
        !            23:  */
        !            24: 
        !            25: /* 
        !            26:  * Mach Operating System
        !            27:  * Copyright (c) 1989 Carnegie-Mellon University
        !            28:  * Copyright (c) 1988 Carnegie-Mellon University
        !            29:  * Copyright (c) 1987 Carnegie-Mellon University
        !            30:  * All rights reserved.  The CMU software License Agreement specifies
        !            31:  * the terms and conditions for use and redistribution.
        !            32:  */
        !            33: /*
        !            34:  * HISTORY
        !            35:  * Revision 1.1.1.1  1997/09/30 02:44:35  wsanchez
        !            36:  * Import of kernel from umeshv/kernel
        !            37:  *
        !            38:  * Revision 2.9  89/12/22  15:54:21  rpd
        !            39:  *     Minor stylistic change to TIMER_DELTA, plus explanatory comment.
        !            40:  *     [89/11/28            dlb]
        !            41:  * 
        !            42:  * Revision 2.8  89/10/11  14:35:23  dlb
        !            43:  *     Change internal representation of timers: flags field replaced
        !            44:  *     by high_bits_check field.
        !            45:  *     [89/09/12            dlb]
        !            46:  * 
        !            47:  *     Added TIMER_LOW_FULL mask to check for possible overflow of
        !            48:  *     low_bits field.  Removed TIMER_SERVICE flag.
        !            49:  *     [88/10/27            dlb]
        !            50:  * 
        !            51:  * Revision 2.7  89/03/09  20:17:32  rpd
        !            52:  *     More cleanup.
        !            53:  * 
        !            54:  * Revision 2.6  89/02/25  18:10:52  gm0w
        !            55:  *     Kernel code cleanup.
        !            56:  *     Put entire file under #indef KERNEL.
        !            57:  *     [89/02/15            mrt]
        !            58:  * 
        !            59:  * Revision 2.5  89/02/07  01:05:51  mwyoung
        !            60:  * Relocated from sys/timer.h
        !            61:  * 
        !            62:  * Revision 2.4  89/01/30  22:08:37  rpd
        !            63:  *     Updated macro definitions to the new style.
        !            64:  *     Made declarations use "extern".
        !            65:  *     [89/01/25  15:24:36  rpd]
        !            66:  * 
        !            67:  * Revision 2.3  88/08/24  02:49:17  mwyoung
        !            68:  *     Adjusted include file references.
        !            69:  *     [88/08/17  02:25:43  mwyoung]
        !            70:  *
        !            71:  *  7-Apr-88  David Black (dlb) at Carnegie-Mellon University
        !            72:  *     Added interface definitions and null routines for STAT_TIME.
        !            73:  *
        !            74:  * 19-Feb-88  David Black (dlb) at Carnegie-Mellon University
        !            75:  *     Renamed fields, added timer_save structure.
        !            76:  *
        !            77:  * 31-May-87  Avadis Tevanian (avie) at Carnegie-Mellon University
        !            78:  *     machine/machtimer.h -> machine/timer.h
        !            79:  *
        !            80:  * 23-Feb-87  David L. Black (dlb) at Carnegie-Mellon University
        !            81:  *     Created.
        !            82:  */ 
        !            83: 
        !            84: #ifndef        _KERN_TIMER_H_
        !            85: #define _KERN_TIMER_H_
        !            86: 
        !            87: #ifdef KERNEL_BUILD
        !            88: #import <cpus.h>
        !            89: #import <stat_time.h>
        !            90: #else  /* KERNEL_BUILD */
        !            91: #import <mach/features.h>
        !            92: #endif /* KERNEL_BUILD */
        !            93: 
        !            94: #import <kernserv/macro_help.h>
        !            95: 
        !            96: #if    STAT_TIME
        !            97: /*
        !            98:  *     Statistical timer definitions - use microseconds in timer, seconds
        !            99:  *     in high unit field.  No adjustment needed to convert to time_value_t
        !           100:  *     as a result.  Service timers once an hour.
        !           101:  */
        !           102: 
        !           103: #define TIMER_RATE     1000000
        !           104: #define TIMER_HIGH_UNIT        TIMER_RATE
        !           105: #undef TIMER_ADJUST
        !           106: 
        !           107: #else  /* STAT_TIME */
        !           108: /*
        !           109:  *     Machine dependent definitions based on hardware support.
        !           110:  */
        !           111: 
        !           112: #import <machine/timer.h>
        !           113: 
        !           114: #endif /* STAT_TIME */
        !           115: 
        !           116: /*
        !           117:  *     Definitions for accurate timers.  high_bits_check is a copy of
        !           118:  *     high_bits that allows reader to verify that values read are ok.
        !           119:  */
        !           120: 
        !           121: struct timer {
        !           122:        unsigned        low_bits;
        !           123:        unsigned        high_bits;
        !           124:        unsigned        high_bits_check;
        !           125:        unsigned        tstamp;
        !           126: };
        !           127: 
        !           128: typedef struct timer           timer_data_t;
        !           129: typedef        struct timer            *timer_t;
        !           130: 
        !           131: /*
        !           132:  *     Mask to check if low_bits is in danger of overflowing
        !           133:  */
        !           134: 
        !           135: #define        TIMER_LOW_FULL  0x80000000
        !           136: 
        !           137: /*
        !           138:  *     Kernel timers and current timer array.  [Exported]
        !           139:  */
        !           140: 
        !           141: extern timer_t         current_timer[NCPUS];
        !           142: extern timer_data_t    kernel_timer[NCPUS];
        !           143: 
        !           144: /*
        !           145:  *     save structure for timer readings.  This is used to save timer
        !           146:  *     readings for elapsed time computations.
        !           147:  */
        !           148: 
        !           149: struct timer_save {
        !           150:        unsigned        low;
        !           151:        unsigned        high;
        !           152: };
        !           153: 
        !           154: typedef struct timer_save      timer_save_data_t, *timer_save_t;
        !           155: 
        !           156: /*
        !           157:  *     Exported kernel interface to timers
        !           158:  */
        !           159: 
        !           160: #if    STAT_TIME
        !           161: #define start_timer(timer)
        !           162: #define timer_switch(timer)
        !           163: #else  /* STAT_TIME */
        !           164: extern void    start_timer();
        !           165: extern void    timer_switch();
        !           166: #endif /* STAT_TIME */
        !           167: 
        !           168: extern void            timer_read();
        !           169: extern void            thread_read_times();
        !           170: extern unsigned                timer_delta();
        !           171: 
        !           172: #if    STAT_TIME
        !           173: /*
        !           174:  *     Macro to bump timer values.
        !           175:  */    
        !           176: #define timer_bump(timer, usec)                                        \
        !           177: MACRO_BEGIN                                                    \
        !           178:        (timer)->low_bits += usec;                              \
        !           179:        if ((timer)->low_bits & TIMER_LOW_FULL) {               \
        !           180:                timer_normalize(timer);                         \
        !           181:        }                                                       \
        !           182: MACRO_END
        !           183: 
        !           184: #else  /* STAT_TIME */
        !           185: /*
        !           186:  *     Exported hardware interface to timers
        !           187:  */
        !           188: extern void    time_trap_uentry();
        !           189: extern void    time_trap_uexit();
        !           190: extern timer_t time_int_entry();
        !           191: extern void    time_int_exit();
        !           192: #endif /* STAT_TIME */
        !           193: 
        !           194: /*
        !           195:  *     TIMER_DELTA finds the difference between a timer and a saved value,
        !           196:  *     and updates the saved value.  Look at high_bits check field after
        !           197:  *     reading low because that's the first written by a normalize
        !           198:  *     operation; this isn't necessary for current usage because
        !           199:  *     this macro is only used when the timer can't be normalized:
        !           200:  *     thread is not running, or running thread calls it on itself at
        !           201:  *     splsched().
        !           202:  */
        !           203: 
        !           204: #define TIMER_DELTA(timer, save, result)                       \
        !           205: MACRO_BEGIN                                                    \
        !           206:        register unsigned       temp;                           \
        !           207:                                                                \
        !           208:        temp = (timer).low_bits;                                \
        !           209:        if ((save).high != (timer).high_bits_check) {           \
        !           210:                result += timer_delta(&(timer), &(save));       \
        !           211:        }                                                       \
        !           212:        else {                                                  \
        !           213:                result += temp - (save).low;                    \
        !           214:                (save).low = temp;                              \
        !           215:        }                                                       \
        !           216: MACRO_END
        !           217: 
        !           218: #endif /* _KERN_TIMER_H_ */
        !           219: 

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