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Annotation of XNU/osfmk/kern/timer.h, revision 1.1

1.1     ! root        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  [email protected]
        !            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: #ifndef        _KERN_TIMER_H_
        !            54: #define _KERN_TIMER_H_
        !            55: 
        !            56: #include <cpus.h>
        !            57: #include <stat_time.h>
        !            58: 
        !            59: #include <kern/macro_help.h>
        !            60: #include <kern/kern_types.h>
        !            61: 
        !            62: #if    STAT_TIME
        !            63: /*
        !            64:  *     Statistical timer definitions - use microseconds in timer, seconds
        !            65:  *     in high unit field.  No adjustment needed to convert to time_value_t
        !            66:  *     as a result.  Service timers once an hour.
        !            67:  */
        !            68: 
        !            69: #define TIMER_RATE     1000000
        !            70: #define TIMER_HIGH_UNIT        TIMER_RATE
        !            71: #undef TIMER_ADJUST
        !            72: 
        !            73: #else  /* STAT_TIME */
        !            74: /*
        !            75:  *     Machine dependent definitions based on hardware support.
        !            76:  */
        !            77: 
        !            78: #include <machine/timer.h>
        !            79: 
        !            80: #endif /* STAT_TIME */
        !            81: 
        !            82: /*
        !            83:  *     Definitions for accurate timers.  high_bits_check is a copy of
        !            84:  *     high_bits that allows reader to verify that values read are ok.
        !            85:  */
        !            86: 
        !            87: struct timer {
        !            88:        unsigned        low_bits;
        !            89:        unsigned        high_bits;
        !            90:        unsigned        high_bits_check;
        !            91:        unsigned        tstamp;
        !            92: };
        !            93: 
        !            94: typedef struct timer           timer_data_t;
        !            95: typedef        struct timer            *timer_t;
        !            96: 
        !            97: /*
        !            98:  *     Mask to check if low_bits is in danger of overflowing
        !            99:  */
        !           100: 
        !           101: #define        TIMER_LOW_FULL  0x80000000
        !           102: 
        !           103: /*
        !           104:  *     Kernel timers and current timer array.  [Exported]
        !           105:  */
        !           106: 
        !           107: extern timer_t         current_timer[NCPUS];
        !           108: extern timer_data_t    kernel_timer[NCPUS];
        !           109: 
        !           110: /*
        !           111:  *     save structure for timer readings.  This is used to save timer
        !           112:  *     readings for elapsed time computations.
        !           113:  */
        !           114: 
        !           115: struct timer_save {
        !           116:        unsigned        low;
        !           117:        unsigned        high;
        !           118: };
        !           119: 
        !           120: typedef struct timer_save      timer_save_data_t, *timer_save_t;
        !           121: 
        !           122: /*
        !           123:  *     Exported kernel interface to timers
        !           124:  */
        !           125: 
        !           126: #if    STAT_TIME
        !           127: #define start_timer(timer)
        !           128: #define timer_switch(timer)
        !           129: #else  /* STAT_TIME */
        !           130: /* Start timer for this cpu */
        !           131: extern void            start_timer(
        !           132:                                timer_t         timer);
        !           133: 
        !           134: /* Switch to a new timer */
        !           135: extern void            timer_switch(
        !           136:                                timer_t         new_timer);
        !           137: #endif /* STAT_TIME */
        !           138: 
        !           139: /* Initialize timer module */
        !           140: extern void            init_timers(void);
        !           141: 
        !           142: /*
        !           143:  * Initializes a single timer.
        !           144:  */
        !           145: extern void            timer_init(
        !           146:                                timer_t this_timer);
        !           147: 
        !           148: /* Normalize timer value */
        !           149: extern void            timer_normalize(
        !           150:                                timer_t timer);
        !           151: 
        !           152: /* Read value of timer into tv */
        !           153: extern void            timer_read(
        !           154:                                timer_t timer,
        !           155:                                time_value_t *tv);
        !           156: 
        !           157: /* Read thread times */
        !           158: extern void            thread_read_times(
        !           159:                                thread_t        thread,
        !           160:                                time_value_t    *user_time_p,
        !           161:                                time_value_t    *system_time_p);
        !           162: 
        !           163: /* Compute timer difference */
        !           164: extern unsigned                timer_delta(
        !           165:                                timer_t         timer,
        !           166:                                timer_save_t    save);
        !           167: 
        !           168: #if    STAT_TIME
        !           169: /*
        !           170:  *     Macro to bump timer values.
        !           171:  */    
        !           172: #define timer_bump(timer, usec)                                        \
        !           173: MACRO_BEGIN                                                    \
        !           174:        (timer)->low_bits += usec;                              \
        !           175:        if ((timer)->low_bits & TIMER_LOW_FULL) {               \
        !           176:                timer_normalize(timer);                         \
        !           177:        }                                                       \
        !           178: MACRO_END
        !           179: 
        !           180: #else  /* STAT_TIME */
        !           181: /*
        !           182:  *     Exported hardware interface to timers
        !           183:  */
        !           184: /* Time trap entry */
        !           185: extern void            time_trap_uentry(
        !           186:                                unsigned        ts);
        !           187: 
        !           188: /* Time trap exit */
        !           189: extern void            time_trap_uexit(
        !           190:                                unsigned        ts);
        !           191: 
        !           192: /* Time interrupt entry */
        !           193: extern timer_t         time_int_entry(
        !           194:                                unsigned        ts,
        !           195:                                timer_t         new_timer);
        !           196: 
        !           197: /* Time interrrupt exit */
        !           198: extern void            time_int_exit(
        !           199:                                unsigned        ts,
        !           200:                                timer_t         old_timer);
        !           201: 
        !           202: #endif /* STAT_TIME */
        !           203: 
        !           204: /*
        !           205:  *     TIMER_DELTA finds the difference between a timer and a saved value,
        !           206:  *     and updates the saved value.  Look at high_bits check field after
        !           207:  *     reading low because that's the first written by a normalize
        !           208:  *     operation; this isn't necessary for current usage because
        !           209:  *     this macro is only used when the timer can't be normalized:
        !           210:  *     thread is not running, or running thread calls it on itself at
        !           211:  *     splsched().
        !           212:  */
        !           213: 
        !           214: #define TIMER_DELTA(timer, save, result)                       \
        !           215: MACRO_BEGIN                                                    \
        !           216:        register unsigned       temp;                           \
        !           217:                                                                \
        !           218:        temp = (timer).low_bits;                                \
        !           219:        if ((save).high != (timer).high_bits_check) {           \
        !           220:                result += timer_delta(&(timer), &(save));       \
        !           221:        }                                                       \
        !           222:        else {                                                  \
        !           223:                result += temp - (save).low;                    \
        !           224:                (save).low = temp;                              \
        !           225:        }                                                       \
        !           226: MACRO_END
        !           227: 
        !           228: #endif /* _KERN_TIMER_H_ */

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