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Annotation of XNU/osfmk/mach/flipc_locks.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: /*
        !            27:  * HISTORY
        !            28:  * 
        !            29:  * Revision 1.1.1.1  1998/09/22 21:05:30  wsanchez
        !            30:  * Import of Mac OS X kernel (~semeria)
        !            31:  *
        !            32:  * Revision 1.1.1.1  1998/03/07 02:25:45  wsanchez
        !            33:  * Import of OSF Mach kernel (~mburg)
        !            34:  *
        !            35:  * Revision 1.1.4.1  1995/06/13  18:20:29  sjs
        !            36:  *     Merged from flipc_shared.
        !            37:  *     [95/06/07            sjs]
        !            38:  *
        !            39:  * Revision 1.1.2.3  1995/03/09  19:42:30  rwd
        !            40:  *     Move yield function out of macro and prototype.
        !            41:  *     [1995/03/09  19:36:25  rwd]
        !            42:  * 
        !            43:  * Revision 1.1.2.2  1995/02/21  17:23:11  randys
        !            44:  *     Re-indented code to four space indentation
        !            45:  *     [1995/02/21  16:25:39  randys]
        !            46:  * 
        !            47:  * Revision 1.1.2.1  1994/12/20  19:02:06  randys
        !            48:  *     Moved definition of flipc_simple_lock to flipc_cb.h
        !            49:  *     [1994/12/20  17:34:44  randys]
        !            50:  * 
        !            51:  *     Separated the lock macros out into machine dependent and independent files;
        !            52:  *     this is the machine independent file.
        !            53:  *     [1994/12/20  16:43:38  randys]
        !            54:  * 
        !            55:  * $EndLog$
        !            56:  */
        !            57: 
        !            58: /*
        !            59:  * mach/flipc_locks.h
        !            60:  *
        !            61:  * The machine independent part of the flipc_simple_locks definitions.
        !            62:  * Most of the locks definitions is in flipc_dep.h, but what isn't
        !            63:  * dependent on the platform being used is here.
        !            64:  */
        !            65: 
        !            66: /*
        !            67:  * Note that the locks defined in this file and in flipc_dep.h are only
        !            68:  * for use by user level code.  The reason why this file is visible to
        !            69:  * the kernel is that the kernel section of flipc needs to initialize
        !            70:  * these locks.
        !            71:  */
        !            72: 
        !            73: #ifndef _MACH_FLIPC_LOCKS_H_
        !            74: #define _MACH_FLIPC_LOCKS_H_
        !            75: 
        !            76: /* Get the simple lock type.  */
        !            77: #include <mach/flipc_cb.h>
        !            78: 
        !            79: /*
        !            80:  * Lock function prototypes.  This needs to be before any lock definitions
        !            81:  * that happen to be macros.
        !            82:  */
        !            83: 
        !            84: /* Initializes lock.  Always a macro (so that kernel code can use it without
        !            85:    library assistance).  */
        !            86: void flipc_simple_lock_init(flipc_simple_lock *lock);
        !            87: 
        !            88: /* Returns 1 if lock gained, 0 otherwise.  */
        !            89: int flipc_simple_lock_try(flipc_simple_lock *lock);
        !            90: 
        !            91: /* Returns 1 if lock is locked, 0 otherwise.  */
        !            92: int flipc_simple_lock_locked(flipc_simple_lock *lock);
        !            93: 
        !            94: /* Releases the lock.  */
        !            95: void flipc_simple_lock_release(flipc_simple_lock *lock);
        !            96: 
        !            97: /* Take the lock.  */
        !            98: void flipc_simple_lock_acquire(flipc_simple_lock *lock);
        !            99: 
        !           100: /* Take two locks.  Does not hold one while spinning on the
        !           101:    other.  */
        !           102: void flipc_simple_lock_acquire_2(flipc_simple_lock *lock1,
        !           103:                           flipc_simple_lock *lock2);
        !           104: 
        !           105: /* Get the machine dependent stuff.  The things that need to be
        !           106:  * defined in a machine dependent fashion are:
        !           107:  *
        !           108:  *   flipc_simple_lock_init    (must be a macro)
        !           109:  *   flipc_simple_lock_try
        !           110:  *   flipc_simple_lock_locked
        !           111:  *   flipc_simple_lock_release
        !           112:  *
        !           113:  * These last three don't necessarily have to be macros, but if they
        !           114:  * aren't definitions must be included in the machine dependent
        !           115:  * part of the user level library code.
        !           116:  */
        !           117: #include <mach/machine/flipc_dep.h>
        !           118: 
        !           119: /*
        !           120:  * Set at flipc initialization time to thread_yield argument to
        !           121:  * FLIPC_domain_init
        !           122:  */
        !           123: 
        !           124: extern void (*flipc_simple_lock_yield_fn)(void);
        !           125: 
        !           126: /*
        !           127:  * Machine independent definitions; defined in terms of above routines.
        !           128:  */
        !           129: 
        !           130: /* Take the lock.  Assumes an external define saying how long to
        !           131:    spin, and an external function to call when we've spun too long.  */
        !           132: #define flipc_simple_lock_acquire(lock)                \
        !           133: do {                                           \
        !           134:   int __spin_count = 0;                                \
        !           135:                                                \
        !           136:   while (flipc_simple_lock_locked(lock)                \
        !           137:         || !flipc_simple_lock_try(lock))       \
        !           138:     if (++__spin_count > LOCK_SPIN_LIMIT) {    \
        !           139:       (*flipc_simple_lock_yield_fn)();         \
        !           140:       __spin_count = 0;                                \
        !           141:     }                                          \
        !           142: } while (0)
        !           143: 
        !           144: /* Take two locks.  Hold neither while spinning on the other.  */
        !           145: #define flipc_simple_lock_acquire_2(lock1, lock2)      \
        !           146: do {                                                   \
        !           147:   int __spin_count = 0;                                        \
        !           148:                                                        \
        !           149:   while (1) {                                          \
        !           150:     while (flipc_simple_lock_locked(lock1)             \
        !           151:           || !flipc_simple_lock_try(lock1))            \
        !           152:       if (++__spin_count > LOCK_SPIN_LIMIT) {          \
        !           153:        (*flipc_simple_lock_yield_fn)();                \
        !           154:        __spin_count = 0;                               \
        !           155:       }                                                        \
        !           156:                                                        \
        !           157:     if (flipc_simple_lock_try(lock2))                  \
        !           158:       break;                                           \
        !           159:     flipc_simple_lock_release(lock1);                  \
        !           160:                                                        \
        !           161:     while (flipc_simple_lock_locked(lock2)             \
        !           162:           || !flipc_simple_lock_try(lock2))            \
        !           163:       if (++__spin_count > LOCK_SPIN_LIMIT) {          \
        !           164:        (*flipc_simple_lock_yield_fn)();                \
        !           165:        __spin_count = 0;                               \
        !           166:       }                                                        \
        !           167:                                                        \
        !           168:     if (flipc_simple_lock_try(lock1))                  \
        !           169:       break;                                           \
        !           170:     flipc_simple_lock_release(lock2);                  \
        !           171:   }                                                    \
        !           172: } while (0)
        !           173: 
        !           174: #endif /* _MACH_FLIPC_LOCKS_H_ */

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