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Annotation of OSKit-Mach/vm/vm_external.h, revision 1.1

1.1     ! root        1: /*
        !             2:  * Mach Operating System
        !             3:  * Copyright (c) 1991,1990,1989 Carnegie Mellon University
        !             4:  * All Rights Reserved.
        !             5:  *
        !             6:  * Permission to use, copy, modify and distribute this software and its
        !             7:  * documentation is hereby granted, provided that both the copyright
        !             8:  * notice and this permission notice appear in all copies of the
        !             9:  * software, derivative works or modified versions, and any portions
        !            10:  * thereof, and that both notices appear in supporting documentation.
        !            11:  *
        !            12:  * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
        !            13:  * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
        !            14:  * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
        !            15:  *
        !            16:  * Carnegie Mellon requests users of this software to return to
        !            17:  *
        !            18:  *  Software Distribution Coordinator  or  [email protected]
        !            19:  *  School of Computer Science
        !            20:  *  Carnegie Mellon University
        !            21:  *  Pittsburgh PA 15213-3890
        !            22:  *
        !            23:  * any improvements or extensions that they make and grant Carnegie Mellon
        !            24:  * the rights to redistribute these changes.
        !            25:  */
        !            26: 
        !            27: #ifndef        _VM_VM_EXTERNAL_H_
        !            28: #define _VM_VM_EXTERNAL_H_
        !            29: 
        !            30: /*
        !            31:  *     External page management hint technology
        !            32:  *
        !            33:  *     The data structure exported by this module maintains
        !            34:  *     a (potentially incomplete) map of the pages written
        !            35:  *     to external storage for a range of virtual memory.
        !            36:  */
        !            37: 
        !            38: /*
        !            39:  *     The data structure representing the state of pages
        !            40:  *     on external storage.
        !            41:  */
        !            42: 
        !            43: typedef struct vm_external {
        !            44:        int             existence_size; /* Size of the following bitmap */
        !            45:        char            *existence_map; /* A bitmap of pages that have
        !            46:                                         * been written to backing
        !            47:                                         * storage.
        !            48:                                         */
        !            49:        int             existence_count;/* Number of bits turned on in
        !            50:                                         * existence_map.
        !            51:                                         */
        !            52: } *vm_external_t;
        !            53: 
        !            54: #define        VM_EXTERNAL_NULL        ((vm_external_t) 0)
        !            55: 
        !            56: #define VM_EXTERNAL_SMALL_SIZE 128
        !            57: #define VM_EXTERNAL_LARGE_SIZE 8192
        !            58: 
        !            59: /*
        !            60:  *     The states that may be recorded for a page of external storage.
        !            61:  */
        !            62: 
        !            63: typedef int    vm_external_state_t;
        !            64: #define        VM_EXTERNAL_STATE_EXISTS                1
        !            65: #define        VM_EXTERNAL_STATE_UNKNOWN               2
        !            66: #define        VM_EXTERNAL_STATE_ABSENT                3
        !            67: 
        !            68: 
        !            69: /*
        !            70:  *     Routines exported by this module.
        !            71:  */
        !            72: 
        !            73: extern void            vm_external_module_initialize();
        !            74:                                                /* Initialize the module */
        !            75: 
        !            76: extern vm_external_t   vm_external_create();   /* Create a vm_external_t */
        !            77: extern void vm_external_destroy();             /* Destroy one */
        !            78: 
        !            79: extern void            vm_external_state_set();/* Set state of a page. */
        !            80: #define        vm_external_state_get(e,offset) (((e) != VM_EXTERNAL_NULL) ? \
        !            81:                                          _vm_external_state_get(e, offset) : \
        !            82:                                          VM_EXTERNAL_STATE_UNKNOWN)
        !            83:                                                /* Retrieve the state
        !            84:                                                 * for a given page, if known.
        !            85:                                                 */
        !            86: extern vm_external_state_t _vm_external_state_get();
        !            87:                                                /* HIDDEN routine */
        !            88: 
        !            89: #endif /* _VM_VM_EXTERNAL_H_ */

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