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Annotation of OSKit-Mach/vm/vm_external.h, revision 1.1.1.1

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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