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Annotation of Gnu-Mach/include/mach/vm_param.h, revision 1.1

1.1     ! root        1: /* 
        !             2:  * Mach Operating System
        !             3:  * Copyright (c) 1991,1990,1989,1988,1987 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:  *     File:   mach/vm_param.h
        !            28:  *     Author: Avadis Tevanian, Jr., Michael Wayne Young
        !            29:  *     Date:   1985
        !            30:  *
        !            31:  *     Machine independent virtual memory parameters.
        !            32:  *
        !            33:  */
        !            34: 
        !            35: #ifndef        _MACH_VM_PARAM_H_
        !            36: #define _MACH_VM_PARAM_H_
        !            37: 
        !            38: #include <mach/machine/vm_param.h>
        !            39: #include <mach/machine/vm_types.h>
        !            40: 
        !            41: /*
        !            42:  *     The machine independent pages are refered to as PAGES.  A page
        !            43:  *     is some number of hardware pages, depending on the target machine.
        !            44:  *
        !            45:  *     All references to the size of a page should be done
        !            46:  *     with PAGE_SIZE, PAGE_SHIFT, or PAGE_MASK.
        !            47:  *     They may be implemented as either constants or variables,
        !            48:  *     depending on more-specific code.
        !            49:  *     If they're variables, they had better be initialized
        !            50:  *     by the time system-independent code starts getting called.
        !            51:  *
        !            52:  *     Regardless whether it is implemented with a constant or a variable,
        !            53:  *     the PAGE_SIZE is assumed to be a power of two throughout the
        !            54:  *     virtual memory system implementation.
        !            55:  *
        !            56:  *     More-specific code must at least provide PAGE_SHIFT;
        !            57:  *     we can calculate the others if necessary.
        !            58:  *     (However, if PAGE_SHIFT really refers to a variable,
        !            59:  *     PAGE_SIZE and PAGE_MASK should also be variables
        !            60:  *     so their values don't have to be constantly recomputed.)
        !            61:  */
        !            62: #ifndef PAGE_SHIFT
        !            63: #error mach/machine/vm_param.h needs to define PAGE_SHIFT.
        !            64: #endif
        !            65: 
        !            66: #ifndef PAGE_SIZE
        !            67: #define PAGE_SIZE (1 << PAGE_SHIFT)
        !            68: #endif
        !            69: 
        !            70: #ifndef PAGE_MASK
        !            71: #define PAGE_MASK (PAGE_SIZE-1)
        !            72: #endif
        !            73: 
        !            74: /*
        !            75:  *     Convert addresses to pages and vice versa.
        !            76:  *     No rounding is used.
        !            77:  */
        !            78: 
        !            79: #define atop(x)                (((vm_size_t)(x)) >> PAGE_SHIFT)
        !            80: #define ptoa(x)                ((vm_offset_t)((x) << PAGE_SHIFT))
        !            81: 
        !            82: /*
        !            83:  *     Round off or truncate to the nearest page.  These will work
        !            84:  *     for either addresses or counts.  (i.e. 1 byte rounds to 1 page
        !            85:  *     bytes.
        !            86:  */
        !            87: 
        !            88: #define round_page(x)  ((vm_offset_t)((((vm_offset_t)(x)) + PAGE_MASK) & ~PAGE_MASK))
        !            89: #define trunc_page(x)  ((vm_offset_t)(((vm_offset_t)(x)) & ~PAGE_MASK))
        !            90: 
        !            91: /*
        !            92:  *     Determine whether an address is page-aligned, or a count is
        !            93:  *     an exact page multiple.
        !            94:  */
        !            95: 
        !            96: #define        page_aligned(x) ((((vm_offset_t) (x)) & PAGE_MASK) == 0)
        !            97: 
        !            98: #endif /* _MACH_VM_PARAM_H_ */

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