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Annotation of Gnu-Mach/include/mach/vm_param.h, revision 1.1.1.1

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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