Source to mach/vm_param.h

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/* 
 * Mach Operating System
 * Copyright (c) 1991,1990,1989,1988,1987 Carnegie Mellon University
 * All Rights Reserved.
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 * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
 * 
 * Carnegie Mellon requests users of this software to return to
 * 
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 */
/*
 *	File:	mach/vm_param.h
 *	Author:	Avadis Tevanian, Jr., Michael Wayne Young
 *	Date:	1985
 *
 *	Machine independent virtual memory parameters.
 *
 */

#ifndef	_MACH_VM_PARAM_H_
#define _MACH_VM_PARAM_H_

#import <mach/machine/vm_param.h>
#import <mach/machine/vm_types.h>

#ifdef	KERNEL
/*
 *	The machine independent pages are refered to as PAGES.  A page
 *	is some number of hardware pages, depending on the target machine.
 */

/*
 *	All references to the size of a page should be done with PAGE_SIZE
 *	or PAGE_SHIFT.  The fact they are variables is hidden here so that
 *	we can easily make them constant if we so desire.
 */

/*
 *	Regardless whether it is implemented with a constant or a variable,
 *	the PAGE_SIZE is assumed to be a power of two throughout the
 *	virtual memory system implementation.
 */

#ifndef	PAGE_SIZE_FIXED
#define PAGE_SIZE	page_size	/* size of page in addressible units */
#define PAGE_SHIFT	page_shift	/* number of bits to shift for pages */
#endif	/* PAGE_SIZE_FIXED */

#ifndef	__ASSEMBLER__
/*
 *	Convert addresses to pages and vice versa.
 *	No rounding is used.
 */

#define atop(x)		(((vm_size_t)(x)) >> page_shift)
#define ptoa(x)		((vm_offset_t)((x) << page_shift))

/*
 *	Round off or truncate to the nearest page.  These will work
 *	for either addresses or counts.  (i.e. 1 byte rounds to 1 page
 *	bytes.
 */

#define round_page(x)	((vm_offset_t)((((vm_offset_t)(x)) + page_mask) & ~page_mask))
#define trunc_page(x)	((vm_offset_t)(((vm_offset_t)(x)) & ~page_mask))

/*
 *	Determine whether an address is page-aligned, or a count is
 *	an exact page multiple.
 */

#define	page_aligned(x)	((((vm_offset_t) (x)) & page_mask) == 0)

#ifndef	PAGE_SIZE_FIXED
extern vm_size_t	page_size;	/* machine independent page size */
extern vm_size_t	page_mask;	/* page_size - 1; mask for
						   offset within page */
extern int		page_shift;	/* shift to use for page size */
#else	/* PAGE_SIZE_FIXED */
#define	page_mask	(PAGE_SIZE-1)
#endif	/* PAGE_SIZE_FIXED */

extern vm_size_t	mem_size;	/* size of physical memory (bytes) */
extern vm_offset_t	first_addr;	/* first physical page */
extern vm_offset_t	last_addr;	/* last physical page */

#endif	/* __ASSEMBLER__ */

#else
#define	round_page(x)	((((vm_offset_t)(x) + (vm_page_size - 1)) \
						/ vm_page_size) * vm_page_size)
#define	trunc_page(x)	((((vm_offset_t)(x)) / vm_page_size) * vm_page_size)
#endif

#endif	/* _MACH_VM_PARAM_H_ */