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      1 /*	$NetBSD: uvm_page_array.h,v 1.3 2020/05/25 21:15:10 ad Exp $	*/
      2 
      3 /*-
      4  * Copyright (c)2011 YAMAMOTO Takashi,
      5  * All rights reserved.
      6  *
      7  * Redistribution and use in source and binary forms, with or without
      8  * modification, are permitted provided that the following conditions
      9  * are met:
     10  * 1. Redistributions of source code must retain the above copyright
     11  *    notice, this list of conditions and the following disclaimer.
     12  * 2. Redistributions in binary form must reproduce the above copyright
     13  *    notice, this list of conditions and the following disclaimer in the
     14  *    documentation and/or other materials provided with the distribution.
     15  *
     16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
     17  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     18  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     19  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
     20  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     21  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     22  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     23  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     24  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     25  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     26  * SUCH DAMAGE.
     27  */
     28 
     29 #if !defined(_UVM_UVM_PAGE_ARRAY_H_)
     30 #define _UVM_UVM_PAGE_ARRAY_H_
     31 
     32 /*
     33  * uvm_page_array: an array of pages.
     34  *
     35  * these structure and functions simply manipulate struct vm_page pointers.
     36  * it's caller's responsibity to acquire and keep the object lock so that
     37  * the result is valid.
     38  *
     39  * typical usage:
     40  *
     41  *	struct uvm_page_array a;
     42  *
     43  *	uvm_page_array_init(&a, uobj, ...);
     44  *	while ((pg = uvm_page_array_fill_and_peek(&a, off, 0)) != NULL) {
     45  *		off = pg->offset + PAGE_SIZE;
     46  *		do_something(pg);
     47  *		uvm_page_array_advance(&a);
     48  *	}
     49  *	uvm_page_array_fini(&a);
     50  *
     51  * if scanning forwards the "off" argument may not go backwards.
     52  * if scanning backwards, the "off" argument may not go forwards.
     53  */
     54 
     55 struct vm_page;
     56 
     57 struct uvm_page_array {
     58 	unsigned int ar_npages;		/* valid elements in ar_pages */
     59 	unsigned int ar_idx;		/* index in ar_pages */
     60 	struct uvm_object *ar_uobj;
     61 	unsigned int ar_flags;
     62 	voff_t ar_lastoff;
     63 	struct vm_page *ar_pages[16];	/* XXX tune */
     64 };
     65 
     66 void uvm_page_array_init(struct uvm_page_array *, struct uvm_object *,
     67     unsigned int);
     68 void uvm_page_array_fini(struct uvm_page_array *);
     69 void uvm_page_array_clear(struct uvm_page_array *);
     70 struct vm_page *uvm_page_array_peek(struct uvm_page_array *);
     71 void uvm_page_array_advance(struct uvm_page_array *);
     72 int uvm_page_array_fill(struct uvm_page_array *, voff_t, unsigned int);
     73 struct vm_page *uvm_page_array_fill_and_peek(struct uvm_page_array *,
     74     voff_t, unsigned int);
     75 
     76 /*
     77  * flags for uvm_page_array_fill and uvm_page_array_fill_and_peek
     78  */
     79 #define	UVM_PAGE_ARRAY_FILL_DIRTY	1	/* dirty pages */
     80 #define	UVM_PAGE_ARRAY_FILL_WRITEBACK	2	/* dirty or written-back */
     81 #define	UVM_PAGE_ARRAY_FILL_DENSE	4	/* stop on a hole */
     82 #define	UVM_PAGE_ARRAY_FILL_BACKWARD	8	/* descend order */
     83 
     84 #endif /* defined(_UVM_UVM_ARRAY_H_) */
     85