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
55struct vm_page;
56
57struct 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
66void uvm_page_array_init(struct uvm_page_array *, struct uvm_object *,
67    unsigned int);
68void uvm_page_array_fini(struct uvm_page_array *);
69void uvm_page_array_clear(struct uvm_page_array *);
70struct vm_page *uvm_page_array_peek(struct uvm_page_array *);
71void uvm_page_array_advance(struct uvm_page_array *);
72int uvm_page_array_fill(struct uvm_page_array *, voff_t, unsigned int);
73struct 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