[CRYPTO] Add alignmask for low-level cipher implementations
[linux-3.10.git] / crypto / scatterwalk.h
1 /*
2  * Cryptographic API.
3  *
4  * Copyright (c) 2002 James Morris <jmorris@intercode.com.au>
5  * Copyright (c) 2002 Adam J. Richter <adam@yggdrasil.com>
6  * Copyright (c) 2004 Jean-Luc Cooke <jlcooke@certainkey.com>
7  *
8  * This program is free software; you can redistribute it and/or modify it
9  * under the terms of the GNU General Public License as published by the Free
10  * Software Foundation; either version 2 of the License, or (at your option)
11  * any later version.
12  *
13  */
14
15 #ifndef _CRYPTO_SCATTERWALK_H
16 #define _CRYPTO_SCATTERWALK_H
17 #include <linux/mm.h>
18 #include <asm/scatterlist.h>
19
20 struct scatter_walk {
21         struct scatterlist      *sg;
22         struct page             *page;
23         void                    *data;
24         unsigned int            len_this_page;
25         unsigned int            len_this_segment;
26         unsigned int            offset;
27 };
28
29 /* Define sg_next is an inline routine now in case we want to change
30    scatterlist to a linked list later. */
31 static inline struct scatterlist *sg_next(struct scatterlist *sg)
32 {
33         return sg + 1;
34 }
35
36 static inline int scatterwalk_samebuf(struct scatter_walk *walk_in,
37                                       struct scatter_walk *walk_out)
38 {
39         return walk_in->page == walk_out->page &&
40                walk_in->offset == walk_out->offset;
41 }
42
43 static inline unsigned int scatterwalk_clamp(struct scatter_walk *walk,
44                                              unsigned int nbytes)
45 {
46         return nbytes > walk->len_this_page ? walk->len_this_page : nbytes;
47 }
48
49 static inline void scatterwalk_advance(struct scatter_walk *walk,
50                                        unsigned int nbytes)
51 {
52         walk->data += nbytes;
53         walk->offset += nbytes;
54         walk->len_this_page -= nbytes;
55         walk->len_this_segment -= nbytes;
56 }
57
58 static inline unsigned int scatterwalk_aligned(struct scatter_walk *walk,
59                                                unsigned int alignmask)
60 {
61         return !(walk->offset & alignmask);
62 }
63
64 void scatterwalk_start(struct scatter_walk *walk, struct scatterlist *sg);
65 int scatterwalk_copychunks(void *buf, struct scatter_walk *walk, size_t nbytes, int out);
66 void scatterwalk_map(struct scatter_walk *walk, int out);
67 void scatterwalk_done(struct scatter_walk *walk, int out, int more);
68
69 #endif  /* _CRYPTO_SCATTERWALK_H */