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 int scatterwalk_across_pages(struct scatter_walk *walk,
  44                                            unsigned int nbytes)
  45 {
  46         return nbytes > walk->len_this_page;
  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 void scatterwalk_start(struct scatter_walk *walk, struct scatterlist *sg);
  59 int scatterwalk_copychunks(void *buf, struct scatter_walk *walk, size_t nbytes, int out);
  60 void scatterwalk_map(struct scatter_walk *walk, int out);
  61 void scatterwalk_done(struct scatter_walk *walk, int out, int more);
  62
  63 #endif  /* _CRYPTO_SCATTERWALK_H */