LXR linux/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
  20struct 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. */
  31static inline struct scatterlist *sg_next(struct scatterlist *sg)
  32{
  33        return sg + 1;
  34}
  35
  36static 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
  43static 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
  49static 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
  58static inline unsigned int scatterwalk_aligned(struct scatter_walk *walk,
  59                                               unsigned int alignmask)
  60{
  61        return !(walk->offset & alignmask);
  62}
  63
  64void scatterwalk_start(struct scatter_walk *walk, struct scatterlist *sg);
  65int scatterwalk_copychunks(void *buf, struct scatter_walk *walk, size_t nbytes, int out);
  66void scatterwalk_map(struct scatter_walk *walk, int out);
  67void scatterwalk_done(struct scatter_walk *walk, int out, int more);
  68
  69#endif  /* _CRYPTO_SCATTERWALK_H */
  70