linux/crypto/scatterwalk.h

/*
 * Cryptographic API.
 *
 * Copyright (c) 2002 James Morris <jmorris@intercode.com.au>
 * Copyright (c) 2002 Adam J. Richter <adam@yggdrasil.com>
 * Copyright (c) 2004 Jean-Luc Cooke <jlcooke@certainkey.com>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the Free
 * Software Foundation; either version 2 of the License, or (at your option)
 * any later version.
 *
 */

#ifndef _CRYPTO_SCATTERWALK_H
#define _CRYPTO_SCATTERWALK_H
#include <linux/mm.h>
#include <asm/scatterlist.h>

struct scatter_walk {
	struct scatterlist	*sg;
	struct page		*page;
	void			*data;
	unsigned int		len_this_page;
	unsigned int		len_this_segment;
	unsigned int		offset;
};

/* Define sg_next is an inline routine now in case we want to change
   scatterlist to a linked list later. */
static inline struct scatterlist *sg_next(struct scatterlist *sg)
{
	return sg + 1;
}

static inline int scatterwalk_samebuf(struct scatter_walk *walk_in,
				      struct scatter_walk *walk_out)
{
	return walk_in->page == walk_out->page &&
	       walk_in->offset == walk_out->offset;
}

static inline unsigned int scatterwalk_clamp(struct scatter_walk *walk,
					     unsigned int nbytes)
{
	return nbytes > walk->len_this_page ? walk->len_this_page : nbytes;
}

static inline void scatterwalk_advance(struct scatter_walk *walk,
				       unsigned int nbytes)
{
	walk->data += nbytes;
	walk->offset += nbytes;
	walk->len_this_page -= nbytes;
	walk->len_this_segment -= nbytes;
}

static inline unsigned int scatterwalk_aligned(struct scatter_walk *walk,
					       unsigned int alignmask)
{
	return !(walk->offset & alignmask);
}

void scatterwalk_start(struct scatter_walk *walk, struct scatterlist *sg);
int scatterwalk_copychunks(void *buf, struct scatter_walk *walk, size_t nbytes, int out);
void scatterwalk_map(struct scatter_walk *walk, int out);
void scatterwalk_done(struct scatter_walk *walk, int out, int more);

#endif  /* _CRYPTO_SCATTERWALK_H */