#ifndef __LINUX_TEXTSEARCH_H
  #define __LINUX_TEXTSEARCH_H
  
  #include <linux/types.h>
  #include <linux/list.h>
  #include <linux/kernel.h>
  #include <linux/err.h>
  #include <linux/slab.h>
  
  struct module;
  
  struct ts_config;
  
  #define TS_AUTOLOAD	1 /* Automatically load textsearch modules when needed */
  #define TS_IGNORECASE	2 /* Searches string case insensitively */
  
  /**
   * struct ts_state - search state
   * @offset: offset for next match
   * @cb: control buffer, for persistent variables of get_next_block()
   */
  struct ts_state
  {
  	unsigned int		offset;
  	char			cb[40];
  };
  
  /**
   * struct ts_ops - search module operations
   * @name: name of search algorithm
   * @init: initialization function to prepare a search
   * @find: find the next occurrence of the pattern
   * @destroy: destroy algorithm specific parts of a search configuration
   * @get_pattern: return head of pattern
   * @get_pattern_len: return length of pattern
   * @owner: module reference to algorithm
   */
  struct ts_ops
  {
  	const char		*name;
  	struct ts_config *	(*init)(const void *, unsigned int, gfp_t, int);
  	unsigned int		(*find)(struct ts_config *,
  					struct ts_state *);
  	void			(*destroy)(struct ts_config *);
  	void *			(*get_pattern)(struct ts_config *);
  	unsigned int		(*get_pattern_len)(struct ts_config *);
  	struct module		*owner;
  	struct list_head	list;
  };
  
  /**
   * struct ts_config - search configuration
   * @ops: operations of chosen algorithm
   * @flags: flags
   * @get_next_block: callback to fetch the next block to search in
   * @finish: callback to finalize a search
   */
  struct ts_config
  {
  	struct ts_ops		*ops;
  	int 			flags;
  
  	/**
  	 * get_next_block - fetch next block of data
  	 * @consumed: number of bytes consumed by the caller
  	 * @dst: destination buffer
  	 * @conf: search configuration
  	 * @state: search state
  	 *
  	 * Called repeatedly until 0 is returned. Must assign the
  	 * head of the next block of data to &*dst and return the length
  	 * of the block or 0 if at the end. consumed == 0 indicates
  	 * a new search. May store/read persistent values in state->cb.
  	 */
  	unsigned int		(*get_next_block)(unsigned int consumed,
  						  const u8 **dst,
  						  struct ts_config *conf,
  						  struct ts_state *state);
  
  	/**
  	 * finish - finalize/clean a series of get_next_block() calls
  	 * @conf: search configuration
  	 * @state: search state
  	 *
  	 * Called after the last use of get_next_block(), may be used
  	 * to cleanup any leftovers.
  	 */
  	void			(*finish)(struct ts_config *conf,
  					  struct ts_state *state);
  };
  
  /**
   * textsearch_next - continue searching for a pattern
   * @conf: search configuration
   * @state: search state
   *
   * Continues a search looking for more occurrences of the pattern.
   * textsearch_find() must be called to find the first occurrence
   * in order to reset the state.
   *
   * Returns the position of the next occurrence of the pattern or
   * UINT_MAX if not match was found.
   */ 
  static inline unsigned int textsearch_next(struct ts_config *conf,
  					   struct ts_state *state)
  {
  	unsigned int ret = conf->ops->find(conf, state);
  
  	if (conf->finish)
  		conf->finish(conf, state);
  
  	return ret;
  }
  
  /**
   * textsearch_find - start searching for a pattern
   * @conf: search configuration
   * @state: search state
   *
   * Returns the position of first occurrence of the pattern or
   * UINT_MAX if no match was found.
   */ 
  static inline unsigned int textsearch_find(struct ts_config *conf,
  					   struct ts_state *state)
  {
  	state->offset = 0;
  	return textsearch_next(conf, state);
  }
  
  /**
   * textsearch_get_pattern - return head of the pattern
   * @conf: search configuration
   */
  static inline void *textsearch_get_pattern(struct ts_config *conf)
  {
  	return conf->ops->get_pattern(conf);
  }
  
  /**
   * textsearch_get_pattern_len - return length of the pattern
   * @conf: search configuration
   */
  static inline unsigned int textsearch_get_pattern_len(struct ts_config *conf)
  {
  	return conf->ops->get_pattern_len(conf);
  }
  
  extern int textsearch_register(struct ts_ops *);
  extern int textsearch_unregister(struct ts_ops *);
  extern struct ts_config *textsearch_prepare(const char *, const void *,
  					    unsigned int, gfp_t, int);
  extern void textsearch_destroy(struct ts_config *conf);
  extern unsigned int textsearch_find_continuous(struct ts_config *,
  					       struct ts_state *,
  					       const void *, unsigned int);
  
  
  #define TS_PRIV_ALIGNTO	8
  #define TS_PRIV_ALIGN(len) (((len) + TS_PRIV_ALIGNTO-1) & ~(TS_PRIV_ALIGNTO-1))
  
  static inline struct ts_config *alloc_ts_config(size_t payload,
  						gfp_t gfp_mask)
  {
  	struct ts_config *conf;
  
  	conf = kzalloc(TS_PRIV_ALIGN(sizeof(*conf)) + payload, gfp_mask);
  	if (conf == NULL)
  		return ERR_PTR(-ENOMEM);
  
  	return conf;
  }
  
  static inline void *ts_config_priv(struct ts_config *conf)
  {
  	return ((u8 *) conf + TS_PRIV_ALIGN(sizeof(struct ts_config)));
  }
  
  #endif