text: #ifndef __RADIOTAP_ITER_H
  #define __RADIOTAP_ITER_H
  
  #include <stdint.h>
  #include "radiotap.h"
  
  /* Radiotap header iteration
   *   implemented in radiotap.c
   */
  
  struct radiotap_override {
  	uint8_t field;
  	uint8_t align:4, size:4;
  };
  
  struct radiotap_align_size {
  	uint8_t align:4, size:4;
  };
  
  struct ieee80211_radiotap_namespace {
  	const struct radiotap_align_size *align_size;
  	int n_bits;
  	uint32_t oui;
  	uint8_t subns;
  };
  
  struct ieee80211_radiotap_vendor_namespaces {
  	const struct ieee80211_radiotap_namespace *ns;
  	int n_ns;
  };
  
  /**
   * struct ieee80211_radiotap_iterator - tracks walk thru present radiotap args
   * @this_arg_index: index of current arg, valid after each successful call
   *	to ieee80211_radiotap_iterator_next()
   * @this_arg: pointer to current radiotap arg; it is valid after each
   *	call to ieee80211_radiotap_iterator_next() but also after
   *	ieee80211_radiotap_iterator_init() where it will point to
   *	the beginning of the actual data portion
   * @this_arg_size: length of the current arg, for convenience
   * @current_namespace: pointer to the current namespace definition
   *	(or internally %NULL if the current namespace is unknown)
   * @is_radiotap_ns: indicates whether the current namespace is the default
   *	radiotap namespace or not
   *
   * @overrides: override standard radiotap fields
   * @n_overrides: number of overrides
   *
   * @_rtheader: pointer to the radiotap header we are walking through
   * @_max_length: length of radiotap header in cpu byte ordering
   * @_arg_index: next argument index
   * @_arg: next argument pointer
   * @_next_bitmap: internal pointer to next present u32
   * @_bitmap_shifter: internal shifter for curr u32 bitmap, b0 set == arg present
   * @_vns: vendor namespace definitions
   * @_next_ns_data: beginning of the next namespace's data
   * @_reset_on_ext: internal; reset the arg index to 0 when going to the
   *	next bitmap word
   *
   * Describes the radiotap parser state. Fields prefixed with an underscore
   * must not be used by users of the parser, only by the parser internally.
   */
  
  struct ieee80211_radiotap_iterator {
  	struct ieee80211_radiotap_header *_rtheader;
  	const struct ieee80211_radiotap_vendor_namespaces *_vns;
  	const struct ieee80211_radiotap_namespace *current_namespace;
  
  	unsigned char *_arg, *_next_ns_data;
  	uint32_t *_next_bitmap;
  
  	unsigned char *this_arg;
  #ifdef RADIOTAP_SUPPORT_OVERRIDES
  	const struct radiotap_override *overrides;
  	int n_overrides;
  #endif
  	int this_arg_index;
  	int this_arg_size;
  
  	int is_radiotap_ns;
  
  	int _max_length;
  	int _arg_index;
  	uint32_t _bitmap_shifter;
  	int _reset_on_ext;
  };
  
  extern int ieee80211_radiotap_iterator_init(
  	struct ieee80211_radiotap_iterator *iterator,
  	struct ieee80211_radiotap_header *radiotap_header,
  	int max_length, const struct ieee80211_radiotap_vendor_namespaces *vns);
  
  extern int ieee80211_radiotap_iterator_next(
  	struct ieee80211_radiotap_iterator *iterator);
  
  #endif /* __RADIOTAP_ITER_H */
  