my_bitmap.h

Go to the documentation of this file.

/*
   Copyright (c) 2001, 2025, Oracle and/or its affiliates.
 
   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License, version 2.0,
   as published by the Free Software Foundation.
 
   This program is designed to work with certain software (including
   but not limited to OpenSSL) that is licensed under separate terms,
   as designated in a particular file or component or in included license
   documentation.  The authors of MySQL hereby grant you an additional
   permission to link the program and your derivative works with the
   separately licensed software that they have either included with
   the program or referenced in the documentation.
 
   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License, version 2.0, for more details.
 
   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA */
 
#ifndef MY_BITMAP_INCLUDED
#define MY_BITMAP_INCLUDED
 
/**
  @file include/my_bitmap.h
*/
 
#define MY_BIT_NONE (~(uint)0)
 
#include <assert.h>
#include <limits.h>
#include <string.h>
#include <sys/types.h>
 
#include "my_inttypes.h"
 
typedef uint32 my_bitmap_map;
 
struct MY_BITMAP {
  my_bitmap_map *bitmap{nullptr};
  uint n_bits{0}; /* number of bits occupied by the above */
  my_bitmap_map last_word_mask{0};
  my_bitmap_map *last_word_ptr{nullptr};
};
 
extern void create_last_word_mask(MY_BITMAP *map);
extern bool bitmap_init(MY_BITMAP *map, my_bitmap_map *buf, uint n_bits);
extern bool bitmap_is_clear_all(const MY_BITMAP *map);
extern bool bitmap_is_prefix(const MY_BITMAP *map, uint prefix_size);
extern bool bitmap_is_set_all(const MY_BITMAP *map);
extern bool bitmap_is_subset(const MY_BITMAP *map1, const MY_BITMAP *map2);
extern bool bitmap_is_overlapping(const MY_BITMAP *map1, const MY_BITMAP *map2);
extern bool bitmap_is_valid(const MY_BITMAP *map);
extern bool bitmap_test_and_set(MY_BITMAP *map, uint bitmap_bit);
extern uint bitmap_set_next(MY_BITMAP *map);
extern uint bitmap_get_first(const MY_BITMAP *map);
extern uint bitmap_get_first_set(const MY_BITMAP *map);
extern uint bitmap_get_next_set(const MY_BITMAP *map, uint bitmap_bit);
extern uint bitmap_bits_set(const MY_BITMAP *map);
extern void bitmap_free(MY_BITMAP *map);
extern void bitmap_set_above(MY_BITMAP *map, uint from_byte, bool use_bit);
extern void bitmap_set_prefix(MY_BITMAP *map, uint prefix_size);
extern void bitmap_intersect(MY_BITMAP *to, const MY_BITMAP *from);
extern void bitmap_subtract(MY_BITMAP *map, const MY_BITMAP *map2);
extern void bitmap_union(MY_BITMAP *map, const MY_BITMAP *map2);
extern void bitmap_xor(MY_BITMAP *map, const MY_BITMAP *map2);
extern void bitmap_invert(MY_BITMAP *map);
extern void bitmap_copy(MY_BITMAP *map, const MY_BITMAP *map2);
extern uint bitmap_n_copy(MY_BITMAP *dst, const MY_BITMAP *src,
                          uint max_bits_to_copy = UINT_MAX);
 
#define bitmap_buffer_size(bits) (((bits) + 31) / 32) * 4
#define no_bytes_in_map(map) (((map)->n_bits + 7) / 8)
#define no_words_in_map(map) (((map)->n_bits + 31) / 32)
 
static inline void bitmap_set_bit(MY_BITMAP *map, uint bit) {
  assert(bit < map->n_bits);
  ((uchar *)map->bitmap)[bit / 8] |= (1 << (bit & 7));
}
 
static inline void bitmap_flip_bit(MY_BITMAP *map, uint bit) {
  assert(bit < map->n_bits);
  ((uchar *)map->bitmap)[bit / 8] ^= (1 << (bit & 7));
}
 
static inline void bitmap_clear_bit(MY_BITMAP *map, uint bit) {
  assert(bit < map->n_bits);
  ((uchar *)map->bitmap)[bit / 8] &= ~(1 << (bit & 7));
}
 
static inline bool bitmap_is_set(const MY_BITMAP *map, uint bit) {
  assert(bit < map->n_bits);
  return ((uchar *)map->bitmap)[bit / 8] & (1 << (bit & 7));
}
 
/**
   Quite unlike other C comparison functions ending with 'cmp', e.g. memcmp(),
   strcmp(), this function returns true if the bitmaps are equal, and false
   otherwise.
 
   @retval true The bitmaps are equal.
   @retval false The bitmaps differ.
 */
static inline bool bitmap_cmp(const MY_BITMAP *map1, const MY_BITMAP *map2) {
  assert(map1->n_bits > 0);
  assert(map2->n_bits > 0);
 
  if (memcmp(map1->bitmap, map2->bitmap, 4 * (no_words_in_map(map1) - 1)) != 0)
    return false;
  return ((*map1->last_word_ptr | map1->last_word_mask) ==
          (*map2->last_word_ptr | map2->last_word_mask));
}
 
/*
  Clears all bits. This is allowed even for a zero-size bitmap.
 */
static inline void bitmap_clear_all(MY_BITMAP *map) {
  memset(map->bitmap, 0, 4 * no_words_in_map(map));
}
 
/*
  Sets all bits. This is allowed even for a zero-size bitmap.
 */
static inline void bitmap_set_all(MY_BITMAP *map) {
  memset(map->bitmap, 0xFF, 4 * no_words_in_map(map));
}
 
#endif  // MY_BITMAP_INCLUDED