mariadb/mysys/my_bitmap.c

/* Copyright (C) 2000 MySQL AB

   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.

   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 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA */

/*
  Handling of uchar arrays as large bitmaps.
  We assume that the size of the used bitmap is less than ~(uint) 0

  TODO:
  Make assembler THREAD safe versions of these using test-and-set instructions
*/

#include "mysys_priv.h"
#include <my_bitmap.h>
#include <assert.h>
#include <m_string.h>

inline void bitmap_lock(MY_BITMAP *map)
{
#ifdef THREAD
  if (map->thread_safe)
    pthread_mutex_lock(&map->mutex);
#endif
}

inline void bitmap_unlock(MY_BITMAP *map)
{
#ifdef THREAD
  if (map->thread_safe)
    pthread_mutex_unlock(&map->mutex);
#endif
}

my_bool bitmap_init(MY_BITMAP *map, uchar *buf, uint bitmap_size, my_bool thread_safe)
{
  if (!(map->bitmap=buf) &&
      !(map->bitmap=(uchar*) my_malloc((bitmap_size+7)/8,
				       MYF(MY_WME | MY_ZEROFILL))))
    return 1;
  DBUG_ASSERT(bitmap_size != ~(uint) 0);
#ifdef THREAD
  if ((map->thread_safe = thread_safe))
    pthread_mutex_init(&map->mutex, MY_MUTEX_INIT_FAST);
#endif
  map->bitmap_size=bitmap_size;
  return 0;
}

void bitmap_free(MY_BITMAP *map)
{
  if (map->bitmap)
  {
    my_free((char*) map->bitmap, MYF(0));
    map->bitmap=0;
#ifdef THREAD
    if (map->thread_safe)
      pthread_mutex_destroy(&map->mutex);
#endif
  }
}

void bitmap_set_bit(MY_BITMAP *map, uint bitmap_bit)
{
  DBUG_ASSERT(map->bitmap);
  if (bitmap_bit < map->bitmap_size)
  {
    bitmap_lock(map);
    map->bitmap[bitmap_bit / 8] |= (1 << (bitmap_bit & 7));
    bitmap_unlock(map);
  }
}

uint bitmap_set_next(MY_BITMAP *map)
{
  uchar *bitmap=map->bitmap;
  uint bit_found = MY_BIT_NONE;
  uint bitmap_size=map->bitmap_size;
  uint i;

  DBUG_ASSERT(map->bitmap);
  bitmap_lock(map);
  for (i=0; i < bitmap_size ; i++, bitmap++)
  {
    if (*bitmap != 0xff)
    {						/* Found slot with free bit */
      uint b;
      for (b=0; ; b++)
      {
	if (!(*bitmap & (1 << b)))
	{
	  *bitmap |= 1<<b;
	  bit_found = (i*8)+b;
	  break;
	}
      }
      break;					/* Found bit */
    }
  }
  bitmap_unlock(map);
  return bit_found;
}

void bitmap_clear_bit(MY_BITMAP *map, uint bitmap_bit)
{
  DBUG_ASSERT(map->bitmap);
  if (bitmap_bit < map->bitmap_size)
  {
    bitmap_lock(map);
    map->bitmap[bitmap_bit / 8] &= ~ (1 << (bitmap_bit & 7));
    bitmap_unlock(map);
  }
}

void bitmap_set_prefix(MY_BITMAP *map, uint prefix_size)
{
  uint l, m;

  DBUG_ASSERT(map->bitmap);
  bitmap_lock(map);
  set_if_smaller(prefix_size, map->bitmap_size);
  if ((l=prefix_size / 8))
    memset(map->bitmap, 0xff, l);
  if ((m=prefix_size & 7))
    map->bitmap[l++]= (1 << m)-1;
  if (l < (m=(map->bitmap_size+7)/8))
    bzero(map->bitmap+l, m-l);
  bitmap_unlock(map);
}

void bitmap_clear_all(MY_BITMAP *map)
{
  bitmap_set_prefix(map, 0);
}

void bitmap_set_all(MY_BITMAP *map)
{
  bitmap_set_prefix(map, map->bitmap_size);
}

my_bool bitmap_is_prefix(MY_BITMAP *map, uint prefix_size)
{
  uint l=prefix_size/8, m=prefix_size & 7, i, res=0;

  DBUG_ASSERT(map->bitmap);
  if (prefix_size > map->bitmap_size)
    return 0;

  bitmap_lock(map);
  for (i=0; i < l; i++)
    if (map->bitmap[i] != 0xff)
      goto ret;

  if (m && map->bitmap[i++] != (1 << m)-1)
    goto ret;

  for (m=(map->bitmap_size+7)/8; i < m; i++)
    if (map->bitmap[i] != 0)
      goto ret;

  res=1;
ret:
  bitmap_unlock(map);
  return res;
}

my_bool bitmap_is_clear_all(MY_BITMAP *map)
{
  return bitmap_is_prefix(map, 0);
}

my_bool bitmap_is_set_all(MY_BITMAP *map)
{
  return bitmap_is_prefix(map, map->bitmap_size);
}

my_bool bitmap_is_set(MY_BITMAP *map, uint bitmap_bit)
{
  DBUG_ASSERT(map->bitmap);
  return (bitmap_bit < map->bitmap_size) ?
    (map->bitmap[bitmap_bit / 8] & (1 << (bitmap_bit & 7))) : 0;
}

my_bool bitmap_is_subset(MY_BITMAP *map1, MY_BITMAP *map2)
{
  uint l1, l2, i, res=0;
  uchar *m1=map1->bitmap, *m2=map2->bitmap;

  DBUG_ASSERT(map1->bitmap);
  DBUG_ASSERT(map2->bitmap);
  bitmap_lock(map1);
  bitmap_lock(map2);

  l1=(map1->bitmap_size+7)/8;
  l2=(map2->bitmap_size+7)/8;
  set_if_smaller(l2, l1);

  for (i=0; i < l2; i++)
    if ((*m1++) & ~(*m2++))
      goto ret;

  for (; i < l1; i++)
    if (*m1++)
      goto ret;

  res=1;
ret:
  bitmap_unlock(map2);
  bitmap_unlock(map1);
  return res;
}

my_bool bitmap_cmp(MY_BITMAP *map1, MY_BITMAP *map2)
{
  uint res;

  DBUG_ASSERT(map1->bitmap);
  DBUG_ASSERT(map2->bitmap);
  bitmap_lock(map1);
  bitmap_lock(map2);

  res= map1->bitmap_size == map2->bitmap_size &&
       memcmp(map1->bitmap, map2->bitmap, (map1->bitmap_size+7)/8)==0;

  bitmap_unlock(map2);
  bitmap_unlock(map1);
  return res;
}

void bitmap_intersect(MY_BITMAP *map, MY_BITMAP *map2)
{
  uint l1, l2, i;
  uchar *m=map->bitmap, *m2=map2->bitmap;

  DBUG_ASSERT(map->bitmap);
  DBUG_ASSERT(map2->bitmap);
  bitmap_lock(map);
  bitmap_lock(map2);

  l1=(map->bitmap_size+7)/8;
  l2=(map2->bitmap_size+7)/8;
  set_if_smaller(l2, l1);

  for (i=0; i < l2; i++)
    *m++ &= *m2++;

  if (l1 > l2)
    bzero(m, l1-l2);

  bitmap_unlock(map2);
  bitmap_unlock(map);
}

void bitmap_subtract(MY_BITMAP *map, MY_BITMAP *map2)
{
  uint l1, l2, i;
  uchar *m=map->bitmap, *m2=map2->bitmap;

  DBUG_ASSERT(map->bitmap);
  DBUG_ASSERT(map2->bitmap);
  bitmap_lock(map);
  bitmap_lock(map2);

  l1=(map->bitmap_size+7)/8;
  l2=(map2->bitmap_size+7)/8;
  set_if_smaller(l2, l1);

  for (i=0; i < l2; i++)
    *m++ &= ~(*m2++);

  bitmap_unlock(map2);
  bitmap_unlock(map);
}

void bitmap_union(MY_BITMAP *map, MY_BITMAP *map2)
{
  uint l1, l2, i;
  uchar *m=map->bitmap, *m2=map2->bitmap;

  DBUG_ASSERT(map->bitmap);
  DBUG_ASSERT(map2->bitmap);
  bitmap_lock(map);
  bitmap_lock(map2);

  l1=(map->bitmap_size+7)/8;
  l2=(map2->bitmap_size+7)/8;
  set_if_smaller(l2, l1);

  for (i=0; i < l2; i++)
    *m++ |= *m2++;

  bitmap_unlock(map2);
  bitmap_unlock(map);
}