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/* Copyright (C) 2000 MySQL AB & MySQL Finland AB & TCX DataKonsult AB
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public
License as published by the Free Software Foundation; either
version 2 of the License, or (at your option) any later version.
This library 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
Library General Public License for more details.
You should have received a copy of the GNU Library General Public
License along with this library; 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>
my_bool bitmap_init(MY_BITMAP *map, uint bitmap_size)
{
if (!(map->bitmap=(uchar*) my_malloc((bitmap_size+7)/8,
MYF(MY_WME | MY_ZEROFILL))))
return 1;
dbug_assert(bitmap_size != ~(uint) 0);
#ifdef THREAD
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
pthread_mutex_destroy(&map->mutex);
#endif
}
}
void bitmap_set_bit(MY_BITMAP *map, uint bitmap_bit)
{
if (bitmap_bit < map->bitmap_size)
{
pthread_mutex_lock(&map->mutex);
map->bitmap[bitmap_bit / 8] |= (1 << (bitmap_bit & 7));
pthread_mutex_unlock(&map->mutex);
}
}
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;
pthread_mutex_lock(&map->mutex);
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 */
}
}
pthread_mutex_unlock(&map->mutex);
return bit_found;
}
void bitmap_clear_bit(MY_BITMAP *map, uint bitmap_bit)
{
if (bitmap_bit < map->bitmap_size)
{
pthread_mutex_lock(&map->mutex);
map->bitmap[bitmap_bit / 8] &= ~ (1 << (bitmap_bit & 7));
pthread_mutex_unlock(&map->mutex);
}
}
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