mirror of
https://github.com/MariaDB/server.git
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145 lines
3.2 KiB
C
145 lines
3.2 KiB
C
/* Copyright (C) 2000 MySQL AB
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */
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/*
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Handling of uchar arrays as large bitmaps.
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We assume that the size of the used bitmap is less than ~(uint) 0
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TODO:
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Make assembler THREAD safe versions of these using test-and-set instructions
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*/
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#include "mysys_priv.h"
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#include <my_bitmap.h>
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#include <assert.h>
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#include <m_string.h>
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inline void bitmap_lock(MY_BITMAP* map)
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{
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#ifdef THREAD
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if (map->thread_safe)
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pthread_mutex_lock(&map->mutex);
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#endif
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}
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inline void bitmap_unlock(MY_BITMAP* map)
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{
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#ifdef THREAD
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if (map->thread_safe)
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pthread_mutex_unlock(&map->mutex);
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#endif
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}
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my_bool bitmap_init(MY_BITMAP *map, uint bitmap_size, my_bool thread_safe)
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{
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if (!(map->bitmap=(uchar*) my_malloc((bitmap_size+7)/8,
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MYF(MY_WME | MY_ZEROFILL))))
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return 1;
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DBUG_ASSERT(bitmap_size != ~(uint) 0);
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#ifdef THREAD
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if ((map->thread_safe = thread_safe))
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pthread_mutex_init(&map->mutex, MY_MUTEX_INIT_FAST);
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#endif
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map->bitmap_size=bitmap_size;
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return 0;
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}
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void bitmap_free(MY_BITMAP *map)
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{
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if (map->bitmap)
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{
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my_free((char*) map->bitmap, MYF(0));
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map->bitmap=0;
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#ifdef THREAD
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if (map->thread_safe)
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pthread_mutex_destroy(&map->mutex);
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#endif
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}
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}
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void bitmap_set_bit(MY_BITMAP *map, uint bitmap_bit)
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{
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if (bitmap_bit < map->bitmap_size)
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{
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bitmap_lock(map);
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map->bitmap[bitmap_bit / 8] |= (1 << (bitmap_bit & 7));
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bitmap_unlock(map);
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}
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}
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uint bitmap_set_next(MY_BITMAP *map)
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{
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uchar *bitmap=map->bitmap;
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uint bit_found = MY_BIT_NONE;
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uint bitmap_size=map->bitmap_size;
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uint i;
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bitmap_lock(map);
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for (i=0; i < bitmap_size ; i++, bitmap++)
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{
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if (*bitmap != 0xff)
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{ /* Found slot with free bit */
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uint b;
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for (b=0; ; b++)
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{
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if (!(*bitmap & (1 << b)))
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{
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*bitmap |= 1<<b;
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bit_found = (i*8)+b;
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break;
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}
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}
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break; /* Found bit */
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}
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}
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bitmap_unlock(map);
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return bit_found;
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}
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void bitmap_clear_bit(MY_BITMAP *map, uint bitmap_bit)
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{
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if (bitmap_bit < map->bitmap_size)
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{
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bitmap_lock(map);
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map->bitmap[bitmap_bit / 8] &= ~ (1 << (bitmap_bit & 7));
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bitmap_unlock(map);
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}
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}
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void bitmap_set_all(MY_BITMAP* map)
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{
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bitmap_lock(map);
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memset(map->bitmap, 0xff, (map->bitmap_size+7)/8);
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bitmap_unlock(map);
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}
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my_bool bitmap_is_set(MY_BITMAP* map, uint bitmap_bit)
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{
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return (bitmap_bit < map->bitmap_size) ?
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(map->bitmap[bitmap_bit / 8] & (1 << (bitmap_bit & 7))) :
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0;
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}
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void bitmap_clear_all(MY_BITMAP* map)
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{
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bitmap_lock(map);
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bzero(map->bitmap,(map->bitmap_size+7)/8);
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bitmap_unlock(map);
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}
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