libvirt/src/util/bitmap.c
2010-06-18 11:56:04 -04:00

153 lines
3.5 KiB
C

/*
* bitmap.h: Simple bitmap operations
*
* Copyright (C) 2010 Red Hat, Inc.
* Copyright (C) 2010 Novell, Inc.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser 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
*
* Author: Jim Fehlig <jfehlig@novell.com>
*/
#include <config.h>
#include <limits.h>
#include <stdint.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <sys/types.h>
#include "bitmap.h"
#include "memory.h"
struct _virBitmap {
size_t size;
uint32_t *map;
};
#define VIR_BITMAP_BITS_PER_UNIT (sizeof(uint32_t) * CHAR_BIT)
#define VIR_BITMAP_UNIT_OFFSET(b) ((b) / VIR_BITMAP_BITS_PER_UNIT)
#define VIR_BITMAP_BIT_OFFSET(b) ((b) % VIR_BITMAP_BITS_PER_UNIT)
/**
* virBitmapAlloc:
* @size: number of bits
*
* Allocate a bitmap capable of containing @size bits.
*
* Returns a pointer to the allocated bitmap or NULL if
* memory cannot be allocated.
*/
virBitmapPtr virBitmapAlloc(size_t size)
{
virBitmapPtr bitmap;
size_t sz;
if (SIZE_MAX - VIR_BITMAP_BITS_PER_UNIT < size || size == 0)
return NULL;
sz = (size + VIR_BITMAP_BITS_PER_UNIT - 1) /
VIR_BITMAP_BITS_PER_UNIT;
if (VIR_ALLOC(bitmap) < 0)
return NULL;
if (VIR_ALLOC_N(bitmap->map, sz) < 0) {
VIR_FREE(bitmap);
return NULL;
}
return bitmap;
}
/**
* virBitmapFree:
* @bitmap: previously allocated bitmap
*
* Free @bitmap previously allocated by virBitmapAlloc.
*/
void virBitmapFree(virBitmapPtr bitmap)
{
if (bitmap) {
VIR_FREE(bitmap->map);
VIR_FREE(bitmap);
}
}
/**
* virBitmapSetBit:
* @bitmap: Pointer to bitmap
* @b: bit position to set
*
* Set bit position @b in @bitmap
*
* Returns 0 on if bit is successfully set, -1 on error.
*/
int virBitmapSetBit(virBitmapPtr bitmap, size_t b)
{
if (bitmap->size <= b)
return -1;
bitmap->map[VIR_BITMAP_UNIT_OFFSET(b)] |= (1 << VIR_BITMAP_BIT_OFFSET(b));
return 0;
}
/**
* virBitmapClearBit:
* @bitmap: Pointer to bitmap
* @b: bit position to clear
*
* Clear bit position @b in @bitmap
*
* Returns 0 on if bit is successfully clear, -1 on error.
*/
int virBitmapClearBit(virBitmapPtr bitmap, size_t b)
{
if (bitmap->size <= b)
return -1;
bitmap->map[VIR_BITMAP_UNIT_OFFSET(b)] &= ~(1 << VIR_BITMAP_BIT_OFFSET(b));
return 0;
}
/**
* virBitmapGetBit:
* @bitmap: Pointer to bitmap
* @b: bit position to get
* @result: bool pointer to receive bit setting
*
* Get setting of bit position @b in @bitmap and store in @result
*
* On success, @result will contain the setting of @b and 0 is
* returned. On failure, -1 is returned and @result is unchanged.
*/
int virBitmapGetBit(virBitmapPtr bitmap, size_t b, bool *result)
{
uint32_t bit;
if (bitmap->size <= b)
return -1;
bit = bitmap->map[VIR_BITMAP_UNIT_OFFSET(b)] &
(1 << VIR_BITMAP_BIT_OFFSET(b));
*result = bit != 0;
return 0;
}