1 /*
2 * linux/fs/ext2/bitmap.c
3 *
4 * Copyright (C) 1992, 1993, 1994, 1995
5 * Remy Card (card@masi.ibp.fr)
6 * Laboratoire MASI - Institut Blaise Pascal
7 * Universite Pierre et Marie Curie (Paris VI)
8 */
9
10 #include <linux/fs.h>
11 #include <linux/ext2_fs.h>
12
13
14 static int nibblemap[] = {4, 3, 3, 2, 3, 2, 2, 1, 3, 2, 2, 1, 2, 1, 1, 0};
15
ext2_count_free(struct buffer_head * map,unsigned int numchars)16 unsigned long ext2_count_free (struct buffer_head * map, unsigned int numchars)
17 {
18 unsigned int i;
19 unsigned long sum = 0;
20
21 if (!map)
22 return (0);
23 for (i = 0; i < numchars; i++)
24 sum += nibblemap[map->b_data[i] & 0xf] +
25 nibblemap[(map->b_data[i] >> 4) & 0xf];
26 return (sum);
27 }
28