Root/fs/ext4/bitmap.c

1/*
2 * linux/fs/ext4/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/buffer_head.h>
11#include <linux/jbd2.h>
12#include "ext4.h"
13
14#ifdef EXT4FS_DEBUG
15
16static const int nibblemap[] = {4, 3, 3, 2, 3, 2, 2, 1, 3, 2, 2, 1, 2, 1, 1, 0};
17
18unsigned int ext4_count_free(struct buffer_head *map, unsigned int numchars)
19{
20    unsigned int i, sum = 0;
21
22    if (!map)
23        return 0;
24    for (i = 0; i < numchars; i++)
25        sum += nibblemap[map->b_data[i] & 0xf] +
26            nibblemap[(map->b_data[i] >> 4) & 0xf];
27    return sum;
28}
29
30#endif /* EXT4FS_DEBUG */
31
32

Archive Download this file



interactive