https://github.com/torvalds/linux
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Tip revision: 39403865d2e4590802553370a56c9ab93131e4ee authored by Linus Torvalds on 13 May 2007, 01:45:56 UTC
Linux 2.6.22-rc1
Tip revision: 3940386
bitmap.c
/*
 *  linux/fs/ext4/bitmap.c
 *
 * Copyright (C) 1992, 1993, 1994, 1995
 * Remy Card (card@masi.ibp.fr)
 * Laboratoire MASI - Institut Blaise Pascal
 * Universite Pierre et Marie Curie (Paris VI)
 */

#include <linux/buffer_head.h>
#include <linux/jbd2.h>
#include <linux/ext4_fs.h>

#ifdef EXT4FS_DEBUG

static int nibblemap[] = {4, 3, 3, 2, 3, 2, 2, 1, 3, 2, 2, 1, 2, 1, 1, 0};

unsigned long ext4_count_free (struct buffer_head * map, unsigned int numchars)
{
	unsigned int i;
	unsigned long sum = 0;

	if (!map)
		return (0);
	for (i = 0; i < numchars; i++)
		sum += nibblemap[map->b_data[i] & 0xf] +
			nibblemap[(map->b_data[i] >> 4) & 0xf];
	return (sum);
}

#endif  /*  EXT4FS_DEBUG  */

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