fs/ext2/bitmap.c

   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/buffer_head.h>
  11
  12 static int nibblemap[] = {4, 3, 3, 2, 3, 2, 2, 1, 3, 2, 2, 1, 2, 1, 1, 0};
  13
  14 unsigned long ext2_count_free (struct buffer_head * map, unsigned int numchars)
  15 {
  16         unsigned int i;
  17         unsigned long sum = 0;
  18
  19         if (!map)
  20                 return (0);
  21         for (i = 0; i < numchars; i++)
  22                 sum += nibblemap[map->b_data[i] & 0xf] +
  23                         nibblemap[(map->b_data[i] >> 4) & 0xf];
  24         return (sum);
  25 }