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 <linux/ext4_fs.h> 13 14 #ifdef EXT4FS_DEBUG 15 16 static const int nibblemap[] = {4, 3, 3, 2, 3, 2, 2, 1, 3, 2, 2, 1, 2, 1, 1, 0}; 17 18 unsigned long ext4_count_free (struct buffer_head * map, unsigned int numchars) 19 { 20 unsigned int i; 21 unsigned long sum = 0; 22 23 if (!map) 24 return (0); 25 for (i = 0; i < numchars; i++) 26 sum += nibblemap[map->b_data[i] & 0xf] + 27 nibblemap[(map->b_data[i] >> 4) & 0xf]; 28 return (sum); 29 } 30 31 #endif /* EXT4FS_DEBUG */ 32 33