/*
   * QNX4 file system, Linux implementation.
   *
   * Version : 0.2.1
   *
   * Using parts of the xiafs filesystem.
   *
   * History :
   *
   * 28-05-1998 by Richard Frowijn : first release.
   * 20-06-1998 by Frank Denis : basic optimisations.
   * 25-06-1998 by Frank Denis : qnx4_is_free, qnx4_set_bitmap, qnx4_bmap .
   * 28-06-1998 by Frank Denis : qnx4_free_inode (to be fixed) .
   */

  #include <linux/buffer_head.h>
  #include <linux/bitops.h>

  #include "qnx4.h"

  static void count_bits(register const char *bmPart, register int size,
  		       int *const tf)
  {
  	char b;
  	int tot = *tf;
  
  	if (size > QNX4_BLOCK_SIZE) {
  		size = QNX4_BLOCK_SIZE;
  	}
  	do {
  		b = *bmPart++;

  		tot += 8 - hweight8(b);

  		size--;
  	} while (size != 0);
  	*tf = tot;
  }
  
  unsigned long qnx4_count_free_blocks(struct super_block *sb)
  {
  	int start = le32_to_cpu(qnx4_sb(sb)->BitMap->di_first_xtnt.xtnt_blk) - 1;
  	int total = 0;
  	int total_free = 0;
  	int offset = 0;
  	int size = le32_to_cpu(qnx4_sb(sb)->BitMap->di_size);
  	struct buffer_head *bh;
  
  	while (total < size) {
  		if ((bh = sb_bread(sb, start + offset)) == NULL) {

  			printk(KERN_ERR "qnx4: I/O error in counting free blocks
  ");

  			break;
  		}
  		count_bits(bh->b_data, size - total, &total_free);
  		brelse(bh);
  		total += QNX4_BLOCK_SIZE;
  		offset++;
  	}
  
  	return total_free;
  }