bitmap.c 639 B

12345678910111213141516171819202122232425262728293031
  1. /*
  2. * linux/fs/ext3/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. #include "ext3.h"
  10. #ifdef EXT3FS_DEBUG
  11. static const int nibblemap[] = {4, 3, 3, 2, 3, 2, 2, 1, 3, 2, 2, 1, 2, 1, 1, 0};
  12. unsigned long ext3_count_free (struct buffer_head * map, unsigned int numchars)
  13. {
  14. unsigned int i;
  15. unsigned long sum = 0;
  16. if (!map)
  17. return (0);
  18. for (i = 0; i < numchars; i++)
  19. sum += nibblemap[map->b_data[i] & 0xf] +
  20. nibblemap[(map->b_data[i] >> 4) & 0xf];
  21. return (sum);
  22. }
  23. #endif /* EXT3FS_DEBUG */