From: Goswin von Brederlow <goswin-v-b@web.de>
Subject: Suggestions for a 64bit bitmap api
Date: Wed, 16 Jul 2008 14:12:02 +0200
Message-ID: <87y742110t.fsf@frosties.localdomain>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
To: linux-ext4@vger.kernel.org
Sender: linux-ext4-owner@vger.kernel.org

Hi,

which api would you prefer?

Option 1
========

typedef enum {TYPE1, TYPE2} bitmap_type;

struct ext2fs_abstract_bitmap {
  bitmap_type type;
};

struct ext2fs_type1_bitmap {
  bitmap_type type;
  type1_data data;
};

struct ext2fs_type2_bitmap {
  bitmap_type type;
  type2_data data;
};

int ext2fs_fast_test_block_type1_bitmap(ext2fs_type1_bitmap *map, blk64_t i);
int ext2fs_fast_test_block_type2_bitmap(ext2fs_type2_bitmap *map, blk64_t i);
int ext2fs_fast_test_block_abstract_bitmap(ext2fs_abstract_bitmap *map, blk64_t i) {
  switch(map->type) {
    case TYPE1: return ext2fs_fast_test_block_type1_bitmap((ext2fs_type1_bitmap*)map, i);
    case TYPE2: return ext2fs_fast_test_block_type2_bitmap((ext2fs_type2_bitmap*)map, i);
  };
  return 0;
}


Option 2
========

struct ext2fs_abstract_bitmap {
  int (*fast_test_block)(void *map, blk64_t i);
  void *map;
};

int ext2fs_fast_test_block_abstract_bitmap(ext2fs_abstract_bitmap *map, blk64_t i) {
  return map->fast_test_block(map->map, i);
}


Option 3
========

struct ext2fs_bitmap_ops {
  int (*fast_test_block)(ext2fs_abstract_bitmap *map, blk64_t i); 
};

struct ext2fs_abstract_bitmap {
  ext2fs_bitmap_ops *ops;
};

struct ext2fs_type1_bitmap {
  ext2fs_bitmap_ops *ops;
  type1_data data;
};

struct ext2fs_type2_bitmap {
  ext2fs_bitmap_ops *ops;
  type2_data data;
};

int ext2fs_fast_test_block_abstract_bitmap(ext2fs_abstract_bitmap *map, blk64_t i) {
  return map->ops->fast_test_block(map, i);
}


Or something completly different?

MfG
        Goswin