use io;

fn getblockdata(filesystem: *bfs, blockid: u64, data: []u8) (void | io::error) = {
	const blockaddr = (blockid << filesystem.bootsector.blocksize): io::off;

	pread(filesystem.device, data, blockaddr)?;
};

fn setblockdata(filesystem: *bfs, blockid: u64, data: []u8) (void | io::error) = {
	const blockaddr = (blockid << filesystem.bootsector.blocksize): io::off;

	pwrite(filesystem.device, data, blockaddr)?;
};

// Inode block: a block used to store
// inodes
export type inode_block = struct {
	// Previous inode block containing
	// free inodes, or 0
	@offset(0) prevblock: u64,

	// Next inode block containing
	// free inodes, or 0
	@offset(8) nextblock: u64,

	// Next free inode in the block
	@offset(16) nextinode: u64,

	// Lowest yet to be allocated inode
	@offset(24) freeinode: u64,

	// Count of free inodes in block
	@offset(32) freecount: u64,
};

export fn getinblock(filesystem: *bfs, blockid: u64, inblock: *inode_block) (void | io::error) = {
	getblockdata(filesystem, blockid, inblock: *[size(inode_block)]u8)?;
};

export fn setinblock(filesystem: *bfs, blockid: u64, inblock: *inode_block) (void | io::error) = {
	setblockdata(filesystem, blockid, inblock: *[size(inode_block)]u8)?;
};

// Free block: a block that has been
// previously freed
export type free_block = struct {
	// Previous freeblock in freelist
	// or 0
	@offset(0) prevblock: u64,
};

export fn getfreeblock(filesystem: *bfs, blockid: u64, freeblock: *free_block) (void | io::error) = {
	getblockdata(filesystem, blockid, freeblock: *[size(free_block)]u8)?;
};

export fn setfreeblock(filesystem: *bfs, blockid: u64, freeblock: *free_block) (void | io::error) = {
	setblockdata(filesystem, blockid, freeblock: *[size(free_block)]u8)?;
};