// `callconv` in function types: `fn(…) callconv(.c) R` in type position makes
// a C-ABI function pointer spellable as a field type — the v-table shape. The
// convention sits between the parameter list and the return, exactly as on a
// declaration signature; parameters cross as ptr+len because callconv(.c)
// forbids slices. One field carries a default, so a table constructed with it
// omitted falls back to the stub.
//
// Lives in examples/register/ (post-v0.5 grammar — the frozen stage0
// bootstrap compiler cannot parse it; gated by `zig build fixpoint`).

pub const SuperBlock = struct {
    _handle u8,
}

pub const File = struct {
    _handle u8,
}

pub const BlockDev = extern struct {
    read_fn ?*fn(u32, *mut [512]u8) callconv(.c) i32,
    write_fn ?*fn(u32, *[512]u8) callconv(.c) i32,
}

pub const VfsOps = extern struct {
    open *fn(*mut SuperBlock, [*]u8, usize) callconv(.c) c_int,
    read *fn(*mut SuperBlock, *mut File, [*]mut u8, u64) callconv(.c) i64,
    close *fn(*mut SuperBlock, *mut File) callconv(.c),
    readdir *fn(*mut SuperBlock, [*]u8, usize, u64) callconv(.c) c_int = defaultReaddir,
}

fn defaultReaddir(sb *mut SuperBlock, path_ptr [*]u8, path_len usize, index u64) callconv(.c) c_int {
    _ = sb
    _ = path_ptr
    _ = path_len
    _ = index
    return -1
}