storage.nct

//! Allocator, layout, and raw-buffer representations.

see ./index.nct

use /internal/ptr.from_addr

primitive current_allocator_state(): usize

primitive current_allocator_kind(): usize

primitive allocation_failure_error(): error

copy struct Layout {
    size: usize
    align: usize
}

struct RawBuffer {
    ptr: *u8
    len: usize
    align: usize
    allocator_state: usize
    allocator_kind: usize
}

struct Allocator {
    state: usize
    kind: usize
}

struct AllocationContext {
    state: usize
    kind: usize
}

struct TryAllocator {
    state: usize
    kind: usize
}

func current_allocator(): Allocator {
    return Allocator {
        state: current_allocator_state(),
        kind: current_allocator_kind(),
    }
}

func page_allocator(): Allocator {
    return Allocator { state: 0, kind: 0 }
}

func page_try_allocator(): TryAllocator {
    return TryAllocator { state: 0, kind: 0 }
}

func empty_page_buffer(align: usize): RawBuffer {
    // Kind 2 is an unbound empty sentinel. It owns no storage and therefore
    // carries no allocator origin. The first growth operation binds it to the
    // allocator selected at that operation.
    return RawBuffer {
        ptr: from_addr(1),
        len: 0,
        align: align,
        allocator_state: 0,
        allocator_kind: 2,
    }
}

func take_raw_buffer(buffer: &+RawBuffer): RawBuffer {
    let result = RawBuffer {
        ptr: buffer.ptr,
        len: buffer.len,
        align: buffer.align,
        allocator_state: buffer.allocator_state,
        allocator_kind: buffer.allocator_kind,
    }
    buffer.ptr = from_addr(1)
    buffer.len = 0
    buffer.align = 1
    buffer.allocator_state = 0
    buffer.allocator_kind = 2
    return move result
}