resize

fn resize(
    ctx: *anyopaque,
    buf: []u8,
    alignment: Alignment,
    new_len: usize,
    return_address: usize,
) bool

File

Code

fn resize(
    ctx: *anyopaque,
    buf: []u8,
    alignment: Alignment,
    new_len: usize,
    return_address: usize,
) bool {
    _ = ctx;
    _ = return_address;
    // We don't want to move anything from one size class to another, but we
    // can recover bytes in between powers of two.
    const buf_align = alignment.toByteUnits();
    const old_actual_len = @max(buf.len + @sizeOf(usize), buf_align);
    const new_actual_len = @max(new_len +| @sizeOf(usize), buf_align);
    const old_small_slot_size = math.ceilPowerOfTwoAssert(usize, old_actual_len);
    const old_small_class = math.log2(old_small_slot_size) - min_class;
    if (old_small_class < size_class_count) {
        const new_small_slot_size = math.ceilPowerOfTwo(usize, new_actual_len) catch return false;
        return old_small_slot_size == new_small_slot_size;
    } else {
        const old_bigpages_needed = bigPagesNeeded(old_actual_len);
        const old_big_slot_pages = math.ceilPowerOfTwoAssert(usize, old_bigpages_needed);
        const new_bigpages_needed = bigPagesNeeded(new_actual_len);
        const new_big_slot_pages = math.ceilPowerOfTwo(usize, new_bigpages_needed) catch return false;
        return old_big_slot_pages == new_big_slot_pages;
    }
}