#include "data_pool.hpp"

#include <cassert>

namespace vk_capture
{

//
// internal defines
//

//
// internal constants
//

//
// internal types
//

//
// internal variables
//

//
// internal functions
//

//
// public functions
//

void* DataPool::allocate(std::size_t bytes, std::size_t alignment)
{
    assert(bytes > 0 && bytes <= PAGE_SIZE);
    assert(alignment > 0 && alignment <= alignof(std::max_align_t));

    if (offset % alignment != 0) {
        offset += alignment - (offset % alignment);
    }

    const std::size_t remainingOnPage = PAGE_SIZE - (offset % PAGE_SIZE);
    const std::size_t page = offset / PAGE_SIZE;
    const std::size_t localOffset = offset % PAGE_SIZE;
    if (remainingOnPage == PAGE_SIZE || remainingOnPage < bytes)
    {
        // next page
        if (page + 1 >= pages.size()) {
            pages.push_back(std::make_unique<Page>());
        }
        offset = PAGE_SIZE * (pages.size() - 1);
    }
    std::uint8_t* result = &(*pages[page])[localOffset];
    offset += bytes;
    assert(reinterpret_cast<std::uintptr_t>(result) % alignment == 0);
    return result;
}

} // namespace vk_capture