mesh_binary_layout_internal.h

#pragma once
 
#include "pixelbullet/filesystem/native_path.h"
 
#include <cstdint>
#include <filesystem>
#include <limits>
#include <string>
#include <system_error>
 
namespace pixelbullet::mesh_binary_internal
{
[[nodiscard]] inline bool AddBytes(std::uint64_t& total, const std::uint64_t bytes) noexcept
{
    if (bytes > std::numeric_limits<std::uint64_t>::max() - total)
    {
        return false;
    }
    total += bytes;
    return true;
}
 
[[nodiscard]] inline bool MultiplyBytes(const std::uint64_t count, const std::uint64_t stride, std::uint64_t& bytes) noexcept
{
    if (count != 0u && stride > std::numeric_limits<std::uint64_t>::max() / count)
    {
        return false;
    }
    bytes = count * stride;
    return true;
}
 
[[nodiscard]] inline bool AddRepeatedBytes(std::uint64_t& total, const std::uint64_t count, const std::uint64_t stride) noexcept
{
    std::uint64_t bytes = 0u;
    return MultiplyBytes(count, stride, bytes) && AddBytes(total, bytes);
}
 
[[nodiscard]] inline bool TryGetFileSize(const std::filesystem::path& path, std::uint64_t& size, std::string* error_message)
{
    std::error_code error_code;
    const std::uintmax_t raw_size = std::filesystem::file_size(filesystem::to_native_file_io_path(path), error_code);
    if (error_code)
    {
        if (error_message != nullptr)
        {
            *error_message = error_code.message();
        }
        return false;
    }
 
    if (raw_size > static_cast<std::uintmax_t>(std::numeric_limits<std::uint64_t>::max()))
    {
        if (error_message != nullptr)
        {
            *error_message = "file size exceeds supported range";
        }
        return false;
    }
 
    size = static_cast<std::uint64_t>(raw_size);
    return true;
}
 
[[nodiscard]] inline bool FitsFileSize(const std::uint64_t required_size, const std::uint64_t file_size) noexcept
{
    return required_size <= file_size;
}
} // namespace pixelbullet::mesh_binary_internal