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#pragma once
#include "packbits-impl.hpp"
#include "compat/assert.hpp"
#include <type_traits>
#include <concepts>
#include <tuple>
#include <Corrade/Utility/Move.h>
namespace floormat::Pack_impl {
template<std::unsigned_integral T, size_t LENGTH>
struct input_field final
{
static_assert(LENGTH > 0);
static_assert(LENGTH <= sizeof(T)*8);
static constexpr size_t Length = LENGTH;
T value;
constexpr T operator*() const { return value; }
constexpr operator T() const { return value; }
};
template<std::unsigned_integral T, size_t LEFT>
struct input
{
static_assert(LEFT > 0);
static_assert(LEFT <= sizeof(T)*8);
static constexpr size_t Left = LEFT;
T value;
template<size_t N>
struct next_
{
static_assert(N <= LEFT);
using type = input<T, LEFT - N>;
};
template<size_t N> using next = typename next_<N>::type;
template<size_t N>
constexpr CORRADE_ALWAYS_INLINE T get() const
{
static_assert(N > 0);
static_assert(N <= sizeof(T)*8);
static_assert(N <= LEFT);
return T(value & (T{1} << N) - T{1});
}
template<size_t N>
constexpr T advance() const
{
static_assert(N <= sizeof(T)*8);
static_assert(N <= LEFT);
return T(value >> N);
}
constexpr bool operator==(const input&) const noexcept = default;
[[nodiscard]] constexpr inline bool check_zero() const { return value == T{0}; }
};
template<std::unsigned_integral T>
struct input<T, 0>
{
static constexpr size_t Left = 0;
using Type = T;
T value;
template<size_t N> [[maybe_unused]] constexpr T get() const = delete;
template<size_t N> [[maybe_unused]] constexpr T advance() const = delete;
constexpr bool operator==(const input&) const noexcept = default;
[[nodiscard]] constexpr inline bool check_zero() const { return true; }
template<size_t N> struct next
{
static_assert(!N, "reading past the end");
static_assert( N, "reading past the end");
};
};
template<typename T> struct is_input_field : std::bool_constant<false> {};
template<std::unsigned_integral T, size_t N> struct is_input_field<input_field<T, N>> : std::bool_constant<true> { static_assert(N > 0); };
template<typename Field>
requires requires (Field& x)
{
{ size_t{Field::Length} > 0 };
sizeof(std::decay_t<decltype(x.value)>);
requires std::unsigned_integral<std::decay_t<decltype(x.value)>>;
}
struct is_input_field<Field> : std::bool_constant<true> {};
template<std::unsigned_integral T, typename Tuple, size_t Left, size_t I, size_t... Is>
constexpr CORRADE_ALWAYS_INLINE void read_(Tuple&& tuple, input<T, Left> st, std::index_sequence<I, Is...>)
{
using U = std::decay_t<Tuple>;
static_assert(Left <= sizeof(T)*8, "bits to read count too large");
static_assert(Left > 0, "too many bits to write");
static_assert(std::tuple_size_v<U> >= sizeof...(Is)+1, "index count larger than tuple element count");
static_assert(I < std::tuple_size_v<U>, "too few tuple elements");
using Field = std::decay_t<std::tuple_element_t<I, U>>;
static_assert(is_input_field<Field>{}, "tuple element must be input_field<T, N>");
constexpr size_t Size = Field::Length;
static_assert(Size <= Left, "data type too small");
using next_type = typename input<T, Left>::template next<Size>;
std::get<I>(tuple).value = st.template get<Size>();
T next_value = st.template advance<Size>();
read_(Utility::forward<Tuple>(tuple), next_type{ next_value }, std::index_sequence<Is...>{});
}
template<std::unsigned_integral T, typename Tuple, size_t Left>
constexpr CORRADE_ALWAYS_INLINE void read_(Tuple&&, input<T, Left> st, std::index_sequence<>)
{
if (!st.check_zero()) [[unlikely]]
throw_on_read_nonzero();
}
} // namespace floormat::Pack_impl
namespace floormat {
template<std::unsigned_integral T, typename Tuple> constexpr void pack_read(Tuple&& tuple, T value)
requires requires (const Tuple& tuple) {
std::tuple_size_v<Tuple> > 0uz;
Pack_impl::is_input_field<std::decay_t<decltype(std::get<0>(tuple))>>::value;
}
{
constexpr size_t nbits = sizeof(T)*8,
tuple_size = std::tuple_size_v<std::decay_t<Tuple>>;
Pack_impl::read_(Utility::forward<Tuple>(tuple),
Pack_impl::input<T, nbits>{value},
std::make_index_sequence<tuple_size>{});
}
} // namespace floormat
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