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🎨 Use enums with bit_mask #272

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🎨 Use enums with bit_mask #272

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15 changes: 9 additions & 6 deletions include/stdx/bit.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -399,21 +399,24 @@ template <typename T, std::size_t N> struct bitmask_subtract<std::array<T, N>> {
};
} // namespace detail

template <typename T, std::size_t Msb = detail::num_digits_v<T> - 1,
template <typename T,
std::size_t Msb = detail::num_digits_v<underlying_type_t<T>> - 1,
std::size_t Lsb = 0>
[[nodiscard]] CONSTEVAL auto bit_mask() noexcept -> T {
static_assert(Msb < detail::num_digits_v<T>,
using U = underlying_type_t<T>;
static_assert(Msb < detail::num_digits_v<U>,
"bit_mask requested exceeds the range of the type");
static_assert(Msb >= Lsb, "bit_mask range is invalid");
return detail::bitmask_subtract<T>{}(detail::mask_bits_t<T>{}(Msb + 1),
detail::mask_bits_t<T>{}(Lsb));
return static_cast<T>(detail::bitmask_subtract<U>{}(
detail::mask_bits_t<U>{}(Msb + 1), detail::mask_bits_t<U>{}(Lsb)));
}

template <typename T>
[[nodiscard]] constexpr auto bit_mask(std::size_t Msb,
std::size_t Lsb = 0) noexcept -> T {
return detail::bitmask_subtract<T>{}(detail::mask_bits_t<T>{}(Msb + 1),
detail::mask_bits_t<T>{}(Lsb));
using U = underlying_type_t<T>;
return static_cast<T>(detail::bitmask_subtract<U>{}(
detail::mask_bits_t<U>{}(Msb + 1), detail::mask_bits_t<U>{}(Lsb)));
}

template <typename T> constexpr auto bit_size() -> std::size_t {
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14 changes: 14 additions & 0 deletions test/bit.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -296,6 +296,15 @@ TEST_CASE("template bit_mask (large array type)", "[bit]") {
CHECK(m == A{0, 0, 0, 1});
}

namespace {
enum struct scoped_enum : std::uint8_t { A, B, C };
} // namespace

TEST_CASE("template bit_mask (enum type)", "[bit]") {
constexpr auto m = stdx::bit_mask<scoped_enum>();
STATIC_REQUIRE(m == scoped_enum{0xffu});
}

TEST_CASE("arg bit_mask (whole range)", "[bit]") {
constexpr auto m = stdx::bit_mask<std::uint64_t>(63);
STATIC_REQUIRE(m == std::numeric_limits<std::uint64_t>::max());
Expand Down Expand Up @@ -326,6 +335,11 @@ TEST_CASE("arg bit_mask (single bit)", "[bit]") {
STATIC_REQUIRE(std::is_same_v<decltype(m), std::uint8_t const>);
}

TEST_CASE("arg bit_mask (enum type)", "[bit]") {
constexpr auto m = stdx::bit_mask<scoped_enum>(1);
STATIC_REQUIRE(m == scoped_enum{0b11u});
}

TEMPLATE_TEST_CASE("bit_size", "[bit]", std::uint8_t, std::uint16_t,
std::uint32_t, std::uint64_t, std::int8_t, std::int16_t,
std::int32_t, std::int64_t) {
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