Bit Conversions

IEEE 754 specifies two different encodings for decimal floating point types: Binary Integer Significand Field (BID), and Densely Packed Decimal Significand Field (DPD). Internally this library is implemented in the BID format for the IEEE-754 compliant types. Should the user want to capture the bit format in BID or convert to DPD we offer a family of conversion functions: to_bid, from_bid, to_dpd, and from_dpd that allow conversion to or from the bit strings regardless of encoding.

#include <boost/decimal/bid_conversions.hpp>
#include <boost/decimal/dpd_conversions.hpp>

namespace boost {
namespace decimal {

namespace detail {

struct uint128_t
{
    std::uint64_t high;
    std::uint64_t low;
};

} // namespace detail

// ----- BID Conversions -----

constexpr std::uint32_t to_bid_d32(decimal32_t val) noexcept;

constexpr decimal32_t from_bid_d32(std::uint32_t bits) noexcept;

constexpr std::uint32_t to_bid_d32f(decimal_fast32_t val) noexcept;

constexpr decimal_fast32_t from_bid_d32f(std::uint32_t bits) noexcept;

constexpr std::uint64_t to_bid_d64(decimal64_t val) noexcept;

constexpr decimal64_t from_bid_d64(std::uint64_t bits) noexcept;

constexpr std::uint64_t to_bid_d64f(decimal_fast64_t val) noexcept;

constexpr decimal_fast64_t from_bid_d64f(std::uint64_t bits) noexcept;

constexpr detail::uint128 to_bid_d128(decimal128_t val) noexcept;

constexpr decimal128_t from_bid_d128(detail::uint128 bits) noexcept;

// Automatic detection if your platform has built-in unsigned __int128 or not to enable/disable the overload
#ifdef BOOST_DECIMAL_HAS_INT128

constexpr decimal128_t from_bid_d128(unsigned __int128 bits) noexcept;

#endif // BOOST_DECIMAL_HAS_INT128

constexpr detail::uint128_t to_bid_d128f(decimal_fast128_t val) noexcept;

constexpr decimal128_t from_bid_d128f(detail::uint128_t bits) noexcept;

#ifdef BOOST_DECIMAL_HAS_INT128

constexpr decimal128_t from_bid_d128f(unsigned __int128 bits) noexcept;

#endif // BOOST_DECIMAL_HAS_INT128

template <typename T>
constexpr auto to_bid(T val) noexcept;

template <typename T = decimal32_t>
constexpr T from_bid(std::uint32_t bits) noexcept;

template <typename T = decimal64_t>
constexpr T from_bid(std::uint64_t bits) noexcept;

template <typename T = decimal128_t>
constexpr T from_bid(detail::uint128 bits) noexcept;

// ----- DPD Conversions -----

constexpr std::uint32_t to_dpd_d32(decimal32_t val) noexcept;

constexpr std::uint32_t to_dpd_d32f(decimal_fast32_t val) noexcept;

constexpr std::uint64_t to_dpd_d64(decimal64_t val) noexcept;

constexpr std::uint64_t to_dpd_d64f(decimal_fast64_t val) noexcept;

constexpr detail::uint128 to_dpd_d128(decimal128_t val) noexcept;

constexpr detail::uint128 to_dpd_d128f(decimal_fast128_t val) noexcept;

template <typename T>
constexpr auto to_dpd(T val) noexcept;

template <typename T = decimal32_t>
constexpr T from_dpd(std::uint32_t bits) noexcept;

template <typename T = decimal64_t>
constexpr T from_dpd(std::uint64_t bits) noexcept;

template <typename T = decimal128_t>
constexpr T from_dpd(detail::uint128 bits) noexcept;

#ifdef BOOST_DECIMAL_HAS_INT128
template <typename T = decimal128_t>
constexpr T from_dpd(unsigned __int128 bits) noexcept;
#endif

} // namespace decimal
} // namespace boost

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