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Merged
ckormanyos merged 4 commits into from
Sep 20, 2025
Merged

Simplify syntax cpp_double_fp_backend #739

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ef77359
Simplify syntax cpp_double_fp_backend
ckormanyos Sep 20, 2025
ba43d82
Patch up syntax error
ckormanyos Sep 20, 2025
156c878
Simplify rd_string() and improve syntax
ckormanyos Sep 20, 2025
156e03e
Improve rd_string inf-check and add tests
ckormanyos Sep 20, 2025
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2 changes: 1 addition & 1 deletion include/boost/multiprecision/cpp_df_qf/cpp_df_qf_detail_constants.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -12,7 +12,7 @@

#include <type_traits>

#if (defined(__GNUC__) && defined(BOOST_MP_CPP_DOUBLE_FP_HAS_FLOAT128))
#if (defined(BOOST_GCC) && defined(BOOST_MP_CPP_DOUBLE_FP_HAS_FLOAT128))
//
// This is the only way we can avoid
// warning: non-standard suffix on floating constant [-Wpedantic]
Expand Down
210 changes: 117 additions & 93 deletions include/boost/multiprecision/cpp_double_fp.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -249,11 +249,7 @@ class cpp_double_fp_backend
typename ::std::enable_if<( cpp_df_qf_detail::is_floating_point<OtherFloatType>::value
&& (!std::is_same<FloatingPointType, OtherFloatType>::value))>::type const* = nullptr>
constexpr cpp_double_fp_backend(const cpp_double_fp_backend<OtherFloatType>& a)
: cpp_double_fp_backend(a.my_first())
{
// TBD: Maybe specialize this constructor for cases either wider or less wide.
operator+=(a.my_second());
}
: cpp_double_fp_backend(cpp_double_fp_backend(a.my_first()) += a.my_second()) { }

// Constructors from integers.
template <typename SignedIntegralType,
Expand Down Expand Up @@ -281,7 +277,7 @@ class cpp_double_fp_backend
{
using local_unsigned_integral_type = UnsignedIntegralType;

if (u > cpp_df_qf_detail::float_mask<UnsignedIntegralType, float_type>())
if (u > cpp_df_qf_detail::float_mask<local_unsigned_integral_type, float_type>())
{
local_unsigned_integral_type
local_flt_mask
Expand Down Expand Up @@ -332,9 +328,9 @@ class cpp_double_fp_backend

constexpr cpp_double_fp_backend(const cpp_df_qf_detail::pair<float_type, float_type>& p) noexcept : data(p) { }

cpp_double_fp_backend(const char* s)
cpp_double_fp_backend(const char* p_str)
{
*this = s;
*this = p_str;
}

// Assignment operator.
Expand Down Expand Up @@ -377,9 +373,9 @@ class cpp_double_fp_backend
return operator=(cpp_double_fp_backend(n));
}

auto operator=(const char* v) -> cpp_double_fp_backend&
auto operator=(const char* p_str) -> cpp_double_fp_backend&
{
rd_string(v);
rd_string(p_str);

return *this;
}
Expand All @@ -388,9 +384,6 @@ class cpp_double_fp_backend
{
std::size_t result { UINT8_C(0) };

int n_first { };
int n_second { };

#if defined(BOOST_MP_CPP_DOUBLE_FP_HAS_FLOAT128)
using local_float_type = typename std::conditional<::std::is_same<float_type, ::boost::float128_type>::value,
long double,
Expand All @@ -399,10 +392,8 @@ class cpp_double_fp_backend
using local_float_type = float_type;
#endif

boost::multiprecision::detail::hash_combine(result, static_cast<local_float_type>(cpp_df_qf_detail::ccmath::frexp(data.first, &n_first)));
boost::multiprecision::detail::hash_combine(result, static_cast<local_float_type>(cpp_df_qf_detail::ccmath::frexp(data.second, &n_second)));
boost::multiprecision::detail::hash_combine(result, n_first);
boost::multiprecision::detail::hash_combine(result, n_second);
boost::multiprecision::detail::hash_combine(result, static_cast<local_float_type>(data.first));
boost::multiprecision::detail::hash_combine(result, static_cast<local_float_type>(data.second));

return result;
}
Expand Down Expand Up @@ -895,9 +886,9 @@ class cpp_double_fp_backend
// Use cpp_bin_float when writing to string. This is similar
// to the use of cpp_bin_float when reading from string.

cpp_bin_float_read_write_type f_bin { data.first };
cpp_bin_float_read_write_backend_type f_bin { data.first };

f_bin += data.second;
eval_add(f_bin, cpp_bin_float_read_write_backend_type(data.second));

return f_bin.str(number_of_digits, format_flags);
}
Expand Down Expand Up @@ -1029,11 +1020,8 @@ class cpp_double_fp_backend
rep_type data;

using cpp_bin_float_read_write_backend_type = boost::multiprecision::backends::cpp_bin_float<static_cast<unsigned>(my_digits), digit_base_2, void, int, cpp_df_qf_detail::ccmath::numeric_limits<float_type>::min_exponent, cpp_df_qf_detail::ccmath::numeric_limits<float_type>::max_exponent>;
using cpp_bin_float_read_write_exp_type = typename cpp_bin_float_read_write_backend_type::exponent_type;

using cpp_bin_float_read_write_type = boost::multiprecision::number<cpp_bin_float_read_write_backend_type, boost::multiprecision::et_off>;

constexpr auto rd_string(const char* pstr) -> bool;
constexpr auto rd_string(const char* p_str) -> bool;

constexpr auto add_unchecked(const cpp_double_fp_backend& v) -> void
{
Expand Down Expand Up @@ -1171,11 +1159,15 @@ class cpp_double_fp_backend
};

template <typename FloatingPointType>
constexpr auto cpp_double_fp_backend<FloatingPointType>::rd_string(const char* pstr) -> bool
constexpr auto cpp_double_fp_backend<FloatingPointType>::rd_string(const char* p_str) -> bool
{
cpp_bin_float_read_write_type f_bin { pstr };
// Use an intermediate cpp_bin_float backend type for reading string input.

cpp_bin_float_read_write_backend_type f_bin { };

const int fpc { fpclassify(f_bin) };
f_bin = p_str;

const int fpc { eval_fpclassify(f_bin) };

const bool is_definitely_nan { (fpc == FP_NAN) };

Expand All @@ -1184,98 +1176,130 @@ constexpr auto cpp_double_fp_backend<FloatingPointType>::rd_string(const char* p
if (is_definitely_nan)
{
static_cast<void>(operator=(local_double_fp_type::my_value_nan()));

return true;
}
else
{
const bool b_neg { (signbit(f_bin) == 1) };

if (b_neg) { f_bin = -f_bin; }
const bool b_neg { (eval_signbit(f_bin) == 1) };

const int
expval_from_f_bin
if (b_neg) { f_bin.negate(); }

const int
expval_from_f_bin
{
[&f_bin]()
{
[&f_bin]()
{
int expval;
int expval { };

frexp(f_bin, &expval);
cpp_bin_float_read_write_backend_type dummy { };

return expval;
}()
};
eval_frexp(dummy, f_bin, &expval);

const auto is_zero_or_subnormal =
(
(fpc == FP_ZERO)
|| (expval_from_f_bin < static_cast<cpp_bin_float_read_write_exp_type>(local_double_fp_type::my_min_exponent))
);
return expval;
}()
};

if (is_zero_or_subnormal)
const auto is_zero_or_subnormal =
(
(fpc == FP_ZERO)
|| (expval_from_f_bin < static_cast<typename cpp_bin_float_read_write_backend_type::exponent_type>(local_double_fp_type::my_min_exponent))
);

if (is_zero_or_subnormal)
{
data.first = float_type { 0.0F };
data.second = float_type { 0.0F };

return true;
}

float_type flt_inf_check_first { };

eval_convert_to(&flt_inf_check_first, f_bin);

bool is_definitely_inf { ((fpc == FP_INFINITE) || cpp_df_qf_detail::ccmath::isinf(flt_inf_check_first)) };

if (!is_definitely_inf)
{
if (flt_inf_check_first > my_value_max().my_first())
{
data.first = float_type { 0.0F };
data.second = float_type { 0.0F };
cpp_bin_float_read_write_backend_type f_bin_inf_check(f_bin);

eval_subtract(f_bin_inf_check, cpp_bin_float_read_write_backend_type(flt_inf_check_first));

float_type flt_inf_check_second { };

eval_convert_to(&flt_inf_check_second, f_bin_inf_check);

is_definitely_inf = eval_gt(local_double_fp_type(flt_inf_check_first, flt_inf_check_second), my_value_max());
}
else
};

if (is_definitely_inf)
{
static_cast<void>(operator=(local_double_fp_type::my_value_inf()));

if (b_neg)
{
const auto is_definitely_inf = (f_bin > (::std::numeric_limits<cpp_bin_float_read_write_type>::max)());
negate();
}

if (is_definitely_inf)
{
static_cast<void>(operator=(local_double_fp_type::my_value_inf()));
return true;
}

if (b_neg) { negate(); }
}
else
{
data.first = float_type { 0.0F };
data.second = float_type { 0.0F };
// The input string is normal. We will now extract its value.

using local_builtin_float_type = typename std::conditional<(sizeof(float_type) <= sizeof(double)), double, float_type>::type;
data.first = float_type { 0.0F };
data.second = float_type { 0.0F };

constexpr int pow2_scaling_for_small_input { cpp_df_qf_detail::ccmath::numeric_limits<float_type>::digits };
constexpr int pow2_scaling_for_small_input { cpp_df_qf_detail::ccmath::numeric_limits<float_type>::digits };

const auto has_pow2_scaling_for_small_input =
(
expval_from_f_bin < static_cast<int>(local_double_fp_type::my_min_exponent + pow2_scaling_for_small_input)
);
const auto has_pow2_scaling_for_small_input =
(
expval_from_f_bin < static_cast<int>(local_double_fp_type::my_min_exponent + pow2_scaling_for_small_input)
);

if (has_pow2_scaling_for_small_input)
{
f_bin = ldexp(f_bin, pow2_scaling_for_small_input);
}
if (has_pow2_scaling_for_small_input)
{
eval_ldexp(f_bin, f_bin, pow2_scaling_for_small_input);
}

constexpr auto dig_lim =
static_cast<unsigned>
(
static_cast<int>
(
(local_double_fp_type::my_digits / cpp_df_qf_detail::ccmath::numeric_limits<local_builtin_float_type>::digits)
+ (((local_double_fp_type::my_digits % cpp_df_qf_detail::ccmath::numeric_limits<local_builtin_float_type>::digits) != 0) ? 1 : 0)
)
* cpp_df_qf_detail::ccmath::numeric_limits<local_builtin_float_type>::digits
);
using local_builtin_float_type = typename std::conditional<(sizeof(float_type) <= sizeof(double)), double, float_type>::type;

for(auto i = static_cast<unsigned>(UINT8_C(0));
i < dig_lim;
i = static_cast<unsigned>(i + static_cast<unsigned>(cpp_df_qf_detail::ccmath::numeric_limits<local_builtin_float_type>::digits)))
{
const local_builtin_float_type f { static_cast<local_builtin_float_type>(f_bin) };
constexpr unsigned
digit_limit
{
static_cast<unsigned>
(
static_cast<int>
(
(local_double_fp_type::my_digits / cpp_df_qf_detail::ccmath::numeric_limits<local_builtin_float_type>::digits)
+ (((local_double_fp_type::my_digits % cpp_df_qf_detail::ccmath::numeric_limits<local_builtin_float_type>::digits) != 0) ? 1 : 0)
)
* cpp_df_qf_detail::ccmath::numeric_limits<local_builtin_float_type>::digits
)
};

f_bin -= cpp_bin_float_read_write_type { f };
for(auto i = static_cast<unsigned>(UINT8_C(0));
i < digit_limit;
i = static_cast<unsigned>(i + static_cast<unsigned>(cpp_df_qf_detail::ccmath::numeric_limits<local_builtin_float_type>::digits)))
{
local_builtin_float_type flt_part { };

eval_add(*this, local_double_fp_type { f });
}
eval_convert_to(&flt_part, f_bin);

if (has_pow2_scaling_for_small_input)
{
eval_ldexp(*this, *this, -pow2_scaling_for_small_input);
}
eval_subtract(f_bin, cpp_bin_float_read_write_backend_type(flt_part));

if (b_neg) { negate(); }
}
}
eval_add(*this, local_double_fp_type { flt_part });
}

if (has_pow2_scaling_for_small_input)
{
eval_ldexp(*this, *this, -pow2_scaling_for_small_input);
}

if (b_neg) { negate(); }

return true;
}

Expand Down
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