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Port default_float_traits

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Matt Borland
2023-03-10 11:15:30 -08:00
parent a857ee8772
commit ebb08e02c8
1 changed files with 49 additions and 27 deletions
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76
include/boost/charconv/detail/dragonbox.hpp
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@@ -110,79 +110,101 @@ namespace boost { namespace charconv {
// Extract exponent bits from a bit pattern.
// The result must be aligned to the LSB so that there is no additional zero paddings
// on the right. This function does not do bias adjustment.
static constexpr unsigned int extract_exponent_bits(carrier_uint u) noexcept {
constexpr unsigned int extract_exponent_bits(carrier_uint u) noexcept
{
constexpr int significand_bits = format::significand_bits;
constexpr int exponent_bits = format::exponent_bits;
static_assert(detail::value_bits<unsigned int> > exponent_bits);
constexpr auto exponent_bits_mask =
(static_cast<unsigned int>(1) << exponent_bits) - 1;
constexpr auto exponent_bits_mask = (static_cast<unsigned int>(1) << exponent_bits) - 1;
return static_cast<unsigned int>(u >> significand_bits) & exponent_bits_mask;
}
// Extract significand bits from a bit pattern.
// The result must be aligned to the LSB so that there is no additional zero paddings
// on the right. The result does not contain the implicit bit.
static constexpr carrier_uint extract_significand_bits(carrier_uint u) noexcept {
constexpr carrier_uint extract_significand_bits(carrier_uint u) noexcept
{
constexpr auto mask = carrier_uint((carrier_uint(1) << format::significand_bits) - 1);
return carrier_uint(u & mask);
}
// Remove the exponent bits and extract significand bits together with the sign bit.
static constexpr carrier_uint remove_exponent_bits(carrier_uint u,
unsigned int exponent_bits) noexcept {
constexpr carrier_uint remove_exponent_bits(carrier_uint u, unsigned int exponent_bits) noexcept
{
return u ^ (carrier_uint(exponent_bits) << format::significand_bits);
}
// Shift the obtained signed significand bits to the left by 1 to remove the sign bit.
static constexpr carrier_uint remove_sign_bit_and_shift(carrier_uint u) noexcept {
return carrier_uint(carrier_uint(u) << 1);
constexpr carrier_uint remove_sign_bit_and_shift(carrier_uint u) noexcept
{
return carrier_uint(u << 1);
}
// The actual value of exponent is obtained by adding this value to the extracted exponent
// bits.
static constexpr int exponent_bias =
1 - (1 << (carrier_bits - format::significand_bits - 2));
constexpr int exponent_bias = 1 - (1 << (carrier_bits - format::significand_bits - 2));
// Obtain the actual value of the binary exponent from the extracted exponent bits.
static constexpr int binary_exponent(unsigned int exponent_bits) noexcept {
if (exponent_bits == 0) {
static constexpr int binary_exponent(unsigned int exponent_bits) noexcept
{
if (exponent_bits == 0)
{
return format::min_exponent;
}
else {
return int(exponent_bits) + format::exponent_bias;
else
{
return static_cast<int>(exponent_bits) + format::exponent_bias;
}
}
// Obtain the actual value of the binary exponent from the extracted significand bits and
// exponent bits.
static constexpr carrier_uint binary_significand(carrier_uint significand_bits,
unsigned int exponent_bits) noexcept {
if (exponent_bits == 0) {
constexpr carrier_uint binary_significand(carrier_uint significand_bits, unsigned int exponent_bits) noexcept
{
if (exponent_bits == 0)
{
return significand_bits;
}
else {
return significand_bits | (carrier_uint(1) << format::significand_bits);
else
{
return significand_bits | (static_cast<carrier_uint>(1) << format::significand_bits);
}
}
/* Various boolean observer functions */
static constexpr bool is_nonzero(carrier_uint u) noexcept { return (u << 1) != 0; }
static constexpr bool is_positive(carrier_uint u) noexcept {
constexpr auto sign_bit = carrier_uint(1)
<< (format::significand_bits + format::exponent_bits);
constexpr bool is_nonzero(carrier_uint u) noexcept
{
return (u << 1) != 0;
}
constexpr bool is_positive(carrier_uint u) noexcept
{
constexpr auto sign_bit = carrier_uint(1) << (format::significand_bits + format::exponent_bits);
return u < sign_bit;
}
static constexpr bool is_negative(carrier_uint u) noexcept { return !is_positive(u); }
static constexpr bool is_finite(unsigned int exponent_bits) noexcept {
static constexpr bool is_negative(carrier_uint u) noexcept
{
return !is_positive(u);
}
static constexpr bool is_finite(unsigned int exponent_bits) noexcept
{
constexpr unsigned int exponent_bits_all_set = (1u << format::exponent_bits) - 1;
return exponent_bits != exponent_bits_all_set;
}
static constexpr bool has_all_zero_significand_bits(carrier_uint u) noexcept {
static constexpr bool has_all_zero_significand_bits(carrier_uint u) noexcept
{
return (u << 1) == 0;
}
static constexpr bool has_even_significand_bits(carrier_uint u) noexcept {
static constexpr bool has_even_significand_bits(carrier_uint u) noexcept
{
return u % 2 == 0;
}
};