implements the Grisu2 algorithm for binary to decimal floating-point conversion. More...

Classes
struct	diyfp
struct	boundaries
struct	cached_power

Functions
template<typename Target, typename Source>
Target	reinterpret_bits (const Source source)
template<typename FloatType>
boundaries	compute_boundaries (FloatType value)
	Compute the (normalized) diyfp representing the input number 'value' and its boundaries.
cached_power	get_cached_power_for_binary_exponent (int e)
	For a normalized diyfp w = f * 2^e, this function returns a (normalized) cached power-of-ten c = f_c * 2^e_c, such that the exponent of the product w * c satisfies (Definition 3.2 from [1]).
int	find_largest_pow10 (const std::uint32_t n, std::uint32_t &pow10)
	For n != 0, returns k, such that pow10 := 10^(k-1) <= n < 10^k.
void	grisu2_round (char *buf, int len, std::uint64_t dist, std::uint64_t delta, std::uint64_t rest, std::uint64_t ten_k)
void	grisu2_digit_gen (char *buffer, int &length, int &decimal_exponent, diyfp M_minus, diyfp w, diyfp M_plus)
	Generates V = buffer * 10^decimal_exponent, such that M- <= V <= M+.
void	grisu2 (char *buf, int &len, int &decimal_exponent, diyfp m_minus, diyfp v, diyfp m_plus)
	v = buf * 10^decimal_exponent len is the length of the buffer (number of decimal digits) The buffer must be large enough, i.e.
template<typename FloatType>
void	grisu2 (char *buf, int &len, int &decimal_exponent, FloatType value)
	v = buf * 10^decimal_exponent len is the length of the buffer (number of decimal digits) The buffer must be large enough, i.e.
JSON_HEDLEY_RETURNS_NON_NULL char *	append_exponent (char *buf, int e)
	appends a decimal representation of e to buf
JSON_HEDLEY_RETURNS_NON_NULL char *	format_buffer (char *buf, int len, int decimal_exponent, int min_exp, int max_exp)
	prettify v = buf * 10^decimal_exponent

Variables
constexpr int	kAlpha = -60
constexpr int	kGamma = -32

Detailed Description

implements the Grisu2 algorithm for binary to decimal floating-point conversion.

This implementation is a slightly modified version of the reference implementation which may be obtained from http://florian.loitsch.com/publications (bench.tar.gz).

For a detailed description of the algorithm see:

[1] Loitsch, "Printing Floating-Point Numbers Quickly and Accurately with Integers", Proceedings of the ACM SIGPLAN 2010 Conference on Programming Language Design and Implementation, PLDI 2010 [2] Burger, Dybvig, "Printing Floating-Point Numbers Quickly and Accurately", Proceedings of the ACM SIGPLAN 1996 Conference on Programming Language Design and Implementation, PLDI 1996

Function Documentation

◆ append_exponent()

JSON_HEDLEY_RETURNS_NON_NULL char * detail::dtoa_impl::append_exponent	(	char *	buf,
		int	e )

inline

appends a decimal representation of e to buf

Returns: a pointer to the element following the exponent.

Precondition: -1000 < e < 1000

Definition at line 17835 of file json.hpp.

References append_exponent(), and JSON_ASSERT.

Referenced by append_exponent(), and format_buffer().

◆ compute_boundaries()

template<typename FloatType>

boundaries detail::dtoa_impl::compute_boundaries ( FloatType value )

Compute the (normalized) diyfp representing the input number 'value' and its boundaries.

Precondition: value must be finite and positive

Definition at line 17096 of file json.hpp.

References compute_boundaries(), detail::dtoa_impl::diyfp::e, detail::dtoa_impl::diyfp::f, JSON_ASSERT, detail::dtoa_impl::diyfp::normalize(), detail::dtoa_impl::diyfp::normalize_to(), reinterpret_bits(), and detail::static_const< T >::value.

Referenced by compute_boundaries(), and grisu2().

◆ find_largest_pow10()

int detail::dtoa_impl::find_largest_pow10	(	const std::uint32_t	n,
		std::uint32_t &	pow10 )

inline

For n != 0, returns k, such that pow10 := 10^(k-1) <= n < 10^k.

For n == 0, returns 1 and sets pow10 := 1.

Definition at line 17399 of file json.hpp.

References find_largest_pow10().

Referenced by find_largest_pow10(), and grisu2_digit_gen().

◆ format_buffer()

JSON_HEDLEY_RETURNS_NON_NULL char * detail::dtoa_impl::format_buffer	(	char *	buf,
		int	len,
		int	decimal_exponent,
		int	min_exp,
		int	max_exp )

inline

prettify v = buf * 10^decimal_exponent

If v is in the range [10^min_exp, 10^max_exp) it will be printed in fixed-point notation. Otherwise it will be printed in exponential notation.

Precondition: min_exp < 0; max_exp > 0

Definition at line 17887 of file json.hpp.

References append_exponent(), format_buffer(), and JSON_ASSERT.

Referenced by format_buffer(), and detail::to_chars().

◆ get_cached_power_for_binary_exponent()

cached_power detail::dtoa_impl::get_cached_power_for_binary_exponent ( int e )

inline

For a normalized diyfp w = f * 2^e, this function returns a (normalized) cached power-of-ten c = f_c * 2^e_c, such that the exponent of the product w * c satisfies (Definition 3.2 from [1]).