geos::precision::CommonBits Class Reference

Determines the maximum number of common most-significant bits in the mantissa of one or numbers. More...

#include <CommonBits.h>

Public Member Functions
void	add (double num)
double	getCommon ()

Static Public Member Functions
static int64_t	signExpBits (int64_t num)
	Computes the bit pattern for the sign and exponent of a double-precision number. More...
static int	numCommonMostSigMantissaBits (int64_t num1, int64_t num2)
	This computes the number of common most-significant bits in the mantissas of two double-precision numbers. More...
static int64_t	zeroLowerBits (int64_t bits, int nBits)
	Zeroes the lower n bits of a bitstring. More...
static int	getBit (int64_t bits, int i)
	Extracts the i'th bit of a bitstring. More...

Detailed Description

Determines the maximum number of common most-significant bits in the mantissa of one or numbers.

Can be used to compute the double-precision number which is represented by the common bits. If there are no common bits, the number computed is 0.0.

Member Function Documentation

getBit()

static int geos::precision::CommonBits::getBit ( int64_t  bits, int  i  )

static

Extracts the i'th bit of a bitstring.

Parameters

bits	the bitstring to extract from
i	the bit to extract

Returns

the value of the extracted bit

numCommonMostSigMantissaBits()

static int geos::precision::CommonBits::numCommonMostSigMantissaBits ( int64_t  num1, int64_t  num2  )

static

This computes the number of common most-significant bits in the mantissas of two double-precision numbers.

It does not count the hidden bit, which is always 1. It does not determine whether the numbers have the same exponent - if they do not, the value computed by this function is meaningless.

Parameters

num1
num2

Returns

the number of common most-significant mantissa bits

signExpBits()

static int64_t geos::precision::CommonBits::signExpBits ( int64_t  num )

static

Computes the bit pattern for the sign and exponent of a double-precision number.

Parameters

num

Returns

the bit pattern for the sign and exponent

zeroLowerBits()

static int64_t geos::precision::CommonBits::zeroLowerBits ( int64_t  bits, int  nBits  )

static

Zeroes the lower n bits of a bitstring.

Parameters

bits	the bitstring to alter
nBits	the number of bits to zero

Returns

the zeroed bitstring

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The documentation for this class was generated from the following file:

• CommonBits.h