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#ifndef __fixed_point_header_h__
#define __fixed_point_header_h__
#include <boost/assert.hpp>
#include <boost/static_assert.hpp>
#include <boost/operators.hpp>
#include <limits>
#endif
namespace fp {
template<typename FP, unsigned char I, unsigned char F = std::numeric_limits<FP>::digits - I>
class fixed_point: boost::ordered_field_operators<fp::fixed_point<FP, I, F> >
{
BOOST_CONCEPT_ASSERT((boost::Integer<FP>));
BOOST_STATIC_ASSERT(I + F == std::numeric_limits<FP>::digits);
template<int P,typename T = void>
struct power2
{
static const long long value = 2 * power2<P-1,T>::value;
};
template <typename P>
struct power2<0, P>
{
static const long long value = 1;
};
fixed_point(FP value,bool): fixed_(value){ } // initializer list
public:
typedef FP base_type; /// fixed point base type of this fixed_point class.
static const unsigned char integer_bit_count = I; /// integer part bit count.
static const unsigned char fractional_bit_count = F; /// fractional part bit count.
fixed_point(){ } /// Default constructor.
//Conversion by constructors.
//Integer to Fixed point
template<typename T> fixed_point(T value) : fixed_((FP)value << F)
{
BOOST_CONCEPT_ASSERT((boost::Integer<T>));
}
// Converting constructor.
//!
//! This constructor takes a numeric value of type bool and converts it to
//! this fixed_point type.
fixed_point(
/// The value to convert.
bool value)
: fixed_((FP)(value * power2<F>::value))
{ }
fixed_point(float value) :fixed_((FP)(value * power2<F>::value))
{ }
fixed_point(double value) : fixed_((FP)(value * power2<F>::value))
{ }
fixed_point(long double value) : fixed_((FP)(value * power2<F>::value))
{ }
/// Copy constructor,explicit definition
fixed_point(
/// The right hand side.
fixed_point<FP, I, F> const& rhs)
: fixed_(rhs.fixed_)
{ }
// copy-and-swap idiom.
/// Copy assignment operator.
fp::fixed_point<FP, I, F> & operator =(fp::fixed_point<FP, I, F> const& rhs)
{
fp::fixed_point<FP, I, F> temp(rhs);
swap(temp); .
return *this; //return by reference
}
/// Exchanges the elements of two fixed_point objects.
void swap(
/// The right hand side.
fp::fixed_point<FP, I, F> & rhs)
{
std::swap(fixed_, rhs.fixed_);
}
bool operator <(
/// Right hand side.
fp::fixed_point<FP, I, F> const& rhs) const
{
return
fixed_ < rhs.fixed_; //return by value
}
bool operator ==(
/// Right hand side.
fp::fixed_point<FP, I, F> const& rhs) const
{
return
fixed_ == rhs.fixed_; //return by value
}
/// Negation operator.
bool operator !() const
{
return fixed_ == 0; //return true if equal to zero, false otherwise.
}
/// Unary minus operator.
fp::fixed_point<FP, I, F> operator -() const
{
fp::fixed_point<FP, I, F> result;
result.fixed_ = -fixed_;
return result; // return The negative value.
}
/// Addition.
fp::fixed_point<FP, I, F> & operator +=(fp::fixed_point<FP, I, F> const& summation)
{
fixed_ += summation.fixed_;
return *this; //! /return A reference to this object.
}
/// Subtraction.
fp::fixed_point<FP, I, F> & operator -=(fp::fixed_point<FP, I, F> const& subtraction)
{
fixed_ -= subtraction.fixed_;
return *this; // return A reference to this object.
}
/// Multiplication.
fp::fixed_point<FP, I, F> & operator *=(
/// Factor for mutliplication.
fp::fixed_point<FP, I, F> const& factor)
{
fixed_ = ( fixed_ * (factor.fixed_ >> F) ) +
( ( fixed_ * (factor.fixed_ & (power2<F>::value-1) ) ) >> F );
return *this; //return A reference to this object.
}
/// Division.
fp::fixed_point<FP, I, F> & operator /=(
/// Divisor for division.
fp::fixed_point<FP, I, F> const& divisor)
{
fp::fixed_point<FP, I, F> fp_z=1;
fp_z.fixed_ = ( (fp_z.fixed_) << (F-2) ) / ( divisor.fixed_ >> (2) );
*this *= fp_z;
return *this; //return A reference to this object
}
friend fp::fixed_point<FP, I, F> fmod(fp::fixed_point<FP, I, F> a,fp::fixed_point<FP, I, F> b)
{
fp::fixed_point<FP, I, F> result;
result.fixed_ = a.fixed_ % b.fixed_ ;
return result;
}
//cos_sin cordic function
static fp::fixed_point<FP, I, F> cossin_cordic(fp::fixed_point<int, 15> beta, int n)
//beta angle in radians
//n number of iterations
{
# define ANGLES_LENGTH 60 //local parameter
# define KPROD_LENGTH 33 //local parameter
//Initialization of tables of constants used by CORDIC
//need a table of arctangents of negative powers of two, in radians: atan(2.^-(0:59));
fp::fixed_point<FP, I, F> angle;
fp::fixed_point<FP, I, F> angles[ANGLES_LENGTH] = {
7.8539816339744830962E-01, // arctan(2.^(0))
4.6364760900080611621E-01, // arctan(2.^(-1))
2.4497866312686415417E-01,
1.2435499454676143503E-01,
6.2418809995957348474E-02,
3.1239833430268276254E-02,
1.5623728620476830803E-02,
7.8123410601011112965E-03,
3.9062301319669718276E-03,};
//A table of products of reciprocal lengths of vectors [1, 2^-2i]: 1 / sqrt ( 1 + (1/2)^(2i) ).
fp::fixed_point<FP, I, F> kprod[KPROD_LENGTH] = {
0.70710678118654752440,
0.63245553203367586640,
0.61357199107789634961,
0.60883391251775242102,
0.60764825625616820093,
0.60735177014129595905,
0.60727764409352599905,
0.60725911229889273006,
0.60725447933256232972,
0.60725332108987516334,
0.60725303152913433540,
0.60725295913894481363,
};
double pi = 3.141592653589793;
int j;
double sign_factor;
fp::fixed_point<FP, I, F> factor;
fp::fixed_point<FP, I, F> poweroftwo;
fp::fixed_point<FP, I, F> sigma;
fp::fixed_point<FP, I, F> c2;
fp::fixed_point<FP, I, F> s2;
// fp::fixed_point<FP, I, F> theta;
// Shift angle to interval [-pi/2,pi/2] and account for signs.
if ( beta < - 0.5 * pi )
{
beta = beta + pi;
sign_factor = -1.0;
}
else if ( 0.5 * pi < beta)
{
beta = beta - pi;
sign_factor = -1.0;
}
else
{
sign_factor = +1.0;
}
// Initialize loop variables: start with 2-vector, cosine of 1 and sine of zero
fp::fixed_point<FP, I, F> c= 1.0; //c will give the value cos(beta)
fp::fixed_point<FP, I, F> s= 0.0; //s will give the value sin(beta)
poweroftwo = 1;
angle =angles[0];
// Iterations
for ( j = 1; j <= n; j++ )
{
if ( beta < 0.0 )
{
sigma = -1.0; //theta is -ve sigma is -ve
}
else
{
sigma = 1.0; //theta is +ve sigma is +ve
}
factor = sigma * poweroftwo; //used in matrix multiplication
//2-by-2 matrix multiplication
c2 = c - factor * s;
s2 = factor * c + s;
c = c2;
s = s2;
beta = beta - sigma * angle; // update the remaining angle
poweroftwo = poweroftwo / 2;
// Update the angle from table, or eventually by just dividing by two.
if ( ANGLES_LENGTH < j + 1 )
{
angle = angle / 2.0;
}
else
{
angle = angles[j];
}
}
// Adjust length of output vector to be [cos(beta), sin(beta)]
// KPROD is essentially constant after a certain point, so if n is
// large, just take the last available value.
c = c * kprod [ std::min ( n, KPROD_LENGTH ) ];
s = s * kprod [ std::min ( n, KPROD_LENGTH ) ];
return c;
return s;
# undef ANGLES_LENGTH
# undef KPROD_LENGTH
}
private:
/// The value in fixed point format.
FP fixed_;
};
} // namespace fmpl
#endif
#endif // __fixed_point_h__
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