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/* -*- c++ -*- */
/*
* Copyright 2003,2005,2008 Free Software Foundation, Inc.
*
* This file is part of GNU Radio
*
* GNU Radio is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 3, or (at your option)
* any later version.
*
* GNU Radio is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with GNU Radio; see the file COPYING. If not, write to
* the Free Software Foundation, Inc., 51 Franklin Street,
* Boston, MA 02110-1301, USA.
*/
/*
* mathematical odds and ends.
*/
#ifndef _GR_MATH_H_
#define _GR_MATH_H_
#include <gr_core_api.h>
#include <gr_complex.h>
static inline bool
gr_is_power_of_2(long x)
{
return x != 0 && (x & (x-1)) == 0;
}
/*!
* \brief Fast arc tangent using table lookup and linear interpolation
* \ingroup misc
*
* \param y component of input vector
* \param x component of input vector
* \returns float angle angle of vector (x, y) in radians
*
* This function calculates the angle of the vector (x,y) based on a
* table lookup and linear interpolation. The table uses a 256 point
* table covering -45 to +45 degrees and uses symetry to determine the
* final angle value in the range of -180 to 180 degrees. Note that
* this function uses the small angle approximation for values close
* to zero. This routine calculates the arc tangent with an average
* error of +/- 0.045 degrees.
*/
GR_CORE_API float gr_fast_atan2f(float y, float x);
static inline float gr_fast_atan2f(gr_complex z)
{
return gr_fast_atan2f(z.imag(), z.real());
}
/* This bounds x by +/- clip without a branch */
static inline float gr_branchless_clip(float x, float clip)
{
float x1 = fabsf(x+clip);
float x2 = fabsf(x-clip);
x1 -= x2;
return 0.5*x1;
}
static inline float gr_clip(float x, float clip)
{
float y = x;
if(x > clip)
y = clip;
else if(x < -clip)
y = -clip;
return y;
}
// Slicer Functions
static inline unsigned int gr_binary_slicer(float x)
{
if(x >= 0)
return 1;
else
return 0;
}
static inline unsigned int gr_quad_45deg_slicer(float r, float i)
{
unsigned int ret = 0;
if((r >= 0) && (i >= 0))
ret = 0;
else if((r < 0) && (i >= 0))
ret = 1;
else if((r < 0) && (i < 0))
ret = 2;
else
ret = 3;
return ret;
}
static inline unsigned int gr_quad_0deg_slicer(float r, float i)
{
unsigned int ret = 0;
if(fabsf(r) > fabsf(i)) {
if(r > 0)
ret = 0;
else
ret = 2;
}
else {
if(i > 0)
ret = 1;
else
ret = 3;
}
return ret;
}
static inline unsigned int gr_quad_45deg_slicer(gr_complex x)
{
return gr_quad_45deg_slicer(x.real(), x.imag());
}
static inline unsigned int gr_quad_0deg_slicer(gr_complex x)
{
return gr_quad_0deg_slicer(x.real(), x.imag());
}
// Branchless Slicer Functions
static inline unsigned int gr_branchless_binary_slicer(float x)
{
return (x >= 0);
}
static inline unsigned int gr_branchless_quad_0deg_slicer(float r, float i)
{
unsigned int ret = 0;
ret = (fabsf(r) > fabsf(i)) * (((r < 0) << 0x1)); // either 0 (00) or 2 (10)
ret |= (fabsf(i) > fabsf(r)) * (((i < 0) << 0x1) | 0x1); // either 1 (01) or 3 (11)
return ret;
}
static inline unsigned int gr_branchless_quad_0deg_slicer(gr_complex x)
{
return gr_branchless_quad_0deg_slicer(x.real(), x.imag());
}
static inline unsigned int gr_branchless_quad_45deg_slicer(float r, float i)
{
char ret = (r <= 0);
ret |= ((i <= 0) << 1);
return (ret ^ ((ret & 0x2) >> 0x1));
}
static inline unsigned int gr_branchless_quad_45deg_slicer(gr_complex x)
{
return gr_branchless_quad_45deg_slicer(x.real(), x.imag());
}
/*!
* \param x any value
* \param pow2 must be a power of 2
* \returns \p x rounded down to a multiple of \p pow2.
*/
static inline size_t
gr_p2_round_down(size_t x, size_t pow2)
{
return x & -pow2;
}
/*!
* \param x any value
* \param pow2 must be a power of 2
* \returns \p x rounded up to a multiple of \p pow2.
*/
static inline size_t
gr_p2_round_up(size_t x, size_t pow2)
{
return gr_p2_round_down(x + pow2 - 1, pow2);
}
/*!
* \param x any value
* \param pow2 must be a power of 2
* \returns \p x modulo \p pow2.
*/
static inline size_t
gr_p2_modulo(size_t x, size_t pow2)
{
return x & (pow2 - 1);
}
/*!
* \param x any value
* \param pow2 must be a power of 2
* \returns \p pow2 - (\p x modulo \p pow2).
*/
static inline size_t
gr_p2_modulo_neg(size_t x, size_t pow2)
{
return pow2 - gr_p2_modulo(x, pow2);
}
#endif /* _GR_MATH_H_ */
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