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Diffstat (limited to 'gnuradio-core/src/lib/general/gr_math.h')
| -rw-r--r-- | gnuradio-core/src/lib/general/gr_math.h | 209 |
1 files changed, 209 insertions, 0 deletions
diff --git a/gnuradio-core/src/lib/general/gr_math.h b/gnuradio-core/src/lib/general/gr_math.h new file mode 100644 index 000000000..b9a802da8 --- /dev/null +++ b/gnuradio-core/src/lib/general/gr_math.h @@ -0,0 +1,209 @@ +/* -*- 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_ */ |