volk_32f_atan_32f.h

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/* -*- c++ -*- */
/*
 * Copyright 2014 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.
 */

#include <stdio.h>
#include <math.h>
#include <inttypes.h>

/* This is the number of terms of Taylor series to evaluate, increase this for more accuracy*/
#define TERMS 2

#ifndef INCLUDED_volk_32f_atan_32f_a_H
#define INCLUDED_volk_32f_atan_32f_a_H

#ifdef LV_HAVE_SSE4_1
#include <smmintrin.h>
/*!
  \brief Computes arctangent of input vector and stores results in output vector
  \param bVector The vector where results will be stored
  \param aVector The input vector of floats
  \param num_points Number of points for which arctangent is to be computed
*/
static inline void volk_32f_atan_32f_a_sse4_1(float* bVector, const float* aVector, unsigned int num_points){

    float* bPtr = bVector;
    const float* aPtr = aVector;

    unsigned int number = 0;
    unsigned int quarterPoints = num_points / 4;
    int i, j;

    __m128 aVal, pio2, x, y, z, arctangent;
    __m128 fzeroes, fones, ftwos, ffours, condition;

    pio2 = _mm_set1_ps(3.14159265358979323846/2);
    fzeroes = _mm_setzero_ps();
    fones = _mm_set1_ps(1.0);
    ftwos = _mm_set1_ps(2.0);
    ffours = _mm_set1_ps(4.0);

    for(;number < quarterPoints; number++){
        aVal = _mm_load_ps(aPtr);
        z = aVal;
        condition = _mm_cmplt_ps(z, fzeroes);
        z = _mm_sub_ps(z, _mm_and_ps(_mm_mul_ps(z, ftwos), condition));
        x = z;
        condition = _mm_cmplt_ps(z, fones);
        x = _mm_add_ps(x, _mm_and_ps(_mm_sub_ps(_mm_div_ps(fones, z), z), condition));

        for(i = 0; i < 2; i++){
            x = _mm_add_ps(x, _mm_sqrt_ps(_mm_add_ps(fones, _mm_mul_ps(x, x))));
        }
        x = _mm_div_ps(fones, x);
        y = fzeroes;
        for(j = TERMS - 1; j >=0 ; j--){
            y = _mm_add_ps(_mm_mul_ps(y, _mm_mul_ps(x, x)), _mm_set1_ps(pow(-1,j)/(2*j+1)));
        }

        y = _mm_mul_ps(y, _mm_mul_ps(x, ffours));
        condition = _mm_cmpgt_ps(z, fones);

        y = _mm_add_ps(y, _mm_and_ps(_mm_sub_ps(pio2, _mm_mul_ps(y, ftwos)), condition));
        arctangent = y;
        condition = _mm_cmplt_ps(aVal, fzeroes);
        arctangent = _mm_sub_ps(arctangent, _mm_and_ps(_mm_mul_ps(arctangent, ftwos), condition));

        _mm_store_ps(bPtr, arctangent);
        aPtr += 4;
        bPtr += 4;
    }

    number = quarterPoints * 4;
    for(;number < num_points; number++){
        *bPtr++ = atan(*aPtr++);
    }
}

#endif /* LV_HAVE_SSE4_1 for aligned */

#endif /* INCLUDED_volk_32f_atan_32f_a_H */

#ifndef INCLUDED_volk_32f_atan_32f_u_H
#define INCLUDED_volk_32f_atan_32f_u_H

#ifdef LV_HAVE_SSE4_1
#include <smmintrin.h>
/*!
  \brief Computes arctangent of input vector and stores results in output vector
  \param bVector The vector where results will be stored
  \param aVector The input vector of floats
  \param num_points Number of points for which arctangent is to be computed
*/
static inline void volk_32f_atan_32f_u_sse4_1(float* bVector, const float* aVector, unsigned int num_points){

    float* bPtr = bVector;
    const float* aPtr = aVector;

    unsigned int number = 0;
    unsigned int quarterPoints = num_points / 4;
    int i, j;

    __m128 aVal, pio2, x, y, z, arctangent;
    __m128 fzeroes, fones, ftwos, ffours, condition;

    pio2 = _mm_set1_ps(3.14159265358979323846/2);
    fzeroes = _mm_setzero_ps();
    fones = _mm_set1_ps(1.0);
    ftwos = _mm_set1_ps(2.0);
    ffours = _mm_set1_ps(4.0);

    for(;number < quarterPoints; number++){
        aVal = _mm_loadu_ps(aPtr);
        z = aVal;
        condition = _mm_cmplt_ps(z, fzeroes);
        z = _mm_sub_ps(z, _mm_and_ps(_mm_mul_ps(z, ftwos), condition));
        x = z;
        condition = _mm_cmplt_ps(z, fones);
        x = _mm_add_ps(x, _mm_and_ps(_mm_sub_ps(_mm_div_ps(fones, z), z), condition));

        for(i = 0; i < 2; i++)  x = _mm_add_ps(x, _mm_sqrt_ps(_mm_add_ps(fones, _mm_mul_ps(x, x))));
        x = _mm_div_ps(fones, x);
        y = fzeroes;
        for(j = TERMS - 1; j >= 0; j--) y = _mm_add_ps(_mm_mul_ps(y, _mm_mul_ps(x, x)), _mm_set1_ps(pow(-1,j)/(2*j+1)));

        y = _mm_mul_ps(y, _mm_mul_ps(x, ffours));
        condition = _mm_cmpgt_ps(z, fones);

        y = _mm_add_ps(y, _mm_and_ps(_mm_sub_ps(pio2, _mm_mul_ps(y, ftwos)), condition));
        arctangent = y;
        condition = _mm_cmplt_ps(aVal, fzeroes);
        arctangent = _mm_sub_ps(arctangent, _mm_and_ps(_mm_mul_ps(arctangent, ftwos), condition));

        _mm_storeu_ps(bPtr, arctangent);
        aPtr += 4;
        bPtr += 4;
    }

    number = quarterPoints * 4;
    for(;number < num_points; number++){
        *bPtr++ = atan(*aPtr++);
    }
}

#endif /* LV_HAVE_SSE4_1 for unaligned */

#ifdef LV_HAVE_GENERIC
/*!
  \brief Computes arctangent of input vector and stores results in output vector
  \param bVector The vector where results will be stored
  \param aVector The input vector of floats
  \param num_points Number of points for which arctangent is to be computed
*/
static inline void volk_32f_atan_32f_generic(float* bVector, const float* aVector, unsigned int num_points){
    float* bPtr = bVector;
    const float* aPtr = aVector;
    unsigned int number = 0;

    for(number = 0; number < num_points; number++){
        *bPtr++ = atan(*aPtr++);
    }

}
#endif /* LV_HAVE_GENERIC */

#endif /* INCLUDED_volk_32f_atan_32f_u_H */