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/* PROLOG END TAG zYx                                              */

#ifdef __SPU__

#ifndef _ACOSHD2_H_

#define _ACOSHD2_H_     1

#include <spu_intrinsics.h>

#include "logd2.h"

#include "sqrtd2.h"

/*

 * FUNCTION

 *  vector double _acoshd2(vector double x)

 *

 * DESCRIPTION

 *  The acoshd2 function returns a vector containing the hyperbolic

 *  arccosines of the corresponding elements of the input vector.

 *

 *  We are using the formula:

 *    acosh = ln(x + sqrt(x^2 - 1))

 *

 *  For x near one, we use the Taylor series:

 *

 *                infinity

 *                 ------

 *                  -   '

 *                   -                 k

 *    acosh x =       -      C  (x - 1)

 *                   -        k

 *                  -   ,

 *                 ------

 *                 k = 0

 *

 *

 *  Special Cases:

 *      - acosh(1)        = +0

 *      - acosh(NaN)      = NaN

 *      - acosh(Infinity) = Infinity

 *      - acosh(x < 1)    = NaN

 *

 */

/*

 * Taylor Series Coefficients

 * for x around 1.

 */

#define SDM_ACOSHD2_TAY01  1.000000000000000000000000000000000E0  /* 1 / 1                            */

#define SDM_ACOSHD2_TAY02 -8.333333333333333333333333333333333E-2 /* 1 / 12                           */

#define SDM_ACOSHD2_TAY03  1.875000000000000000000000000000000E-2 /* 3 / 160                          */

#define SDM_ACOSHD2_TAY04 -5.580357142857142857142857142857142E-3 /* 5 / 896                          */

#define SDM_ACOSHD2_TAY05  1.898871527777777777777777777777777E-3 /* 35 / 18432                       */

#define SDM_ACOSHD2_TAY06 -6.991299715909090909090909090909090E-4 /* 63 / 90112                       */

#define SDM_ACOSHD2_TAY07  2.711369441105769230769230769230769E-4 /* 231 / 851968                     */

#define SDM_ACOSHD2_TAY08 -1.091003417968750000000000000000000E-4 /* 143 / 1310720                    */

#define SDM_ACOSHD2_TAY09  4.512422225054572610294117647058823E-5 /* 6435 / 142606336                 */

#define SDM_ACOSHD2_TAY10 -1.906564361170718544407894736842105E-5 /* 12155 / 637534208                */

#define SDM_ACOSHD2_TAY11  8.193687314078921363467261904761904E-6 /* 46189 / 5637144576               */

#define SDM_ACOSHD2_TAY12 -3.570569274218186088230298913043478E-6 /* 88179 / 24696061952              */

#define SDM_ACOSHD2_TAY13  1.574025955051183700561523437500000E-6 /* 676039 / 429496729600            */

#define SDM_ACOSHD2_TAY14 -7.006881922414457356488263165509259E-7 /* 1300075 / 1855425871872          */

#define SDM_ACOSHD2_TAY15  3.145330616650332150788142763335129E-7 /* 5014575 / 15942918602752         */

static __inline vector double _acoshd2(vector double x)

{

    vec_uchar16 dup_even  = ((vec_uchar16) { 0,1,2,3,  0,1,2,3, 8,9,10,11, 8,9,10,11 });

    vec_double2 minus_oned = spu_splats(-1.0);

    vec_double2 twod       = spu_splats(2.0);

    /* Where we switch from taylor to formula */

    vec_float4  switch_approx = spu_splats(1.15f);

    vec_double2 result, fresult, mresult;;

    vec_double2 xminus1 = spu_add(x, minus_oned);

    vec_float4  xf = spu_roundtf(x);

    xf = spu_shuffle(xf, xf, dup_even);

    vec_ullong2 use_form = (vec_ullong2)spu_cmpgt(xf, switch_approx);

    vec_double2 sqrtargformula = spu_madd(x, x, minus_oned);

    vec_double2 sqrtargtaylor  = spu_mul(xminus1, twod);

    vec_double2 sqrtarg = spu_sel(sqrtargtaylor, sqrtargformula, use_form);

    vec_double2 sqrtresult = _sqrtd2(sqrtarg);

    /*

     * Formula:

     *   acosh = ln(x + sqrt(x^2 - 1))

     */

    fresult = spu_add(x, sqrtresult);

    fresult = _logd2(fresult);

    /*

     * Taylor Series

     */

    mresult = spu_splats(SDM_ACOSHD2_TAY15);

    mresult = spu_madd(xminus1, mresult, spu_splats(SDM_ACOSHD2_TAY14));

    mresult = spu_madd(xminus1, mresult, spu_splats(SDM_ACOSHD2_TAY13));

    mresult = spu_madd(xminus1, mresult, spu_splats(SDM_ACOSHD2_TAY12));

    mresult = spu_madd(xminus1, mresult, spu_splats(SDM_ACOSHD2_TAY11));

    mresult = spu_madd(xminus1, mresult, spu_splats(SDM_ACOSHD2_TAY10));

    mresult = spu_madd(xminus1, mresult, spu_splats(SDM_ACOSHD2_TAY09));

    mresult = spu_madd(xminus1, mresult, spu_splats(SDM_ACOSHD2_TAY08));

    mresult = spu_madd(xminus1, mresult, spu_splats(SDM_ACOSHD2_TAY07));

    mresult = spu_madd(xminus1, mresult, spu_splats(SDM_ACOSHD2_TAY06));

    mresult = spu_madd(xminus1, mresult, spu_splats(SDM_ACOSHD2_TAY05));

    mresult = spu_madd(xminus1, mresult, spu_splats(SDM_ACOSHD2_TAY04));

    mresult = spu_madd(xminus1, mresult, spu_splats(SDM_ACOSHD2_TAY03));

    mresult = spu_madd(xminus1, mresult, spu_splats(SDM_ACOSHD2_TAY02));

    mresult = spu_madd(xminus1, mresult, spu_splats(SDM_ACOSHD2_TAY01));

    mresult = spu_mul(mresult, sqrtresult);

    /*

     * Select series or formula

     */

    result = spu_sel(mresult, fresult, use_form);

    return result;

}

#endif /* _ACOSHD2_H_ */

#endif /* __SPU__ */