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/* PROLOG END TAG zYx                                              */

#ifdef __SPU__

#ifndef _ASINHD2_H_

#define _ASINHD2_H_     1

#include <spu_intrinsics.h>

#include "logd2.h"

#include "sqrtd2.h"

/*

 * FUNCTION

 *  vector double _asinhd2(vector double x)

 *

 * DESCRIPTION

 *  The asinhd2 function returns a vector containing the hyperbolic

 *  arcsines of the corresponding elements of the input vector.

 *

 *  We are using the formula:

 *    asinh = ln(|x| + sqrt(x^2 + 1))

 *  and the anti-symmetry of asinh.

 *

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

 *

 *                infinity

 *                 ------

 *                  -   '  P  (0)

 *                   -      k-1    k

 *    asinh x =       -    -----  x

 *                   -       k

 *                  -   ,

 *                 ------

 *                 k = 1

 *

 *  Special Cases:

 *    asinh(+0)        returns +0

 *    asinh(-0)        returns -0

 *    asinh(+infinity) returns +infinity

 *    asinh(-infinity) returns -infinity

 *    asinh(NaN)       returns NaN

 *

 */

/*

 * Maclaurin Series Coefficients

 * for x near 0.

 */

#define SDM_ASINHD2_MAC01     1.000000000000000000000000000000000000000000E0

#define SDM_ASINHD2_MAC03    -1.666666666666666666666666666666666666666667E-1

#define SDM_ASINHD2_MAC05     7.500000000000000000000000000000000000000000E-2

#define SDM_ASINHD2_MAC07    -4.464285714285714285714285714285714285714286E-2

#define SDM_ASINHD2_MAC09     3.038194444444444444444444444444444444444444E-2

#define SDM_ASINHD2_MAC11    -2.237215909090909090909090909090909090909091E-2

#define SDM_ASINHD2_MAC13     1.735276442307692307692307692307692307692308E-2

#define SDM_ASINHD2_MAC15    -1.396484375000000000000000000000000000000000E-2

#define SDM_ASINHD2_MAC17     1.155180089613970588235294117647058823529412E-2

static __inline vector double _asinhd2(vector double x)

{

    vec_double2 sign_mask = spu_splats(-0.0);

    vec_double2 oned      = spu_splats(1.0);

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

    vec_uint4   infminus1 = spu_splats(0x7FEFFFFFU);

    vec_uint4   isinfnan;

    vec_double2 xabs, xsqu;

    vec_uint4   xabshigh;

    vec_float4  switch_approx = spu_splats(0.165f);  /* Where we switch from maclaurin to formula */

    vec_uint4   use_form;

    vec_float4  xf;

    vec_double2 result, fresult, mresult;

    xabs = spu_andc(x, sign_mask);

    xsqu = spu_mul(x, x);

    xf = spu_roundtf(xabs);

    xf = spu_shuffle(xf, xf, dup_even);

    /*

     * Formula:

     *   asinh = ln(|x| + sqrt(x^2 + 1))

     */

    fresult = _sqrtd2(spu_add(xsqu, oned));

    fresult = spu_add(xabs, fresult);

    fresult = _logd2(fresult);

    /*

     * Maclaurin Series approximation

     */

    mresult = spu_splats(SDM_ASINHD2_MAC17);

    mresult = spu_madd(xsqu, mresult, spu_splats(SDM_ASINHD2_MAC15));

    mresult = spu_madd(xsqu, mresult, spu_splats(SDM_ASINHD2_MAC13));

    mresult = spu_madd(xsqu, mresult, spu_splats(SDM_ASINHD2_MAC11));

    mresult = spu_madd(xsqu, mresult, spu_splats(SDM_ASINHD2_MAC09));

    mresult = spu_madd(xsqu, mresult, spu_splats(SDM_ASINHD2_MAC07));

    mresult = spu_madd(xsqu, mresult, spu_splats(SDM_ASINHD2_MAC05));

    mresult = spu_madd(xsqu, mresult, spu_splats(SDM_ASINHD2_MAC03));

    mresult = spu_madd(xsqu, mresult, spu_splats(SDM_ASINHD2_MAC01));

    mresult = spu_mul(xabs, mresult);

    /*

     * Choose between series and formula

     */

    use_form = spu_cmpgt(xf, switch_approx);

    result = spu_sel(mresult, fresult, (vec_ullong2)use_form);

    /* Special Cases */

    /* Infinity and NaN */

    xabshigh = (vec_uint4)spu_shuffle(xabs, xabs, dup_even);

    isinfnan = spu_cmpgt(xabshigh, infminus1);

    result = spu_sel(result, x, (vec_ullong2)isinfnan);

    /* Restore sign - asinh is an anti-symmetric */

    result = spu_sel(result, x, (vec_ullong2)sign_mask);

    return result;

}

#endif /* _ASINHD2_H_ */

#endif /* __SPU__ */