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/* PROLOG END TAG zYx                                              */

#ifdef __SPU__

#ifndef _ATAN2F4_H_

#define _ATAN2F4_H_     1

#include <spu_intrinsics.h>

#include "divf4.h"

#include "atanf4.h"

/*

 * FUNCTION

 *  vector float _atan2f4(vector float y, vector float x)

 *

 * DESCRIPTION

 *  The atan2f4 function returns a vector containing the angles

 *  whose tangets are y/x for the corresponding elements of the

 *  input vectors.

 *

 *  The reason this function exists is to use the signs of the

 *  arguments to determine the quadrant of the result. Consider

 *  sin(x)/cos(x) on the domain (-pi, pi]. Four quadrants are

 *  defined by the signs of sin and cos on this domain.

 *

 *  Special Cases:

 *      - If the corresponding elements of x and y are zero, the

 *    resulting element is undefined.

 *

 */

static __inline vector float _atan2f4(vector float y, vector float x)

{

    vector float pi   = spu_splats((float)SM_PI);

    vector float zero = spu_splats(0.0f);

    vector unsigned int quad1;

    vector unsigned int quad4;

    vector float result;

    vector unsigned int xlt0;

    vector unsigned int yge0;

    vector unsigned int ylt0;

    xlt0 = (vec_uint4)spu_rlmaska((vec_int4)x, 31);

    ylt0 = (vec_uint4)spu_rlmaska((vec_int4)y, 31);

    yge0 = spu_cmpeq(ylt0, (vec_uint4)zero);

    quad1 = spu_and(ylt0, xlt0);

    quad4 = spu_and(yge0, xlt0);

    result = _atanf4(_divf4(y,x));

    result = spu_sel(result, spu_sub(result, pi), quad1);

    result = spu_sel(result, spu_add(result, pi), quad4);

    return result;

}

#endif /* _ATAN2F4_H_ */

#endif /* __SPU__ */