Retro68/gcc/newlib/libm/machine/spu/headers/atan2d2.h
2012-03-27 01:51:53 +02:00

97 lines
4.2 KiB
C

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/* PROLOG END TAG zYx */
#ifdef __SPU__
#ifndef _ATAN2D2_H_
#define _ATAN2D2_H_ 1
#include <spu_intrinsics.h>
#include "divd2.h"
#include "atand2.h"
/*
* FUNCTION
* vector double _atan2d2(vector double y, vector double x)
*
* DESCRIPTION
* The atan2d2 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 double _atan2d2(vector double y, 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 });
vector double pi = spu_splats(SM_PI);
vector unsigned long long ones = spu_splats(0xFFFFFFFFFFFFFFFFull);
vector unsigned long long quad1;
vector unsigned long long quad4;
vector double result;
vector unsigned long long xlt0;
vector unsigned long long yge0;
vector unsigned long long ylt0;
xlt0 = (vec_ullong2)spu_rlmaska((vec_int4)spu_shuffle(x,x,dup_even), 31);
ylt0 = (vec_ullong2)spu_rlmaska((vec_int4)spu_shuffle(y,y,dup_even), 31);
yge0 = spu_xor(ylt0, ones);
quad1 = spu_and(ylt0, xlt0);
quad4 = spu_and(yge0, xlt0);
result = _atand2(_divd2(y,x));
result = spu_sel(result, spu_sub(result, pi), quad1);
result = spu_sel(result, spu_add(result, pi), quad4);
return result;
}
#endif /* _ATAN2D2_H_ */
#endif /* __SPU__ */