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37 /* PROLOG END TAG zYx                                              */
38 #ifdef __SPU__
39 #ifndef _ATAN2D2_H_
40 #define _ATAN2D2_H_	1
41 
42 #include <spu_intrinsics.h>
43 
44 #include "divd2.h"
45 #include "atand2.h"
46 
47 /*
48  * FUNCTION
49  *  vector double _atan2d2(vector double y, vector double x)
50  *
51  * DESCRIPTION
52  *  The atan2d2 function returns a vector containing the angles
53  *  whose tangets are y/x for the corresponding elements of the
54  *  input vectors.
55  *
56  *  The reason this function exists is to use the signs of the
57  *  arguments to determine the quadrant of the result. Consider
58  *  sin(x)/cos(x) on the domain (-pi, pi]. Four quadrants are
59  *  defined by the signs of sin and cos on this domain.
60  *
61  *  Special Cases:
62  *	- If the corresponding elements of x and y are zero, the
63  *    resulting element is undefined.
64  *
65  */
66 
_atan2d2(vector double y,vector double x)67 static __inline vector double _atan2d2(vector double y, vector double x)
68 {
69     vec_uchar16 dup_even  = ((vec_uchar16) { 0,1,2,3,  0,1,2,3, 8,9,10,11, 8,9,10,11 });
70     vector double pi   = spu_splats(SM_PI);
71     vector unsigned long long ones = spu_splats(0xFFFFFFFFFFFFFFFFull);
72     vector unsigned long long quad1;
73     vector unsigned long long quad4;
74     vector double result;
75 
76     vector unsigned long long xlt0;
77     vector unsigned long long yge0;
78     vector unsigned long long ylt0;
79 
80     xlt0 = (vec_ullong2)spu_rlmaska((vec_int4)spu_shuffle(x,x,dup_even), 31);
81     ylt0 = (vec_ullong2)spu_rlmaska((vec_int4)spu_shuffle(y,y,dup_even), 31);
82     yge0 = spu_xor(ylt0, ones);
83 
84     quad1 = spu_and(ylt0, xlt0);
85     quad4 = spu_and(yge0, xlt0);
86 
87     result = _atand2(_divd2(y,x));
88 
89     result = spu_sel(result, spu_sub(result, pi), quad1);
90     result = spu_sel(result, spu_add(result, pi), quad4);
91 
92     return result;
93 }
94 
95 #endif /* _ATAN2D2_H_ */
96 #endif /* __SPU__ */
97