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37 /* PROLOG END TAG zYx */
38 #ifdef __SPU__
39 #ifndef _ATAN2F4_H_
40 #define _ATAN2F4_H_ 1
41
42 #include <spu_intrinsics.h>
43
44 #include "divf4.h"
45 #include "atanf4.h"
46
47 /*
48 * FUNCTION
49 * vector float _atan2f4(vector float y, vector float x)
50 *
51 * DESCRIPTION
52 * The atan2f4 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
_atan2f4(vector float y,vector float x)67 static __inline vector float _atan2f4(vector float y, vector float x)
68 {
69 vector float pi = spu_splats((float)SM_PI);
70 vector float zero = spu_splats(0.0f);
71 vector unsigned int quad1;
72 vector unsigned int quad4;
73 vector float result;
74
75 vector unsigned int xlt0;
76 vector unsigned int yge0;
77 vector unsigned int ylt0;
78
79 xlt0 = (vec_uint4)spu_rlmaska((vec_int4)x, 31);
80 ylt0 = (vec_uint4)spu_rlmaska((vec_int4)y, 31);
81 yge0 = spu_cmpeq(ylt0, (vec_uint4)zero);
82
83 quad1 = spu_and(ylt0, xlt0);
84 quad4 = spu_and(yge0, xlt0);
85
86 result = _atanf4(_divf4(y,x));
87 result = spu_sel(result, spu_sub(result, pi), quad1);
88 result = spu_sel(result, spu_add(result, pi), quad4);
89
90 return result;
91 }
92
93 #endif /* _ATAN2F4_H_ */
94 #endif /* __SPU__ */
95
