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40 /* PROLOG END TAG zYx */
41 #ifdef __SPU__
42 #ifndef _TAND2_H_
43 #define _TAND2_H_ 1
44
45 #include <spu_intrinsics.h>
46
47 #include "cos_sin.h"
48 #include "divd2.h"
49
50 /*
51 * FUNCTION
52 * vector double _tand2(vector double angle)
53 *
54 * DESCRIPTION
55 * The _tand2 function computes the tangent of a vector of "angle"s
56 * (expressed in radians) to an accuracy of double precision floating
57 * point.
58 *
59 */
_tand2(vector double angle)60 static __inline vector double _tand2(vector double angle)
61 {
62 vec_int4 octant;
63 vec_ullong2 select;
64 vec_double2 cos, sin;
65 vec_double2 num, den;
66 vec_double2 toggle_sign, answer;
67
68 /* Range reduce the input angle x into the range -PI/4 to PI/4
69 * by performing simple modulus.
70 */
71 MOD_PI_OVER_FOUR(angle, octant);
72
73 /* Compute the cosine and sine of the range reduced input.
74 */
75 COMPUTE_COS_SIN(angle, cos, sin);
76
77 /* For each SIMD element, select the numerator, denominator, and sign
78 * correction depending upon the octant of the original angle.
79 *
80 * octants angles numerator denominator sign toggle
81 * ------- ------------ --------- ----------- -----------
82 * 0 0 to 45 sin cos no
83 * 1,2 45 to 135 cos sin no,yes
84 * 3,4 135 to 225 sin cos yes,no
85 * 5,6 225 to 315 cos sin no,yes
86 * 7 315 to 360 sin cos yes
87 */
88 octant = spu_shuffle(octant, octant, ((vec_uchar16) {
89 0,1, 2, 3, 0,1, 2, 3,
90 8,9,10,11, 8,9,10,11 }));
91
92 toggle_sign = spu_and((vec_double2)spu_sl(octant, 30),
93 (vec_double2) spu_splats(0x8000000000000000ULL));
94
95 select = (vec_ullong2)spu_cmpeq(spu_and(octant, 2), 0);
96 num = spu_sel(cos, sin, select);
97 den = spu_sel(sin, cos, select);
98
99 answer = spu_xor(_divd2(num, den), toggle_sign);
100
101 return (answer);
102 }
103
104 #endif /* _TAND2_H_ */
105 #endif /* __SPU__ */
106
