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39 /* -------------------------------------------------------------- */
40 /* PROLOG END TAG zYx */
41 #ifdef __SPU__
42 #ifndef _TANF4_H_
43 #define _TANF4_H_ 1
44
45 #include <spu_intrinsics.h>
46
47 #include "cos_sin.h"
48 #include "divf4.h"
49
50 /*
51 * FUNCTION
52 * vector float _tanf4(vector float angle)
53 *
54 * DESCRIPTION
55 * The _tanf4 function computes the tangent of a vector of "angle"s
56 * (expressed in radians) to an accuracy of single precision floating
57 * point.
58 *
59 */
_tanf4(vector float angle)60 static __inline vector float _tanf4(vector float angle)
61 {
62 vec_int4 octant;
63 vec_uint4 select;
64 vec_float4 cos, sin;
65 vec_float4 num, den;
66 vec_float4 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_F(angle, octant);
72
73 /* Compute the cosine and sine of the range reduced input.
74 */
75 COMPUTE_COS_SIN_F(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 toggle_sign = (vec_float4)spu_sl(spu_and(octant, 2), 30);
89
90 select = spu_cmpeq(spu_and(octant, 2), 0);
91 num = spu_sel(cos, sin, select);
92 den = spu_sel(sin, cos, select);
93
94 answer = spu_xor(_divf4(num, den), toggle_sign);
95
96 return (answer);
97 }
98
99 #endif /* _TANF4_H_ */
100 #endif /* __SPU__ */
101
