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39 /* -------------------------------------------------------------- */
40 /* PROLOG END TAG zYx */
41 #ifdef __SPU__
42 #ifndef _POWD2_H_
43 #define _POWD2_H_ 1
44
45 #include "exp2d2.h"
46 #include "log2d2.h"
47
48 /*
49 * FUNCTION
50 * vector double _powd2(vector double x, vector double y)
51 *
52 * DESCRIPTION
53 * The _powd2 function computes x raised to the power y for the set of
54 * vectors. The powd2 function is computed as by decomposing
55 * the problem into:
56 *
57 * x^y = 2^(y*log2(x))
58 *
59 *
60 */
_powd2(vector double x,vector double y)61 static __inline vector double _powd2(vector double x, vector double y)
62 {
63 vec_uchar16 splat_hi = (vec_uchar16) { 0,1,2,3,0,1,2,3, 8,9,10,11, 8,9,10,11 };
64 vec_int4 exp, shift;
65 vec_uint4 sign = (vec_uint4) { 0x80000000, 0, 0x80000000, 0 };
66 vec_uint4 or_mask, and_mask, evenmask, intmask;
67 vec_double2 in_hi;
68 vector double signmask = spu_splats(-0.0);
69 vector signed int error = spu_splats(-1);
70 vector double zero = spu_splats(0.0);
71 vector unsigned int y_is_int, y_is_odd, y_is_even;
72 vector unsigned int x_is_neg;
73 vector double xabs, xsign;
74 vector double out;
75
76
77 xsign = spu_and(x, signmask);
78 xabs = spu_andc(x, signmask);
79 x_is_neg = (vec_uint4)spu_cmpgt(zero, x);
80
81
82 /* First we solve assuming x was non-negative */
83 out = _exp2d2(spu_mul(y, _log2d2(xabs)));
84
85 in_hi = spu_shuffle(y, y, splat_hi);
86 exp = spu_and(spu_rlmask((vec_int4)in_hi, -20), 0x7FF);
87
88 /* Determine if y is an integer */
89 shift = spu_sub(((vec_int4) { 1023, 1043, 1023, 1043 }), exp);
90 or_mask = spu_andc(spu_cmpgt(shift, 0), sign);
91 and_mask = spu_rlmask(((vec_uint4) { 0xFFFFF, -1, 0xFFFFF, -1 }), shift);
92 intmask = spu_or(spu_and(and_mask, spu_cmpgt(shift, -32)), or_mask);
93 y_is_int = (vec_uint4)spu_cmpeq(y, spu_andc(y, (vec_double2)(intmask)));
94
95 /* Determine if y is an even integer */
96 shift = spu_sub(((vec_int4) { 1024, 1044, 1024, 1044 }), exp);
97 or_mask = spu_andc(spu_cmpgt(shift, 0), sign);
98 and_mask = spu_rlmask(((vec_uint4) { 0xFFFFF, -1, 0xFFFFF, -1 }), shift);
99 evenmask = spu_or(spu_and(and_mask, spu_cmpgt(shift, -32)), or_mask);
100 y_is_even = (vec_uint4)spu_cmpeq(y, spu_andc(y, (vec_double2)(evenmask)));
101
102 y_is_odd = spu_andc(y_is_int, y_is_even);
103
104
105 /* Special Cases
106 */
107
108 /* x < 0 is only ok when y integer */
109 out = spu_sel(out, (vec_double2)error, (vec_ullong2)spu_andc(x_is_neg, y_is_int));
110
111 /* Preserve the sign of x if y is an odd integer */
112 out = spu_sel(out, spu_or(out, xsign), (vec_ullong2)y_is_odd);
113
114 /* x = anything, y = +/- 0, returns 1 */
115 out = spu_sel(out, spu_splats(1.0), spu_cmpabseq(y, zero));
116
117 return(out);
118 }
119
120 #endif /* _POWD2_H_ */
121 #endif /* __SPU__ */
122
