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37 /* PROLOG END TAG zYx */
38 #ifdef __SPU__
39 #ifndef _NEXTAFTERF4_H_
40 #define _NEXTAFTERF4_H_ 1
41
42 #include <spu_intrinsics.h>
43
44 /*
45 * FUNCTION
46 * vector float _nextafterf4(vector float x, vector float y)
47 *
48 * DESCRIPTION
49 * The nextafterf4 function returns a vector containing the next representable
50 * floating-point number after the element of x, in the direction of the
51 * corresponding element y.
52 *
53 * Special Cases:
54 * - Infinity and NaN are not supported in single-precision on SPU. They are treated
55 * as normal numbers.
56 * - x != y, and result = 0 is considered an underflow.
57 *
58 *
59 */
60
_nextafterf4(vector float x,vector float y)61 static __inline vector float _nextafterf4(vector float x, vector float y)
62 {
63 vec_float4 n1ulp = (vec_float4)spu_splats(0x80000001);
64 vec_float4 zerof = spu_splats(0.0f);
65 vec_int4 one = spu_splats(1);
66 vec_uint4 xlt0, xgty, xeqy, xeq0;
67 vec_int4 xint;
68 vec_int4 delta, deltap1;
69 vec_float4 result;
70
71 /*
72 * The idea here is to treat x as a signed int value, which allows us to
73 * add or subtact one to/from it to get the next representable value.
74 */
75
76 xeq0 = spu_cmpeq(x, zerof);
77 xlt0 = spu_cmpgt(zerof, x);
78 xeqy = spu_cmpeq(x, y);
79 xgty = spu_cmpgt(x, y);
80
81 /* If x = -0.0, set x = 0.0 */
82 x = spu_andc(x, (vec_float4)xeq0);
83
84 xint = (vec_int4)x;
85
86 /* Determine value to add to x */
87 delta = (vec_int4)spu_xor(xgty, xlt0);
88 deltap1 = spu_add(delta,one);
89 delta = spu_sel(deltap1, delta, (vec_uint4)delta);
90
91 xint = spu_add(xint, delta);
92
93 /* Fix the case of x = 0, and answer should be -1 ulp */
94 result = spu_sel((vec_float4)xint, n1ulp, spu_and((vec_uint4)delta, xeq0));
95
96 /*
97 * Special Cases
98 */
99
100 /* x = y */
101 result = spu_sel(result, y, xeqy);
102
103 return result;
104
105 }
106
107 #endif /* _NEXTAFTERF4_H_ */
108 #endif /* __SPU__ */
109
