1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
|
/* -------------------------------------------------------------- */
/* (C)Copyright 2006,2007, */
/* International Business Machines Corporation */
/* All Rights Reserved. */
/* */
/* Redistribution and use in source and binary forms, with or */
/* without modification, are permitted provided that the */
/* following conditions are met: */
/* */
/* - Redistributions of source code must retain the above copyright*/
/* notice, this list of conditions and the following disclaimer. */
/* */
/* - Redistributions in binary form must reproduce the above */
/* copyright notice, this list of conditions and the following */
/* disclaimer in the documentation and/or other materials */
/* provided with the distribution. */
/* */
/* - Neither the name of IBM Corporation nor the names of its */
/* contributors may be used to endorse or promote products */
/* derived from this software without specific prior written */
/* permission. */
/* Redistributions of source code must retain the above copyright */
/* notice, this list of conditions and the following disclaimer. */
/* */
/* Redistributions in binary form must reproduce the above */
/* copyright notice, this list of conditions and the following */
/* disclaimer in the documentation and/or other materials */
/* provided with the distribution. */
/* */
/* Neither the name of IBM Corporation nor the names of its */
/* contributors may be used to endorse or promote products */
/* derived from this software without specific prior written */
/* permission. */
/* */
/* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND */
/* CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, */
/* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF */
/* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE */
/* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR */
/* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, */
/* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT */
/* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; */
/* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) */
/* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN */
/* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR */
/* OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, */
/* EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */
/* -------------------------------------------------------------- */
/* PROLOG END TAG zYx */
#ifdef __SPU__
#ifndef _LOGBF4_H_
#define _LOGBF4_H_ 1
#include <spu_intrinsics.h>
#include <vec_types.h>
/*
* FUNCTION
* vector float _scalbnf4(vector float x, vector signed int exp)
*
* DESCRIPTION
* The _scalbnf4 function returns a vector containing each element of x
* multiplied by 2^n computed efficiently. This function is computed
* without the assistance of any floating point operations and as such
* does not set any floating point exceptions.
*
* Special Cases:
* - if the exponent is 0, then x is either 0 or a subnormal, and the
* result will be returned as 0.
* - if the result if underflows, it will be returned as 0.
* - if the result overflows, it will be returned as FLT_MAX.
*
*/
static __inline vector float _logbf4(vector float x)
{
vec_uint4 lzero = (vector unsigned int) {0, 0, 0, 0};
vec_uint4 exp_mask = (vector unsigned int) {0xFF, 0xFF, 0xFF, 0xFF};
vec_int4 exp_shift = (vector signed int) { -23, -23, -23, -23};
vec_int4 exp_bias = (vector signed int) {-127, -127, -127, -127};
vec_uint4 sign_mask = (vector unsigned int) {0x80000000, 0x80000000,
0x80000000, 0x80000000};
vec_uint4 linf = (vector unsigned int) {0x7F800000, 0x7F800000,
0x7F800000, 0x7F800000};
vec_uint4 lminf = (vector unsigned int) {0xFF800000, 0xFF800000,
0xFF800000, 0xFF800000};
vec_uint4 exp;
vec_uint4 xabs;
vec_float4 exp_unbias;
xabs = spu_andc((vec_uint4)x, sign_mask);
exp = spu_and(spu_rlmask((vec_uint4)x, exp_shift), exp_mask);
exp_unbias = spu_convtf(spu_add((vec_int4)exp, exp_bias), 0);
/* Zero */
exp_unbias = spu_sel(exp_unbias, (vec_float4)lminf, (vec_uint4)spu_cmpeq(xabs, lzero));
/* NaN */
exp_unbias = spu_sel(exp_unbias, x, (vec_uint4)spu_cmpgt(xabs, linf));
/* Infinite */
exp_unbias = spu_sel(exp_unbias, (vec_float4)linf, (vec_uint4)spu_cmpeq(xabs, linf));
return (exp_unbias);
}
#endif /* _LOGBF4_H_ */
#endif /* __SPU__ */
|
