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
112
|
/* -------------------------------------------------------------- */
/* (C)Copyright 2001,2008, */
/* International Business Machines Corporation, */
/* Sony Computer Entertainment, Incorporated, */
/* Toshiba 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. */
/* */
/* 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 _EXPF4_H_
#define _EXPF4_H_ 1
#include "floorf4.h"
#include "ldexpf4.h"
/*
* FUNCTION
* vector float _expf4(vector float x)
*
* DESCRIPTION
* The _expf4 function computes e raised to the input x for
* each of the element of the float vector.
*
*/
static __inline vector float _expf4(vector float x)
{
// log2(e)
vec_float4 log2e = spu_splats(1.4426950408889634074f);
// Extra precision for the ln2 multiply
vec_float4 ln2_hi = spu_splats(0.693359375f);
vec_float4 ln2_lo = spu_splats(-2.12194440E-4f);
// Coefficents for the Taylor series
vec_float4 f02 = spu_splats(5.0000000000000000E-1f); // 1/2!
vec_float4 f03 = spu_splats(1.6666666666666667E-1f); // 1/3!
vec_float4 f04 = spu_splats(4.1666666666666667E-2f); // 1/4!
vec_float4 f05 = spu_splats(8.3333333333333333E-3f); // 1/5!
vec_float4 f06 = spu_splats(1.3888888888888889E-3f); // 1/6!
vec_float4 f07 = spu_splats(1.9841269841269841E-4f); // 1/7!
// Range reduce input, so that:
// e^x = e^z * 2^n
// e^x = e^z * e^(n * ln(2))
// e^x = e^(z + (n * ln(2)))
vec_int4 n; // exponent of reduction
vec_float4 q; // range reduced result
vec_float4 z;
vec_float4 r;
z = spu_madd(x,log2e,spu_splats(0.5f));
z = _floorf4(z);
r = spu_nmsub(z,ln2_hi,x);
r = spu_nmsub(z,ln2_lo,r);
n = spu_convts(z,0);
z = spu_mul(r,r);
// Use Horner's method on the Taylor series
q = spu_madd(r,f07,f06);
q = spu_madd(q,r,f05);
q = spu_madd(q,r,f04);
q = spu_madd(q,r,f03);
q = spu_madd(q,r,f02);
q = spu_madd(q,z,r);
q = spu_add(q,spu_splats(1.0f));
// Adjust the result by the range reduction
r = _ldexpf4( q, n );
return(r);
}
#endif /* _EXPF4_H_ */
#endif /* __SPU__ */
|
