1 /*-
2 * Copyright (c) 2011 David Schultz <das@FreeBSD.ORG>
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 * SUCH DAMAGE.
25 */
26
27 #include <sys/cdefs.h>
28 __FBSDID("$FreeBSD$");
29
30 #include <complex.h>
31
32 #include "math.h"
33 #include "math_private.h"
34
35 static const uint32_t k = 235; /* constant for reduction */
36 static const float kln2 = 162.88958740F; /* k * ln2 */
37
38 /*
39 * See k_exp.c for details.
40 *
41 * Input: ln(FLT_MAX) <= x < ln(2 * FLT_MAX / FLT_MIN_DENORM) ~= 192.7
42 * Output: 2**127 <= y < 2**128
43 */
44 static float
__frexp_expf(float x,int * expt)45 __frexp_expf(float x, int *expt)
46 {
47 float exp_x;
48 uint32_t hx;
49
50 exp_x = expf(x - kln2);
51 GET_FLOAT_WORD(hx, exp_x);
52 *expt = (hx >> 23) - (0x7f + 127) + k;
53 SET_FLOAT_WORD(exp_x, (hx & 0x7fffff) | ((0x7f + 127) << 23));
54 return (exp_x);
55 }
56
57 float
__ldexp_expf(float x,int expt)58 __ldexp_expf(float x, int expt)
59 {
60 float exp_x, scale;
61 int ex_expt;
62
63 exp_x = __frexp_expf(x, &ex_expt);
64 expt += ex_expt;
65 SET_FLOAT_WORD(scale, (0x7f + expt) << 23);
66 return (exp_x * scale);
67 }
68
69 float complex
__ldexp_cexpf(float complex z,int expt)70 __ldexp_cexpf(float complex z, int expt)
71 {
72 float x, y, exp_x, scale1, scale2;
73 int ex_expt, half_expt;
74
75 x = crealf(z);
76 y = cimagf(z);
77 exp_x = __frexp_expf(x, &ex_expt);
78 expt += ex_expt;
79
80 half_expt = expt / 2;
81 SET_FLOAT_WORD(scale1, (0x7f + half_expt) << 23);
82 half_expt = expt - half_expt;
83 SET_FLOAT_WORD(scale2, (0x7f + half_expt) << 23);
84
85 return (cpackf(cosf(y) * exp_x * scale1 * scale2,
86 sinf(y) * exp_x * scale1 * scale2));
87 }
88