1 /*-
2 * SPDX-License-Identifier: BSD-2-Clause
3 *
4 * Copyright (c) 2011 David Schultz <das@FreeBSD.ORG>
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 */
28
29 #include <sys/cdefs.h>
30 __FBSDID("$FreeBSD$");
31
32 #include <complex.h>
33
34 #include "math.h"
35 #include "math_private.h"
36
37 static const uint32_t k = 235; /* constant for reduction */
38 static const float kln2 = 162.88958740F; /* k * ln2 */
39
40 /*
41 * See k_exp.c for details.
42 *
43 * Input: ln(FLT_MAX) <= x < ln(2 * FLT_MAX / FLT_MIN_DENORM) ~= 192.7
44 * Output: 2**127 <= y < 2**128
45 */
46 static float
__frexp_expf(float x,int * expt)47 __frexp_expf(float x, int *expt)
48 {
49 float exp_x;
50 uint32_t hx;
51
52 exp_x = expf(x - kln2);
53 GET_FLOAT_WORD(hx, exp_x);
54 *expt = (hx >> 23) - (0x7f + 127) + k;
55 SET_FLOAT_WORD(exp_x, (hx & 0x7fffff) | ((0x7f + 127) << 23));
56 return (exp_x);
57 }
58
59 float
__ldexp_expf(float x,int expt)60 __ldexp_expf(float x, int expt)
61 {
62 float exp_x, scale;
63 int ex_expt;
64
65 exp_x = __frexp_expf(x, &ex_expt);
66 expt += ex_expt;
67 SET_FLOAT_WORD(scale, (0x7f + expt) << 23);
68 return (exp_x * scale);
69 }
70
71 float complex
__ldexp_cexpf(float complex z,int expt)72 __ldexp_cexpf(float complex z, int expt)
73 {
74 float c, exp_x, s, scale1, scale2, x, y;
75 int ex_expt, half_expt;
76
77 x = crealf(z);
78 y = cimagf(z);
79 exp_x = __frexp_expf(x, &ex_expt);
80 expt += ex_expt;
81
82 half_expt = expt / 2;
83 SET_FLOAT_WORD(scale1, (0x7f + half_expt) << 23);
84 half_expt = expt - half_expt;
85 SET_FLOAT_WORD(scale2, (0x7f + half_expt) << 23);
86
87 sincosf(y, &s, &c);
88 return (CMPLXF(c * exp_x * scale1 * scale2,
89 s * exp_x * scale1 * scale2));
90 }
91