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 <complex.h>
30
31 #include "math.h"
32 #include "math_private.h"
33
34 static const uint32_t k = 235; /* constant for reduction */
35 static const float kln2 = 162.88958740F; /* k * ln2 */
36
37 /*
38 * See k_exp.c for details.
39 *
40 * Input: ln(FLT_MAX) <= x < ln(2 * FLT_MAX / FLT_MIN_DENORM) ~= 192.7
41 * Output: 2**127 <= y < 2**128
42 */
43 static float
__frexp_expf(float x,int * expt)44 __frexp_expf(float x, int *expt)
45 {
46 float exp_x;
47 uint32_t hx;
48
49 exp_x = expf(x - kln2);
50 GET_FLOAT_WORD(hx, exp_x);
51 *expt = (hx >> 23) - (0x7f + 127) + k;
52 SET_FLOAT_WORD(exp_x, (hx & 0x7fffff) | ((0x7f + 127) << 23));
53 return (exp_x);
54 }
55
56 float
__ldexp_expf(float x,int expt)57 __ldexp_expf(float x, int expt)
58 {
59 float exp_x, scale;
60 int ex_expt;
61
62 exp_x = __frexp_expf(x, &ex_expt);
63 expt += ex_expt;
64 SET_FLOAT_WORD(scale, (0x7f + expt) << 23);
65 return (exp_x * scale);
66 }
67
68 float complex
__ldexp_cexpf(float complex z,int expt)69 __ldexp_cexpf(float complex z, int expt)
70 {
71 float c, exp_x, s, scale1, scale2, x, y;
72 int ex_expt, half_expt;
73
74 x = crealf(z);
75 y = cimagf(z);
76 exp_x = __frexp_expf(x, &ex_expt);
77 expt += ex_expt;
78
79 half_expt = expt / 2;
80 SET_FLOAT_WORD(scale1, (0x7f + half_expt) << 23);
81 half_expt = expt - half_expt;
82 SET_FLOAT_WORD(scale2, (0x7f + half_expt) << 23);
83
84 sincosf(y, &s, &c);
85 return (CMPLXF(c * exp_x * scale1 * scale2,
86 s * exp_x * scale1 * scale2));
87 }
88