1/*-
2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
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
37static const uint32_t k = 235;			/* constant for reduction */
38static 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 */
46static float
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
59float
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
71float complex
72__ldexp_cexpf(float complex z, int expt)
73{
74	float x, y, exp_x, scale1, scale2;
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	return (CMPLXF(cosf(y) * exp_x * scale1 * scale2,
88	    sinf(y) * exp_x * scale1 * scale2));
89}
90